(Bio)degradable polymeric materials for sustainable future—Part 3: Degradation studies of the PHA/wood flour-based composites and preliminary tests of antimicrobial activity

© 2020 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/ma13092200The need for a cost reduction of the materials derived from (bio)degradable polymers forces research development into the formation of biocomposites with cheaper fillers. As additives can be made using the post-consumer wood, generated during wood products processing, re-use of recycled waste materials in the production of biocomposites can be an environmentally friendly way to minimalize and/or utilize the amount of the solid waste. Also, bioactive materials, which possess small amounts of antimicrobial additives belong to a very attractive packaging industry solution. This paper presents a study into the biodegradation, under laboratory composting conditions, of the composites that consist of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate)] and wood flour as a polymer matrix and natural filler, respectively. Thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy were used to evaluate the degradation progress of the obtained composites with different amounts of wood flour. The degradation products were characterized by multistage electrospray ionization mass spectrometry. Also, preliminary tests of the antimicrobial activity of selected materials with the addition of nisin were performed. The obtained results suggest that the different amount of filler has a significant influence on the degradation profile.Published onlin

Bioactive oligomers from natural polyhydroxyalkanoates and their synthetic analogues

Contemporary reports on the bioactive oligomers derived from natural aliphatic (co)polyesters (PHA) and their synthetic analogues, formed through anionic ring-opening polymerization (ROP) of β-substituted β-lactones are presented. Synthetic routes for such oligomers, developed mostly by Polish authors, are discussed. The described approaches enable design of novel biodegradable and bioactive oligomers for diverse applications in medicine, cosmetic industry and agrochemistry. Abstrakt: Przedstawiono przegląd aktualnych wyników badań dotyczących bioaktywnych oligomerów otrzymywanych z naturalnych alifatycznych (ko)poliestrów (PHA) oraz ich syntetycznych analogów, uzyskanych na drodze anionowej polimeryzacji z otwarciem pierścienia (ROP) β-podstawionych β-laktonów. Omówiono ścieżki syntezy tych oligomerów opracowane głównie przez polskich badaczy. Zaprezentowane metody umożliwiają projektowanie nowych biodegradowalnych a zarazem bioaktywnych oligomerów dla różnorodnych zastosowań w medycynie, przemyśle kosmetyczny i agrochemii

From anionic ring-opening polymerization of β-butyrolactone to biodegradable poly(hydroxyalkanoate)s: Our contributions in this field

© 2021 The Authors. Published by MDPI. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.3390/polym13244365The feasibility of synthesis of functionalized poly(3-hydroxybutanoic acid) analogue and its copolymers via ring-opening polymerization of β-butyrolactone mediated by activated anionic initiators is presented. Using these new synthetic approaches, polyesters with a defined chemical structure of the end groups, as well as block, graft, and random copolymers, have been obtained and characterized by modern instrumental techniques, with special emphasis on ESI-MS. The relationship between the structure and properties of the prepared polymeric materials is also discussed.This research is partly supported by the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement, No. 872152, project GREEN-MAP.Published onlin

Bioactive and functional oligomers derived from natural PHA and their synthetic analogs

This is an accepted manuscript of a chapter published by CRC Press in The Handbook of Polyhydroxyalkanoates Postsynthetic Treatment, Processing and Application on 05/11/2020, available online: https://www.taylorfrancis.com/books/e/9781003087663/chapters/10.1201/9781003087663-5 The accepted version of the publication may differ from the final published version.Polyhydroxyalkanoate oligomers (oligo-PHA) are low molar mass PHA consisting of a small number of 3-hydroxyacid repeat units (usually not more than 200 residue units). They can be synthesized either naturally in eukaryotic cells and in prokaryotic cells through intracellular or extracellular degradation of storage PHA to yield natural oligomers, or via several chemical modifications such as basic hydrolysis or transesterification. The synthetic analogs of natural PHA oligomers are obtained by anionic ring-opening polymerization (ROP) of β-substituted β-lactones. These synthetic and biodegradable oligomers, through various chemical modifications, can further allow the preparation of bioactive oligomers with attractive properties for novel and high value-added applications, especially in medicine, agrochemistry, and cosmetology. Bioactive oligomers are also biodegradable: they possess enhanced properties, controlled functional end groups, and thus can be potential components of copolymers or blends with other biodegradable polymers. The natural and synthetic routes used for the preparation of selected bioactive PHA oligomers and their detailed characterization by mass spectrometry are discussed in this chapter

Chemical Modifications of Starch: Microwave Effect

This paper presents basic methods of starch chemical modification, the effect of microwave radiation on the modification process, and the physicochemical properties of starch. It has been shown that the modifications contribute to improvement of the material performance and likewise to significant improvement of its mechanical properties. As a result, more and more extensive use of starch is possible in various industries. In addition, methods of oxidized starch and starch esters preparation are discussed. Properties of microwave radiation and its impact on starch (with particular regard to modifications described in literature) are characterized

Biomimetic polyesters and their role in ion transport across cell membranes.

Syntheses of biomimetic low-molecular weight poly-(R)-3-hydroxybutanoate mediated by three types of supramolecular catalysts are presented. The utility of these synthetic polyesters for preparation of artificial channels in phospholipid bilayers capable of sodium and calcium ion transport across cell membranes, is discussed. Further studies on possible applications of these bio-polymers for manufacturing drugs of prolonged activity are under way

Anionic Polymerization of β-Butyrolactone Initiated with Sodium Phenoxides. The Effect of the Initiator Basicity/Nucleophilicity on the ROP Mechanism

It was shown that selected sodium phenoxide derivatives with different basicity and nucleophilicity, such as sodium p-nitrophenoxide, p-chlorophenoxide, 1-napthoxide, phenoxide and p-methoxyphenoxide, are effective initiators in anionic ring-opening polymerization (AROP) of β-butyrolactone in mild conditions. It was found that phenoxides as initiators in anionic ring-opening polymerization of β-butyrolactone behave as strong nucleophiles, or weak nucleophiles, as well as Brønsted bases. The resulting polyesters possessing hydroxy, phenoxy and crotonate initial groups are formed respectively by the attack of phenoxide anion at (i) C2 followed by an elimination reaction with hydroxide formation, (ii) C4 and (iii) abstraction of acidic proton at C3. The obtained poly(3-hydroxybutyrate) possesses carboxylate growing species. The ratio of the observed initial groups strongly depends on the basicity and nucleophilicity of the sodium phenoxide derivative used as initiator. The proposed mechanism of this polymerization describes the reactions leading to formation of observed end groups. Moreover, the possibility of formation of a crotonate group during the propagation step of this polymerization is also discussed

Macromolecular engineering of lactones and lactides. 24. Controlled synthesis of (R,S)-β-butyrolactone-b-ε-caprolactone block copolymers by anionic and coordination polymerization

Block copolymers of (R,S)-β-butyrolactone and ε-caprolactone have been synthesized by combining the anionic polymerization of the first monomer with the coordinative ring-opening polymerization of the second one. The copolymerization yield is close to 100% and the final molecular weight of each sequence can be predicted from the initial monomer-to-initiator molar ratio. The molecular weight distribution of copolymers obtained is quite narrow (Mw/Mn ≤ 1.3). According to NMR and DSC analysis, the polybutyrolactone block is atactic and totally amorphous, in contrast to the polycaprolactone block which is semicrystalline. A partial miscibility of the two blocks in the amorphous phase has however been detected. Thermal and enzymatic degradations of the block copolymers have been investigated. The enzymatic degradation rate promoted by the lipase form Rhizopus arrhizus strongly depends on the copolyester composition and increases with the β-butyrolactone content