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Polymers
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Bio-based Polymers Functionalized by Post-polymerization Modification
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Bio-based Polymers Functionalized by Post-polymerization Modification

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

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 19809

Special Issue Editors

Dr. Elisa Passaglia

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Guest Editor
Institute of chemistry of organometallic compounds (ICCOM), National Research Council (CNR) SS Pisa, Via Moruzzi 1, Pisa, Italy
Interests: polymer functionalization; polymer-based nanocomposites; polymer blending
Special Issues, Collections and Topics in MDPI journals
Dr. Serena Coiai

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Guest Editor
National Research Council (CNR), Institute of Chemistry of Organometallic Compounds - SS Pisa, CNR Research Area, via Moruzzi 1, 56124 Pisa, Italy
Interests: polymer functionalization; 2D layered materials; preparation and characterization of functional host–guest inorganic–organic systems; polymer nanocomposites; compatibilization; polymer blending; recycling
Special Issues, Collections and Topics in MDPI journals
Dr. Francesca Cicogna

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Guest Editor
Institute of Chemistry of Organometallic Compounds (ICCOM), National Research Council (CNR) SS Pisa, Via Moruzzi 1, Pisa, Italy
Interests: functionalization of polymers (from oil and biobased sources) by free radical post-polymerization reactions; functional polymers containing active molecules (chromophores and antioxidant), functional nanocomposites; surface modifications of polymers by photografting
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The growing importance of bio-based polymers as fundamental materials for the circular economy has led to research geared towards optimizing their structural, thermal, and mechanical characteristics to favor—at least for some applications—the replacement of traditional oil-derived commodities. In general, these polymers are characterized by the presence of reactive groups (residues of polymerization processes comprised of building blocks rich in different functionalities) that can be used to widen the application range of bio-based polymers. In fact, these functional groups can act as sites for post-polymerization modification (PPM) by introducing new functionalities or active groups, tailoring their ultimate properties. This SI therefore has as its fundamental purpose to collect the most advanced results concerning the PPM of bio-based polymers with particular reference to the chemistry of the reactions involved and the relationships between the structure of functionalized products and the properties realized in terms of specific required application.

Prof. Dr. Elisa Passaglia
Prof. Dr. Serena Coiai
Prof. Dr. Francesca Cicogna
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

  • bio-based polymers
  • post-polymerization modification
  • grafting
  • end-group reactions

Published Papers (6 papers)

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Research

26 pages, 15270 KiB  
Article
Chain Extension of Poly(Lactic Acid) (PLA)–Based Blends and Composites Containing Bran with Biobased Compounds for Controlling Their Processability and Recyclability
by Maria-Beatrice Coltelli, Alice Bertolini, Laura Aliotta, Vito Gigante, Alessandro Vannozzi and Andrea Lazzeri
Polymers 2021, 13(18), 3050; https://doi.org/10.3390/polym13183050 - 09 Sep 2021
Cited by 17 | Viewed by 3647
Abstract
The present work focused on the research, design, and study of innovative chain extender systems of renewable origin for PLA–based biocomposites, reinforced with wheat bran as filler. The majority of employed chain extender compounds belongs to fossil world, affecting the biodegradability property which [...] Read more.
The present work focused on the research, design, and study of innovative chain extender systems of renewable origin for PLA–based biocomposites, reinforced with wheat bran as filler. The majority of employed chain extender compounds belongs to fossil world, affecting the biodegradability property which characterizes biopolymers. The aim of this work was thus to find promising biobased and sustainable alternatives to provide the same enhancements. According to this objective, epoxidized soybean oil (ESO) was chosen as principal component of the chain extender systems, together with a dicarboxylic acid, malic acid (MA), or succinic acid (SA). The reactivity of the modifier systems was previously studied through thermogravimetric analysis (TGA) and IR spectroscopy, to hypothesize the reaction mechanism in bran–filled blends. Hence, small–scale extrusion was carried out to investigate the effects of ESO/MA and ESO/SA on formulations of different composition (both pure PLA blends and composites). The variation of melt fluidity parameters was analyzed to define the optimized concentration of modifier systems. A comparison between the effects on blends of designed biobased systems and the action of fossil–based Joncryl was performed, to understand if the developed green solutions could represent competitive and efficient substitutes. The modified composites were characterized in terms of mechanical tests, degradation and thermal studies (TGA and DSC), and morphological analysis (SEM), to figure out their main features and to understand their potential in possible industrial applications. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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12 pages, 19066 KiB  
Article
Water-Induced Breaking of Interfacial Cohesiveness in a Poly(lactic acid)/Miscanthus Fibers Biocomposite
by Nicolas Delpouve, Hajar Faraj, Clément Demarest, Eric Dontzoff, Marie-Rose Garda, Laurent Delbreilh, Benjamin Berton and Eric Dargent
Polymers 2021, 13(14), 2285; https://doi.org/10.3390/polym13142285 - 12 Jul 2021
Cited by 4 | Viewed by 1421
Abstract
The impact of the immersion in water on the morphology and the thermomechanical properties of a biocomposite made of a matrix of poly (lactic acid) (PLA) modified with an ethylene acrylate toughening agent, and reinforced with miscanthus fibers, has been investigated. Whereas no [...] Read more.
The impact of the immersion in water on the morphology and the thermomechanical properties of a biocomposite made of a matrix of poly (lactic acid) (PLA) modified with an ethylene acrylate toughening agent, and reinforced with miscanthus fibers, has been investigated. Whereas no evidence of hydrolytic degradation has been found, the mechanical properties of the biocomposite have been weakened by the immersion. Scanning electron microscopy (SEM) pictures reveal that the water-induced degradation is mainly driven by the cracking of the fiber/matrix interface, suggesting that the cohesiveness is a preponderant factor to consider for the control of the biocomposite decomposition in aqueous environments. Interestingly, it is observed that the loss of mechanical properties is aggravated when the stereoregularity of PLA is the highest, and when increasing the degree of crystallinity. To investigate the influence of the annealing on the matrix behavior, crystallization at various temperatures has been performed on tensile bars of PLA made by additive manufacturing with an incomplete filling to enhance the contact area between water and polymer. While a clear fragilization occurs in the material crystallized at high temperature, PLA crystallized at low temperature better maintains its properties and even shows high elongation at break likely due to the low size of the spherulites in these annealing conditions. These results show that the tailoring of the mesoscale organization in biopolymers and biocomposites can help control their property evolution and possibly their degradation in water. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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15 pages, 1542 KiB  
Article
Effect of the Degree of Substitution on the Hydrophobicity, Crystallinity, and Thermal Properties of Lauroylated Amaranth Starch
by Vicente Espinosa-Solis, Yunia Verónica García-Tejeda, Everth Jimena Leal-Castañeda and Víctor Barrera-Figueroa
Polymers 2020, 12(11), 2548; https://doi.org/10.3390/polym12112548 - 30 Oct 2020
Cited by 5 | Viewed by 2685
Abstract
In this paper, we consider amaranth starch extracted from the seeds of Amaranthus hypochondriacus L. An amphiphilic character is conferred to the starch by a chemical modification, which involves an esterification by lauroyl chloride at three modification levels. The degree of substitution (DS) [...] Read more.
In this paper, we consider amaranth starch extracted from the seeds of Amaranthus hypochondriacus L. An amphiphilic character is conferred to the starch by a chemical modification, which involves an esterification by lauroyl chloride at three modification levels. The degree of substitution (DS) after the modification ranged from 0.06 to 1.16. X-ray photoelectron spectroscopy analysis confirmed the presence of fatty acyl chains on the surface of the esterified starches. The hydrophobicity of starches was confirmed by their adsorption isotherms, which showed a decrease in the moisture adsorption of lauroylated as DS increased. X-ray diffraction analysis revealed a higher crystallinity, which was observed in the two samples subjected to the highest levels of modification. A higher crystallinity is related to a higher gelatinization enthalpy. These results are in agreement with the thermal characterization obtained by differential scanning calorimetry (DSC). An inhibition of the retrogradation properties of lauroylated amaranth starches was also observed. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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16 pages, 1824 KiB  
Article
Preparation and Properties of Plant-Oil-Based Epoxy Acrylate-Like Resins for UV-Curable Coatings
by Jijun Tang, Jinshuai Zhang, Jianyu Lu, Jia Huang, Fei Zhang, Yun Hu, Chengguo Liu, Rongrong An, Hongcheng Miao, Yuanyuan Chen, Tian Huang and Yonghong Zhou
Polymers 2020, 12(9), 2165; https://doi.org/10.3390/polym12092165 - 22 Sep 2020
Cited by 36 | Viewed by 4788
Abstract
Novel oil-based epoxy acrylate (EA)-like prepolymers were synthesized via the ring-opening reaction of epoxidized plant oils with a new unsaturated carboxyl acid precursor (MAAMA) synthesized by reacting maleic anhydride (MA) with methallyl alcohol (MAA). Since the employed epoxidized oils including epoxidized soybean oil [...] Read more.
Novel oil-based epoxy acrylate (EA)-like prepolymers were synthesized via the ring-opening reaction of epoxidized plant oils with a new unsaturated carboxyl acid precursor (MAAMA) synthesized by reacting maleic anhydride (MA) with methallyl alcohol (MAA). Since the employed epoxidized oils including epoxidized soybean oil (ESO), epoxidized rubber seed oil (ERSO), and epoxidized wilsoniana seed oil (EWSO) possessed epoxy values of 7.34–4.38%, the obtained epoxy acrylate (EA)-like prepolymers (MMESO, MMERSO, and MMEWSO) indicated a C=C functionality of 7.81–4.40 per triglyceride. Furthermore, effects of the C=C functionality and the addition of hydroxyethyl methacrylate (HEMA) diluent on the ultimate properties of the resulting UV-cured EA-like materials were investigated and compared with those of commercially available acrylated ESO (AESO) resins. As the C=C functionality increased, the storage modulus at 25 °C (E’25), glass transition temperature (Tg), 5% weight–loss temperature (T5), tensile strength and modulus (σ and E), and hardness of the coating for both the pure EA and EA/HEMA resins increased significantly as well. These properties indicated similar trends when comparing the EA materials with 30% of HEMA with those pure EA materials. Specially, although ERSO had a clearly lower epoxy value that ESO, both the UV-cured pure MMERSO and MMERSO/HEMA materials showed much better E’25, Tg, σ, and E than their AESO counterparts, indicating that the MAAMA modification of epoxidized plant oils was much more effective than the modification of acrylic acid to achieve high-performance oil-based epoxy acrylate resins. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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24 pages, 5093 KiB  
Article
Macromolecular Dyes by Chromophore-Initiated Ring Opening Polymerization of L-Lactide
by Francesca Cicogna, Guido Giachi, Luca Rosi, Elisa Passaglia, Serena Coiai, Roberto Spiniello, Federico Prescimone and Marco Frediani
Polymers 2020, 12(9), 1979; https://doi.org/10.3390/polym12091979 - 31 Aug 2020
Cited by 4 | Viewed by 2924
Abstract
End functionalized polylactides are prepared by ring opening polymerization of L-lactide in the presence of stannous octoate (Sn(Oct)2). Three chromophores, 9H-carbazol-ethanol (CA), 9-fluorenyl-methanol (FM), and 2-(4-(2-chloro-4-nitrophenylazo)-N-ethylphenylamino)ethanol (Disperse Red 13, DR), are for the first time used as co-initiators in the polymerization [...] Read more.
End functionalized polylactides are prepared by ring opening polymerization of L-lactide in the presence of stannous octoate (Sn(Oct)2). Three chromophores, 9H-carbazol-ethanol (CA), 9-fluorenyl-methanol (FM), and 2-(4-(2-chloro-4-nitrophenylazo)-N-ethylphenylamino)ethanol (Disperse Red 13, DR), are for the first time used as co-initiators in the polymerization process. The polymerization reaction is initiated by conventional thermal treatment, but in the case of FM, microwave-assisted polymerization is also carried out. CA and FM absorb and emit in the UV portion of the electromagnetic spectrum, whereas DR absorbs in the visible part. The obtained end-capped polylactides derivatives show the same photophysical properties as the initiator, so they are “macromolecular dyes” (MDs) that can be used “as synthesized” or can be blended with commercial poly(lactic acid) (PLA). The blends of PLA with MDs have ultraviolet-visible (UV-Vis) absorption and fluorescence emission features similar to that of MDs and thermal properties typical of PLA. Finally, migration tests, carried out onto the blends of PLA with MDs and PLA with free chromophores, show that MDs are less released than free chromophores both in solution and in the solid phase. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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10 pages, 2279 KiB  
Article
Rheology in the Presence of Carbon Dioxide (CO2) to Study the Melt Behavior of Chemically Modified Polylactide (PLA)
by Dominik Dörr, Tobias Standau, Svenja Murillo Castellón, Christian Bonten and Volker Altstädt
Polymers 2020, 12(5), 1108; https://doi.org/10.3390/polym12051108 - 13 May 2020
Cited by 13 | Viewed by 3358
Abstract
For the preparation of polylactide (PLA)-based foams, it is commonly necessary to increase the melt strength of the polymer. Additives such as chain extenders (CE) or peroxides are often used to build up the molecular weight by branching or even crosslinking during reactive [...] Read more.
For the preparation of polylactide (PLA)-based foams, it is commonly necessary to increase the melt strength of the polymer. Additives such as chain extenders (CE) or peroxides are often used to build up the molecular weight by branching or even crosslinking during reactive extrusion. Furthermore, a blowing agent with a low molecular weight, such as carbon dioxide (CO2), is introduced in the foaming process, which might affect the reactivity during extrusion. Offline rheological tests can help to measure and better understand the kinetics of the reaction, especially the reaction between the polymer and the chemical modifier. However, rheological measurements are mostly done in an inert nitrogen atmosphere without an equivalent gas loading of the polymer melt, like during the corresponding reactive extrusion process. Therefore, the influence of the blowing agent itself is not considered within these standard rheological measurements. Thus, in this study, a rheometer equipped with a pressure cell is used to conduct rheological measurements of neat and chemical-modified polymers in the presence of CO2 at pressures up to 40 bar. The specific effects of CO2 at elevated pressure on the reactivity between the polymer and the chemical modifiers (an organic peroxide and as second choice, an epoxy-based CE) were investigated and compared. It could be shown in the rheological experiments that the reactivity of the chain extender is reduced in the presence of CO2, while the peroxide is less affected. Finally, it was possible to detect the recrystallization temperature Trc of the unmodified and unbranched sample by the torque maximum in the rheometer, representing the tear off of the stamp from the sample. Trc was about 13 K lower in the CO2-loaded sample. Furthermore, it was possible to detect the influences of branching and gas loading simultaneously. Here the influence of the branching on Trc was much higher in comparison to a gas loading. Full article
(This article belongs to the Special Issue Bio-based Polymers Functionalized by Post-polymerization Modification)
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