Synthesis of Unsaturated Poly(ester-ether)s with Ultrahigh Thermal Resistance and Biodegradability Using Hydroxyl-yne Click Polymerization

With increasingly hotter and longer summers, there is a need to improve the heat stability of biodegradable polymers and plastics. In this study, we synthesized unsaturated poly(ester-ether)s prepared by successive hydroxyl-yne click reaction (polymerization) of 1,4:3,6-diandydroglucitol (IS)-containing dialkyne (ISDP) or 1,4:3,6-diandydromannitol (IM)-containing dialkyne (IMDP) with several diols, and investigated their stability by thermal gravity measurement and their biodegradability under industrial conditions by biochemical oxygen demand (BOD) testing in an activated sludge according to ISO guideline 14851. We found that poly(IMDP-alt-IM), prepared by step polymerization of IMDP and IM, has an ultrahigh glass transition temperature (Tg) of 176 °C. Thermal gravity measurement of this unsaturated poly(ester-ether) indicated a 5% weight loss of 333 °C, reflecting high thermal resistance. In the biodegradation test, the ratio of biochemical oxygen demand BOD to hypothetical biochemical oxygen demand (TOD) was 23% after 28 days, indicating good biodegradation for poly(IMDP-alt-IM). Collectively, our results will provide a frontier framework for synthesizing a series of biomass-based polyesters aimed at the development of heat-resistant biodegradable polymers.