Grafting Polymerization of N-isopropylacrylamide on the Surfaces of Silica by ATRP and Its Application in HPLC

Abstract Poly(N-isopropylacrylamide) was grafted on the surface of ultrafine silica beads through Atom Transfer Radical Polymerization (ATRP). The synthetic included the introduction of initiator and ATRP polymerization. Scanning electron microscopy revealed that a homogeneous and smooth poly(N-isopropylacrylamide (PNIPAm) layer was formed on the silica surface. The differential scanning calorimetry indicated the composite particles were thermosensitive. The polymer (PNIPAm) was cleaved from the silica composites to be analyzed. The molecular weight of the PNIPAm can be well-controlled by adjusting the feed ratio of the monomers and the polydispersity index was very narrow. The PNIPAm-modified silica particles were used as packing materials in high performance liquid chromatography (HPLC) for separating organic compounds. The result indicated that the satisfactory separations could be successfully achieved only by controlling the temperature of the column. Keywords: Atom transfer radical polymerizationHPLCN-isopropylacrylamidSilica gel ACKNOWLEDGMENT We are grateful for the support of NSFC(10974044)and State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (fund: 2007490611).