Herein we report a means that has been developed to prepare smart polymeric microgels consisting of thermosensitive cores with pH-sensitive shells. The microgels were obtained directly from seed polymerization of N-isopropylacrylamide in supercritical carbon dioxide (ScCO2). The effects of initial amounts of crosslinker, and Poly (dimethylsiloxane)-graft-polyacrylates (PDMS-g-PAA) on the yield and morphology of the resulting polymer were investigated. PDMS-g-PAA and crosslinker worked effectively as surfactant. PNIPA/ PDMS-g-PAA particles with diameters in 50 nm were produced in ScCO2, in high yield and in short reaction times. (C) 2008 Wiley Periodicals, Inc.