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13 pages, 1127 KiB

Open AccessFeature PaperArticle

Zinc Amido-Oxazolinate Catalyzed Ring Opening Copolymerization and Terpolymerization of Maleic Anhydride and Epoxides

by Muneer Shaik, Vamshi K. Chidara, Srinivas Abbina and Guodong Du

Molecules 2020, 25(18), 4044; https://doi.org/10.3390/molecules25184044 - 04 Sep 2020

Cited by 6 | Viewed by 2924

Abstract

Ring opening copolymerization (ROCOP) of epoxides and cyclic anhydrides has become an attractive approach for the synthesis of biodegradable polyesters with various compositions. Encouraged by the efficiency and versatility of a series of amido-oxazolinate zinc complexes, in this study they were shown to [...] Read more.

Ring opening copolymerization (ROCOP) of epoxides and cyclic anhydrides has become an attractive approach for the synthesis of biodegradable polyesters with various compositions. Encouraged by the efficiency and versatility of a series of amido-oxazolinate zinc complexes, in this study they were shown to be active catalysts for the synthesis of unsaturated polyesters via ROCOP of maleic anhydride and various epoxides. The relative activity of epoxides in these reactions was observed to be styrene oxide > cyclohexene oxide > phenyl glycidyl ether, which could be correlated with the electronic and steric features of the substrate. To provide more structural possibilities for the polyesters, the difference in epoxide reactivity was exploited in an attempt to prepare block terpolymers from one anhydride and two epoxides. Terpolymerization was carried out in one or two steps in a single pot. The thermal characterization by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques suggested that the resulting materials were mostly random terpolymers. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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15 pages, 3488 KiB

Open AccessFeature PaperArticle

Preparation and Compatibilization of PBS/Whey Protein Isolate Based Blends

by Maria-Beatrice Coltelli, Laura Aliotta, Vito Gigante, Maria Bellusci, Patrizia Cinelli, Elodie Bugnicourt, Markus Schmid, Andreas Staebler and Andrea Lazzeri

Molecules 2020, 25(14), 3313; https://doi.org/10.3390/molecules25143313 - 21 Jul 2020

Cited by 12 | Viewed by 3715

Abstract

In this paper the production of biopolymeric blends of poly(butylene succinate) PBS and plasticized whey protein (PWP), obtained from a natural by-product from cheese manufacturing, has been investigated for the production of films and/or sheets. In order to add the highest possible whey [...] Read more.

In this paper the production of biopolymeric blends of poly(butylene succinate) PBS and plasticized whey protein (PWP), obtained from a natural by-product from cheese manufacturing, has been investigated for the production of films and/or sheets. In order to add the highest possible whey protein content, different formulations (from 30 to 50 wt.%) were studied. It was found that by increasing the amount of PWP added to PBS, the mechanical properties were worsened accordingly. This trend was attributed to the low compatibility between PWP and PBS. Consequently, the effect of the addition of soy lecithin and glycerol monostearate (GMS) as compatibilizers was investigated and compared to the use of whey protein modified with oleate and laurate groups obtained by Schotten-Baumann reaction. Soy lecithin and the Schotten-Baumann modified whey were effective in compatibilizing the PWP/PBS blend. In fact, a significant increase in elastic modulus, tensile strength and elongation at break with respect to the not compatibilized blend was observed and the length of aliphatic chains as well as the degree of modification of the Schotten–Baumann proteins affected the results. Moreover, thanks to DSC investigations, these compatibilizers were also found effective in increasing the PBS crystallinity. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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11 pages, 7612 KiB

Open AccessArticle

Water-Dependent Blending of Pectin Films: The Mechanics of Conjoined Biopolymers

by Yifan Zheng, Aidan Pierce, Willi L. Wagner, Henrik V. Scheller, Debra Mohnen, Maximilian Ackermann and Steven J. Mentzer

Molecules 2020, 25(9), 2108; https://doi.org/10.3390/molecules25092108 - 30 Apr 2020

Cited by 6 | Viewed by 2572

Abstract

Biodegradable pectin polymers have been recommended for a variety of biomedical applications, ranging from the delivery of oral drugs to the repair of injured visceral organs. A promising approach to regulate pectin biostability is the blending of pectin films. To investigate the development [...] Read more.

Biodegradable pectin polymers have been recommended for a variety of biomedical applications, ranging from the delivery of oral drugs to the repair of injured visceral organs. A promising approach to regulate pectin biostability is the blending of pectin films. To investigate the development of conjoined films, we examined the physical properties of high-methoxyl pectin polymer-polymer (homopolymer) interactions at the adhesive interface. Pectin polymers were tested in glass phase (10–13% w/w water content) and gel phase (38–41% w/w water content). The tensile strength of polymer-polymer adhesion was measured after variable development time and compressive force. Regardless of pretest parameters, the adhesive strength of two glass phase films was negligible. In contrast, adhesion testing of two gel phase films resulted in significant tensile adhesion strength (p < 0.01). Adhesion was also observed between glass phase and gel phase films—likely reflecting the diffusion of water from the gel phase to the glass phase films. In studies of the interaction between two gel phase films, the polymer-polymer adhesive strength increased linearly with increasing compressive force (range 10–80 N) (R² = 0.956). In contrast, adhesive strength increased logarithmically with time (range 10–10,000 s) (R² = 0.913); most of the adhesive strength was observed within minutes of contact. Fracture mechanics demonstrated that the adhesion of two gel phase films resulted in a conjoined film with distinctive physical properties including increased extensibility, decreased stiffness and a 30% increase in the work of cohesion relative to native polymers (p < 0.01). Scanning electron microscopy of the conjoined films demonstrated cross-grain adhesion at the interface between the adhesive homopolymers. These structural and functional data suggest that blended pectin films have emergent physical properties resulting from the cross-grain intermingling of interfacial pectin chains. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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11 pages, 2962 KiB

Open AccessFeature PaperArticle

An Investigation of the Organoborane/Lewis Base Pairs on the Copolymerization of Propylene Oxide with Succinic Anhydride

by Lan-Fang Hu, Dan-Jing Chen, Jia-Liang Yang and Xing-Hong Zhang

Molecules 2020, 25(2), 253; https://doi.org/10.3390/molecules25020253 - 08 Jan 2020

Cited by 22 | Viewed by 4071

Abstract

The copolymerization of biorenewable succinic anhydride (SA) with propylene oxide (PO) is a promising way to synthesize biodegradable aliphatic polyesters. However, the catalytic systems for this reaction still deserve to be explored because the catalytic activity of the reported catalysts and the molecular [...] Read more.

The copolymerization of biorenewable succinic anhydride (SA) with propylene oxide (PO) is a promising way to synthesize biodegradable aliphatic polyesters. However, the catalytic systems for this reaction still deserve to be explored because the catalytic activity of the reported catalysts and the molecular weights of produced polyesters are unsatisfied. Herein, we investigate the copolymerization of SA with PO catalyzed by the organoborane/base pairs. The types of Lewis bases, organoboranes, and their loadings all have a large impact on the activity and selectivity of the copolymerization. High ester content of >99% was achieved when performed the PO/SA copolymerization using triethyl borane (TEB)/phosphazene base P1-t-Bu (t-BuP₁) pair with a molar ratio of 1/1 at 30–80 °C. Using TEB/t-BuP₁ pair with the molar ratio of 4/1 at 80 °C, the turnover of frequency (TOF) was up to 128 h⁻¹ and clearly higher than the known TOF values (0.5–34 h⁻¹) of the PO/SA copolymerization by previously reported catalysts. The number-average molecular weights (M_ns) of the resultant polyesters reached up to 20.4 kg/mol when copolymerization was carried out using TEB/t-BuP₁ (1/1, in molar ratio) at 30 °C. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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20 pages, 5464 KiB

Open AccessArticle

Production and Characterization of Bioplastic by Polyhydroxybutyrate Accumulating Erythrobacter aquimaris Isolated from Mangrove Rhizosphere

by Yasser S. Mostafa, Sulaiman A. Alrumman, Kholod A. Otaif, Saad A. Alamri, Mohamed S. Mostafa and Taher Sahlabji

Molecules 2020, 25(1), 179; https://doi.org/10.3390/molecules25010179 - 01 Jan 2020

Cited by 58 | Viewed by 6290

Abstract

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-β-hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the [...] Read more.

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-β-hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the extracted polymer. The efficient marine bacterial isolates were identified by the phylogenetic analysis of the 16S rRNA genes as Tamlana crocina, Bacillus aquimaris, Erythrobacter aquimaris, and Halomonas halophila. The optimization of PHB accumulation by E. aquimaris was achieved at 120 h, pH 8.0, 35 °C, and 2% NaCl, using glucose and peptone as the best carbon and nitrogen sources at a C:N ratio of 9.2:1. The characterization of the extracted biopolymer by Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Gas chromatography-mass spectrometry (GC-MS) proves the presence of hydroxyl, methyl, methylene, methine, and ester carbonyl groups, as well as derivative products of butanoic acid, that confirmed the structure of the polymer as PHB. This is the first report on E. aquimaris as a PHB producer, which promoted the hypothesis that marine rhizospheric bacteria were a new area of research for the production of biopolymers of commercial value. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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20 pages, 3262 KiB

Open AccessFeature PaperArticle

Gelatin-Based Antimicrobial Films Incorporating Pomegranate (Punica granatum L.) Seed Juice by-Product

by Arantzazu Valdés, Esther Garcia-Serna, Antonio Martínez-Abad, Francisco Vilaplana, Alfonso Jimenez and María Carmen Garrigós

Molecules 2020, 25(1), 166; https://doi.org/10.3390/molecules25010166 - 31 Dec 2019

Cited by 36 | Viewed by 4325

Abstract

Pomegranate (Punica granatum L.) seed juice by-product (PSP) was added as reinforcing and antimicrobial agent to fish gelatin (FG) films as a promising eco-friendly active material for food packaging applications. A complete linkage analysis of polysaccharides in PSP showed xylan and cellulose [...] Read more.

Pomegranate (Punica granatum L.) seed juice by-product (PSP) was added as reinforcing and antimicrobial agent to fish gelatin (FG) films as a promising eco-friendly active material for food packaging applications. A complete linkage analysis of polysaccharides in PSP showed xylan and cellulose as main components. This residue showed also high total phenolic content and antioxidant activity. Three formulations were processed by adding PSP to FG (0, 10, 30 wt. %) by the casting technique, showing films with 10 wt. % of PSP the best performance. The addition of PSP decreased elongation at break and increased stiffness in the FG films, particularly for 30 wt. % loading. A good compatibility between FG and PSP was observed by SEM. No significant (p < 0.05) differences were obtained for barrier properties to oxygen and water vapour permeability compared to the control with the incorporation of PSP, whereas water resistance considerably increased and transparency values decreased (p < 0.05). High thermal stability of films and inhibition against S. aureus were observed. The addition of PSP at 10 wt. % into FG was shown as a potential strategy to maintain the integrity of the material and protect food against lipid oxidation, reducing huge amounts of pomegranate and fish wastes. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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14 pages, 4906 KiB

Open AccessArticle

Novel Functionalized Cellulose Microspheres for Efficient Separation of Lithium Ion and Its Isotopes: Synthesis and Adsorption Performance

by Ichen Chen, Chenxi Xu, Jing Peng, Dong Han, Siqi Liu and Maolin Zhai

Molecules 2019, 24(15), 2762; https://doi.org/10.3390/molecules24152762 - 30 Jul 2019

Cited by 17 | Viewed by 4341

Abstract

The adsorption of lithium ions(Li⁺) and the separation of lithium isotopes have attracted interests due to their important role in energy storage and nuclear energy, respectively. However, it is still challenging to separate the Li⁺ and its isotopes with high [...] Read more.

The adsorption of lithium ions(Li⁺) and the separation of lithium isotopes have attracted interests due to their important role in energy storage and nuclear energy, respectively. However, it is still challenging to separate the Li⁺ and its isotopes with high efficiency and selectivity. A novel cellulose-based microsphere containing crown ethers groups (named as MCM-g-AB15C5) was successfully synthesized by pre-irradiation-induced emulsion grafting of glycidyl methacrylate (GMA) and followed by the chemical reaction between the epoxy group of grafted polymer and 4′-aminobenzo-15-crown-5 (AB15C5). By using MCM-g-AB15C5 as adsorbent, the effects of solvent, metal ions, and adsorption temperature on the adsorption uptake of Li⁺ and separation factor of ⁶Li/⁷Li were investigated in detail. Solvent with low polarity, high adsorption temperature in acetonitrile could improve the uptake of Li⁺ and separation factor of lithium isotopes. The MCM-g-AB15C5 exhibited the strongest adsorption affinity to Li⁺ with a separation factor of 1.022 ± 0.002 for ⁶Li/⁷Li in acetonitrile. The adsorption isotherms in acetonitrile is fitted well with the Langmuir model with an ultrahigh adsorption capacity up to 12.9 mg·g⁻¹, indicating the unexpected complexation ratio of 1:2 between MCM-g-AB15C5 and Li⁺. The thermodynamics study confirmed the adsorption process is the endothermic, spontaneous, and chemisorption adsorption. As-prepared novel cellulose-based adsorbents are promising materials for the efficient and selective separation of Li⁺ and its isotopes. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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23 pages, 1182 KiB

Open AccessReview

Cyanobacterial Polyhydroxyalkanoates: A Sustainable Alternative in Circular Economy

by Diana Gomes Gradíssimo, Luciana Pereira Xavier and Agenor Valadares Santos

Molecules 2020, 25(18), 4331; https://doi.org/10.3390/molecules25184331 - 22 Sep 2020

Cited by 29 | Viewed by 5916

Abstract

Conventional petrochemical plastics have become a serious environmental problem. Its unbridled use, especially in non-durable goods, has generated an accumulation of waste that is difficult to measure, threatening aquatic and terrestrial ecosystems. The replacement of these plastics with cleaner alternatives, such as polyhydroxyalkanoates [...] Read more.

Conventional petrochemical plastics have become a serious environmental problem. Its unbridled use, especially in non-durable goods, has generated an accumulation of waste that is difficult to measure, threatening aquatic and terrestrial ecosystems. The replacement of these plastics with cleaner alternatives, such as polyhydroxyalkanoates (PHA), can only be achieved by cost reductions in the production of microbial bioplastics, in order to compete with the very low costs of fossil fuel plastics. The biggest costs are carbon sources and nutrients, which can be appeased with the use of photosynthetic organisms, such as cyanobacteria, that have a minimum requirement for nutrients, and also using agro-industrial waste, such as the livestock industry, which in turn benefits from the by-products of PHA biotechnological production, for example pigments and nutrients. Circular economy can help solve the current problems in the search for a sustainable production of bioplastic: reducing production costs, reusing waste, mitigating CO₂, promoting bioremediation and making better use of cyanobacteria metabolites in different industries. Full article

(This article belongs to the Special Issue Biobased Biodegradable Polymers)

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