Controlled polymerization of methylmethacrylate from fumed SiO2 nanoparticles through atom transfer radical polymerization

摘要

Atom transfer radical polymerization (ATRP) is a promising method to synthesize well-defined polymer/inorganic nanoparticles. However, the surface-initiated ATRP from commercially mass produced inorganic nanoparticles has seldom been studied. In this study, the surface-initiated ATRP of methylmethacrylate (MMA) from commercially mass produced fumed silica (SiO2) nanoparticles was investigated. Unlike the ATRP of MMA initiated from a free initiator, the controllability of ATRP of MMA from the surface of fumed silica nanoparticles was much better using ligand 2,2'-bipyridine (bpy) than N,N,N',N",N"-pentamethyldiethylenetriamine (PMOETA) as the initiator was immobilized on the surface of the SiO2 nanoparticles and the presence of the SiO2 nanoparticles made the CuCI/bpy catalyst system a homogeneous catalyst system and CuCI/PMDETA a heterogeneous one. The appropriate molar ratio of monomer and initiator was essential for preparing controlled PMMA/SiO2 nanoparticles. The entire process of ATRP of MMA from the surface of SiO2 nanoparticles was controllable when using bpy as ligand, xylene as solvent and with a monomer to initiator ratio of 300:1. The 'H NMR results indicated that the PMMA on the surface of the SiO2 was prepared via ATRP initiated from 4-(chloromethyl)phenyltrimethoxysilane. The well-defined PMMA/SiO2 nanoparticles obtained have good thermal stability and are well dispersed in organic media as proved by TGA, dynamic light scattering and transmission electron microscopy.