Polymers

Editorial

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11 pages, 1343 KiB

Open AccessEditorial

A Brief Overview of Polymers Science and Technology, in Spain

by Carmen Mijangos

Polymers 2022, 14(4), 652; https://doi.org/10.3390/polym14040652 - 9 Feb 2022

Cited by 1 | Viewed by 3636

Abstract

This Special Issue State-of-the-Art on Polymer Science and Technology in Spain is comprised of a collection of 42 publications/contributions related to very different topics undertaken by the numerous research groups working in Spain in Polymer Science and Technology. This monograph collects the contributions [...] Read more.

This Special Issue State-of-the-Art on Polymer Science and Technology in Spain is comprised of a collection of 42 publications/contributions related to very different topics undertaken by the numerous research groups working in Spain in Polymer Science and Technology. This monograph collects the contributions of more than 200 different authors from 24 different national Institutions (>30 different centers/departments) from Universities and CSIC centers distributed throughout the whole of Spain. Two-thirds of the contributions to this Special Issue arise from Institutional collaborations, half of which are international collaborations with European research groups and the other half with other international research groups outside Europe including China, Australia or United States of America among others. This brief overview communication provides a general overview of the research lines in Polymer Science and Technology covered in Spain and show most of the representative polymer groups and their distribution throughout Spain. Most of Spanish polymer groups belong to the Grupo Especializado de Polímeros (GEP) being part of the European Polymer Federation (EPF). It also shows how Spanish science about polymers is positioned at European level. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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Research

Jump to: Editorial, Review

19 pages, 4986 KiB

Open AccessArticle

Biomimetic Gradient Scaffolds Containing Hyaluronic Acid and Sr/Zn Folates for Osteochondral Tissue Engineering

by Gerardo Asensio, Lorena Benito-Garzón, Rosa Ana Ramírez-Jiménez, Yasmina Guadilla, Julian Gonzalez-Rubio, Cristina Abradelo, Juan Parra, María Rocío Martín-López, María Rosa Aguilar, Blanca Vázquez-Lasa and Luis Rojo

Polymers 2022, 14(1), 12; https://doi.org/10.3390/polym14010012 - 21 Dec 2021

Cited by 23 | Viewed by 5426

Abstract

Regenerative therapies based on tissue engineering are becoming the most promising alternative for the treatment of osteoarthritis and rheumatoid arthritis. However, regeneration of full-thickness articular osteochondral defects that reproduces the complexity of native cartilage and osteochondral interface still remains challenging. Hence, in this [...] Read more.

Regenerative therapies based on tissue engineering are becoming the most promising alternative for the treatment of osteoarthritis and rheumatoid arthritis. However, regeneration of full-thickness articular osteochondral defects that reproduces the complexity of native cartilage and osteochondral interface still remains challenging. Hence, in this work, we present the fabrication, physic-chemical characterization, and in vitro and in vivo evaluation of biomimetic hierarchical scaffolds that mimic both the spatial organization and composition of cartilage and the osteochondral interface. The scaffold is composed of a composite porous support obtained by cryopolymerization of poly(ethylene glycol) dimethacrylate (PEGDMA) in the presence of biodegradable poly(D,L-lactide-co-glycolide) (PLGA), bioactive tricalcium phosphate β-TCP and the bone promoting strontium folate (SrFO), with a gradient biomimetic photo-polymerized methacrylated hyaluronic acid (HAMA) based hydrogel containing the bioactive zinc folic acid derivative (ZnFO). Microscopical analysis of hierarchical scaffolds showed an open interconnected porous open microstructure and the in vitro behaviour results indicated high swelling capacity with a sustained degradation rate. In vitro release studies during 3 weeks indicated the sustained leaching of bioactive compounds, i.e., Sr²⁺, Zn²⁺ and folic acid, within a biologically active range without negative effects on human osteoblast cells (hOBs) and human articular cartilage cells (hACs) cultures. In vitro co-cultures of hOBs and hACs revealed guided cell colonization and proliferation according to the matrix microstructure and composition. In vivo rabbit-condyle experiments in a critical-sized defect model showed the ability of the biomimetic scaffold to promote the regeneration of cartilage-like tissue over the scaffold and neoformation of osteochondral tissue. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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15 pages, 32209 KiB

Open AccessArticle

Nano-Second Laser Interference Photoembossed Microstructures for Enhanced Cell Alignment

by Alba Martínez, Sandra González-Lana, Laura Asín, Jesús M. de la Fuente, Cees W. M. Bastiaansen, Dirk J. Broer and Carlos Sánchez-Somolinos

Polymers 2021, 13(17), 2958; https://doi.org/10.3390/polym13172958 - 31 Aug 2021

Cited by 7 | Viewed by 2494

Abstract

Photoembossing is a powerful photolithographic technique to prepare surface relief structures relying on polymerization-induced diffusion in a solventless development step. Conveniently, surface patterns are formed by two or more interfering laser beams without the need for a lithographic mask. The use of nanosecond [...] Read more.

Photoembossing is a powerful photolithographic technique to prepare surface relief structures relying on polymerization-induced diffusion in a solventless development step. Conveniently, surface patterns are formed by two or more interfering laser beams without the need for a lithographic mask. The use of nanosecond pulsed light-based interference lithography strengthens the pattern resolution through the absence of vibrational line pattern distortions. Typically, a conventional photoembossing protocol consists of an exposure step at room temperature that is followed by a thermal development step at high temperature. In this work, we explore the possibility to perform the pulsed holographic exposure directly at the development temperature. The surface relief structures generated using this modified photoembossing protocol are compared with those generated using the conventional one. Importantly, the enhancement of surface relief height has been observed by exposing the samples directly at the development temperature, reaching approximately double relief heights when compared to samples obtained using the conventional protocol. Advantageously, the light dose needed to reach the optimum height and the amount of photoinitiator can be substantially reduced in this modified protocol, demonstrating it to be a more efficient process for surface relief generation in photopolymers. Kidney epithelial cell alignment studies on substrates with relief-height optimized structures generated using the two described protocols demonstrate improved cell alignment in samples generated with exposure directly at the development temperature, highlighting the relevance of the height enhancement reached by this method. Although cell alignment is well-known to be enhanced by increasing the relief height of the polymeric grating, our work demonstrates nano-second laser interference photoembossing as a powerful tool to easily prepare polymeric gratings with tunable topography in the range of interest for fundamental cell alignment studies. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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14 pages, 3998 KiB

Open AccessArticle

Poly(butylene succinate-co-ε-caprolactone) Copolyesters: Enzymatic Synthesis in Bulk and Thermal Properties

by María Núñez, Sebastián Muñoz-Guerra and Antxon Martínez de Ilarduya

Polymers 2021, 13(16), 2679; https://doi.org/10.3390/polym13162679 - 11 Aug 2021

Cited by 8 | Viewed by 2962

Abstract

This work explores for the first time the enzymatic synthesis of poly(butylene-co-ε-caprolactone) (PBSCL) copolyesters in bulk using commercially available monomers (dimethyl succinate (DMS), 1,4-butanediol (BD), and ε-caprolactone (CL)). A preliminary kinetic study was carried out which demonstrated the higher reactivity of [...] Read more.

This work explores for the first time the enzymatic synthesis of poly(butylene-co-ε-caprolactone) (PBSCL) copolyesters in bulk using commercially available monomers (dimethyl succinate (DMS), 1,4-butanediol (BD), and ε-caprolactone (CL)). A preliminary kinetic study was carried out which demonstrated the higher reactivity of DMS over CL in the condensation/ring opening polymerization reaction, catalyzed by Candida antarctica lipase B. PBSCL copolyesters were obtained with high molecular weights and a random microstructure, as determined by ¹³C NMR. They were thermally stable up to 300 °C, with thermal stability increasing with the content of CL in the copolyester. All of them were semicrystalline, with melting temperatures and enthalpies decreasing up to the eutectic point observed at intermediate compositions, and glass transition temperatures decreasing with the content of CL in the copolyester. The use of CALB provided copolyesters free from toxic metallic catalyst, which is very useful if the polymer is intended to be used for biomedical applications. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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15 pages, 5617 KiB

Open AccessArticle

Enhancing an Aerospace Grade Benzoxazine Resin by Means of Graphene Nanoplatelets Addition

by Vanessa García-Martínez, Maria R. Gude, Silvia Calvo and Alejandro Ureña

Polymers 2021, 13(15), 2544; https://doi.org/10.3390/polym13152544 - 31 Jul 2021

Cited by 18 | Viewed by 3220

Abstract

Two different contents of graphene nanoplatelets (GNPs: 0.5 and 2 wt.%) were introduced into benzoxazine resin. The main objective of this work is to obtain a polymeric nanocomposite with multifunctional properties as high electrical and thermal conductivity, maintaining or improving its mechanical performance. [...] Read more.

Two different contents of graphene nanoplatelets (GNPs: 0.5 and 2 wt.%) were introduced into benzoxazine resin. The main objective of this work is to obtain a polymeric nanocomposite with multifunctional properties as high electrical and thermal conductivity, maintaining or improving its mechanical performance. The quality of the dispersion, performed with a three-roll calender, was studied. Afterward, a complete characterization of the nanocomposites was carried out in order to analyse the benefits of neat resin. The main features of the nanocomposites such as the mechanical and thermo-mechanical properties, their electrical and thermal conductivity and the behaviour under hygrothermal aging, were evaluated. Results allowed us to confirm that benzoxazine/GNPs composites exhibited an increase in the tensile strength of polymeric matrix which was accompanied by a rise in elongation at break. The electrical and thermal conductivities exhibited a remarkable increment with the addition of 2 wt.% of GNPs (six orders of magnitude and 49% respectively). Finally, the barrier properties of benzoxazine resin were also favoured with the presence of GNPs because the maximum water absorbed in a hot-water environment decreased from 2.52% to 2.14% when 0.5 wt.% of graphene nanoplatelets was added. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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21 pages, 5982 KiB

Open AccessArticle

Extruded-Calendered Sheets of Fully Recycled PP/Opaque PET Blends: Mechanical and Fracture Behaviour

by David Loaeza, Jonathan Cailloux, Orlando Santana Pérez, Miguel Sánchez-Soto and Maria Lluïsa Maspoch

Polymers 2021, 13(14), 2360; https://doi.org/10.3390/polym13142360 - 19 Jul 2021

Cited by 4 | Viewed by 3658

Abstract

This work presents the experimental results of the mechanical and fracture behaviour of three polymeric blends prepared from two recycled plastics, namely polypropylene and opaque poly (ethylene terephthalate), where the second one acted as a reinforcement phase. The raw materials were two commercial [...] Read more.

This work presents the experimental results of the mechanical and fracture behaviour of three polymeric blends prepared from two recycled plastics, namely polypropylene and opaque poly (ethylene terephthalate), where the second one acted as a reinforcement phase. The raw materials were two commercial degrees of recycled post-consumer waste, i.e., rPP and rPET-O. Sheets were manufactured by a semi-industrial extrusion-calendering process. The mechanical and fracture behaviours of manufactured sheets were analyzed via tensile tests and the essential work of fracture approach. SEM micrographics of cryofractured sheets revelated the development of in situ rPP/rPET-O microfibrillar composites when 30 wt.% of rPET-O was added. It was observed that the yield stress was not affected with the addition of rPET-O. However, the microfibrillar structure increased the Young’s modulus by more than a third compared with rPP, fulfilling the longitudinal value predicted by the additive rule of mixtures. Regarding the EWF analysis, the resistance to crack initiation was highly influenced by the resistance to its propagation owing to morphology-related instabilities during tearing. To analyze the initiation stage, a partition energy method was successfully applied by splitting the total work of fracture into two specific energetic contributions, namely initiation and propagation. The results revelated that the specific essential initiation-related work of fracture was mainly affected by rPET-O phase. Remarkably, its value was significantly improved by a factor of three with the microfibrillar structure of rPET-O phase. The results allowed the exploration of the potential ability of manufacturing in situ MFCs without a “precursor” morphology, providing an economical way to promote the recycling rate of PET-O, as this material is being discarded from current recycling processes. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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15 pages, 3000 KiB

Open AccessArticle

Photodynamic Inactivation of Pseudomonas aeruginosa by PHEMA Films Loaded with Rose Bengal: Potentiation Effect of Potassium Iodide

by Ana M. López-Fernández, Ignacio Muñoz Resta, Rosa de Llanos and Francisco Galindo

Polymers 2021, 13(14), 2227; https://doi.org/10.3390/polym13142227 - 6 Jul 2021

Cited by 13 | Viewed by 3432

Abstract

Four formulations have been used to produce different poly(2-hydroxyethyl methacrylate) (PHEMA) thin films, containing singlet oxygen photosensitizer Rose Bengal (RB). The polymers have been characterized employing Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption Spectroscopy. [...] Read more.

Four formulations have been used to produce different poly(2-hydroxyethyl methacrylate) (PHEMA) thin films, containing singlet oxygen photosensitizer Rose Bengal (RB). The polymers have been characterized employing Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption Spectroscopy. When irradiated with white light (400–700 nm) films generated singlet oxygen (¹O₂), as demonstrated by the reactivity with ¹O₂ trap 9,10-dimethylanthracene (DMA). Material with the highest RB loading (polymer A4, 835 nmol RB/g polymer) was able to perform up to ten cycles of DMA oxygenation reactions at high conversion rates (ca. 90%). Polymer A4 was also able to produce the complete eradication of a Pseudomonas aeruginosa planktonic suspension of 8 log₁₀ CFU/mL, when irradiated with white light (total dose 72 J/cm²). The antimicrobial photodynamic effect was remarkably enhanced by adding potassium iodide (100 mM). In such conditions the complete bacterial reduction occurred with a total light dose of 24 J/cm². Triiodide anion (I₃⁻) generation was confirmed by UV-vis absorption spectroscopy. This species was detected inside the PHEMA films after irradiation and at concentrations ca. 1 M. The generation of this species and its retention in the matrix imparts long-lasting bactericidal effects to the RB@PHEMA polymeric hydrogels. The polymers here described could find potential applications in the medical context, when optimized for their use in everyday objects, helping to prevent bacterial contagion by contact with surfaces. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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13 pages, 2966 KiB

Open AccessEditor’s ChoiceArticle

Easy-to-Make Polymer Hydrogels by UV-Curing for the Cleaning of Acrylic Emulsion Paint Films

by Irene Cárdaba, Luca Porcarelli, Antonela Gallastegui, David Mecerreyes and Miren Itxaso Maguregui

Polymers 2021, 13(13), 2108; https://doi.org/10.3390/polym13132108 - 26 Jun 2021

Cited by 2 | Viewed by 3690

Abstract

The cleaning of acrylic emulsion paint surfaces poses a great challenge in the conservation field, due to their high water sensitivity. In this article, we present easy-to-make polymer hydrogels, made by UV-photopolymerization, that show excellent cleaning properties. The formulation of hydrogels obtained by [...] Read more.

The cleaning of acrylic emulsion paint surfaces poses a great challenge in the conservation field, due to their high water sensitivity. In this article, we present easy-to-make polymer hydrogels, made by UV-photopolymerization, that show excellent cleaning properties. The formulation of hydrogels obtained by UV-curing and their performance as dry cleaners for acrylic paints was investigated. First, different hydrogel formulations based on functional acrylic monomers were used to formulate a series of UV cross-linked hydrogels by fast UV photopolymerization. Their effectiveness on surface dirt removal was investigated by SEM microscopy and colorimetry. The hydrogels showed excellent cleaning properties and controlled water release, and they still performed satisfactorily after several cleaning uses. The obtained UV-hydrogels were compared to the well-known agar gels, showing benefits in terms of reducing excess water. This article shows that easy-to-make UV-cured hydrogels are an efficient tool for the cleaning of surface dirt from water-sensitive paintings, overcoming the limits of traditional cleaning methods. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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13 pages, 1900 KiB

Open AccessArticle

Ring-Opening Copolymerization of Cyclohexene Oxide and Cyclic Anhydrides Catalyzed by Bimetallic Scorpionate Zinc Catalysts

by Felipe de la Cruz-Martínez, Marc Martínez de Sarasa Buchaca, Almudena del Campo-Balguerías, Juan Fernández-Baeza, Luis F. Sánchez-Barba, Andrés Garcés, Carlos Alonso-Moreno, José A. Castro-Osma and Agustín Lara-Sánchez

Polymers 2021, 13(10), 1651; https://doi.org/10.3390/polym13101651 - 19 May 2021

Cited by 11 | Viewed by 5428

Abstract

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO₂ as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts [...] Read more.

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO₂ as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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20 pages, 4141 KiB

Open AccessArticle

Actuator Behaviour of Tailored Poly(thiourethane) Shape Memory Thermosets

by Francesco Gamardella, Angels Serra, Xavier Ramis and Silvia De la Flor

Polymers 2021, 13(10), 1571; https://doi.org/10.3390/polym13101571 - 13 May 2021

Cited by 4 | Viewed by 2598

Abstract

In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation [...] Read more.

In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation of the formulation. Rheological studies of the curing process confirm the latent character of the formulations. The glass transition temperatures and the mechanical properties can be modified by varying the proportion of diisocyanates (hexamethylene diisocyanate, HDI, and isophorone diisocyanate, IPDI) with stoichiometric amounts of trimethylolpropane tris(3-mercaptopropionate). The shape-memory behavior was deeply investigated under three different conditions: unconstrained, partially constrained, and fully constrained. Tests were performed in single cantilever bending mode to simulate conditions closer to real complex mechanics of thermomechanical actuators under flexural performances. The complex recovery process in single cantilever bending mode was compared with that obtained using tensile mode. The results evidenced that the amount of recovery force in fully constrained conditions, or energy released during the recovery process in partially constrained, can be modulated by simply changing the proportion of both diisocyanates. A simple model based on Timoshenko beam theory was used for the prediction of the amount of work performed. The reported results are an important guideline to design shape-memory materials based on poly(thiourethane) networks, establishing criteria for the choice of the material depending on the expected application. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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13 pages, 2963 KiB

Open AccessArticle

Doxycycline-Doped Polymeric Membranes Induced Growth, Differentiation and Expression of Antigenic Phenotype Markers of Osteoblasts

by Manuel Toledano-Osorio, Francisco J. Manzano-Moreno, Manuel Toledano, Antonio L. Medina-Castillo, Victor J. Costela-Ruiz, Concepción Ruiz and Raquel Osorio

Polymers 2021, 13(7), 1063; https://doi.org/10.3390/polym13071063 - 28 Mar 2021

Cited by 16 | Viewed by 3314

Abstract

Polymeric membranes are employed in guided bone regeneration (GBR) as physical barriers to facilitate bone in-growth. A bioactive and biomimetic membrane with the ability to participate in the healing and regeneration of the bone is necessary. The aim of the present study was [...] Read more.

Polymeric membranes are employed in guided bone regeneration (GBR) as physical barriers to facilitate bone in-growth. A bioactive and biomimetic membrane with the ability to participate in the healing and regeneration of the bone is necessary. The aim of the present study was to analyze how novel silicon dioxide composite membranes functionalized with zinc or doxycycline can modulate the osteoblasts’ proliferation, differentiation, and expression of selected antigenic markers related to immunomodulation. Nanostructured acrylate-based membranes were developed, blended with silica, and functionalized with zinc or doxycycline. They were subjected to MG63 osteoblast-like cells culturing. Proliferation was assessed by MTT-assay, differentiation by evaluating the alkaline phosphatase activity by a spectrophotometric method and antigenic phenotype was assessed by flow cytometry for selected markers. Mean comparisons were conducted by one-way ANOVA and Tukey tests (p < 0.05). The blending of silica nanoparticles in the tested non-resorbable polymeric scaffold improved the proliferation and differentiation of osteoblasts, but doxycycline doped scaffolds attained the best results. Osteoblasts cultured on doxycycline functionalized membranes presented higher expression of CD54, CD80, CD86, and HLA-DR, indicating a beneficial immunomodulation activity. Doxycycline doped membranes may be a potential candidate for use in GBR procedures in several challenging pathologies, including periodontal disease. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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18 pages, 3174 KiB

Open AccessArticle

Gas Separation by Mixed Matrix Membranes with Porous Organic Polymer Inclusions within o-Hydroxypolyamides Containing m-Terphenyl Moieties

by Cenit Soto, Edwin S. Torres-Cuevas, Alfonso González-Ortega, Laura Palacio, Ángel E. Lozano, Benny D. Freeman, Pedro Prádanos and Antonio Hernández

Polymers 2021, 13(6), 931; https://doi.org/10.3390/polym13060931 - 18 Mar 2021

Cited by 15 | Viewed by 3803

Abstract

A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed [...] Read more.

A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed matrix membranes (MMMs) loaded with 20% (w/w) of two porous polymer networks (triptycene-isatin, PPN-1, and triptycene-trifluoroacetophenone, PPN-2). These MMMs, and also the thermally rearranged membranes (TR-MMMs) that underwent a thermal treatment process to convert the o-hydroxypolyamide moieties to polybenzoxazole ones, were characterized, and their gas separation properties evaluated for H₂, N₂, O₂, CH₄, and CO₂. Both TR process and the addition of PPN increased permeability with minor decreases in selectivity for all gases tested. Excellent results were obtained, in terms of the permeability versus selectivity compromise, for H₂/CH₄ and H₂/N₂ separations with membranes approaching the 2008 Robeson’s trade-off line. The best gas separation properties were obtained when PPN-2 was used. Finally, gas permeation was characterized in terms of chain intersegmental distance and fraction of free volume of the membrane along with the kinetic diameters of the permeated gases. The intersegmental distance increased after TR and/or the addition of PPN-2. Permeability followed an exponential dependence with free volume and a quadratic function of the kinetic diameter of the gas. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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27 pages, 10576 KiB

Open AccessArticle

Supramolecular Functionalizable Linear–Dendritic Block Copolymers for the Preparation of Nanocarriers by Microfluidics

by Miriam Abad, Alejandro Martínez-Bueno, Gracia Mendoza, Manuel Arruebo, Luis Oriol, Víctor Sebastián and Milagros Piñol

Polymers 2021, 13(5), 684; https://doi.org/10.3390/polym13050684 - 25 Feb 2021

Cited by 11 | Viewed by 4029

Abstract

Hybrid linear–dendritic block copolymers (LDBCs) having dendrons with a precise number of peripheral groups that are able to supramolecular bind functional moieties are challenging materials as versatile polymeric platforms for the preparation of functional polymeric nanocarriers. PEG_2k-b-dxDAP LDBCs that [...] Read more.

Hybrid linear–dendritic block copolymers (LDBCs) having dendrons with a precise number of peripheral groups that are able to supramolecular bind functional moieties are challenging materials as versatile polymeric platforms for the preparation of functional polymeric nanocarriers. PEG_2k-b-dxDAP LDBCs that are based on polyethylene glycol (PEG) as hydrophilic blocks and dendrons derived from bis-MPA having 2,6-diacylaminopyridine (DAP) units have been efficiently synthesized by the click coupling of preformed blocks, as was demonstrated by spectroscopic techniques and mass spectrometry. Self-assembly ability was first checked by nanoprecipitation. A reproducible and fast synthesis of aggregates was accomplished by microfluidics optimizing the total flow rate and phase ratio to achieve spherical micelles and/or vesicles depending on dendron generation and experimental parameters. The morphology and size of the self-assemblies were studied by TEM, Cryogenic Transmission Electron Microscopy (cryo-TEM), and Dynamic Light Scattering (DLS). The cytotoxicity of aggregates synthesized by microfluidics and the influence on apoptosis and cell cycle evaluation was studied on four cell lines. The self-assemblies are not cytotoxic at doses below 0.4 mg mL⁻¹. Supramolecular functionalization using thymine derivatives was explored for reversibly cross-linking the hydrophobic blocks. The results open new possibilities for their use as drug nanocarriers with a dynamic cross-linking to improve nanocarrier stability but without hindering disassembly to release molecular cargoes. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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19 pages, 6787 KiB

Open AccessArticle

Thermodynamic Modeling and Validation of the Temperature Influence in Ternary Phase Polymer Systems

by Marta Romay, Nazely Diban and Ane Urtiaga

Polymers 2021, 13(5), 678; https://doi.org/10.3390/polym13050678 - 24 Feb 2021

Cited by 18 | Viewed by 7282

Abstract

The effect of the temperature, as a process variable in the fabrication of polymeric membranes by the non-solvent induced phase separation (NIPS) technique, has been scarcely studied. In the present work, we studied the influence of temperature, working at 293, 313 and 333 [...] Read more.

The effect of the temperature, as a process variable in the fabrication of polymeric membranes by the non-solvent induced phase separation (NIPS) technique, has been scarcely studied. In the present work, we studied the influence of temperature, working at 293, 313 and 333 K, on the experimental binodal curves of four ternary systems composed of PVDF and PES as the polymers, DMAc and NMP as the solvents and water as the non-solvent. The increase of the temperature caused an increase on the solubility gap of the ternary system, as expected. The shift of the binodal curve with the temperature was more evident in PVDF systems than in PES systems indicating the influence of the rubbery or glassy state of the polymer on the thermodynamics of phase separation. As a novelty, the present work has introduced the temperature influence on the Flory–Huggins model to fit the experimental cloud points. Binary interaction parameters were calculated as a function of the temperature: (i) non-solvent/solvent (g₁₂) expressions with UNIFAC-Dortmund methodology and (ii) non-solvent/polymer (χ₁₃) and solvent/polymer (χ₂₃) using Hansen solubility parameters. Additionally, the effect of the ternary interaction term was not negligible in the model. Estimated ternary interaction parameters (χ₁₂₃) presented a linear relation with temperature and negative values, indicating that the solubility of the polymers in mixtures of solvent/non-solvent was higher than expected for single binary interaction. Finally, PES ternary systems exhibited higher influence of the ternary interaction parameter than PVDF systems. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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16 pages, 894 KiB

Open AccessArticle

Continuous Based Direct Ink Write for Tubular Cardiovascular Medical Devices

by Enric Casanova-Batlle, Antonio J. Guerra and Joaquim Ciurana

Polymers 2021, 13(1), 77; https://doi.org/10.3390/polym13010077 - 28 Dec 2020

Cited by 8 | Viewed by 3921

Abstract

Bioresorbable cardiovascular applications are increasing in demand as fixed medical devices cause episodes of late restenosis. The autologous treatment is, so far, the gold standard for vascular grafts due to the similarities to the replaced tissue. Thus, the possibility of customizing each application [...] Read more.

Bioresorbable cardiovascular applications are increasing in demand as fixed medical devices cause episodes of late restenosis. The autologous treatment is, so far, the gold standard for vascular grafts due to the similarities to the replaced tissue. Thus, the possibility of customizing each application to its end user is ideal for treating pathologies within a dynamic system that receives constant stimuli, such as the cardiovascular system. Direct Ink Writing (DIW) is increasingly utilized for biomedical purposes because it can create composite bioinks by combining polymers and materials from other domains to create DIW-printable materials that provide characteristics of interest, such as anticoagulation, mechanical resistance, or radiopacity. In addition, bioinks can be tailored to encounter the optimal rheological properties for the DIW purpose. This review delves into a novel emerging field of cardiovascular medical applications, where this technology is applied in the tubular 3D printing approach. Cardiovascular stents and vascular grafts manufactured with this new technology are reviewed. The advantages and limitations of blending inks with cells, composite materials, or drugs are highlighted. Furthermore, the printing parameters and the different possibilities of designing these medical applications have been explored. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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18 pages, 4087 KiB

Open AccessArticle

Recyclable Organocatalyzed Poly(Thiourethane) Covalent Adaptable Networks

by Francesco Gamardella, Sara Muñoz, Silvia De la Flor, Xavier Ramis and Angels Serra

Polymers 2020, 12(12), 2913; https://doi.org/10.3390/polym12122913 - 4 Dec 2020

Cited by 29 | Viewed by 4140

Abstract

A new type of tetraphenylborate salts derived from highly basic and nucleophilic amines, namely 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) and triazabicyclodecene (TBD), was applied to the preparation of networked poly(thiourethane)s (PTUs), which showed a vitrimer-like behavior, with higher stress-relaxation rates than PTUs prepared by [...] Read more.

A new type of tetraphenylborate salts derived from highly basic and nucleophilic amines, namely 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) and triazabicyclodecene (TBD), was applied to the preparation of networked poly(thiourethane)s (PTUs), which showed a vitrimer-like behavior, with higher stress-relaxation rates than PTUs prepared by using dibutyl thin dilaurate (DBTDL) as the catalyst. The use of these salts, which release the amines when heated, instead of the pure amines, allows the formulation to be easily manipulated to prepare any type of samples. The materials prepared from stoichiometric mixtures of hexamethylene diisocyanate (HDI), trithiol (S3) and with a 10% of molar excess of isocyanate or thiol were characterized by FTIR, thermomechanical analysis, thermogravimetry, stress-relaxation tests and tensile tests, thus obtaining a complete thermal and mechanical characterization of the materials. The recycled materials obtained by grinding the original PTUs and hot-pressing the small pieces in the optimized time and temperature conditions were fully characterized by mechanical, thermomechanical and FTIR studies. This allowed us to confirm their recyclability, without appreciable changes in the network structure and performance. From several observations, the dissociative interchange trans-thiocarbamoylation mechanism was evidenced as the main responsible of the topological rearrangements at high temperature, resulting in a vitrimeric-like behavior. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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11 pages, 3647 KiB

Open AccessArticle

Micellar Nanocarriers from Dendritic Macromolecules Containing Fluorescent Coumarin Moieties

by Alberto Concellón, María San Anselmo, Silvia Hernández-Ainsa, Pilar Romero, Mercedes Marcos and José Luis Serrano

Polymers 2020, 12(12), 2872; https://doi.org/10.3390/polym12122872 - 30 Nov 2020

Cited by 17 | Viewed by 3178

Abstract

The design of efficient drug-delivery vehicles remains a big challenge in materials science. Herein, we describe a novel class of amphiphilic hybrid dendrimers that consist of a poly(amidoamine) (PAMAM) dendritic core functionalized with bisMPA dendrons bearing cholesterol and coumarin moieties. Their self-assembly [...] Read more.

The design of efficient drug-delivery vehicles remains a big challenge in materials science. Herein, we describe a novel class of amphiphilic hybrid dendrimers that consist of a poly(amidoamine) (PAMAM) dendritic core functionalized with bisMPA dendrons bearing cholesterol and coumarin moieties. Their self-assembly behavior both in bulk and in water was investigated. All dendrimers exhibited smectic A or hexagonal columnar liquid crystal organizations, depending on the generation of the dendrimer. In water, these dendrimers self-assembled to form stable spherical micelles that could encapsulate Nile Red, a hydrophobic model compound. The cell viability in vitro of the micelles was studied in HeLa cell line, and proved to be non-toxic up to 72 h of incubation. Therefore, these spherical micelles allow the encapsulation of hydrophobic molecules, and at the same time provided fluorescent traceability due to the presence of coumarin units in their chemical structure, demonstrating the potential of these dendrimers as nanocarriers for drug-delivery applications. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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11 pages, 1869 KiB

Open AccessArticle

Chemical Hydrogels Bearing Thiazolium Groups with a Broad Spectrum of Antimicrobial Behavior

by Alexandra Muñoz-Bonilla, Jakub Zagora, Daniela Plachá, Coro Echeverría, Alberto Chiloeches and Marta Fernández-García

Polymers 2020, 12(12), 2853; https://doi.org/10.3390/polym12122853 - 29 Nov 2020

Cited by 13 | Viewed by 2959

Abstract

Several hydrogels based on 2-hydroxyethyl methacrylate and a methacrylic monomer containing a thiazole group in its lateral chain have been prepared by thermal polymerization at 60 °C in water solution varying the chemical composition of the gels. The posterior quaternization of the thiazole [...] Read more.

Several hydrogels based on 2-hydroxyethyl methacrylate and a methacrylic monomer containing a thiazole group in its lateral chain have been prepared by thermal polymerization at 60 °C in water solution varying the chemical composition of the gels. The posterior quaternization of the thiazole groups with methyl iodine has rendered positively charged hydrogels with potential antimicrobial activity. This modification has been structurally characterized by infrared spectroscopy, whereas the thermal stability of all hydrogels has been studied by thermal degradation in inert atmosphere. The swelling behavior in distilled water and the rheology of the different hydrogels have been analyzed as a function of 2-(4-methylthiazol-5-yl)ethyl methacrylate (MTA) monomer content as well as its methylation. Finally, the active character of hydrogels against Gram-positive and Gram-negative bacteria and fungi has been evaluated, revealing excellent antimicrobial activity against all tested microorganisms. The methylated hydrogels could be used as potential materials for wound healing or contact lens applications. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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15 pages, 2182 KiB

Open AccessArticle

Cellulose Pulp- and Castor Oil-Based Polyurethanes for Lubricating Applications: Influence of Streptomyces Action on Barley and Wheat Straws

by Antonio M. Borrero-López, Concepción Valencia, Alba Blánquez, Manuel Hernández, María E. Eugenio and José M. Franco

Polymers 2020, 12(12), 2822; https://doi.org/10.3390/polym12122822 - 27 Nov 2020

Cited by 16 | Viewed by 2984

Abstract

The replacement of mineral oils and non-renewable gelling agents is an imperative requirement for the lubricant industry in the near future. In this framework, cellulose pulp and castor oil are proposed as sustainable substitutes for these components. Biological treatment has been explored and [...] Read more.

The replacement of mineral oils and non-renewable gelling agents is an imperative requirement for the lubricant industry in the near future. In this framework, cellulose pulp and castor oil are proposed as sustainable substitutes for these components. Biological treatment has been explored and evaluated to enhance the dispersing and thickening properties of cellulose pulp in oil media. Streptomyces sp. MDG147 and MDG301 strains were employed to modify agricultural wheat and barley straw residues from which cellulose pulp was obtained afterwards. In addition, an environmentally friendly process for the production of cellulose-pulp-/castor-oil-based polyurethanes was applied, in which neither catalysts nor harmful solvents were used, resulting in chemical oleogels. These oleogels were rheologically and tribologically characterized to evaluate their performance as lubricating greases. The enzymatic activity pattern developed was dependent on the raw material, the strain type, and the temperature, influencing the cellulose pulp’s composition, polymerization degree, and crystallinity. These modified characteristics tuned the rheological behavior of the different oleogels, providing a beneficial range of viscoelastic responses and viscosity values that were generally favored by the Streptomyces action. Furthermore, the friction coefficient and dimensions of wear scars measured in a tribological contact were comparable to, or even lower than, those found with commercial and other bio-based lubricating greases that have previously been studied. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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18 pages, 2501 KiB

Open AccessArticle

Tailoring Intrinsic Properties of Polyaniline by Functionalization with Phosphonic Groups

by Beatriz Martínez-Sánchez, Diego Cazorla-Amorós and Emilia Morallón

Polymers 2020, 12(12), 2820; https://doi.org/10.3390/polym12122820 - 27 Nov 2020

Cited by 20 | Viewed by 2843

Abstract

Phosphonated polyanilines were synthesized by copolymerization of aniline (ANI) with both 2- and 4-aminophenylphosphonic acids (APPA). The material composition and the final properties of the copolymers can be easily tailored by controlling the monomers ANI/APPA molar feed ratio. An important influence on the [...] Read more.

Phosphonated polyanilines were synthesized by copolymerization of aniline (ANI) with both 2- and 4-aminophenylphosphonic acids (APPA). The material composition and the final properties of the copolymers can be easily tailored by controlling the monomers ANI/APPA molar feed ratio. An important influence on the reactivity of monomers has been found with the substituent position in the ring, leading to differences in the properties and size of blocks of each monomer in the polymer. As expected, while 2APPA shows more similarities to ANI, 4APPA is much less reactive. Phosphorus loading of ~5 at% was achieved in the poly(aniline-co-2-aminophenylphosphonic acid) (PANI2APPA) with a 50/50 molar feed ratio. All the resulting copolymers were characterized by different techniques. Experimental results and density functional theory (DFT) computational calculations suggest that the presence of phosphonic groups in the polymeric chain gives rise to inter- and intra-chain interactions, as well as important steric effects, which induce a slight twist in the substituted PANI structure. Therefore, the physicochemical, electrical, and electrochemical properties are modified and can be suitably controlled. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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14 pages, 2206 KiB

Open AccessArticle

Fabrication and Characterization of PEEK/PEI Multilayer Composites

by Ángel Alvaredo-Atienza, Lu Chen, Verónica San-Miguel, Álvaro Ridruejo and Juan P. Fernández-Blázquez

Polymers 2020, 12(12), 2765; https://doi.org/10.3390/polym12122765 - 24 Nov 2020

Cited by 28 | Viewed by 5826

Abstract

Polyetheretherketone (PEEK)/polyetherimide (PEI) blends (50/50, v/v) keeping the crystal phase of PEEK have been manufactured by alternate PEEK/PEI layer stacking. This strategy avoided the complete miscibility of both polymers, keeping layers of PEEK and PEI unmixed along the sample thickness, as well [...] Read more.

Polyetheretherketone (PEEK)/polyetherimide (PEI) blends (50/50, v/v) keeping the crystal phase of PEEK have been manufactured by alternate PEEK/PEI layer stacking. This strategy avoided the complete miscibility of both polymers, keeping layers of PEEK and PEI unmixed along the sample thickness, as well as promoting the formation of a smooth interfacial layer where PEEK and PEI were mixed. The properties of this interface after processing at molten state and different times was studied by DSC, DMA, and X-Ray synchrotron. These techniques allowed monitoring the evolution of glass transition, where isolated T_g’s for both pristine polymers were observed even after long processing time. PEEK crystallinity slightly decreased during manufacturing, whereas PEEK crystal parameters did not vary. These observations show that, although the interface—the zone where both polymers are mixed—grew, layers with pristine polymers remained even after prolonged processing time. The preservation of the PEEK crystallinity was also observed in the mechanical properties of the multilayer PEEK/PEI films, which were compared with pristine PEEK and PEI films. Multilayer samples processed for shorter times rendered higher young modulus, tensile strength, and strain at break. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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16 pages, 4585 KiB

Open AccessArticle

Cation Effect in the Corrosion Inhibition Properties of Coumarate Ionic Liquids and Acrylic UV-Coatings

by Esther Udabe, Anthony Sommers, Maria Forsyth and David Mecerreyes

Polymers 2020, 12(11), 2611; https://doi.org/10.3390/polym12112611 - 6 Nov 2020

Cited by 12 | Viewed by 3404

Abstract

Chromate free corrosion inhibitors are searched for to mitigate the economic loss caused by mid-steel corrosion. Here, we show metal-free organic inhibitors having free coumarate anions that can be used either as direct corrosion inhibitors or incorporated into a polymer coating obtained by [...] Read more.

Chromate free corrosion inhibitors are searched for to mitigate the economic loss caused by mid-steel corrosion. Here, we show metal-free organic inhibitors having free coumarate anions that can be used either as direct corrosion inhibitors or incorporated into a polymer coating obtained by UV-curing. Four different ionic liquid monomers and polymer coatings with hexoxycoumarate anion and different polymerizable counter cations were investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy, and surface analyses have verified their corrosion inhibition performance on a mild steel AS1020 surface. In the case of the coumarate ionic liquid monomers, the most promising inhibitor is the one coupled with the ammonium cation, showing an inhibition efficiency of 99.1% in solution followed by the imidazolium, pyridinium, and anilinium. Next, the ionic liquid monomers were covalently integrated into an acrylic polymer coating by UV-photopolymerization. In this case, the barrier effect of the polymer coating is combined with the corrosion inhibitor effect of the pendant coumarate anion. Here, the best polymer coatings are those containing 20% imidazolium and pyridinium cations, presenting a greater impedance in the EIS (Electrochemical Impedance Spectroscopy) measurements and less evidence of corrosion in the scribe tests. This article shows that the cationic moiety of coumarate based ionic liquids and poly(ionic liquid)s has a significant effect on their excellent corrosion inhibition properties for a mild steel surface exposed to aqueous chloride solutions. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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17 pages, 3613 KiB

Open AccessArticle

Polyaniline-Derived N-Doped Ordered Mesoporous Carbon Thin Films: Efficient Catalysts towards Oxygen Reduction Reaction

by Javier Quílez-Bermejo, Emilia Morallón and Diego Cazorla-Amorós

Polymers 2020, 12(10), 2382; https://doi.org/10.3390/polym12102382 - 16 Oct 2020

Cited by 25 | Viewed by 3644

Abstract

One of the most challenging targets in oxygen reduction reaction (ORR) electrocatalysts based on N-doped carbon materials is the control of the pore structure and obtaining nanostructured thin films that can easily be incorporated on the current collector. The carbonization of nitrogen-containing polymers [...] Read more.

One of the most challenging targets in oxygen reduction reaction (ORR) electrocatalysts based on N-doped carbon materials is the control of the pore structure and obtaining nanostructured thin films that can easily be incorporated on the current collector. The carbonization of nitrogen-containing polymers and the heat treatment of a mixture of carbon materials and nitrogen precursor are the most common methods for obtaining N-doped carbon materials. However, in this synthetic protocols, the surface area and pore distribution are not controlled. This work enables the preparation of 2D-ordered N-doped carbon materials through the carbonization of 2D polyaniline. For that purpose, aniline has been electropolymerized within the porous structure of two different templates (ordered mesoporous Silica and ordered mesoporous Titania thin films). Thus, aniline has been impregnated into the porous structure and subsequently electropolymerized by means of chronoamperometry at constant potential. The resultant samples were heat-treated at 900 °C with the aim of obtaining 2D N-doped carbon materials within the template structures. Polyaniline and polyaniline-derived carbon materials have been analyzed via XPS and TEM and characterized by electrochemical measurements. It is worth noting that the obtained 2D-ordered mesoporous N-doped carbon materials have proved to be highly active electrocatalysts for the ORR because of the formation of quaternary nitrogen species during the heat treatment. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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15 pages, 1093 KiB

Open AccessArticle

Polymeric Ionic Liquids Derived from L-Valine for the Preparation of Highly Selective Silica-Supported Stationary Phases in Gas Chromatography

by Jorge González-Rodríguez, Adriana Valls, Pilar Arias Abrodo, María Dolores Gutiérrez Álvarez, Jaime González-Álvarez, Belén Altava and Santiago V. Luis

Polymers 2020, 12(10), 2348; https://doi.org/10.3390/polym12102348 - 14 Oct 2020

Cited by 8 | Viewed by 3685

Abstract

A series of silica-supported polymeric ionic liquid (PIL)-based stationary phases derived from a vinylic L-valine ionic liquid monomer and divinylbenzene (DVB) as the crosslinking agent have been prepared and studied as gas chromatographic stationary phases. These coated gas chromatographic columns exhibited good [...] Read more.

A series of silica-supported polymeric ionic liquid (PIL)-based stationary phases derived from a vinylic L-valine ionic liquid monomer and divinylbenzene (DVB) as the crosslinking agent have been prepared and studied as gas chromatographic stationary phases. These coated gas chromatographic columns exhibited good thermal stabilities (230–300 °C) and high efficiencies (1700–2700 plates/m), and were characterized using a linear solvation parameter model in order to understand the effects of the amount of DVB on the features of the resulting composite systems. Their retention behavior and separation efficiencies were demonstrated using the Grob test. By tuning the crosslinking degree for the IL-derived stationary phase, the separation selectivity and resolution of different compounds were improved. The different retention behaviors observed for many analytes indicate that these stationary phases may be applicable as new types of GC stationary phases. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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20 pages, 11505 KiB

Open AccessArticle

Manufacturing and Characterization of Coatings from Polyamide Powders Functionalized with Nanosilica

by Maria Fernández-Álvarez, Francisco Velasco, Asuncion Bautista, Flavia Cristina M. Lobo, Emanuel M. Fernandes and Rui L. Reis

Polymers 2020, 12(10), 2298; https://doi.org/10.3390/polym12102298 - 8 Oct 2020

Cited by 21 | Viewed by 4497

Abstract

Polyamide coatings are thermoplastics with great advantages such as a good corrosion protection of the base metal and wear resistance. Their application as powder coatings is an environmentally friendly option that is currently attracting growing interest. However, during their life service, they can [...] Read more.

Polyamide coatings are thermoplastics with great advantages such as a good corrosion protection of the base metal and wear resistance. Their application as powder coatings is an environmentally friendly option that is currently attracting growing interest. However, during their life service, they can sometimes be exposed to conditions that they are unable to stand. In this work, a polyamide 11 (PA11) powder was reinforced with different percentages of silica nanoparticles (1–3 wt. %). Powder mixtures were prepared through extrusion followed by compression molding processes to manufacture coatings. For the coatings under study, the effect of 500 h xenon exposure was studied in order to know their ultraviolet (UV) resistance. Attenuated total reflection-Fourier transform infrared spectroscopy (FTIR-ATR) and differential scanning calorimetry (DSC) tests were performed to study changes in polymer structure and if they are affected by nanoparticles. The effect of nanoadditions and xenon exposure on hardness and stiffness were also evaluated. Furthermore, reciprocal wear tests were performed before and after irradiation, and the wear tracks were analyzed using optoelectronic microscopy and scanning electron microscopy (SEM). Finally, the aesthetic properties were measured. The results reveal improvements in mechanical and wear properties when 1% nanosilica is added to the PA11, which then become more relevant after xenon radiation exposure. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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19 pages, 1805 KiB

Open AccessArticle

Study on the Macro and Micromechanics Tensile Strength Properties of Orange Tree Pruning Fiber as Sustainable Reinforcement on Bio-Polyethylene Compared to Oil-Derived Polymers and Its Composites

by Francesc X Espinach, Eduardo Espinosa, Rafel Reixach, Alejandro Rodríguez, Pere Mutjé and Quim Tarrés

Polymers 2020, 12(10), 2206; https://doi.org/10.3390/polym12102206 - 25 Sep 2020

Cited by 16 | Viewed by 3769

Abstract

Agroforestry creates value but also a huge amount of waste outside its value chain. Tree pruning is an example of such a low value waste, that is typically discarded or incinerated in the fields or used to recover energy. Nonetheless, tree prunings are [...] Read more.

Agroforestry creates value but also a huge amount of waste outside its value chain. Tree pruning is an example of such a low value waste, that is typically discarded or incinerated in the fields or used to recover energy. Nonetheless, tree prunings are rich in wood fibers that can be used as polymer reinforcement. Although there are some bio-based polymers, the majority of industries use oil-based ones. The election of the materials is usually based on a ratio between properties and cost. Bio-based polymers are more expensive than oil-based ones. This work shows how a bio-polyethylene matrix can be reinforced with fibers from orange tree prunings to obtain materials with notable tensile properties. These bio-based materials can show a balanced cost due to the use of a cheap reinforcement with an expensive matrix. The matrix used showed a tensile strength of 18.65 MPa, which reached 42.54 MPa after the addition of 50 wt.% of reinforcement. The obtained values allow the use of the studied composite to replace polypropylene and some of its composites under tensile loads. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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14 pages, 4164 KiB

Open AccessArticle

Compression Molded Soy Protein Films with Exopolysaccharides Produced by Cider Lactic Acid Bacteria

by Jone Uranga, Mª Goretti Llamas, Ziortza Agirrezabala, María Teresa Dueñas, Oier Etxebeste, Pedro Guerrero and Koro de la Caba

Polymers 2020, 12(9), 2106; https://doi.org/10.3390/polym12092106 - 16 Sep 2020

Cited by 11 | Viewed by 3304

Abstract

Two exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) strains, Liquorilactobacillus (L.) sp CUPV281 and Liquorilactobacillus (L.) mali CUPV271, were isolated from Spanish apple must. Each of the strains produced a dextran, with different branching degrees, to be incorporated into soy protein isolate (SPI) film-forming [...] Read more.

Two exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) strains, Liquorilactobacillus (L.) sp CUPV281 and Liquorilactobacillus (L.) mali CUPV271, were isolated from Spanish apple must. Each of the strains produced a dextran, with different branching degrees, to be incorporated into soy protein isolate (SPI) film-forming formulations. Films were prepared by compression molding, a more rapid processing method than solution casting and, thus, with a greater potential for scaling-up production. Thermal analysis showed that SPI and EPS start the degradation process at temperatures above 190 °C, confirming that the compression temperature selected (120 °C) was well below the corresponding degradation temperatures. Resulting films were transparent and homogeneous, as shown by UV-Vis spectroscopy and SEM, indicating the good compatibility between SPI and EPS. Furthermore, FTIR analysis showed that the interactions between SPI and EPS were physical interactions, probably by hydrogen bonding among the polar groups of SPI and EPS. Regarding antifungal/fungistatic activity, LAB strains used in this study showed an inhibitory effect on germination of fungal spores. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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20 pages, 3608 KiB

Open AccessArticle

Imprinted Contact Lenses for Ocular Administration of Antiviral Drugs

by Angela Varela-Garcia, José Luis Gomez-Amoza, Angel Concheiro and Carmen Alvarez-Lorenzo

Polymers 2020, 12(9), 2026; https://doi.org/10.3390/polym12092026 - 4 Sep 2020

Cited by 34 | Viewed by 5101

Abstract

A variety of ocular diseases are caused by viruses, and most treatments rely on the use of systemic formulations and eye drops. The efficient ocular barriers that oppose antiviral drug penetration have prompted the development of improved topical delivery platforms. The aim was [...] Read more.

A variety of ocular diseases are caused by viruses, and most treatments rely on the use of systemic formulations and eye drops. The efficient ocular barriers that oppose antiviral drug penetration have prompted the development of improved topical delivery platforms. The aim was to design hydrogel contact lenses endowed with an affinity for acyclovir (ACV) and its prodrug valacyclovir (VACV), first-choice drugs against herpes simplex virus (HSV) ocular keratitis, and that can sustain the release of therapeutic doses during daily wearing. Functional monomers suitable for interaction with these drugs were screened using computational modeling. Imprinted and non-imprinted hydrogels were prepared with various contents in the functional monomer methacrylic acid (MAA) and characterized in terms of swelling, transmittance, mechanical properties, and ocular compatibility (hen’s egg test on chorioallantoic membrane (HET-CAM) assay). The values were in the range typical of soft contact lenses. Compared to ACV, the capability to load VACV was remarkably higher due to stronger electrostatic interactions with MAA. The advantages of the imprinting technology were evidenced for VACV. Stability of VACV loading solution/hydrogels under steam heat sterilization and subsequent drug release was investigated. Permeability studies through bovine and porcine cornea and sclera of the drug released from the hydrogels revealed that VACV accumulates in the cornea and can easily cross the sclera, which may facilitate the treatment of both anterior and posterior eye segments diseases. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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14 pages, 1369 KiB

Open AccessArticle

Heteronuclear Dirhodium-Gold Anionic Complexes: Polymeric Chains and Discrete Units

by Estefania Fernandez-Bartolome, Paula Cruz, Laura Abad Galán, Miguel Cortijo, Patricia Delgado-Martínez, Rodrigo González-Prieto, José L. Priego and Reyes Jiménez-Aparicio

Polymers 2020, 12(9), 1868; https://doi.org/10.3390/polym12091868 - 19 Aug 2020

Cited by 7 | Viewed by 2990

Abstract

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh₂(μ–O₂CCH₂OMe)₄(THF)₂] (1) and [Rh₂(μ–O₂CC₆H₄–p–CMe₃)₄ [...] Read more.

In this article, we report on the synthesis and characterization of the tetracarboxylatodirhodium(II) complexes [Rh₂(μ–O₂CCH₂OMe)₄(THF)₂] (1) and [Rh₂(μ–O₂CC₆H₄–p–CMe₃)₄(OH₂)₂] (2) by metathesis reaction of [Rh₂(μ–O₂CMe)₄] with the corresponding ligand acting also as the reaction solvent. The reaction of the corresponding tetracarboxylato precursor, [Rh₂(μ–O₂CR)₄], with PPh₄[Au(CN)₂] at room temperature, yielded the one-dimensional polymers (PPh₄)_n[Rh₂(μ–O₂CR)₄Au(CN)₂]_n (R = Me (3), CH₂OMe (4), CH₂OEt (5)) and the non-polymeric compounds (PPh₄)₂{Rh₂(μ–O₂CR)₄[Au(CN)₂]₂} (R = CMe₃ (6), C₆H₄–p–CMe₃ (7)). The structural characterization of 1, 3·2CH₂Cl₂, 4·3CH₂Cl₂, 5, 6, and 7·2OCMe₂ is also provided with a detailed description of their crystal structures and intermolecular interactions. The polymeric compounds 3·2CH₂Cl₂, 4·3CH₂Cl₂, and 5 show wavy chains with Rh–Au–Rh and Rh–N–C angles in the ranges 177.18°–178.69° and 163.0°–170.4°, respectively. A comparative study with related rhodium-silver complexes previously reported indicates no significant influence of the gold or silver atoms in the solid-state arrangement of these kinds of complexes. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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12 pages, 2859 KiB

Open AccessArticle

Does Subunit Composition Influence the Intermolecular Crosslinking of Fish Collagen? A Study with Hake and Blue Shark Skin Collagens

by María Blanco, Noelia Sanz, Jesús Valcarcel, Ricardo I. Pérez-Martín and Carmen G. Sotelo

Polymers 2020, 12(8), 1734; https://doi.org/10.3390/polym12081734 - 3 Aug 2020

Cited by 13 | Viewed by 3665

Abstract

Acid-soluble collagens from European hake and Blue shark skin were isolated, characterized, and compared. As the structure of collagen determines its function, the final objective of this study was to investigate biochemical differences between both collagens to identify future potential applications. Chromatographic behavior [...] Read more.

Acid-soluble collagens from European hake and Blue shark skin were isolated, characterized, and compared. As the structure of collagen determines its function, the final objective of this study was to investigate biochemical differences between both collagens to identify future potential applications. Chromatographic behavior revealed differences in collagen from both species. Increases of temperature and stirring time produced no effect on European hake collagen solubility in the mobile phase, resulting in the same chromatographic profiles. Conversely, the application of temperature and stirring-time increments showed a positive effect on Blue shark collagen solubility, resulting in different chromatographic profiles and observing higher molecular weight components when sample is incubated at 50 °C (15 min) after 48 h stirring. To test if the different chromatographic behavior exhibited by both collagens could be influenced by differences in subunit composition (alpha-chains), cation exchange chromatography was employed to separate collagen subunits. The electrophoretic patterns and gel permeation chromatography with light-scattering detection (GPC-LS) results of the obtained cation exchange peak fractions revealed differences regarding subunit composition between both species, influencing the crosslinking pattern. This is the first comparative study using GPC-LS to provide information of European hake and Blue shark collagen subunit composition. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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19 pages, 3855 KiB

Open AccessArticle

Application of the Finite Element Method to the Incremental Forming of Polymer Sheets: The Thermomechanical Coupled Model and Experimental Validations

by A. García-Collado, Gustavo Medina-Sanchez, Munish Kumar Gupta and R. Dorado-Vicente

Polymers 2020, 12(8), 1715; https://doi.org/10.3390/polym12081715 - 30 Jul 2020

Cited by 6 | Viewed by 3398

Abstract

Single Point Incremental Forming (SPIF) is an innovative die-less low-cost forming method. Until now, there have not been viable numerical solutions regarding computational time and accuracy for the incremental forming of polymers. Unlike other numerical approaches, this novel work describes a coupled thermomechanical [...] Read more.

Single Point Incremental Forming (SPIF) is an innovative die-less low-cost forming method. Until now, there have not been viable numerical solutions regarding computational time and accuracy for the incremental forming of polymers. Unlike other numerical approaches, this novel work describes a coupled thermomechanical finite element model that simulates the SPIF of polymer sheets, where a simple elastoplastic constitutive equation rules the mechanical behavior. The resulting simulation attains a commitment between time and accuracy in the prediction of forming forces, generated and transmitted heat, as well as final part dimensions. An experimental test with default process parameters was used to determine an adequate numerical configuration (element type, mesh resolution, and material model). Finally, compared to a set of experimental tests with different thermoplastics, the proposed model, which does not consider complex rheological material models, shows a good agreement with an approximation error of less than 11% in the vertical forming force prediction. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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13 pages, 2847 KiB

Open AccessArticle

A Green Approach towards Native Collagen Scaffolds: Environmental and Physicochemical Assessment

by Mireia Andonegi, Ainhoa Irastorza, Ander Izeta, Sara Cabezudo, Koro de la Caba and Pedro Guerrero

Polymers 2020, 12(7), 1597; https://doi.org/10.3390/polym12071597 - 18 Jul 2020

Cited by 18 | Viewed by 4009

Abstract

Native collagen scaffolds were prepared in this work, in which both materials and environmental approaches were considered with the aim of providing a global strategy towards more sustainable biomaterials. From the environmental perspective, it is worth mentioning that acid and enzymatic treatments have [...] Read more.

Native collagen scaffolds were prepared in this work, in which both materials and environmental approaches were considered with the aim of providing a global strategy towards more sustainable biomaterials. From the environmental perspective, it is worth mentioning that acid and enzymatic treatments have been avoided to extract collagen, allowing the reduction in the use of resources, in terms of chemicals, energy, and time, and leading to a low environmental load of this step in all the impact categories under analysis. With the incorporation of chitosan into the scaffold-forming formulations, physical interactions occurred between collagen and chitosan, but the native collagen structure was preserved, as observed by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The incorporation of chitosan also led to more homogenous porous microstructures, with higher elastic moduli and compression resistance for both dry and hydrated scaffolds. Furthermore, hydrated scaffolds preserved their size and shape after some compression cycles. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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19 pages, 3529 KiB

Open AccessArticle

Why Is the Sensory Response of Organic Probes within a Polymer Film Different in Solution and in the Solid-State? Evidence and Application to the Detection of Amino Acids in Human Chronic Wounds

by Marta Guembe-García, Patricia D. Peredo-Guzmán, Victoria Santaolalla-García, Natalia Moradillo-Renuncio, Saturnino Ibeas, Aranzazu Mendía, Félix Clemente García, José Miguel García and Saúl Vallejos

Polymers 2020, 12(6), 1249; https://doi.org/10.3390/polym12061249 - 29 May 2020

Cited by 12 | Viewed by 3558

Abstract

We anchored a colourimetric probe, comprising a complex containing copper (Cu(II)) and a dye, to a polymer matrix obtaining film-shaped chemosensors with induced selectivity toward glycine. This sensory material is exploited in the selectivity detection of glycine in complex mixtures of amino acids [...] Read more.

We anchored a colourimetric probe, comprising a complex containing copper (Cu(II)) and a dye, to a polymer matrix obtaining film-shaped chemosensors with induced selectivity toward glycine. This sensory material is exploited in the selectivity detection of glycine in complex mixtures of amino acids mimicking elastin, collagen and epidermis, and also in following the protease activity in a beefsteak and chronic human wounds. We use the term inducing because the probe in solution is not selective toward any amino acid and we get selectivity toward glycine using the solid-state. Overall, we found that the chemical behaviour of a chemical probe can be entirely changed by changing its chemical environment. Regarding its behaviour in solution, this change has been achieved by isolating the probe by anchoring the motifs in a polymer matrix, in an amorphous state, avoiding the interaction of one sensory motif with another. Moreover, this selectivity change can be further tuned because of the effectiveness of the transport of targets both by the physical nature of the interface of the polymer matrix/solution, where the target chemicals are dissolved, for instance, and inside the matrix where the recognition takes place. The interest in chronic human wounds is related to the fact that our methods are rapid and inexpensive, and also considering that the protease activity can correlate with the evolution of chronic wounds. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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Review

Jump to: Editorial, Research

27 pages, 4206 KiB

Open AccessReview

Chitosan: An Overview of Its Properties and Applications

by Inmaculada Aranaz, Andrés R. Alcántara, Maria Concepción Civera, Concepción Arias, Begoña Elorza, Angeles Heras Caballero and Niuris Acosta

Polymers 2021, 13(19), 3256; https://doi.org/10.3390/polym13193256 - 24 Sep 2021

Cited by 867 | Viewed by 50726

Abstract

Chitosan has garnered much interest due to its properties and possible applications. Every year the number of publications and patents based on this polymer increase. Chitosan exhibits poor solubility in neutral and basic media, limiting its use in such conditions. Another serious obstacle [...] Read more.

Chitosan has garnered much interest due to its properties and possible applications. Every year the number of publications and patents based on this polymer increase. Chitosan exhibits poor solubility in neutral and basic media, limiting its use in such conditions. Another serious obstacle is directly related to its natural origin. Chitosan is not a single polymer with a defined structure but a family of molecules with differences in their composition, size, and monomer distribution. These properties have a fundamental effect on the biological and technological performance of the polymer. Moreover, some of the biological properties claimed are discrete. In this review, we discuss how chitosan chemistry can solve the problems related to its poor solubility and can boost the polymer properties. We focus on some of the main biological properties of chitosan and the relationship with the physicochemical properties of the polymer. Then, we review two polymer applications related to green processes: the use of chitosan in the green synthesis of metallic nanoparticles and its use as support for biocatalysts. Finally, we briefly describe how making use of the technological properties of chitosan makes it possible to develop a variety of systems for drug delivery. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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35 pages, 16389 KiB

Open AccessReview

Rheology of Polymer Processing in Spain (1995–2020)

by Leire Sangroniz, Mercedes Fernández, Pedro Partal and Antxon Santamaria

Polymers 2021, 13(14), 2314; https://doi.org/10.3390/polym13142314 - 14 Jul 2021

Cited by 6 | Viewed by 4465

Abstract

The contribution of Spanish scientists to the rheology involved in polymer processing during the last 25 years is investigated. It is shown that the performed research covers, at different levels, all industrial polymeric materials: thermoplastics, thermosets, adhesives, biopolymers, composites and nanocomposites, and polymer [...] Read more.

The contribution of Spanish scientists to the rheology involved in polymer processing during the last 25 years is investigated. It is shown that the performed research covers, at different levels, all industrial polymeric materials: thermoplastics, thermosets, adhesives, biopolymers, composites and nanocomposites, and polymer modified bitumen. Therefore, the rheological behaviour of these materials in processing methods such as extrusion, injection moulding, additive manufacturing, and others is discussed, based on the literature results. A detailed view of the most outstanding achievements, based on the rheological criteria of the authors, is offered. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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21 pages, 9707 KiB

Open AccessReview

Synthesis, Structure, Crystallization and Mechanical Properties of Isodimorphic PBS-ran-PCL Copolyesters

by Maryam Safari, Itziar Otaegi, Nora Aramburu, Gonzalo Guerrica-Echevarria, Antxon Martínez de Ilarduya, Haritz Sardon and Alejandro J. Müller

Polymers 2021, 13(14), 2263; https://doi.org/10.3390/polym13142263 - 9 Jul 2021

Cited by 19 | Viewed by 4057

Abstract

Isodimorphic behavior is determined by partial inclusion of comonomer segments within the crystalline structure and arises from the comparatively similar repeating chain units of the parental homopolymers. Isodimorphic random copolymers are able to crystallize irrespective of their composition and exhibit a pseudo-eutectic behavior [...] Read more.

Isodimorphic behavior is determined by partial inclusion of comonomer segments within the crystalline structure and arises from the comparatively similar repeating chain units of the parental homopolymers. Isodimorphic random copolymers are able to crystallize irrespective of their composition and exhibit a pseudo-eutectic behavior when their melting point values are plotted as a function of comonomer content. At the pseudo-eutectic point or region, two crystalline phases can coexist. On the right-hand and the left-hand side of the pseudo-eutectic point or region, only one single crystalline phase can form which is very similar to the crystalline structures of the parent homopolymers. This article aims to study the synthesis method, structure, crystallization behavior and mechanical properties of isodimorphic random PBS-ran-PCL copolyesters. Moreover, this study provides a comprehensive analysis of our main recent results on PBS-ran-PCL random copolyesters with three different molecular weights. The results show that the comonomer composition and crystallization conditions are the major factors responsible for the crystalline morphology, crystallization kinetics and mechanical performance of isodimorphic random copolyesters. Our studies demonstrate that in the pseudo-eutectic region, where both crystalline phases can coexist, the crystallization conditions determine the crystalline phase or phases of the copolymer. The relationships between the comonomer composition and mechanical properties are also addressed in this work. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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30 pages, 69195 KiB

Open AccessReview

Polyelectrolyte Multilayer Films Based on Natural Polymers: From Fundamentals to Bio-Applications

by Miryam Criado-Gonzalez, Carmen Mijangos and Rebeca Hernández

Polymers 2021, 13(14), 2254; https://doi.org/10.3390/polym13142254 - 9 Jul 2021

Cited by 50 | Viewed by 7650

Abstract

Natural polymers are of great interest in the biomedical field due to their intrinsic properties such as biodegradability, biocompatibility, and non-toxicity. Layer-by-layer (LbL) assembly of natural polymers is a versatile, simple, efficient, reproducible, and flexible bottom-up technique for the development of nanostructured materials [...] Read more.

Natural polymers are of great interest in the biomedical field due to their intrinsic properties such as biodegradability, biocompatibility, and non-toxicity. Layer-by-layer (LbL) assembly of natural polymers is a versatile, simple, efficient, reproducible, and flexible bottom-up technique for the development of nanostructured materials in a controlled manner. The multiple morphological and structural advantages of LbL compared to traditional coating methods (i.e., precise control over the thickness and compositions at the nanoscale, simplicity, versatility, suitability, and flexibility to coat surfaces with irregular shapes and sizes), make LbL one of the most useful techniques for building up advanced multilayer polymer structures for application in several fields, e.g., biomedicine, energy, and optics. This review article collects the main advances concerning multilayer assembly of natural polymers employing the most used LbL techniques (i.e., dipping, spray, and spin coating) leading to multilayer polymer structures and the influence of several variables (i.e., pH, molar mass, and method of preparation) in this LbL assembly process. Finally, the employment of these multilayer biopolymer films as platforms for tissue engineering, drug delivery, and thermal therapies will be discussed. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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41 pages, 4292 KiB

Open AccessReview

Polyelectrolyte Multilayers on Soft Colloidal Nanosurfaces: A New Life for the Layer-By-Layer Method

by Ana Mateos-Maroto, Irene Abelenda-Núñez, Francisco Ortega, Ramón G. Rubio and Eduardo Guzmán

Polymers 2021, 13(8), 1221; https://doi.org/10.3390/polym13081221 - 9 Apr 2021

Cited by 40 | Viewed by 5732

Abstract

The Layer-by-Layer (LbL) method is a well-established method for the assembly of nanomaterials with controlled structure and functionality through the alternate deposition onto a template of two mutual interacting molecules, e.g., polyelectrolytes bearing opposite charge. The current development of this methodology has allowed [...] Read more.

The Layer-by-Layer (LbL) method is a well-established method for the assembly of nanomaterials with controlled structure and functionality through the alternate deposition onto a template of two mutual interacting molecules, e.g., polyelectrolytes bearing opposite charge. The current development of this methodology has allowed the fabrication of a broad range of systems by assembling different types of molecules onto substrates with different chemical nature, size, or shape, resulting in numerous applications for LbL systems. In particular, the use of soft colloidal nanosurfaces, including nanogels, vesicles, liposomes, micelles, and emulsion droplets as a template for the assembly of LbL materials has undergone a significant growth in recent years due to their potential impact on the design of platforms for the encapsulation and controlled release of active molecules. This review proposes an analysis of some of the current trends on the fabrication of LbL materials using soft colloidal nanosurfaces, including liposomes, emulsion droplets, or even cells, as templates. Furthermore, some fundamental aspects related to deposition methodologies commonly used for fabricating LbL materials on colloidal templates together with the most fundamental physicochemical aspects involved in the assembly of LbL materials will also be discussed. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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20 pages, 2547 KiB

Open AccessReview

Collagen Type I Biomaterials as Scaffolds for Bone Tissue Engineering

by Gustavo A. Rico-Llanos, Sara Borrego-González, Miguelangel Moncayo-Donoso, José Becerra and Rick Visser

Polymers 2021, 13(4), 599; https://doi.org/10.3390/polym13040599 - 17 Feb 2021

Cited by 167 | Viewed by 10646

Abstract

Collagen type I is the main organic constituent of the bone extracellular matrix and has been used for decades as scaffolding material in bone tissue engineering approaches when autografts are not feasible. Polymeric collagen can be easily isolated from various animal sources and [...] Read more.

Collagen type I is the main organic constituent of the bone extracellular matrix and has been used for decades as scaffolding material in bone tissue engineering approaches when autografts are not feasible. Polymeric collagen can be easily isolated from various animal sources and can be processed in a great number of ways to manufacture biomaterials in the form of sponges, particles, or hydrogels, among others, for different applications. Despite its great biocompatibility and osteoconductivity, collagen type I also has some drawbacks, such as its high biodegradability, low mechanical strength, and lack of osteoinductive activity. Therefore, many attempts have been made to improve the collagen type I-based implants for bone tissue engineering. This review aims to summarize the current status of collagen type I as a biomaterial for bone tissue engineering, as well as to highlight some of the main efforts that have been made recently towards designing and producing collagen implants to improve bone regeneration. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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46 pages, 14189 KiB

Open AccessReview

Aggregation-Induced Emission Properties in Fully π-Conjugated Polymers, Dendrimers, and Oligomers

by Antonio Sánchez-Ruiz, Ana Sousa-Hervés, Juan Tolosa Barrilero, Amparo Navarro and Joaquín C. Garcia-Martinez

Polymers 2021, 13(2), 213; https://doi.org/10.3390/polym13020213 - 9 Jan 2021

Cited by 44 | Viewed by 6827

Abstract

Aggregation-Induced Emission (AIE) in organic molecules has recently attracted the attention of the scientific community because of their potential applications in different fields. Compared to small molecules, little attention has been paid to polymers and oligomers that exhibit AIE, despite having excellent properties [...] Read more.

Aggregation-Induced Emission (AIE) in organic molecules has recently attracted the attention of the scientific community because of their potential applications in different fields. Compared to small molecules, little attention has been paid to polymers and oligomers that exhibit AIE, despite having excellent properties such as high emission efficiency in aggregate and solid states, signal amplification effect, good processability and the availability of multiple functionalization sites. In addition to these features, if the molecular structure is fully conjugated, intramolecular electronic interactions between the composing chromophores may appear, thus giving rise to a wealth of new photophysical properties. In this review, we focus on selected fully conjugated oligomers, dendrimers and polymers, and briefly summarize their synthetic routes, fluorescence properties and potential applications. An exhaustive comparison between spectroscopic results in solution and aggregates or in solid state has been collected in almost all examples, and an opinion on the future direction of the field is briefly stated. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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30 pages, 5422 KiB

Open AccessEditor’s ChoiceReview

Insight into the Structure and Dynamics of Polymers by Neutron Scattering Combined with Atomistic Molecular Dynamics Simulations

by Arantxa Arbe, Fernando Alvarez and Juan Colmenero

Polymers 2020, 12(12), 3067; https://doi.org/10.3390/polym12123067 - 21 Dec 2020

Cited by 18 | Viewed by 4402

Abstract

Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application [...] Read more.

Combining neutron scattering and fully atomistic molecular dynamics simulations allows unraveling structural and dynamical features of polymer melts at different length scales, mainly in the intermolecular and monomeric range. Here we present the methodology developed by us and the results of its application during the last years in a variety of polymers. This methodology is based on two pillars: (i) both techniques cover approximately the same length and time scales and (ii) the classical van Hove formalism allows easily calculating the magnitudes measured by neutron scattering from the simulated atomic trajectories. By direct comparison with experimental results, the simulated cell is validated. Thereafter, the information of the simulations can be exploited, calculating magnitudes that are experimentally inaccessible or extending the parameters range beyond the experimental capabilities. We show how detailed microscopic insight on structural features and dynamical processes of various kinds has been gained in polymeric systems with different degrees of complexity, and how intriguing questions as the collective behavior at intermediate length scales have been faced. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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20 pages, 3149 KiB

Open AccessReview

Directed Self-Assembly of Block Copolymers for the Fabrication of Functional Devices

by Christian Pinto-Gómez, Francesc Pérez-Murano, Joan Bausells, Luis Guillermo Villanueva and Marta Fernández-Regúlez

Polymers 2020, 12(10), 2432; https://doi.org/10.3390/polym12102432 - 21 Oct 2020

Cited by 28 | Viewed by 9680

Abstract

Directed self-assembly of block copolymers is a bottom-up approach to nanofabrication that has attracted high interest in recent years due to its inherent simplicity, high throughput, low cost and potential for sub-10 nm resolution. In this paper, we review the main principles of [...] Read more.

Directed self-assembly of block copolymers is a bottom-up approach to nanofabrication that has attracted high interest in recent years due to its inherent simplicity, high throughput, low cost and potential for sub-10 nm resolution. In this paper, we review the main principles of directed self-assembly of block copolymers and give a brief overview of some of the most extended applications. We present a novel fabrication route based on the introduction of directed self-assembly of block copolymers as a patterning option for the fabrication of nanoelectromechanical systems. As a proof of concept, we demonstrate the fabrication of suspended silicon membranes clamped by dense arrays of single-crystal silicon nanowires of sub-10 nm diameter. Resulting devices can be further developed for building up high-sensitive mass sensors based on nanomechanical resonators. Full article

(This article belongs to the Special Issue State-of-the-Art Polymer Science and Technology in Spain (2020,2021))

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