N-Isopropylacrylamide (NIPAM) and methacrylic acid (MAA) copolymer microgels were prepared by the inverse suspension polymerization technique. Using P(NIPAM-co-MAA) copolymer microgels as the template, amino modified P(NIPAM-co-MAA)/SiO₂ polymer/inorganic composite microgels were prepared by the hydrolysis and condensation of (3-aminopropyl)-triethoxysilane (APTES) under alkaline condition. Finally, dual thermo- and pH-sensitive fluorescent composite microgels with core-shell structures were obtained via the reaction between the fluorescein isothiocyanate (FITC) and amino group. The structures and properties of the prepared composite microgels were characterized by the scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), polarized optical microscopy (POM) with hot stage and laser scanning confocal microscope (CLSM). The results were demonstrated that the composite microgels exhibited good sensitivities both to the temperature and pH, as well as emitted fluorescence in visible light range.

Key words: polymer microgels, temperature-sensitive, pH-sensitive, fluorescent