Facile synthesis of silica-polymer hybrids via simultaneous RAFT process and hydroxyl-alkoxysilane coupling reaction

Abstract

This study aimed at the synthesis of silica particles grafted with better-defined homopolymers and block copolymers by tandem approach. Z-functionalized S-benzyl S′-(3-trimethoxysilyl)propyltrithiocarbonate (BTPT) was used as a couplable RAFT agent to synthesize the target inorganic-organic hybrids. Simultaneous coupling reaction and RAFT process using silica particles and BTPT as raw materials efficiently afforded homopolymers grafted silica, and RAFT-synthesized macro chain transfer agents with ω-terminal trimethoxysilane moiety were utilized to mediate graft reaction to prepare silica particles grafted with di-, tri- and tetrablock copolymers comprised of polymer segments such as polystyrene, polyacrylamides and polyacrylates. When the grafted chains had molecular weights ranging between 3920 and 24800 g/mol, the molar grafting ratios, which were dependent on reaction conditions and types and compositions of grafted chains, were estimated to be in the range of 15.2–101 μmol/g, and grafted polymers usually had polydispersity indices lower than 1.3, revealing that the grafting process was almost controllable. To the best of our knowledge, this versatile tandem approach is one of the most facile techniques to prepare silica particles grafted with polymeric chains with controlled molecular weight, low polydispersity and precise composition due to its minimal reaction steps, mild conditions, straightforward synthesis and satisfactory controllability.