Ring-opening homopolymerization and copolymerization of lactones. Part 2. enzymatic degradability of poly(β-hydroxybutyrate) stereoisomers and copolymers of β-butyrolactone with ɛ-caprolactone and δ-valerolactone

Abstract

In this study, we have prepared poly([R,S ]‐β‐hydroxybutyrate) (P([R,S ]‐β‐HB) or PHB) from [R ,S]‐β‐butyrolactone ([ R,S]‐β‐BL), using different aluminoxane catalyst systems (triethylaluminium/water, triisobutylaluminium/water, trioctylaluminium/water and tetraisobutyldialuminoxane/water). By varying the ratio of catalyst to water and using a method of fractionation of polymers, PHB with different isotactic diad fractions (i) (from 0.41 to 0.72) and crystallinities were obtained. Copolymers poly(butyrolactone‐co‐caprolactone) (P(BL‐co‐CL)) and poly(butyrolactone‐co‐valerolactone) (P(BL‐co‐VL)) have also been synthesized from the ring‐opening copolymerization of [ R,S]‐β‐BL with either ε‐caprolactone (CL) or δ‐valerolactone (VL) using tetraisobutyldialuminoxane (TIBAO) catalyst. The enzymatic degradability of these polymers was studied in aerobic and anaerobic media. The objective of this work was to determine the influence of the tacticity and crystallinity of the polymers on their degree of biodegradation and on their initial degradation rate. It was shown that the degradation rate measured for bacterial PHB 100% [R] was the highest and the degree of aerobic biodegradation reached after 36 days was around 94%. A 40–50% biodegradation was obtained for synthetic PHB, highly isotactic and predominantly syndiotactic. The non‐crystalline and atactic PHB synthesized from TIBAO catalyst had a very high degree of biodegradation of around 88%. This result may suggest that not only are the [R ]‐BL units hydrolysed but also the [S ]‐BL units. The influence of the crystallinity on the initial degradation rate was observed for the copolymers P(BL‐co‐CL) and P(BL‐co ‐VL) of various feed ratios. All these copolymers synthesized from TIBAO catalyst, exhibit a high degree of biodegradation of around 85% except for copolymers containing a very high portion of unsubstituted units, CL or VL. The anaerobic biodegradation of PHB and copolymers P(BL‐co ‐CL) is much lower than the aerobic biodegradation, as are the initial rates, even for bacterial P([R ]‐HB). © 1999 Society of Chemical Industry

Synthesis of γ-valerolactone by hydrogenation of levulinic acid over supported nickel catalysts

“…Furthermore, GVL is utilized to produce various bio-based products like aromatics (fuel additives), short chain alkenes (jet fuel) or long chain alkanes (diesel fuel). [1][2][3] GVL can be synthesized from levulinic acid (LA) either by hydrogenation of LA to γ-hydroxyvaleric acid, which spontaneously condensates to GVL, or by dehydration of LA to angelica lactone, which is subsequently hydrogenated to GVL. [4] The condensation of LA to GVL occurs mainly in the presence of acid functionalities.…”

The global burden of plastics in oral health: prospects for circularity, sustainable materials development and practice

“…167 While naturally-occurring PHB is easily degraded by microorganisms due to its exclusive (R)-conguration of the side chains, synthetic PHBs consisting of a mixture of (R)-and (S)-stereoblocks exhibit different degradation rates; (S)-units undergo a slower enzymatic degradation than (R)units. 168,169 This implies that the material's lifetime can be potentially modied by controlling the stereoregularity during polymer synthesis. Chemical degradation of PHAs can yield products such as crotonic acid, which can be used to produce other high-value chemicals such as poly(crotonic acids) and crotonate esters.…”

Microwave-Assisted γ-Valerolactone Production for Biomass Lignin Extraction: A Cascade Protocol

“…γ-Valerolactone (GVL) is the most attractive and versatile lignocellulose chemical derivative as it is directly used as a fragrance, liquid fuel and food additive [1,2,3,4]. Furthermore, it is an intermediate in the production of fuel additives, biomass-derived polymers, short chain alkenes (jet fuel) and long chain alkanes (diesel fuel) [5,6,7]. GVL is renewable, safe to store, biodegradable and can be used as a green solvent in fine chemicals synthesis [8] and biomass processing [5].…”