Investigation of RAFT polymerization in mesoporous SBA-15 by using various monomers

Abstract

Reversible addition fragmentation transfer (RAFT) polymerization has attracted much attention, because its reaction mechanism has been well studied and it provides a facile approach to prepare the special functional polymer. Herein, mesoporous SBA-15 with pore size of 6 nm was employed as a “microreactor” for the RAFT solution polymerization of methyl methacrylate (MMA), glycidyl methacrylate (GMA) or styrene (St) using a xanthate as a chain transfer agent and AIBN as the initiator. The structures, morphologies and properties of the obtained polymers and in-situ composites were fully characterized. XPS results confirm the presence of sulfur in the obtained polymers, which indicates a RAFT polymerization mechanism. XRD observation found that the in-situ composites exhibited the similar two-dimensional hexagonal pore structures intrinsic to SBA-15. However, the specific surface area, pore size, and pore volumes of the composites decreased dramatically compared with the intrinsic SBA-15 morphology. N2 adsorption studies of polymers synthesized from various monomer mixtures revealed differing properties with adsorption capacity in the order of GMA > MMA > St. The Mn and Mw of polymers produced from within SBA-15 were significantly higher than those produced external to the SBA-15 framework. Meanwhile, the molecular weight distributions of polymers constructed within the SBA-15 were narrower. Lastly, the thermal stability and glass transition temperature of the polymers constructed within the SBA-15 were notably enhanced.