Alternating Copolymerization of Isobutylene Oxide and Cyclic Anhydrides: A New Route to Semicrystalline Polyesters
Lan‐Fang Hu, Xun Zhang, Xun Zhang, Xiao‐Han Cao, Danjing Chen, Yue Sun, Chengjian Zhang, Xinghong Zhang, Xinghong Zhang
Abstract
Alternating copolymerization of epoxides with cyclic anhydrides is a versatile method to produce functional polyesters. However, this strategy remains challenging to synthesize semicrystalline polyesters. Here, we describe a facile and efficient approach to synthesize semicrystalline polyesters via the copolymerization of low-cost isobutylene oxide (IBO) and various cyclic anhydrides. Using a heterogeneous catalyst, zinc–cobalt(III) double metal cyanide complex, inhibits the isomerization of IBO and demonstrates the productivity up to 680 g polyester/g catalyst. The resulting polyesters possess >99% alternating degree, >90% head-to-tail linkages, and molecular weights up to 42.3 kDa. This method also achieves low-molecular weight (3.9–7.1 kDa) hydroxy telechelic polyesters with narrow dispersities (1.3–1.4) upon adding water as the chain transfer agent. These unprecedented polyesters are semicrystalline owing to their high regioregularity and exhibit melting temperatures (Tm) ranging from 67 to 141 °C. Interestingly, upon tuning cis/trans isomerization of the C═C bond, the unsaturated polyester prepared from IBO and maleic anhydride demonstrates a unique crystalline (Tm = 72 °C)-amorphous-crystalline (Tm = 153 °C) transformation.