In Situ Reversible Addition-Fragmentation Chain Transfer Polymerization of Styrene in the Presence of MCM-41 Nanoparticles: Comparing 'Grafting from' and 'Grafting through' Approaches

摘要

The preparation of polystyrene/MCM-41 nanocomposites was carried out by "grafting from" and "grafting through" approaches and in the presence of unmodified MCM-41, using reversible addition-fragmentation chain transfer (RAFT) polymerization. The MCM-41 was modified by attaching S-dodecyl-S'-(α,α'-dimethyl-α"-acetic acid)trithiocarbonate (DDMAT) as the RAFT agent and methacrylate group using 3-methacryloxypropyldimethylchlorosilane. The kinetics of styrene RAFT polymerization by different approaches was compared with the model polymerization mediated by free DDMAT. The quantity of the grafted chain grown from the surface and inside of the pores of MCM-41 and free polymer chains in bulk was determined by thermogravimetric analysis. The molecular weight of the produced polymer chains increased linearly with the monomer conversion for three methods. The gel permeation chromatography showed that the molecular weight of grafted and free polymer chains in the "grafting from" approach is higher than other methods, and molecular weight distributions were relatively narrower whereas the rate of polymerization for "grafting from" was higher.