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

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 temperature-sensitivity of the microgels was investigated by DLS and UV spectrophotomerers. 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 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 latter was in the range of 284-808 nm on heating from 5 to 50 degrees C.