Biodegradability of renewable isosorbide and sebacate-based copolyesters

Abstract

The growing environmental concerns associated with the use of plastics highlight the need to mitigate carbon emissions and environmental pollution via biodegradable plastics development. Herein, biotechnologically accessible and renewable building blocks, namely 1,4-butanediol and sebacic acid, were copolymerized with carbohydrate-derived isosorbide to afford random poly(butylene-co-isosorbide sebacate) with variable isosorbide content. The thermal stabilities of these copolyesters and their biodegradabilities under (non)enzymatic hydrolysis, compost, soil, and marine conditions were examined as functions of isosorbide content. With the increasing isosorbide content, the glass transition temperature increased, whereas the crystallinity and melting temperature decreased. Isosorbide incorporation enhanced hydrolyzability under alkaline and enzymatic conditions, while demonstrating minimal impact under neutral and acidic conditions. The in-compost degradation rate increased with the increasing isosorbide content because of the concomitant decrease in melting temperature and crystallinity. In soil and marine environments, the copolyesters were degraded faster than poly(butylene sebacate). At 30 mol% isosorbide, the degradation extent reached 97.2 and 68.3% after eight-week degradation in soil and 32-week degradation in a marine environment, respectively. This study is the first to report the biodegradability and degradation mechanisms of poly(butylene-co-isosorbide sebacate) and provides valuable insights into customizing the synthesis of biodegradable plastics to meet the degradation cycle requirements under various environmental conditions.