Tailoring the surface of attapulgite by combining redox-initiated RAFT polymerization with alkynyl-thiol click reaction for polycarbonate nanocomposites:Effect of polymer brush chain length on mechanical, thermal and rheological properties

In this work, we proposed the tuning of the interface between attapulgite (ATP) and polycarbonate (PC) by the surface tailoring of ATP via a combination of RAFT polymerization and alkynyl-thiol click reaction. The side alkynyl-functionalized random copolymer poly(MMA-co-PgMA) was synthesized as the immobilization block via redox-initiated room-temperature RAFT copolymerization of MMA and propargyl methacrylate (PgMA). Then, the dispersion block was synthesized by room-temperature RAFT polymerization of MMA using poly(MMA-co-PgMA) as the macro chain transfer agent to afford poly((MMA-co-PgMA)-b-MMA). FTIR, 1H NMR, gel permeation chromatograph (GPC), and kinetic results indicated the successful synthesis of copolymers with well-defined structures. Copolymers with different length of PMMA segment were tethered onto the surface of thiol-functionalized ATP via alkynyl-thiol click reaction to mediate the interfacial interaction between ATP and PC, the successful covalent grafting of copolymers was confirmed by FTIR, TGA, XPS and XRD, and the effects of dispersion blockchain length on nanocomposites were investigated. The functionalized ATP demonstrated an improved dispersity in nanocomposites and enhanced mechanical properties with increasing dispersion blockchain length. The PC nanocomposites with functionalized ATP showed lower Tg and complex viscosity as compared to that of pure PC and nanocomposites with bare ATP, which enhanced the processability of nanocomposites.