Green synthesis and characterization of a wholly bio-based self-healing polyester elastomer and its graphene nanocomposites

Abstract

A new wholly bio-based polyester elastomer (PEE) was synthesized by one-pot condensation polymerization of a fatty diol and a mixture of a fatty tricarboxylic acid and a fatty dicarboxylic acid, all containing multiple alkyl chains, without the use of any solvent or toxic additive. The elastomer shows excellent resilience with low hysteresis, which could fully recover its original state from 200% strain within 5 s. Owing to strong van der Waals interaction among abundant dangling alkyl chains, the polyester elastomer possesses autonomous self-healing behavior at ambient temperature without any external intervention, capable of restoring 96.8% of its original Young's modulus and 52.1% of its original elongation at break within 10 min. Graphene oxide (GO) reduced and modified by p-phenylenediamine (PPD) was used to improve the mechanical properties of PEE to broaden its applications. By incorporating with low loadings of PPD-reduced GO (P-rGO), the Young's modulus, tensile strength, elongation at break and energy at break of PEE are all enhanced, with 0.5 wt% being the optimal loading. However, the self-healing efficiency is reduced by addition of P-rGO due to the restriction of polymer chains. This type of renewable elastomer and its nanocomposites have potential in a variety of applications.