FAST MICROWAVE-MEDIATED EMULSION POLYMERIZATION OF SPIROPYRAN-CONTAINING MONOMERS IN POLYMERIZATION-INDUCED THERMOSENSITIVE MICELLES

摘要

@@20-500 nm diameter polymer nanoparticles containing spiropyran (SP) have been prepared by microwave-mediated emulsion polymerization. This method produces the polymer nanoparticles with tunable size and narrow size distribution. Microwave-mediated emulsion polymerization is conducted in much shorter time than conventional heating bath at rather low temperature between 40-90°C, which provides a promising potential in industrial application. The microwave-mediated emulsion polymerization of styrene with photoswitchable monomer containing SP produced fluorescence-switchable polymer nanoparticles. The prepared nanoparticles could be lighted up affording red fluorescence in the merocyanine (MC) forms of the encapsulated molecules under the irradiation of UV light. Spiro-mero photoisomerization is reversible, allowing the fluorescence to be switched "on" and "off" by alternating UV and visible light. Optimalization of polymerization conditions has been investigated allowing for the best optical properties of nanoparticles. An altemating 780 nm NIR laser two-photon excitation/488 nm laser single-photon excitation induces reversible fluorescence of photoswitchable nanoparticles in terms of targeted cells, such as the SK-BR-3 cell line.