Graft polymerization from pore wall of three-dimensionally ordered macroporous cross-linked polystyrene via atom transfer radical polymerization

The surface-initiated atom-transfer radical polymerization (ATRP) technique was applied to the graft polymerization of methyl methacrylate (MMA) and N-isopropylacrylamide (NIPAm) from three-dimensionally ordered macroporous cross-linked polystyrene (3DOM CLPS) on which the initiator, halogen atom was immobilized onto the pore wall of 3DOM CLPS by chloromethylation. FT-IR and TG-DWA analyses confirm that the graft polymerization of MMA and NIPAm via ATRP had been taken place at the pore wall of 3DOM CLPS. The initiating efficiency of chloromethyl groups was calculated according to the data of TGA-titration, revealed that the benzyl chloride is not only distributed on the surface of the pore walls but also must be present throughout the inner of the cross-linked polystyrene matrix. SEM analyses show that the grafted layers are smooth and homogeneous, and the ordered structure is well preserved after polymerization. By the adjustment of the graft polymerization time, the thickness of grafted polymer layers can be controlled. The max thickness of grafted PMMA layer is 85 nm and the max thickness of grafted PNIPAm layer is 35 nm.