Trithiocarbonates Containing Trimethoxysilyl Functionalities as Mediating Agents in Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization of Methyl Acrylate

Reversible addition-fragmentation chain transfer (RAFT) polymerization with benzyl(3-trimethoxylsilylpropyl)trithiocarbonate (BTPT)and 1,4-bis(3'-trimethoxysilylpropyltrithiocarbonylmethyl)benzene (TPTB) as mediators was performed to produce branched poly(methyl acrylate) (pMA). The deviation of the experimental number average molecular weights towards higher values and the size exclusion chromatography (SEC) traces measured at distinct time instants after polymerization indicated a coupling of the trimethoxysilyl end-groups to form terminal-linked pMA of high molecular weight. The trimethoxysilyl moieties also caused the unusual creation of doubly ionized pMA chains in electrospray ionization mass spectrometry (ESI-MS). BTPT was furthermore anchored onto fumed silica to carry out a RAFT graft polymerization with benzylpropyltrithiocarbonate as additional RAFT agent in solution to afford well-defined pMA chains fixed to silica nanoparticles. A block copolymerization of the living anchored pMA chains with styrene (Sty) produced grafted pMA-b-pSty chains with good agreement between experimental and theoretical molecular weights.