Synthesis of Well-Defined Amphiphilic Diblock Copolymer Brushes on Halloysite Nanotubes via Surface-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization

The structurally well-defined diblock copolymer, poly(methyl methacrylate)-b-poly(N-isopropylacrylamide) (PMMA-b-PNIPAM) amphiphilic diblock copolymer was successfully grafted onto the surface of Halloysite nanotubes (HNTs) via reversible addition-fragmentation chain transfer (RAFT) polymerization. In this approach, S-benzyl S'-trimethoxysilylpropyltrithiocarbonate was first immobilized onto the HNTs as the RAFT agent. The polymerization of MMA and NIPAM was then initiated and propagated on the HNTs surface by RAFT polymerization. The chemical structure and morphology of diblock copolymer grafted onto the HNTs surface were ascertained by FT-IR, and FE-SEM analyses. A moderate degree of functionalization of HNTs by polymer chains was obtained according to TGA results. This study has suggested a facile approach to prepare surface functionalized HNTs via RAFT polymerization, which is promising to open up a wider prospect for the fabrication and novel application of hybrid polymeric materials with diverse functionalities.