A novel route to the preparation of poly(N-isopropylacrylamide) microgels by using inorganic clay as cross-linker-Qingsong Zhang

Adopting inorganic clay (hectorite) and MBA as physical and chemical cross-linking agents,respectively, PNIPAM microgels were synthesized by SFEP. The chemical structure and morphology of the microgels were confirmed by FTIR, WXRD, and SEM. The temperaturesensitivity of the microgels was investigated by DLS and UV spectrophotometers. The results inferred that clay platelets dispersed in an aqueous medium were fully exfoliated and could act as a kind of multifunctional cross-linking agent and significantly reduced the hydrodynamic diameters of the microgels. In fact, the hydrodynamic diameters of the PNIPAM microgels with clay as cross-linker ranged from 154 to 322 nm which was much smaller than that using MBA as chemical cross-linker, the later was in the range of 284–808 nm on heating from 5 to 50⁰C.