Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5180262 | Polymer | 2015 | 7 Pages |
â¢Photochromic uniform microparticles formed by a swelling process of template particles.â¢Fluorescence/photochromic properties of the various composite particles were studied.â¢Photostability of the SP molecules embedded in the composite particles were measured.â¢P(S-BMA)/P(S-MSP) particles show better photochromic reversibility than P(S-BMA)/FSP.
Photochromic fluorescent uniform micrometer-sized particles were prepared in two ways: (1) Swelling of polystyrene (PS) and poly(styrene-butylmethacrylate) (P(S-BMA)) template particles with spiropyran dye (FSP) to obtain PS/FSP and P(S-BMA)/FSP uniform particles; (2) A similar swelling process, replacing FSP by AIBN, styrene and a spiropyran monomer (MSP), followed by co-polymerization of the monomers within the swollen microspheres to obtain P(S-BMA)/P(S-MSP) uniform particles.The spiropyran dyes are not fluorescent in water or in non-polar organic solvents. In contrast, the dyes encapsulated within the particles exhibit strong red fluorescence in the merocyanine conformation. Fluorescence measurements reveal that the P(S-BMA)/FSP microspheres exhibit higher fluorescence than the PS/FSP particles. The microspheres aqueous dispersion was exposed to alternate UV and visible light cycles and it was found that the fluorescence intensity of the PS/FSP and the P(S-BMA)/FSP particles decreased by 30% of its original value after 5 photoswitching cycles while that of the P(S-BMA)/P(S-MSP) particles remained the same.
Graphical abstractDownload full-size image