Special Issue "Feature Papers of Green and Sustainable Chemistry in Polymer Science"

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Circular and Green Polymer Chemistry".

Deadline for manuscript submissions: closed (20 March 2021).

Special Issue Editors

Prof. Dr. Antonio Pizzi
E-Mail Website
Guest Editor
LERMAB, Laboratoire d’Etude et de Recherche sur le MAteriau Bois, Université de Lorraine, 27 rue Philippe Seguin, CS60036, 88021 Epinal, France
Interests: polycondensation; resins; adhesives; thermosetting polymers for adhesives; natural polymers for industrial use; fibrous and wood composites; polymeric wood constituents (cellulose, lignin, tannins)
Special Issues and Collections in MDPI journals
Prof. Dr. Frank Wiesbrock
E-Mail Website
Guest Editor
PCCL - Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben, Austria
Interests: functional polymers; ring-opening polymerizations; crosslinked polymers; biopolyesters; polymeranalogous modifications
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Today’s intense search for alternatives to fossil-derived polymeric materials is evident in the whole field of polymer chemistry and particularly focusses on materials from renewable resources, which are supposed to be of superior performance and lower cost, and based on novel approaches.

This special issue of the open-access journal Polymers aims at collecting cutting-edge original research papers and reviews on the topic of ‘green and sustainable polymer chemistry, comprising

  • novel approaches and concepts, both conceptual or applied,
  • monomer syntheses from renewable resources,
  • polymerizations in solvent-free media or in solvents/media that can be recycled,
  • alternatives to environmentally harmful reaction conditions and catalysts,
  • fundamental chemistry for the design and development of ‘green’ polymers, and
  • mechanisms, applications and technologies of ‘green’ bio-derived polymers.

We as well look forward to receiving publications describing synthetic/bio-derived ‘semi-green’ polymers.

Prof. Dr. Antonio Pizzi
Prof. Dr. Frank Wiesbrock
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 papers will be 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 2200 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

  • Green Polymers
  • Polymer adhesives
  • renewable resources
  • bio-derived polymers
  • Bioapplications

Published Papers (19 papers)

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Research

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Article
Isolation of Two Bacterial Species from Argan Soil in Morocco Associated with Polyhydroxybutyrate (PHB) Accumulation: Current Potential and Future Prospects for the Bio-Based Polymer Production
Polymers 2021, 13(11), 1870; https://doi.org/10.3390/polym13111870 - 04 Jun 2021
Viewed by 349
Abstract
The environmental issues caused by the impacts of synthetic plastics use and derived wastes are arising the attention to bio-based plastics, natural polymers produced from renewable resources, including agricultural, industrial, and domestic wastes. Bio-based plastics represent a potential alternative to petroleum-based materials, due [...] Read more.
The environmental issues caused by the impacts of synthetic plastics use and derived wastes are arising the attention to bio-based plastics, natural polymers produced from renewable resources, including agricultural, industrial, and domestic wastes. Bio-based plastics represent a potential alternative to petroleum-based materials, due to the insufficient availability of fossil resources in the future and the affordable low cost of renewable ones that might be consumed for the biopolymer synthesis. Among the polyhydroxyalkanoates (PHA), the polyhydroxybutyrate (PHB) biopolymer has been synthesized and characterized with great interest due to its wide range of industrial applications. Currently, a wide number of bacterial species from soil, activated sludge, wastewater, industrial wastes, and compost have been identified as PHB producers. This work has the purpose of isolating and characterizing PHB-producing bacteria from the agricultural soil samples of Argania spinosa in the south region of Morocco where the plant species is endemic and preserved. During this research, four heat-resistant bacterial strains have been isolated. Among them, two species have been identified as endospore forming bacteria following the Schaffer-Fulton staining method with Malachite green and the Methylene blue method. Black intracellular granules have been appreciated in microscopy at 100× for both strains after staining with Sudan black B. The morphological and biochemical analyses of the isolates, including sugar fermentation and antibiotic susceptibility tests, preliminarily identified the strains 1B and 2D1 belonging to the genus Serratia and Proteus, respectively. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Waste Fiber-Based Poly(hydroxamic acid) Ligand for Toxic Metals Removal from Industrial Wastewater
Polymers 2021, 13(9), 1486; https://doi.org/10.3390/polym13091486 - 06 May 2021
Viewed by 618
Abstract
Toxic metals in the industrial wastewaters have been liable for drastic pollution hence a powerful and economical treatment technology is needed for water purification. For this reason, some pure cellulosic materials were derived from waste fiber to obtain an economical adsorbent for wastewater [...] Read more.
Toxic metals in the industrial wastewaters have been liable for drastic pollution hence a powerful and economical treatment technology is needed for water purification. For this reason, some pure cellulosic materials were derived from waste fiber to obtain an economical adsorbent for wastewater treatment. Conversion of cellulose into grafting materials such as poly(methyl acrylate)-grafted cellulose was performed by free radical grafting process. Consequently, poly(hydroxamic acid) ligand was produced from the grafted cellulose. The intermediate products and poly(hydroxamic acid) ligand were analyzed by FT-IR, FE-SEM, TEM, EDX, and XPS spectroscopy. The adsorption capacity (qe) of some toxic metals ions by the polymer ligand was found to be excellent, e.g., copper capacity (qe) was 346.7 mg·g−1 at pH 6. On the other hand, several metal ions such as cobalt chromium and nickel also demonstrated noteworthy sorption capacity at pH 6. The adsorption mechanism obeyed the pseudo second-order rate kinetic model due to the satisfactory correlated experimental sorption values (qe). Langmuir model isotherm study showed the significant correlation coefficient with all metal ions (R2 > 0.99), indicating that the single or monolayer adsorption was the dominant mode on the surface of the adsorbent. This polymer ligand showed good properties on reusability. The result shows that the adsorbent may be recycled for 6 cycles without any dropping of starting sorption capabilities. This polymeric ligand showed outstanding toxic metals removal magnitude, up to 90–99% of toxic metal ions can be removed from industrial wastewater. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Thermal Degradation Mechanism and Decomposition Kinetic Studies of Poly(Lactic Acid) and Its Copolymers with Poly(Hexylene Succinate)
Polymers 2021, 13(9), 1365; https://doi.org/10.3390/polym13091365 - 22 Apr 2021
Viewed by 375
Abstract
Ιn this work, new block poly(lactic acid)-block-poly(hexylene succinate) (PLA-b-PHSu) copolymers, in different mass ratios of 95/05, 90/10 and 80/20 w/w, are synthesized and their thermal and mechanical behavior are studied. Thermal degradation and thermal stability of the samples were examined [...] Read more.
Ιn this work, new block poly(lactic acid)-block-poly(hexylene succinate) (PLA-b-PHSu) copolymers, in different mass ratios of 95/05, 90/10 and 80/20 w/w, are synthesized and their thermal and mechanical behavior are studied. Thermal degradation and thermal stability of the samples were examined by Thermogravimetric Analysis (TGA), while thermal degradation kinetics was applied to better understand this process. The Friedman isoconversional method and the “model fitting method” revealed accurate results for the activation energy and the reaction mechanisms (nth order and autocatalysis). Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) was used to provide more details of the degradation process with PHSu’s mechanism being the β-hydrogen bond scission, while on PLA the intramolecular trans-esterification processes domains. PLA-b-PHSu copolymers decompose also through the β-hydrogen bond scission. The mechanical properties have also been tested to understand how PHSu affects PLA’s structure and to give more information about this new material. The tensile measurements gave remarkable results as the elongation at break increases as the content of PHSu increases as well. The study of the thermal and mechanical properties is crucial, to examine if the new material fulfills the requirements for further investigation for medical or other possible uses that might come up. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Starch-Based Super Water Absorbent: A Promising and Sustainable Way to Increase Survival Rate of Trees Planted in Arid Areas
Polymers 2021, 13(8), 1314; https://doi.org/10.3390/polym13081314 - 16 Apr 2021
Viewed by 440
Abstract
This research aimed to scale up the production of starch-based super water absorbent (SWA) and to validate the practical benefits of SWA for agricultural applications. SWA was successfully prepared in an up-scaling production by radiation-induced graft polymerization of acrylic acid onto cassava starch. [...] Read more.
This research aimed to scale up the production of starch-based super water absorbent (SWA) and to validate the practical benefits of SWA for agricultural applications. SWA was successfully prepared in an up-scaling production by radiation-induced graft polymerization of acrylic acid onto cassava starch. Chemical characterization by FTIR and thermal characterization by TGA showed results that differentiated starting materials from the prepared SWA, thus confirming effective preparation of starch-based SWA via radiation-induced graft polymerization. SEM results visibly revealed a highly porous morphology of the synthesized SWA, substantiating its high swelling ability. Results from the field tests, performed for two seasons, revealed that the prepared SWA was able to increase the survival rate of young rubber trees planted in arid area by up to 40%, while simultaneously enhancing the growth characteristics of the young rubber trees. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Dielectric Properties of Shrinkage-Free Poly(2-Oxazoline) Networks from Renewable Resources
Polymers 2021, 13(8), 1263; https://doi.org/10.3390/polym13081263 - 13 Apr 2021
Viewed by 329
Abstract
In the course of this study, the dielectric and physicochemical properties of poly(2-oxazoline) (POx) networks from renewable resources were compared with those of fossil-based polyamide 12 (PA 12) networks. POx was synthesized by the energy-efficient, microwave-assisted copolymerization of 2-oxazoline monomers, which were derived [...] Read more.
In the course of this study, the dielectric and physicochemical properties of poly(2-oxazoline) (POx) networks from renewable resources were compared with those of fossil-based polyamide 12 (PA 12) networks. POx was synthesized by the energy-efficient, microwave-assisted copolymerization of 2-oxazoline monomers, which were derived from fatty acids of coconut and castor oil. For the preparation of composites, aluminum nitride nanoparticles n-AlN and microparticles μ-AlN as well as hexagonal boron nitride BN submicroparticles were used. Additionally, 0, 15, or 30 wt.% of a spiroorthoester (SOE) were added as an expanding monomer aiming to reduce the formation of shrinkage-related defects. For the crosslinking of the polymers and the SOE as well as the double ring-opening reaction of the SOE, a thermally triggered dual-cure system was developed. The fully-cured blends and composites containing SOEs exhibited lower densities than their fully-cured SOE-free analogues, which was indicative of a lower extent of shrinkage (or even volumetric expansion) during the curing reaction, which is referred to as relative expansion RE. The RE amounted to values in the range of 0.46 to 2.48 for PA 12-based samples and 1.39 to 7.50 vol.% for POx-based samples. At 40 Hz, the “green” POx networks show low loss factors, which are competitive to those of the fossil-based PA 12. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Mechanical Properties of FDM Printed PLA Parts before and after Thermal Treatment
Polymers 2021, 13(8), 1239; https://doi.org/10.3390/polym13081239 - 11 Apr 2021
Cited by 2 | Viewed by 696
Abstract
Fused deposition modeling (FDM) is one of the most often-used technologies in additive manufacturing. Several materials are used with this technology, such as poly(lactic acid) (PLA), which is most commonly applied. The mechanical properties of 3D-printed parts depend on the process parameters. This [...] Read more.
Fused deposition modeling (FDM) is one of the most often-used technologies in additive manufacturing. Several materials are used with this technology, such as poly(lactic acid) (PLA), which is most commonly applied. The mechanical properties of 3D-printed parts depend on the process parameters. This is why, in this study, three-point bending tests were carried out to characterize the influence of build orientation, layer thickness, printing temperature and printing speed on the mechanical properties of PLA samples. Not only the process parameters may affect the mechanical properties, but heat after-treatment also has an influence on them. For this reason, additional samples were printed with optimal process parameters and characterized after pure heat treatment as well as after deformation at a temperature above the glass transition temperature, cooling with applied deformation, and subsequent recovery under heat treatment. These findings are planned to be used in a future study on finger orthoses that could either be printed according to shape or in a flat shape and afterwards heated and bent around the finger. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Functional Hydrophilic Membrane for Oil–Water Separation Based on Modified Bio-Based Chitosan–Gelatin
Polymers 2021, 13(7), 1176; https://doi.org/10.3390/polym13071176 - 06 Apr 2021
Viewed by 406
Abstract
In this study, we fabricated a modified biomaterial based on chitosan and gelatin, which is an intrinsic hydrophilic membrane for oil–water separation to clean water contamination by oil. Modification of the membrane with a non-toxic natural crosslinker, genipin, significantly enhanced the stability of [...] Read more.
In this study, we fabricated a modified biomaterial based on chitosan and gelatin, which is an intrinsic hydrophilic membrane for oil–water separation to clean water contamination by oil. Modification of the membrane with a non-toxic natural crosslinker, genipin, significantly enhanced the stability of the biopolymer membrane in a water-based medium towards an eco-friendly environment. The effects of various compositions of genipin-crosslinked chitosan–gelatin membrane on the rheological properties, thermal stability, and morphological structure of the membrane were investigated using a dynamic rotational rheometer, thermogravimetry analysis, and chemical composition by attenuated total reflectance spectroscopy (ATR). Modified chitosan–gelatin membrane showed completely miscible blends, as determined by field-emission scanning electron microscopy, differential scanning calorimetry, and ATR. Morphological results showed membrane with establish microstructure to further experiment as filtration product. The membranes were successfully tested for their oil–water separation efficiencies. The membrane proved to be selective and effective in separating water from an oil–water mixture. The optimum results achieved a stable microporous structure of the membrane (microfiltration) and a separation efficiency of above 98%. The membrane showed a high permeation flux, generated as high as 698 and 420 L m−2 h−1 for cooking and crude oils, respectively. Owing to its outstanding recyclability and anti-fouling performance, the membrane can be washed away easily, ensuring the reusability of the prepared membrane. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance
Polymers 2021, 13(7), 1124; https://doi.org/10.3390/polym13071124 - 02 Apr 2021
Cited by 1 | Viewed by 482
Abstract
Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were [...] Read more.
Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Paper Ageing: The Effect of Paper Chemical Composition on Hydrolysis and Oxidation
Polymers 2021, 13(7), 1029; https://doi.org/10.3390/polym13071029 - 26 Mar 2021
Viewed by 359
Abstract
The degradation of cellulose is an important factor influencing its mechanical, optical, physical, and chemical properties and, hence, the lifetime of paper in libraries and archival collections. Regardless of the complexity of the paper material, the main chemical pathways for its degradation are [...] Read more.
The degradation of cellulose is an important factor influencing its mechanical, optical, physical, and chemical properties and, hence, the lifetime of paper in libraries and archival collections. Regardless of the complexity of the paper material, the main chemical pathways for its degradation are hydrolysis and oxidation. This study presents an overview of the analytical techniques employed in the evaluation of the hydrolysis and oxidation processes; these techniques include size-exclusion chromatography, Fourier-transform infrared and ultraviolet–visible spectroscopy, and X-ray diffraction. This paper aims to determine the extent to which these instrumental methods are useful for studying the aforementioned processes and for which lignin contents. It also highlights how atmospheric humidity could affect the cellulose structure in paper containing lignin. It was found that humidity causes significant changes in the cellulose chain lengths and that a high lignin content in paper could suppress some cellulose degradation pathways. This knowledge can be applied to developing strategies and selective chemical treatments preventing the consequences of paper ageing. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Semi-Crystalline Hydrophobic Polyamidoamines: A New Family of Technological Materials?
Polymers 2021, 13(7), 1018; https://doi.org/10.3390/polym13071018 - 25 Mar 2021
Viewed by 367
Abstract
The hitherto known polyamidoamines (PAAs) are not suitable as structural materials because they are usually water-soluble or swellable in water. This paper deals with the synthesis and characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-sec-amines with bis-acrylamides obtained from [...] Read more.
The hitherto known polyamidoamines (PAAs) are not suitable as structural materials because they are usually water-soluble or swellable in water. This paper deals with the synthesis and characterization of semi-crystalline hydrophobic PAAs (H-PAAs) by combining different bis-sec-amines with bis-acrylamides obtained from C6–C12 bis-prim-amines. H-PAAs were initially obtained in a solution of benzyl alcohol, a solvent suitable for both monomers and polymers. Their number average molecular weights, M¯n, which were determined with 1H-NMR by evaluating the percentage of their terminal units, varied from 6000 to >10,000. The solubility, thermal properties, ignitability and water resistance of H-PAAs were determined. They were soluble in organic solvents, semi-crystalline and thermally stable. The most promising ones were also prepared using a bulk process, which has never been previously reported for PAA synthesis. In the form of films, these H-PAAs were apparently unaffected by water. The films underwent tensile and wettability tests. They showed similar Young moduli (260–263 MPa), whereas the maximum stress and the stress at break depended on the number of methylene groups of the starting bis-acrylamides. Their wettability was somewhat higher than that of common Nylons. Interestingly, none of the H-PAAs considered, either as films or powders, ignited after prolonged exposure to a methane flame. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Rendering Banana Plant Residues into a Potentially Commercial Byproduct by Doping Cellulose Films with Phenolic Compounds
Polymers 2021, 13(5), 843; https://doi.org/10.3390/polym13050843 - 09 Mar 2021
Viewed by 554
Abstract
This study seeks to render residues from banana plants into a useful byproduct with possible applications in wound dressings and food packaging. Films based on cellulose extracted from banana plant pseudostem and doped with phenolic compounds extracted from banana plant leaves were developed. [...] Read more.
This study seeks to render residues from banana plants into a useful byproduct with possible applications in wound dressings and food packaging. Films based on cellulose extracted from banana plant pseudostem and doped with phenolic compounds extracted from banana plant leaves were developed. The phenolic compounds were extracted using batch solid-liquid and Soxhlet methods, with different drying temperatures and periods of time. The total phenolic content and antioxidant activity were quantified. The optimum values were obtained using a three-day period batch-solid extraction at 40 °C (791.74 ± 43.75 mg/L). SEM analysis indicates that the pseudostem (PS) films have a porous structure, as opposed to hydroxyethyl cellulose (HEC) films which presented a homogeneous and dense surface. Mechanical properties confirmed the poor robustness of PS films. By contrast HEC films manifested improved tensile strength at low levels of water activity. FTIR spectroscopy reinforced the need to improve the cellulose extraction process, the success of lignin and hemicellulose removal, and the presence of phenolic compounds. XRD, TGA and contact angle analysis showed similar results for both films, with an amorphous structure, thermal stability and hydrophilic behavior. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Investigation of the Shape-Memory Properties of 3D Printed PLA Structures with Different Infills
Polymers 2021, 13(1), 164; https://doi.org/10.3390/polym13010164 - 05 Jan 2021
Cited by 9 | Viewed by 980
Abstract
Polylactic acid (PLA) belongs to the few thermoplastic polymers that are derived from renewable resources such as corn starch or sugar cane. PLA is often used in 3D printing by fused deposition modeling (FDM) as it is relatively easy to print, does not [...] Read more.
Polylactic acid (PLA) belongs to the few thermoplastic polymers that are derived from renewable resources such as corn starch or sugar cane. PLA is often used in 3D printing by fused deposition modeling (FDM) as it is relatively easy to print, does not show warping and can be printed without a closed building chamber. On the other hand, PLA has interesting mechanical properties which are influenced by the printing parameters and geometries. Here we present shape-memory properties of PLA cubes with different infill patterns and percentages, extending the research reported before in a conference paper. We investigate the material response under defined quasi-static load as well as the possibility to restore the original 3D printed shape. The quasi-static flexural properties are linked to the porosity and the infill structure of the samples under investigation as well as to the numbers of closed top layers, examined optically and by simulations. Our results underline the importance of designing the infill patterns carefully to develop samples with desired mechanical properties. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Temperature-Triggered/Switchable Thermal Conductivity of Epoxy Resins
Polymers 2021, 13(1), 65; https://doi.org/10.3390/polym13010065 - 26 Dec 2020
Cited by 2 | Viewed by 664
Abstract
The pronouncedly low thermal conductivity of polymers in the range of 0.1–0.2 W m−1 K−1 is a limiting factor for their application as an insulating layer in microelectronics that exhibit continuously higher power-to-volume ratios. Two strategies can be applied to increase [...] Read more.
The pronouncedly low thermal conductivity of polymers in the range of 0.1–0.2 W m−1 K−1 is a limiting factor for their application as an insulating layer in microelectronics that exhibit continuously higher power-to-volume ratios. Two strategies can be applied to increase the thermal conductivity of polymers; that is, compounding with thermally conductive inorganic materials as well as blending with aromatic units arranged by the principle of π-π stacking. In this study, both strategies were investigated and compared on the example of epoxy-amine resins of bisphenol A diglycidyl ether (BADGE) and 1,2,7,8-diepoxyoctane (DEO), respectively. These two diepoxy compounds were cured with mixtures of the diamines isophorone diamine (IPDA) and o-dianisidine (DAN). The epoxy-amine resins were cured without filler and with 5 wt.-% of SiO2 nanoparticles. Enhanced thermal conductivity in the range of 0.4 W·m−1·K−1 was observed exclusively in DEO-based polymer networks that were cured with DAN (and do not contain SiO2 fillers). This observation is argued to originate from π-π stacking of the aromatic units of DAN enabled by the higher flexibility of the aliphatic carbon chain of DEO compared with that of BADGE. The enhanced thermal conductivity occurs only at temperatures above the glass-transition point and only if no inorganic fillers, which disrupt the π-π stacking of the aromatic groups, are present. In summary, it can be argued that the bisphenol-free epoxy-amine resin with an epoxy compound derivable from natural resources shows favorably higher thermal conductivity in comparison with the petrol-based bisphenol-based epoxy/amine resins. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
A Novel Silicon/Phosphorus Co-Flame Retardant Polymer Electrolyte for High-Safety All-Solid-State Lithium Ion Batteries
Polymers 2020, 12(12), 2937; https://doi.org/10.3390/polym12122937 - 09 Dec 2020
Cited by 1 | Viewed by 731
Abstract
Developing a solid polymer electrolyte with superior flame retardancy and lithium-ion transportation properties is still a challenge. Herein, an intrinsic silicon/phosphorus co-flame retardant polymer solid electrolyte was prepared by using polyethylene glycol (PEG) co-polymerized with silicon and phosphorus-containing monomers. Due to the synergistic [...] Read more.
Developing a solid polymer electrolyte with superior flame retardancy and lithium-ion transportation properties is still a challenge. Herein, an intrinsic silicon/phosphorus co-flame retardant polymer solid electrolyte was prepared by using polyethylene glycol (PEG) co-polymerized with silicon and phosphorus-containing monomers. Due to the synergistic flame-retardant effect of silicon and phosphorus elements, this polymer electrolyte exhibits excellent thermal stability and flame resistance. Moreover, the ionic conductivity of the electrolyte at 25 °C is as high as 2.98 × 10−5 S/cm when the mass ratio of LiN(SO2CF3)2 (LiTFSI) and the prepared polymer electrolyte is 10:1. What is more, the LiFePO4/Li all-solid-state battery assembled with this solid electrolyte can work stably at a high temperature of 60 °C and exhibits a specific capacity of 129.2 mAh/g at 0.2 C after 100 cycles, providing a promising application prospect for high-safety lithium-ion batteries. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Ambient Temperature Self-Blowing Tannin-Humins Biofoams
Polymers 2020, 12(11), 2732; https://doi.org/10.3390/polym12112732 - 17 Nov 2020
Cited by 3 | Viewed by 521
Abstract
Ambient temperature self-blowing tannin–furanic foams have been prepared by substituting a great part—even a majority—of furfuryl alcohol with humins, a polyfuranic material derived from the acid treatment at high temperature of fructose. Closed-cell foams were prepared at room temperature and curing, while interconnected-cell [...] Read more.
Ambient temperature self-blowing tannin–furanic foams have been prepared by substituting a great part—even a majority—of furfuryl alcohol with humins, a polyfuranic material derived from the acid treatment at high temperature of fructose. Closed-cell foams were prepared at room temperature and curing, while interconnected-cell foams were prepared at 80 °C and curing, this being due to the more vigorous evaporation of the solvent. These foams appear to present similar characteristics as other tannin–furanic foams based only on furfuryl alcohol. A series of tannin–humins–furfuryl alcohol oligomer structures have been defined indicating that all three reagents co-react. Humins appeared to react well with condensed tannins, even higher molecular weight humins species, and even at ambient temperature, but they react slower than furfuryl alcohol. This is due to their high average molecular weight and high viscosity, causing their reaction with other species to be diffusion controlled. Thus, small increases in solvent led to foams with less cracks and open structures. It showed that furfuryl alcohol appears to also have a role as a humins solvent, and not just as a co-reagent and self-polymerization heat generator for foam expansion and hardening. Stress-strain for the different foams showed a higher compressive strength for both the foam with the lowest and the highest proportion of humins, thus in the dominant proportions of either furfuryl alcohol or the humins. Thus, due to their slower reactivity as their proportion increases to a certain critical level, more of them do proportionally participate within the expansion/curing time of the foam to the reaction. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Influence of an Alkoxylation Grade of Acrylates on Shrinkage of UV-Curable Compositions
Polymers 2020, 12(11), 2617; https://doi.org/10.3390/polym12112617 - 06 Nov 2020
Cited by 1 | Viewed by 471
Abstract
Commercially available UV curable restorative materials are composed of inorganic filler hydroxyapatite, multifunctional methacrylate, photoinitiator and alkoxylated acrylate. Especially, the application of alkoxylated monomers with different alkoxylation grade allows the reduction of polymerization shrinkage which plays the major role by application of low [...] Read more.
Commercially available UV curable restorative materials are composed of inorganic filler hydroxyapatite, multifunctional methacrylate, photoinitiator and alkoxylated acrylate. Especially, the application of alkoxylated monomers with different alkoxylation grade allows the reduction of polymerization shrinkage which plays the major role by application of low shrinkage composites as high quality restorative dental materials or other adhesive materials in the form of UV-polymerized self-adhesive acrylics layers (films). There are several ways to reduce polymerization shrinkage of restorative compositions, for example, by adjusting different alkoxylated acrylic monomers, which are integral part of investigated UV curable restorative composites. This article is focused on the studies of contraction-stress measured as shrinkage during UV-initiated curing of restorative composites containing various commercially available alkoxylated acrylates. Moreover, studies with experimental restorative materials and recent developments typical for UV curing technology using special photoreactive monomers are described. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Economic Evaluation and Techno-Economic Sensitivity Analysis of a Mass Integrated Shrimp Biorefinery in North Colombia
Polymers 2020, 12(10), 2397; https://doi.org/10.3390/polym12102397 - 18 Oct 2020
Cited by 2 | Viewed by 697
Abstract
The high freshwater consumption requirements in shrimp biorefinery approaches represents one of the major drawbacks of implementing these technologies within the shrimp processing industry. This also affects the costs associated with the plant operation, and consequently, the overall economic performance of the project. [...] Read more.
The high freshwater consumption requirements in shrimp biorefinery approaches represents one of the major drawbacks of implementing these technologies within the shrimp processing industry. This also affects the costs associated with the plant operation, and consequently, the overall economic performance of the project. The application of mass integration tools such as water pinch analysis can reduce frewshwater consumption by up to 80%, contributing to shrimp biorefinery sustainability. In this work, the economic evaluation and the techno-economic sensitivity analysis for a mass integrated approach for shrimp biorefinery were performed to determine the economic feasibility of the project when located in the North-Colombia region and to identify the critical techno-economic variables affecting the profitability of the process. The integrated approach designed to process 4113.09 tons of fresh shrimp in Colombia reaches a return on investment (%ROI) at 65.88% and a net present value (NPV) at 10.40 MM USD. The process supports decreases of up to 28% in capacity of production and increases of 12% and 11% in the cost of raw materials and variable operating costs without incurring losses, respectively. These findings suggest that the proposed design of the water recycling network coupled to a shrimp biorefinery approach is attractive from an economic point of view. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Article
Comparing Benzodithiophene Unit with Alkylthionaphthyl and Alkylthiobiphenyl Side-Chains in Constructing High-Performance Nonfullerene Solar Cells
Polymers 2020, 12(8), 1673; https://doi.org/10.3390/polym12081673 - 27 Jul 2020
Viewed by 732
Abstract
Using single-bonded and fused aromatic rings are two methods for extending the π-conjugation in the vertical direction of benzo [1,2-b:4,5-b′] dithiophene (BDT) unit. To investigate which method is more efficient in nonfullerene systems, two novel polymers based on alkylthionaphthyl and alkylthiobiphenyl substituted BDT [...] Read more.
Using single-bonded and fused aromatic rings are two methods for extending the π-conjugation in the vertical direction of benzo [1,2-b:4,5-b′] dithiophene (BDT) unit. To investigate which method is more efficient in nonfullerene systems, two novel polymers based on alkylthionaphthyl and alkylthiobiphenyl substituted BDT named PBDTNS-FTAZ and PBDTBPS-FTAZ are designed and synthesized. Two polymers only exhibit small differences in structure, but huge differences in photovoltaic properties. They are studied by blended with 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)indanone)-5,5,11,11-tetrakis(4-hexylphenyl)dithieno [2,3-d’:2,3’-d’]-s-indaceno [1,2-b:5,6-b’] dithiophene (ITIC). The device based on PBDTNS-FTAZ:ITIC showed the best power conversion efficiency (PCE) of 9.63% with the Voc of 0.87 V, a Jsc of 18.06 mA/cm2 and a fill factor of 61.21%, while the PBDTBPS-FTAZ:ITIC only exhibit a maximum PCE of 7.79% with a Voc of 0.86 V, a Jsc of 16.24 mA/cm2 and a relatively low fill factor of 55.92%. Therefore, extending π-conjugation with alkylthionaphthyl is more effective against constructing nonfullerene solar cells. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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Review

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Review
The Prospering of Macromolecular Materials Based on Plant Oils within the Blooming Field of Polymers from Renewable Resources
Polymers 2021, 13(11), 1722; https://doi.org/10.3390/polym13111722 - 25 May 2021
Cited by 1 | Viewed by 573
Abstract
This paper provides an overview of the recent progress in research and development dealing with polymers derived from plant oils. It highlights the widening interest in novel approaches to the synthesis, characterization, and properties of these materials from renewable resources and emphasizes their [...] Read more.
This paper provides an overview of the recent progress in research and development dealing with polymers derived from plant oils. It highlights the widening interest in novel approaches to the synthesis, characterization, and properties of these materials from renewable resources and emphasizes their growing impact on sustainable macromolecular science and technology. The monomers used include unmodified triglycerides, their fatty acids or the corresponding esters, and chemically modified triglycerides and fatty acid esters. Comonomers include styrene, divinylbenzene, acrylics, furan derivatives, epoxides, etc. The synthetic pathways adopted for the preparation of these materials are very varied, going from traditional free radical and cationic polymerizations to polycondensation reactions, as well as metatheses and Diels–Alder syntheses. In addition to this general appraisal, the specific topic of the use of tung oil as a source of original polymers, copolymers, and (nano)composites is discussed in greater detail in terms of mechanisms, structures, properties, and possible applications. Full article
(This article belongs to the Special Issue Feature Papers of Green and Sustainable Chemistry in Polymer Science)
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