Kaolinite-based Janus nanosheets as effective compatibilizer of PLA/PBAT blend

Abstract

To address the increasing global plastic pollution while the reducing oil supply, the biodegradable and bio-derived poly(lactic acid) (PLA) has been developed and considered to be the most promising substitute of petroleum-based plastics. However, the severe brittleness of PLA has become the obstacle of its broad application. Blending modification with poly(butylene-adipate-co-terephthalate) (PBAT) has been proved to be an potentially feasible strategy to toughen PLA, but conflicted by the poor compatibility between PLA and PBAT. To tackle the problem, a comb-type clay-based Janus nanosheet of poly(methyl methacrylate- kaolinite- poly(butylene-adipate-co-terephthalate) (PMMA-Kaol-PBAT) was prepared by selectively grafting PMMA and PBAT separately on either sides of kaolinite Janus nanosheets (JNS). PBAT was functionalized with quaternary amine via aminolysis before being cation-exchanged onto the siloxane tetrahedral surface (STS) side of kaolinite nanosheets, while PMMA chains were grafted onto the aluminoxyl octahedral surface (AOS) side after a beforehand surface modification with the silane coupling agent KH-570. Introduced in the PLA/PBAT blend system, the PMMA-Kaol-PBAT was found to enrich at the interface, enhancing the phase compatibility with the phase separation and aggregation inhibited during the film coating and annealing process.