Synthesis of Poly[(R,S)-3-hydroxybutyrate-block-ethylene glycol-block-(R,S)-3-hydroxybutyrate] via Anionic ROP

Synthesis and physical properties of polyhydroxyalkanoate (PHA)-based block copolymers: A review

Polyhydroxyalkanoates (PHAs) are a group of natural polyesters that are synthesised by microorganisms. In general, their thermoplasticity and (in some forms) their elasticity makes them attractive alternatives to petrochemical-derived polymers. However, the high crystallinity of some PHAs - such as poly(3-hydroxybutyrate) (P3HB) - results in brittleness and a narrow processing window for applications such as packaging. The production of copolymeric PHA materials is one approach to improving the mechanical and thermal properties of PHAs. Another solution is the manufacture of PHA-based block copolymers. The incorporation of different polymer and copolymer blocks coupled to PHA, and the resulting tailorable microstructure of these block copolymers, can result in a step-change improvement in PHA-based material properties. A range of production strategies for PHA-based block copolymers has been reported in the literature, including biological production and chemical synthesis. Biological production is typically less controllable, with products of a broad molecular weight and compositional distribution, unless finely controlled using genetically modified organisms. By contrast, chemical synthesis delivers relatively controllable block structures and narrowly defined compositions. This paper reviews current knowledge in the areas of the production and properties of PHA-based block copolymers, and highlights knowledge gaps and future potential areas of research.

From Anionic Ring-Opening Polymerization of β-Butyrolactone to Biodegradable Poly(hydroxyalkanoate)s: Our Contributions in This Field

The 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.

Polyester-based (bio)degradable polymers as environmentally friendly materials for sustainable development

This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising (bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields.

Synthesis and antiproliferative properties of ibuprofen-oligo(3-hydroxybutyrate) conjugates

Synthesis of novel conjugates of the non-steroidal anti-inflammatory drug - ibuprofen with nontoxic oligo(3-hydroxybutyrate) (OHB) is described. Presented results indicate that anionic ring-opening polymerization of (R,S)-beta-butyrolactone initiated with an alkali metal salt of (S)-(+)-2-(4-isobutylphenyl)propionic acid (ibuprofen) may constitute a convenient method of conjugation of selected drugs with biodegradable OHB. Furthermore using the MTT cell proliferation assay we demonstrated that ibuprofen conjugated with OHB exhibited significantly increased, as compared to free ibuprofen, potential to inhibit proliferation of HT-29 and HCT 116 colon cancer cells. However, the conjugates of ibuprofen and OHB are less toxic as was shown in oral acute toxicity test in rats. Although the mechanism of antiproliferative activity of ibuprofen-OHB conjugates (Ibu-OHB) has to be established, we suggest that partially it can be related to more effective cellular uptake of the conjugate than the free drug. This assumption is based on the observation of much more efficient accumulation of a marker compound - OHB conjugated with fluorescein, in contrast to fluorescein sodium salt, which entered cells inefficiently. Further characterization of biological properties of the ibuprofen-OHB conjugates would provide insight into the mechanism of their antiproliferative effect and assess the potential relevance of their anticancer activity.