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A topical collection in Polymers (ISSN 2073-4360). This collection belongs to the section "Polymer Chemistry".

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Prof. Dr. Arantxa Eceiza Mendiguren

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Materials + Technologies Research Group (GMT), Department of Chemical and Environmental Engineering, Faculty of Engineering of Gipuzkoa, University of Basque Country, Plz. Europa 1, 20018 Donostia-San Sebastian, Spain
Interests: polyurethanes; valorization of biomass-derived products; biobased polymers; (nano)composites; nanocrystals from polysaccharides; advanced processing technologies; functional polymers; smart materials
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Dr. Lorena Ugarte

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Department of Graphical Design and Project Management, Faculty of Engineering of Gipuzkoa, Eibar Section, University of the Basque Country, 20600 Eibar, Spain
Interests: porous polyurethanes; carbon nanostructures; biobased polymers; nanocomposites; conductive nanostructures; circular economy; additive manufacturing

Dr. Tamara Calvo-Correas

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‘Materials + Technologies’ Research Group (GMT), Department of Chemical and Environmental Engineering, Faculty of Engineering of Gipuzkoa, University of the Basque Country, 20018 Donostia-San Sebastián, Spain
Interests: biobased polymers; nanofillers; nanocomposites; stimulus-responsive polymers; additive manufacturing; waste valorization

Topical Collection Information

Dear Colleagues,

Today, polyurethanes are placed in the seventh position among the most produced polymers worldwide, due to their versatility, which enables the obtaining of materials with different properties just by manipulating their composition. In this way, porous (flexible and rigid foams), dispersion (waterborne polyurethanes), and compact (thermoplastic, thermosetting, elastomers) materials can be obtained, making their use possible in multiple applications. Monomers for polyurethane synthesis can be both of petrochemical and renewable origin. However, due to the depletion of the world’s crude oil stock and economic, environmental, and social concerns, interest in the development of polyurethanes derived from renewable sources has skyrocketed. This collection covers all topics related to the science and technology of polyurethanes, including synthesis, characterization, final applications, and manufacturing techniques (advanced and traditional), among other topics. Research on polyurethanes in a porous and compact form, as well as their (nano)composites, is considered in this topic collection with the aim of sharing knowledge related with the last advances in polyurethane-based materials.

Prof. Dr. Arantxa Eceiza Mendiguren
Dr. Lorena Ugarte
Dr. Tamara Calvo-Correas
Collection Editors

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Keywords

compact polyurethanes
polyurethane foams
synthesis
renewable precursors
(nano)composites
manufacturing
characterization
applications
smart materials

Published Papers (11 papers)

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2024

Jump to: 2023, 2022, 2021

17 pages, 3957 KiB

Open AccessArticle

Synthesis of Polyether, Poly(Ether Carbonate) and Poly(Ether Ester) Polyols Using Double Metal Cyanide Catalysts Bearing Organophosphorus Complexing Agents

by Eun-Gyeong Lee, Chinh-Hoang Tran, Ju-Yeong Heo, So-Young Kim, Ha-Kyung Choi, Byeong-Ryeol Moon and Il Kim

Polymers 2024, 16(6), 818; https://doi.org/10.3390/polym16060818 - 14 Mar 2024

Viewed by 650

Abstract

We developed a series of Zn(II)-Co(III) double metal cyanide (DMC) catalysts with exceptional activity for the ring-opening polymerization of various cyclic monomers by employing diverse organophosphorus compounds as complexing agents (CAs). The chemical structure and composition of DMC catalysts were investigated by commonly used analysis such as infrared and X-ray photoelectron spectroscopies, and elemental analysis combining with in situ NMR analysis to determine the complexation types of organophosphorus compounds the catalyst framework. The resulting catalysts exhibited very high turnover frequencies (up to 631.4 min⁻¹) in the ring-opening polymerization (ROP) of propylene oxide and good efficiency for the ROP of ε-caprolactone. The resultant polyester polyols are suitable to use as an macroinitiator to produce well-defined poly(ester ether) triblock copolymers of 1800–6600 g mol⁻¹ and dispersity of 1.16–1.37. Additionally, the DMC catalysts bearing organophosphorus compounds CAs exhibited remarkable selectivity for the copolymerization of PO with CO₂, yielding poly(ether carbonate) polyols with carbonate contents up to 34.5%. This study contributes to the development of efficient DMC catalytic systems that enable the synthesis of high-quality polyols for various applications. Full article

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2023

Jump to: 2024, 2022, 2021

22 pages, 7056 KiB

Open AccessArticle

Understanding the Interactions between Soft Segments in Polyurethanes: Structural Synergies in Blends of Polyester and Polycarbonate Diol Polyols

by Yuliet Paez-Amieva and José Miguel Martín-Martínez

Polymers 2023, 15(23), 4494; https://doi.org/10.3390/polym15234494 - 22 Nov 2023

Cited by 1 | Viewed by 817

Abstract

There are no previous studies on the interactions between polyols of different nature as a model for understanding the interactions between soft segments in PUs. In this study, different blends of two polyols of different natures (polyester—PE, and polycarbonate diol—CD) and similar molecular weights were prepared and their structural, thermal, surface, viscoelastic, and self-adhesion properties were assessed. Different experimental techniques were used: infrared spectroscopy (ATR-IR), differential scanning calorimetry (DSC), X-ray diffraction, thermal gravimetric analysis (TGA), and plate–plate rheology. PE showed a larger number of structural repeating units and a higher number of polar groups than CD, but the carbonate–carbonate interactions in CD were stronger than the ester–ester interactions in PE. The blending of CD and PE imparted synergic structural properties, particularly in the blends containing less than 50 wt.% PE, they were associated with the disrupt of the carbonate–carbonate interactions in CD and the formation of new ester–carbonate and hydroxyl–carbonate interactions. CD + PE blends with less than 50 wt.% PE exhibited higher glass transition temperatures, a new diffraction peak at 2θ = 24°, one additional thermal degradation at 426–436 °C, and a less-steep decline of the storage moduli. Furthermore, the different interactions between the polyol chains in the blends were also evidenced on their surface properties, and all CD + PE blends showed self-adhesion properties which seemed related to the existence of ester–carbonate and carbonate–carbonate interactions. Full article

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18 pages, 1957 KiB

Open AccessArticle

Soybean-Based Polyol as a Substitute of Fossil-Based Polyol on the Synthesis of Thermoplastic Polyurethanes: The Effect of Its Content on Morphological and Physicochemical Properties

by Juliano R. Ernzen, José A. Covas, Angel Marcos-Fernández, Rudinei Fiorio and Otávio Bianchi

Polymers 2023, 15(19), 4010; https://doi.org/10.3390/polym15194010 - 06 Oct 2023

Viewed by 985

Abstract

Thermoplastic polyurethanes (TPUs) are remarkably versatile polymers due to the wide range of raw materials available for their synthesis, resulting in physicochemical characteristics that can be tailored according to the specific requirements of their final applications. In this study, a renewable bio-based polyol obtained from soybean oil is used for the synthesis of TPU via reactive extrusion, and the influence of the bio-based polyol on the multi-phase structure and properties of the TPU is studied. As raw materials, 4,4′-diphenylmethane (MDI), 1,4-butanediol, a fossil-based polyester polyol, and a bio-based polyol are used. The fossil-based to soybean-based polyol ratios studied are 100/0, 99/1, 95/5, 90/10, 80/20, and 50/50% by weight, respectively. The TPUs were characterized by size exclusion chromatography (SEC), gel content analysis, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and contact angle measurements. The results reveal that incorporating the renewable polyol enhances the compatibility between the rigid and flexible segments of the TPU. However, due to its high functionality, the addition of soybean-based polyol can promote cross-linking. This phenomenon reduces the density of hydrogen bonds within the material, also reducing polarity and restricting macromolecular mobility, as corroborated by higher glass transition temperature (T_g) values. Remarkably, the addition of small amounts of the bio-based polyol (up to 5 wt.% of the total polyol content) results in high-molecular-weight TPUs with lower polarity, combined with suitable processability and mechanical properties, thus broadening the range of applications and improving their sustainability. Full article

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2022

Jump to: 2024, 2023, 2021

16 pages, 5083 KiB

Open AccessArticle

Effect of PEG Molecular Weight on the Polyurethane-Based Quasi-Solid-State Electrolyte for Dye-Sensitized Solar Cells

by Kai Sing Liow, Coswald Stephen Sipaut, Rachel Fran Mansa, Mee Ching Ung and Shamsi Ebrahimi

Polymers 2022, 14(17), 3603; https://doi.org/10.3390/polym14173603 - 01 Sep 2022

Cited by 7 | Viewed by 1762

Abstract

Nanosilica was surface modified with polyaniline and incorporated into polyurethane to form a polymer matrix capable of entrapping a liquid electrolyte and functioning as quasi-solid-state electrolyte in the dye-sensitized solar cells. The effect on the S−PANi distribution, surface morphology, thermal stability, gel content, and structural change after varying the PEG molecular weight of the polyurethane matrix was analyzed. Quasi-solid-state electrolytes were prepared by immersing the polyurethane matrix into a liquid electrolyte and the polymer matrix absorbency, conductivity, and ion diffusion were investigated. The formulated quasi-solid-state electrolytes were applied in dye-sensitized solar cells and their charge recombination, photovoltaic performance, and lifespan were measured. The quasi-solid-state electrolyte with a PEG molecular weight of 2000 gmol⁻¹ (PU−PEG 2000) demonstrated the highest light-to-energy conversion efficiency, namely, 3.41%, with an open-circuit voltage of 720 mV, a short-circuit current of 4.52 mA cm⁻², and a fill factor of 0.63. Full article

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13 pages, 3528 KiB

Open AccessArticle

Construction of Bio-Based Polyurethanes via Olefin Metathesis and Their Thermal Reversible Behavior

by Zizhao Liu, Gaosheng Gu, Junwu Chen, Zhongyu Duan and Binyuan Liu

Polymers 2022, 14(17), 3597; https://doi.org/10.3390/polym14173597 - 31 Aug 2022

Cited by 1 | Viewed by 1358

Abstract

With the increase in awareness of environmental protection and the shortage of oil resources, bio-based polyurethane has attracted increasing attention due to its ecological friendliness, low cost and easy degradation. In this paper, using Eugenol (Eug) derived from plant essential oils as the raw resource, syringyl ethanol (Syol) was prepared, and three monomers were obtained by the reaction of the Eug or Syol with Hexamethylene diisocyanate (HDI)or 4,4′-methylene di (phenyl isocyanate) (MDI), respectively. Then, three novel bio-based polyurethanes, P(Eug-HDI), P(Syol-HDI) and P(Syol-MDI), were synthesized by olefin metathesis polymerization. The effects of the catalyst type, reaction solvent, reaction temperature, reaction time, molar ratio of catalyst dosage and metal salts on the Eug-HDI olefin metathesis polymerization were investigated in detail. Under the optimal conditions, the yield reached 64.7%. It is worth noting that the addition of metal Ni salts could significantly promote the polymerization, in which NiI₂ could increase the yield to 86.6%. Furthermore, the thermal decomposition behaviors of these bio-based polyurethanes were explored by DSC and variable temperature infrared spectroscopy. The test results showed that P(Eug-HDI) had a reversible thermal decomposition and a certain self-healing performance. This paper provided a new method for the preparation of bio-based polyurethane. Full article

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17 pages, 3467 KiB

Open AccessArticle

Synthesis of Nonisocyanate Poly(hydroxy)urethanes from Bis(cyclic carbonates) and Polyamines

by Marc Martínez de Sarasa Buchaca, Felipe de la Cruz-Martínez, Enrique Francés-Poveda, Juan Fernández-Baeza, Luis F. Sánchez-Barba, Andrés Garcés, José A. Castro-Osma and Agustín Lara-Sánchez

Polymers 2022, 14(13), 2719; https://doi.org/10.3390/polym14132719 - 02 Jul 2022

Cited by 6 | Viewed by 2887

Abstract

Nonisocyanate polyurethane materials with pending alcohol groups in the polymeric chain were synthesized by polyaddition reaction of bis(cyclic carbonates) onto diamines. For the platform molecule, 1,4-butanediol bis(glycidyl ether carbonate) (BGBC, 1) was used. The polyaddition reaction of 1 onto a wide range of diamines with different electronic and physical properties was explored. All PHUs were obtained quantitatively after 16 h at 80 °C temperature in MeCN as solvent. The low nucleophilicity of L-lysine has proven unable to ring-open the cyclic carbonate and, thus, no reaction occurred. The addition of DBU or TBD as the catalyst was tested and allows the obtention of the desired PHU. However, the presence of strong bases also led to the formation of polyurea fragments in the new PHU. The different poly(hydroxyurethane) materials were characterized using a wide range of spectroscopic techniques such as NMR, IR, MALDI-ToF, and using GPC studies. The thermal properties of the NIPUs were investigated by DSC and TGA analyses. Moreover, reactions employing different monomer ratios were performed, obtaining novel hydroxycarbamate compounds. Finally, sequential and one-pot experiments were also carried out to synthesize the PHUs polymers in one-step reaction. Full article

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13 pages, 2200 KiB

Open AccessArticle

Theoretical and Experimental Studies of Hydrogen Bonded Dihydroxybenzene Isomers Polyurethane Adhesive Material

by Joyanta K. Saha, Mohammad Mizanur Rahman, Md Bashirul Haq, Dhafer A. Al Shehri and Joonkyung Jang

Polymers 2022, 14(9), 1701; https://doi.org/10.3390/polym14091701 - 21 Apr 2022

Cited by 6 | Viewed by 1996

Abstract

Hydrogen bonding in polyurethane (PU) is imposed by molecular parameters. In this study, the effect of structural isomerism of certain monomers on hydrogen bonding of waterborne polyurethane (WBPU) was studied theoretically and experimentally. Two dihydroxybenzene (DHB)-based structural isomers such as catechol (CC) and hydroquinone (HQ), with different OH positions on the inner benzene core, had been used. Two series of WBPU dispersions were prepared using CC and HQ with defined contents. The binding energies between the catechol (CC)/hydroquinone (HQ) (respective OH group) and urethane/urea were calculated theoretically. By using a density functional theory (DFT) method, it was found that the largest binding energy between the urea and CC was higher than that of urea and HQ. The FT-IR analysis of synthesized polymer was also carried out to compare the results with the theoretical values. The CC-based polymers showed a stronger hydrogen bond both theoretically and experimentally than those for HQ-based polymers. The higher level of hydrogen bond was reflected in their properties of CC-based polymers. The adhesive strength, thermal stability, and hydrophobicity were higher for CC-based materials than those for HQ-based materials. The adhesive strength was increased 25% with the addition of 2.0 wt% CC content. This adhesive strength slightly deviated at a moderately high temperature of 80 °C. Full article

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2021

Jump to: 2024, 2023, 2022

17 pages, 5802 KiB

Open AccessArticle

Bio-Based Rigid Polyurethane Foams Modified with Phosphorus Flame Retardants

by Marcin Zemła, Aleksander Prociak and Sławomir Michałowski

Polymers 2022, 14(1), 102; https://doi.org/10.3390/polym14010102 - 28 Dec 2021

Cited by 13 | Viewed by 2805

Abstract

Rigid polyurethane foams (RPURF) containing a bio-polyol from rapeseed oil and different phosphorus-based flame retardants were obtained. Triethyl phosphate (TEP), dimethyl propane phosphonate (DMPP) and cyclic phosphonates Addforce CT 901 (20 parts per hundred polyol by weight) were used in the synthesis of RPURF. The influence of used flame retardants on foaming process, cell structure, and physical–mechanical properties as well as flammability of RPURF were examined. The addition of flame retardants influenced the parameters of the cellular structure and decreased compressive strength. All obtained foam materials had a low thermal conductivity coefficient, which allows them to be used as thermal insulation. The research results of bio-based RPURF were compared with foams obtained without bio-polyol. All modified materials had an oxygen index above 21 vol%; therefore, they can be classified as self-extinguishing materials. The analysis of parameters obtained after the cone calorimeter test showed that the modified RPURF have a lower tendency to fire development compared to the reference foams, which was particularly noticeable for the materials with the addition of DMPP. Full article

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19 pages, 4426 KiB

Open AccessArticle

Sophorolipid-Based Oligomers as Polyol Components for Polyurethane Systems

by Maresa Sonnabend, Suzanne G. Aubin, Annette M. Schmidt and Marc C. Leimenstoll

Polymers 2021, 13(12), 2001; https://doi.org/10.3390/polym13122001 - 18 Jun 2021

Cited by 3 | Viewed by 2314

Abstract

Due to reasons of sustainability and conservation of resources, polyurethane (PU)-based systems with preferably neutral carbon footprints are in increased focus of research and development. The proper design and development of bio-based polyols are of particular interest since such polyols may have special property profiles that allow the novel products to enter new applications. Sophorolipids (SL) represent a bio-based toolbox for polyol building blocks to yield diverse chemical products. For a reasonable evaluation of the potential for PU chemistry, however, further investigations in terms of synthesis, derivatization, reproducibility, and reactivity towards isocyanates are required. It was demonstrated that SL can act as crosslinker or as plasticizer in PU systems depending on employed stoichiometry. (ω-1)-hydroxyl fatty acids can be derived from SL and converted successively to polyester polyols and PU. Additionally, (ω-1)-hydroxyl fatty acid azides can be prepared indirectly from SL and converted to A/B type PU by Curtius rearrangement. Full article

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22 pages, 5007 KiB

Open AccessArticle

Biodegradable Polyurethanes Based on Castor Oil and Poly (3-hydroxybutyrate)

by Pathikrit Saha, Chanin Khomlaem, Hajer Aloui and Beom Soo Kim

Polymers 2021, 13(9), 1387; https://doi.org/10.3390/polym13091387 - 24 Apr 2021

Cited by 11 | Viewed by 3790

Abstract

Biodegradable polyurethanes (PUs) were produced from castor oil (CO) and poly (3-hydroxybutyrate) diol (PHBD) using hexamethylene diisocyanate as a crosslinking agent. PHBDs of different molecular weights were synthesized through transesterification of bacterial PHB and ethylene glycol by changing the reaction time. The synthesized PHBDs were characterized in terms of Fourier transform infrared and proton nuclear magnetic resonance spectroscopy. A series of PUs at different NCO/OH and CO/PHBD ratios were prepared. The resulting CO/PHBD-based PUs were then characterized in terms of mechanical and thermal properties. Increasing PHBD content significantly increased the tensile strength of CO/PHBD-based PUs by 300% compared to neat CO-based PU. CO/PHBD-based PUs synthetized from short chain PHBD exhibited higher tensile strength compared to those produced from long chain PHBD. As revealed by scanning electron microscopy analysis, such improvement in stiffness of the resulting PUs is due to the good compatibility between CO and PHBD. Increasing PHBD content also increased the crystallinity of the resulting PUs. In addition, higher degradation rates were obtained for CO/PHBD-based PUs synthetized from long chain PHBD compared to neat CO PU and PUs produced from short chain PHBD. Full article

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19 pages, 4600 KiB

Open AccessArticle

Cellulose and Graphene Based Polyurethane Nanocomposites for FDM 3D Printing: Filament Properties and Printability

by Izaskun Larraza, Julen Vadillo, Tamara Calvo-Correas, Alvaro Tejado, Sheila Olza, Cristina Peña-Rodríguez, Aitor Arbelaiz and Arantxa Eceiza

Polymers 2021, 13(5), 839; https://doi.org/10.3390/polym13050839 - 09 Mar 2021

Cited by 19 | Viewed by 3858

Abstract

3D printing has exponentially grown in popularity due to the personalization of each printed part it offers, making it extremely beneficial for the very demanding biomedical industry. This technique has been extensively developed and optimized and the advances that now reside in the development of new materials suitable for 3D printing, which may open the door to new applications. Fused deposition modeling (FDM) is the most commonly used 3D printing technique. However, filaments suitable for FDM must meet certain criteria for a successful printing process and thus the optimization of their properties in often necessary. The aim of this work was to prepare a flexible and printable polyurethane filament parting from a biocompatible waterborne polyurethane, which shows potential for biomedical applications. In order to improve filament properties and printability, cellulose nanofibers and graphene were employed to prepare polyurethane based nanocomposites. Prepared nanocomposite filaments showed altered properties which directly impacted their printability. Graphene containing nanocomposites presented sound enough thermal and mechanical properties for a good printing process. Moreover, these filaments were employed in FDM to obtained 3D printed parts, which showed good shape fidelity. Properties exhibited by polyurethane and graphene filaments show potential to be used in biomedical applications. Full article

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Published Papers (11 papers)

2024

Jump to: 2023, 2022, 2021

2023

Jump to: 2024, 2022, 2021

2022

Jump to: 2024, 2023, 2021

2021

Jump to: 2024, 2023, 2022

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