Ring‐opening copolymerization of racemic β‐butyrolactone with ϵ‐caprolactone and δ‐valerolactone by distannoxane derivative catalysts: study of the enzymatic degradation in aerobic media of obtained copolymers

Abstract

AbstractIn this study, we have prepared predominantly syndiotactic poly([R,S]‐β‐hydroxybutyrate) using different distannoxane catalyst systems (1‐hydroxy‐3‐chlorotetrabutyldistannoxane, 1‐ethoxy‐3‐chlorotetrabutyldistannoxane, 1,3‐dichlorotetrabutyldistannoxane, and dibutyltin oxide). Copolymers poly([R,S]‐β‐hydroxybutyrate‐co‐ϵ‐caprolactone), P(BL‐co‐CL), and poly([R,S]‐β‐hydroxybutyrate‐co‐δ‐valerolactone), P(BL‐co‐VL), have also been synthetized from the ring‐opening copolymerization of (R,S)‐β‐BL with ϵ‐caprolactone (CL) and δ‐valerolactone (VL) using hydroxy‐ and ethoxydistannoxanes catalysts. The enzymatic degradability of these polymers was studied in aerobic medium. The objective of this work was to determine the influence of the tacticity and crystallinity of the corresponding polymers on their degree of aerobic biodegradation and on their initial degradation rate. It was shown that the degradation rate value measured for bacterial PHB 100% (R) was the highest and the degree of aerobic biodegradation reached around 94% after 36 days. A percentage of final biodegradation of about 35% was obtained for predominantly syndiotactic PHB. This result is agreement with the calculated result obtained from triads sequences. The influence of 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, synthetized from distannoxane catalysts, exhibit a high degree of biodegradation of around 75–88%.© 2002 Society of Chemical Industry