Feature Papers in Biomacromolecules, Biobased and Biodegradable Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 85413

Special Issue Editors


E-Mail Website
Guest Editor
Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR 54124 Thessaloniki, Greece
Interests: synthesis and characterization of polyesters; development of biobased polymers; biodegradable polymers; polymer composites and nanocomposites; synthesis and characterization of copolymers; polymer blends; recycling of polymers with various techniques; enzymatic hydrolysis studies; modification of natural polymers; polymer for wastewater treatment pollutant removal; polymers for tissue engineering and drug delivery applications; drug–polymer solid dispersions; drug targeting; drug nanoencapsulation and microencapsulation
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Biopolymers Group, Centro de Investigación en Alimentación y Desarrollo, Hermosillo 83304, Mexico
Interests: polysaccharides and their derivatization; polyelectrolyte complexes; smart polymers; functional polymeric materials and nanomaterials for biomedical and biotechnological applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Global mass production of plastics started in the 1950s, with an estimated total number of 8.3 to 9.1 million metric tons (Mt) already manufactured up to now. Around only 9% of these have been recycled and 12% incinerated, whereas the remaining 79% has now been accumulated in landfills or the natural environment, causing serious environmental issues. The worldwide demand for sustainability and green economy leads research interests in the field of polymer technology in three different directions:

  • To replace the use of fossil-derived polymers in various applications with neat biomacromolecules or their derivatives,
  • To employ green synthesis processes in order to recover and/or synthesize monomers derived from renewable resources (biobased monomers), and
  • To produce new eco-friendly, biodegradable in a short time, polymers based on these monomers.

This Special Issue of the international open access journal Polymers aims in particular at collecting cutting-edge, state-of-the-art, original full-length research articles and critical or tutorial reviews on the topic of ‘Biomacromolecules and Biobased and Biodegradable Polymers, including but not limited to:

  • Properties of biomacromolecules and their applications in several fields
  • Synthesis and characterization of macromolecules derivatives with desired properties
  • Eco-friendly processes to recover biobased monomers from biomass
  • Biomass treatment to produce monomers appropriate for polymer synthesis
  • Synthesis, properties and applications of biobased and biodegradable polymers and copolymers
  • Development of biocomposites and nanocomposites
  • Biodegradable blends
  • Biobased polymer recycling methods and depolymerization techniques
  • Advantages of biomacromolecules and/or biobased and biodegradable polymers

Prof. Dr. Dimitrios Bikiaris
Dr. Waldo M. Argüelles-Monal
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Biomass
  • Biobased monomers
  • Eco-friendly polymers
  • Biomacromolecules
  • Biobased Polymers
  • Biodegradable Polymers
  • Polymer applications

Published Papers (16 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

10 pages, 1162 KiB  
Article
Rheological Properties of Cholesteric Liquid Crystal with Visible Reflection from an Etherified Hydroxypropyl Cellulose Derivative
by Kazuma Matsumoto, Yuki Ogiwara, Naoto Iwata and Seiichi Furumi
Polymers 2022, 14(10), 2059; https://doi.org/10.3390/polym14102059 - 18 May 2022
Cited by 2 | Viewed by 2093
Abstract
Optical properties of hydroxypropyl cellulose (HPC) derivatives have been widely investigated for their ability to exhibit cholesteric liquid crystal (CLC) phase. However, there are only a limited number of studies on their rheological properties even though they are quite important for the applications [...] Read more.
Optical properties of hydroxypropyl cellulose (HPC) derivatives have been widely investigated for their ability to exhibit cholesteric liquid crystal (CLC) phase. However, there are only a limited number of studies on their rheological properties even though they are quite important for the applications of such HPC derivatives to the versatile CLC photonic devices. In this article, we report on the optical and rheological properties of an HPC derivative possessing pentyl ether groups in the side-chains. The etherified HPC derivative exhibited thermotropic CLC phase with light reflection in the temperature range between 25 °C and 120 °C. After the HPC derivative was heated once at isotropic phase, followed by being cooled to the CLC phase, the reflection peak could not be observed, even at the CLC phase. At this stage, the HPC derivative exhibited solid-like rheological responses compared to that of sheared at a constant shear rate of 1.0 s−1. Such differences in the optical and rheological properties of the HPC derivative can be ascribed to the difference in CLC orientation state. From the rheological results, the etherified HPC derivative showed liquid-like behavior rather than the esterified HPC derivatives. This evidence provides a promising clue for fabricating high-quality CLC devices by the facile CLC orientation. Full article
Show Figures

Graphical abstract

8 pages, 3027 KiB  
Communication
Single-Chain Mechanical Properties of Gelatin: A Single-Molecule Study
by Lu Qian, Kai Zhang, Xin Guo, Junyu Zhou and Miao Yu
Polymers 2022, 14(5), 869; https://doi.org/10.3390/polym14050869 - 23 Feb 2022
Cited by 2 | Viewed by 1840
Abstract
Gelatin is an important natural biological resource with a wide range of applications in the pharmaceutical, industrial and food industries. We investigated the single-chain behaviors of gelatin by atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS), and found that gelatin exists as long [...] Read more.
Gelatin is an important natural biological resource with a wide range of applications in the pharmaceutical, industrial and food industries. We investigated the single-chain behaviors of gelatin by atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS), and found that gelatin exists as long chains by fitting with the M-FJC model. By comparing the single-chain elasticity in a nonpolar organic solvent (nonane) and DI water, it was surprising to find that there was almost no difference in the single-chain elasticity of gelatin in nonane and DI water. Considering the specificity of gelatin solubility and the solvent size effect of nonane molecules, when a single gelatin chain is pulled into loose nonane, dehydration does not occur due to strong binding water interactions. Gelatin chains can only interact with water molecules at high temperatures; therefore, no further interaction of single gelatin chains with water molecules occurred at the experimental temperature. This eventually led to almost no difference in the single-chain F–E curves under the two conditions. It is expected that our study will enable the deep exploration of the interaction between water molecules and gelatin and provide a theoretical basis and experimental foundation for the design of gelatin-based materials with more functionalities. Full article
Show Figures

Figure 1

13 pages, 1252 KiB  
Article
Statistical Modeling and Optimization of the Drawing Process of Bioderived Polylactide/Poly(dodecylene furanoate) Wet-Spun Fibers
by Daniele Rigotti, Giulia Fredi, Davide Perin, Dimitrios N. Bikiaris, Alessandro Pegoretti and Andrea Dorigato
Polymers 2022, 14(3), 396; https://doi.org/10.3390/polym14030396 - 20 Jan 2022
Cited by 10 | Viewed by 1684
Abstract
Drawing is a well-established method to improve the mechanical properties of wet-spun fibers, as it orients the polymer chains, increases the chain density, and homogenizes the microstructure. This work aims to investigate how drawing variables, such as the draw ratio, drawing speed, and [...] Read more.
Drawing is a well-established method to improve the mechanical properties of wet-spun fibers, as it orients the polymer chains, increases the chain density, and homogenizes the microstructure. This work aims to investigate how drawing variables, such as the draw ratio, drawing speed, and temperature affect the elastic modulus (E) and the strain at break (εB) of biobased wet-spun fibers constituted by neat polylactic acid (PLA) and a PLA/poly(dodecamethylene 2,5-furandicarboxylate) (PDoF) (80/20 wt/wt) blend. Drawing experiments were conducted with a design of experiment (DOE) approach following a 24 full factorial design. The results of the quasi-static tensile tests on the drawn fibers, analyzed by the analysis of variance (ANOVA) and modeled through the response surface methodology (RSM), highlight that the presence of PDoF significantly lowers E, which instead is maximized if the temperature and draw ratio are both low. On the other hand, εB is enhanced when the drawing is performed at a high temperature. Finally, a genetic algorithm was implemented to find the optimal combination of drawing parameters that maximize both E and εB. The resulting Pareto curve highlights that the temperature influences the mechanical results only for neat PLA fibers, as the stiffness increases by drawing at lower temperatures, while optimal Pareto points for PLA/PDoF fibers are mainly determined by the draw ratio and the draw rate. Full article
Show Figures

Figure 1

12 pages, 5783 KiB  
Article
In Vitro Cellular Uptake and Transfection of Oligoarginine-Conjugated Glycol Chitosan/siRNA Nanoparticles
by Eun-Ju Jeong, Jangwook Lee, Hyun-Seung Kim and Kuen-Yong Lee
Polymers 2021, 13(23), 4219; https://doi.org/10.3390/polym13234219 - 1 Dec 2021
Cited by 6 | Viewed by 2031
Abstract
Chitosan and its derivatives have been extensively utilized in gene delivery applications because of their low toxicity and positively charged characteristics. However, their low solubility under physiological conditions often limits their application. Glycol chitosan (GC) is a derivative of chitosan that exhibits excellent [...] Read more.
Chitosan and its derivatives have been extensively utilized in gene delivery applications because of their low toxicity and positively charged characteristics. However, their low solubility under physiological conditions often limits their application. Glycol chitosan (GC) is a derivative of chitosan that exhibits excellent solubility in physiological buffer solutions. However, it lacks the positive characteristics of a gene carrier. Thus, we hypothesized that the introduction of oligoarginine peptide to GC could improve the formation of complexes with siRNA, resulting in enhanced uptake by cells and increased transfection efficiency in vitro. A peptide with nine arginine residues and 10 glycine units (R9G10) was successfully conjugated to GC, which was confirmed by infrared spectroscopy, 1H NMR spectroscopy, and elemental analysis. The physicochemical characteristics of R9G10-GC/siRNA complexes were also investigated. The size and surface charge of the R9G10-GC/siRNA nanoparticles depended on the amount of R9G10 coupled to the GC. In addition, the R9G10-GC/siRNA nanoparticles showed improved uptake in HeLa cells and enhanced in vitro transfection efficiency while maintaining low cytotoxicity determined by the MTT assay. Oligoarginine-modified glycol chitosan may be useful as a potential gene carrier in many therapeutic applications. Full article
Show Figures

Graphical abstract

15 pages, 3099 KiB  
Article
Synthesis, Characterization and Structure Properties of Biobased Hybrid Copolymers Consisting of Polydiene and Polypeptide Segments
by Nikolaos Politakos, Ioannis Moutsios, Gkreti-Maria Manesi, Dimitrios Moschovas, Ainur F. Abukaev, Evgeniia A. Nikitina, Galder Kortaberria, Dimitri A. Ivanov and Apostolos Avgeropoulos
Polymers 2021, 13(21), 3818; https://doi.org/10.3390/polym13213818 - 4 Nov 2021
Cited by 1 | Viewed by 1898
Abstract
Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton [...] Read more.
Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and β-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and β-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and β-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix. Full article
Show Figures

Graphical abstract

12 pages, 2997 KiB  
Article
Fully Biodegradable Poly(hexamethylene succinate)/Cellulose Nanocrystals Composites with Enhanced Crystallization Rate and Mechanical Property
by Siyu Pan and Zhaobin Qiu
Polymers 2021, 13(21), 3667; https://doi.org/10.3390/polym13213667 - 25 Oct 2021
Cited by 6 | Viewed by 1740
Abstract
Through a common solution and casting method, low contents of cellulose nanocrystals (CNC) reinforced biodegradable poly(hexamethylene succinate) based composites were successfully prepared for the first time. CNC homogeneously dispersed in PHS matrix at low loadings, showing no obvious aggregation. PHS/CNC composites showed high [...] Read more.
Through a common solution and casting method, low contents of cellulose nanocrystals (CNC) reinforced biodegradable poly(hexamethylene succinate) based composites were successfully prepared for the first time. CNC homogeneously dispersed in PHS matrix at low loadings, showing no obvious aggregation. PHS/CNC composites showed high thermal stability as PHS. As a heterogeneous nucleating agent, CNC promoted the crystallization of PHS under both nonisothermal and isothermal crystallization conditions. In addition, the higher the CNC content, the faster the crystallization of PHS/CNC composites. The heterogeneous nucleating agent role of CNC was directly confirmed by the crystalline morphology study; moreover, the crystal structure of PHS remained unmodified despite the presence of CNC. As a reinforcing nanofiller, CNC also improved the mechanical property of PHS, especially the Young’s modulus and yield strength. In brief, low contents of CNC may improve both the crystallization and mechanical property of PHS, providing an easy method to tune the physical property and promote the wider application of biodegradable polymers. Full article
Show Figures

Figure 1

12 pages, 3563 KiB  
Article
Comparison of Surface Functionalization of PLGA Composite to Immobilize Extracellular Vesicles
by Jiwon Woo, Kyoung-Won Ko, Seung-Gyu Cha, Yun Heo and Dong Keun Han
Polymers 2021, 13(21), 3643; https://doi.org/10.3390/polym13213643 - 22 Oct 2021
Cited by 5 | Viewed by 2123
Abstract
Endothelialization by materials provides a promising approach for the rapid re-endothelialization of a cardiovascular implantation. Although previous studies have focused on improving endothelialization through the immobilization of bioactive molecules onto the surface of biodegradable implants, comparative studies of effective surface modification have not [...] Read more.
Endothelialization by materials provides a promising approach for the rapid re-endothelialization of a cardiovascular implantation. Although previous studies have focused on improving endothelialization through the immobilization of bioactive molecules onto the surface of biodegradable implants, comparative studies of effective surface modification have not yet been reported. Here, we conducted a comparative study on the surface modification of poly(lactide-co-glycolide) (PLGA)-based composites to graft mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) using three different materials, fibronectin (FN), polyethylenimine (PEI), and polydopamine (PDA), which have different bond strengths of ligand–receptor interaction, ionic bond, and covalent bond, respectively. Further in vitro analysis exhibited that MSC-EVs released from all modified films sustainably, but the MSC-EVs grafted onto the surface coated with PEI are more effective than other groups in increasing angiogenesis and reducing the inflammatory responses in endothelial cells. Therefore, the overall results demonstrated that PEI is a desirable coating reagent for the immobilization of MSC-EVs on the surface of biodegradable implants. Full article
Show Figures

Graphical abstract

17 pages, 3682 KiB  
Article
Superior Gas Barrier Properties of Biodegradable PBST vs. PBAT Copolyesters: A Comparative Study
by Pengkai Qin, Linbo Wu, Bogeng Li, Naixiang Li, Xiaohu Pan and Junming Dai
Polymers 2021, 13(19), 3449; https://doi.org/10.3390/polym13193449 - 8 Oct 2021
Cited by 26 | Viewed by 3551
Abstract
As a bio-based counterpart of poly(butylene adipate-co-terephthalate) (PBAT), the well-known commercially available biodegradable aliphatic-aromatic copolyester, poly(butylene succinate-co-terephthalate) (PBST) has comparable physical and mechanical properties, but its gas barrier properties, which are very important for packaging material and mulch film applications, have not yet [...] Read more.
As a bio-based counterpart of poly(butylene adipate-co-terephthalate) (PBAT), the well-known commercially available biodegradable aliphatic-aromatic copolyester, poly(butylene succinate-co-terephthalate) (PBST) has comparable physical and mechanical properties, but its gas barrier properties, which are very important for packaging material and mulch film applications, have not yet been reported in literature. In this paper, the O2, CO2 and water vapor barrier properties of PBST vs. PBAT were comparatively studied and reported for the first time. Theoretical calculation of O2 and CO2 permeation coefficients via group contribution method was also conducted. The barrier properties of PBST show clear copolymer composition dependence due to different contribution of BS and BT repeat units and composition-dependent crystallinity. Comparing with PBAT, PBST with close copolymer and three-phase (crystalline, amorphous, rigid amorphous) compositions shows 3.5 times O2 and CO2 and 1.5 times water vapor barrier properties. The slower segment movement and less free volume of PBST, and therefore slower gas diffusion in PBST, accounts for its superior O2 and CO2 barrier, while the better hydrophilicity of PBST counteracts partial contribution of slower segment movement so that the improvement in water vapor barrier is not as high as in O2 and CO2 barrier. Full article
Show Figures

Graphical abstract

17 pages, 5968 KiB  
Article
Bioactivated Oxidized Polyvinyl Alcohol towards Next-Generation Nerve Conduits Development
by Elena Stocco, Silvia Barbon, Alessia Lamanna, Enrico De Rose, Annj Zamuner, Deborah Sandrin, Martina Marsotto, Alessandro Auditore, Grazia M. L. Messina, Antonino Licciardello, Giovanna Iucci, Veronica Macchi, Raffaele De Caro, Monica Dettin and Andrea Porzionato
Polymers 2021, 13(19), 3372; https://doi.org/10.3390/polym13193372 - 30 Sep 2021
Cited by 9 | Viewed by 2011
Abstract
The limitations and difficulties that nerve autografts create in normal nerve function recovery after injury is driving research towards using smart materials for next generation nerve conduits (NCs) setup. Here, the new polymer partially oxidized polyvinyl alcohol (OxPVA) was assayed to verify its [...] Read more.
The limitations and difficulties that nerve autografts create in normal nerve function recovery after injury is driving research towards using smart materials for next generation nerve conduits (NCs) setup. Here, the new polymer partially oxidized polyvinyl alcohol (OxPVA) was assayed to verify its future potential as a bioactivated platform for advanced/effective NCs. OxPVA-patterned scaffolds (obtained by a 3D-printed mold) with/without biochemical cues (peptide IKVAV covalently bound (OxPVA-IKVAV) or self-assembling peptide EAK (sequence: AEAEAKAKAEAEAKAK), mechanically incorporated (OxPVA+EAK) versus non-bioactivated scaffold (peptide-free OxPVA (PF-OxPVA) supports, OxPVA without IKVAV and OxPVA without EAK control scaffolds) were compared for their biological effect on neuronal SH-SY5Y cells. After cell seeding, adhesion/proliferation, mediated by (a) precise control over scaffolds surface ultrastructure; (b) functionalization efficacy guaranteed by bioactive cues (IKVAV/EAK), was investigated by MTT assay at 3, 7, 14 and 21 days. As shown by the results, the patterned groove alone stimulates colonization by cells; however, differences were observed when comparing the scaffold types over time. In the long period (21 days), patterned OxPVA+EAK scaffolds distinguished in bioactivity, assuring a significantly higher total cell amount than the other groups. Experimental evidence suggests patterned OxPVA-EAK potential for NCs device fabrication. Full article
Show Figures

Graphical abstract

23 pages, 7183 KiB  
Article
Composites of Poly(vinyl chloride) with Residual Hops after Supercritical Extraction in CO2
by Jacek Mirowski, Rafał Oliwa, Mariusz Oleksy, Edward Rój, Jolanta Tomaszewska, Kamila Mizera and Joanna Ryszkowska
Polymers 2021, 13(16), 2736; https://doi.org/10.3390/polym13162736 - 15 Aug 2021
Cited by 5 | Viewed by 3261
Abstract
The common applications of poly(vinyl chloride) (PVC) in many industries mean that the topic of recycling and disposal of post-consumer waste is still very important. One of the methods of reducing the negative impact of PVC waste on the natural environment is to [...] Read more.
The common applications of poly(vinyl chloride) (PVC) in many industries mean that the topic of recycling and disposal of post-consumer waste is still very important. One of the methods of reducing the negative impact of PVC waste on the natural environment is to use technological or post-consumer waste of this polymer to produce new composite materials with favorable utility properties, with the addition of natural fillers, among which agro-waste, including hop residue, is deserving of special attention. In this study, the effect of the addition of residual hops (H) on the mechanical and physicochemical properties of poly(vinyl chloride) was investigated. PVC blends containing 10, 20 and 30 wt % of hop residue were mixed in an extruder, while the specimens were obtained by the injection molding method. It was observed that the addition of H increased their thermostability, as shown by a Congo red test. Furthermore, thermogravimetric analysis showed that the degradation rate of PVC/H composites in the first and second stages of decomposition was lower in comparison with unmodified PVC. In turn, composite density, impact strength and tensile strength decreased significantly with an increasing concentration of filler in the PVC matrix. At the same time, their Young’s modulus, flexural modulus and Rockwell hardness increased. Flame resistance tests showed that with an increasing residual hop content, the limiting oxygen index (LOI) decreased by 9.0; 11.8 and 13.6%, respectively, compared to unfilled PVC (LOI = 37.4%). In addition, the maximum heat release rate (pHRR) decreased with an increasing filler content by about 16, 24 and 31%, respectively. Overall, these composites were characterized by a good burning resistance and had a flammability rating of V0 according to the UL94 test. Full article
Show Figures

Figure 1

11 pages, 806 KiB  
Article
Synthesis of Poly(Lactic Acid-co-Glycolic Acid) Copolymers with High Glycolide Ratio by Ring-Opening Polymerisation
by Alastair Little, Alan M. Wemyss, David M. Haddleton, Bowen Tan, Zhaoyang Sun, Yang Ji and Chaoying Wan
Polymers 2021, 13(15), 2458; https://doi.org/10.3390/polym13152458 - 26 Jul 2021
Cited by 13 | Viewed by 5950
Abstract
The rise in demand for biodegradable plastic packaging with high barrier properties has spurred interest in poly(lactic acid-co-glycolic acid) (PLGA) copolymers with a relatively high glycolide content. In this work, we examined how reaction conditions affect the synthesis of PLGA25 (L:G [...] Read more.
The rise in demand for biodegradable plastic packaging with high barrier properties has spurred interest in poly(lactic acid-co-glycolic acid) (PLGA) copolymers with a relatively high glycolide content. In this work, we examined how reaction conditions affect the synthesis of PLGA25 (L:G 25:75) through the ring-opening polymerisation of d-l-lactide (L) and glycolide (G), using tin 2-ethylhexanoate (Sn(Oct)2) as the catalyst and 1-dodecanol as the initiator. The effects of varying the initiator concentration, catalyst concentration, reaction time, and temperature on the molecular weight, monomer conversion, and thermal properties of PLGA25 were investigated. Increasing the reaction temperature from 130 to 205 °C significantly reduced the time required for high monomer conversions but caused greater polymer discolouration. Whilst increasing the [M]:[C] from 6500:1 to 50,000:1 reduced polymer discolouration, it also resulted in longer reaction times and higher reaction temperatures being required to achieve high conversions. High Mn and Mw values of 136,000 and 399,000 g mol−1 were achieved when polymerisations were performed in the solid state at 150 °C using low initiator concentrations. These copolymers were analysed using high temperature SEC at 80 °C, employing DMSO instead of HFIP as the eluent. Full article
Show Figures

Graphical abstract

22 pages, 10290 KiB  
Article
Effect of Cellulose and Cellulose Nanocrystal Contents on the Biodegradation, under Composting Conditions, of Hierarchical PLA Biocomposites
by Luciano Miguel Galera Manzano, Miguel Ángel Ruz Cruz, Nora Magally Moo Tun, Alex Valadez González and José Herminsul Mina Hernandez
Polymers 2021, 13(11), 1855; https://doi.org/10.3390/polym13111855 - 2 Jun 2021
Cited by 10 | Viewed by 2810
Abstract
In this work, the effect of microfibrillated cellulose (MFC) and cellulose nanocrystals (CNCs) on the biodegradation, under composting conditions, of hierarchical PLA biocomposites (HBCs) was studied using a full 22 factorial experimental design. The HBCs were prepared by extrusion processing and were [...] Read more.
In this work, the effect of microfibrillated cellulose (MFC) and cellulose nanocrystals (CNCs) on the biodegradation, under composting conditions, of hierarchical PLA biocomposites (HBCs) was studied using a full 22 factorial experimental design. The HBCs were prepared by extrusion processing and were composted for 180 days. At certain time intervals, the specimens were removed from the compost for their chemical, thermal and morphological characterizations. An ANOVA analysis was carried out at different composting times to study MFC and CNCs’ effects on biodegradation. The specimen’s mass loss and molecular weight loss were selected as independent variables. The results show that the presence of MFC enhances the PLA biodegradation, while with CNCs it decreases. However, when both cellulosic fibers are present, a synergistic effect was evident—i.e., in the presence of the MFC, the inclusion of the CNCs accelerates the HBCs biodegradation. Analysis of the ANOVA results confirms the relevance of the synergistic role between both cellulosic fibers over the HBC biodegradation under composting conditions. The results also suggest that during the first 90 days of incubation, the hydrolytic PLA degradation prevails, whereas, beyond that, the enzymatic microbial biodegradation dominates. The SEM results show MFC’s presence enhances the surface biodeterioration to a greater extent than the CNCs and that their simultaneous presence enhances PLA biodegradation. The SEM results also indicate that the biodegradation process begins from hydrophilic cellulosic fibers and promotes PLA biodegradation. Full article
Show Figures

Figure 1

18 pages, 3880 KiB  
Article
Optimization of Polysaccharide Hydrocolloid for the Development of Bioink with High Printability/Biocompatibility for Coextrusion 3D Bioprinting
by Wonseop Lim, Seon Young Shin, Jae Min Cha and Hojae Bae
Polymers 2021, 13(11), 1773; https://doi.org/10.3390/polym13111773 - 28 May 2021
Cited by 22 | Viewed by 3213
Abstract
Bioink is the main component of 3D bioprinting process and is crucial for the generation of sophisticated 3D structures through precise spatial control. Therefore, bioink’s core material must have characteristics that support good printability as well as biocompatibility. However, there is a lack [...] Read more.
Bioink is the main component of 3D bioprinting process and is crucial for the generation of sophisticated 3D structures through precise spatial control. Therefore, bioink’s core material must have characteristics that support good printability as well as biocompatibility. However, there is a lack of bioinks developed that satisfy these characteristics at the same time. In this work, our aim was to develop a bioink that satisfies the needs for both printability and biocompatibility through effectively utilizing hydrocolloid materials. To do so, carboxymethyl cellulose (CMC) and xanthan gum (XG) were used to maintain proper shear properties at high pressure and increase the mechanical properties of bioink without excessively affecting the viscosity, and thus enhance printability and biocompatibility. Various bioink formulations were applied to 3D printing process and the printability optimization was carried out through adjusting the hydrocolloid contents in connection with different cross-linking methods. Through utilization of hydrocolloids, the printability and rheological analysis showed that the bioink has improved mechanical properties and confirmed that the printability could be adjusted by controlling the CMC and XG ratio. Moreover, cell viability and immunocytochemical staining analyses showed cell compatibility with enhanced stability. The proposed convenient method to control the printability with improved biocompatibility suggests more appropriate use of bioink for co-axial 3D bioprinting. Full article
Show Figures

Graphical abstract

13 pages, 3461 KiB  
Article
Mechanical Properties of Biocomposites Using Polypropylene and Sesame Oil Cake
by Ju-Heon Lee, Dong Hwi Kim, Youngjae Ryu, Kwan Hoon Kim, Seong Ho Jeong, Tae Yang Kim and Sung Woon Cha
Polymers 2021, 13(10), 1602; https://doi.org/10.3390/polym13101602 - 15 May 2021
Cited by 4 | Viewed by 2586
Abstract
Sesame oil cakes (SOC) produced during sesame oil production can be classified as plant residues. This study aims to use SOC as a composite material for injection molding. A biocomposite containing polypropylene (PP) and SOC, namely PP/SOC, was developed and its mechanical properties [...] Read more.
Sesame oil cakes (SOC) produced during sesame oil production can be classified as plant residues. This study aims to use SOC as a composite material for injection molding. A biocomposite containing polypropylene (PP) and SOC, namely PP/SOC, was developed and its mechanical properties were evaluated. PP/SOC is largely divided into Homo-PP/SOC (HPS) based on Homo-PP and Block-PP/SOC (BPS) based on block-PP. The specimens containing 0–50 wt% SOC were prepared through extrusion and injection molding. As a result of the evaluation, SOC acted as a reinforcement in the matrix, and HPS and BPS showed improved flexural modulus by 36.4% and 37.3% compared to the neat PP, respectively. Tensile strength, on the other hand, decreased by 58% and 55.1%, respectively. To analyze the cause of this, cross-section observation was conducted through scanning electron microscope (SEM), and phase separation and voids were confirmed to be the cause of this. Impact strength of PP/SOC tended to vary depending on the type of matrix. HPS increased by 30.9% compared to neat PP, and BPS decreased by 25%. This tendency difference appears to be the result of SOC inhibiting crystallization of PP, and it has been confirmed through x ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis. Moreover, PP/SOC can be manufactured at a low cost and is environmentally friendly because it utilizes SOC, a plant residue. It can also be applied to commercial products, such as food packaging, owing to its good moldability and improved mechanical properties. Full article
Show Figures

Figure 1

Review

Jump to: Research

34 pages, 1320 KiB  
Review
Potential Uses of Musaceae Wastes: Case of Application in the Development of Bio-Based Composites
by Juan Pablo Castañeda Niño, José Herminsul Mina Hernandez and Alex Valadez González
Polymers 2021, 13(11), 1844; https://doi.org/10.3390/polym13111844 - 2 Jun 2021
Cited by 10 | Viewed by 3776
Abstract
The Musaceae family has significant potential as a source of lignocellulosic fibres and starch from the plant’s bunches and pseudostems. These materials, which have traditionally been considered waste, can be used to produce fully bio-based composites to replace petroleum-derived synthetic plastics in some [...] Read more.
The Musaceae family has significant potential as a source of lignocellulosic fibres and starch from the plant’s bunches and pseudostems. These materials, which have traditionally been considered waste, can be used to produce fully bio-based composites to replace petroleum-derived synthetic plastics in some sectors such as packaging, the automotive industry, and implants. The fibres extracted from Musaceae have mechanical, thermal, and physicochemical properties that allow them to compete with other natural fibres such as sisal, henequen, fique, and jute, among others, which are currently used in the preparation of bio-based composites. Despite the potential use of Musaceae residues, there are currently not many records related to bio-based composites’ developments using starches, flours, and lignocellulosic fibres from banana and plantain pseudostems. In this sense, the present study focusses on the description of the Musaceae components and the review of experimental reports where both lignocellulosic fibre from banana pseudostem and flour and starch are used with different biodegradable and non-biodegradable matrices, specifying the types of surface modification, the processing techniques used, and the applications achieved. Full article
Show Figures

Figure 1

50 pages, 8474 KiB  
Review
Poly(lactic Acid): A Versatile Biobased Polymer for the Future with Multifunctional Properties—From Monomer Synthesis, Polymerization Techniques and Molecular Weight Increase to PLA Applications
by Evangelia Balla, Vasileios Daniilidis, Georgia Karlioti, Theocharis Kalamas, Myrika Stefanidou, Nikolaos D. Bikiaris, Antonios Vlachopoulos, Ioanna Koumentakou and Dimitrios N. Bikiaris
Polymers 2021, 13(11), 1822; https://doi.org/10.3390/polym13111822 - 31 May 2021
Cited by 260 | Viewed by 42507
Abstract
Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to [...] Read more.
Environmental problems, such as global warming and plastic pollution have forced researchers to investigate alternatives for conventional plastics. Poly(lactic acid) (PLA), one of the well-known eco-friendly biodegradables and biobased polyesters, has been studied extensively and is considered to be a promising substitute to petroleum-based polymers. This review gives an inclusive overview of the current research of lactic acid and lactide dimer techniques along with the production of PLA from its monomers. Melt polycondensation as well as ring opening polymerization techniques are discussed, and the effect of various catalysts and polymerization conditions is thoroughly presented. Reaction mechanisms are also reviewed. However, due to the competitive decomposition reactions, in the most cases low or medium molecular weight (MW) of PLA, not exceeding 20,000–50,000 g/mol, are prepared. For this reason, additional procedures such as solid state polycondensation (SSP) and chain extension (CE) reaching MW ranging from 80,000 up to 250,000 g/mol are extensively investigated here. Lastly, numerous practical applications of PLA in various fields of industry, technical challenges and limitations of PLA use as well as its future perspectives are also reported in this review. Full article
Show Figures

Graphical abstract

Back to TopTop