The Study On Photochromic And Photoswichable Fluorescent Nanoparticles Based On Spiropyran

Spiropyrans are well-known photochromic compounds. In this dissertation, Two indolinebenzopyran derivatives were synthesized and doped in polymet -hylmethacrylate (PMMA) host films with different concentration respectively. The photochromic properties of the two compounds in solution and film were investigated.In this paper, we have designed and synthesized a novel nanohybrids with average particle size less than 70 nm, in which spiropyran comonomer (MAS -P) was covalently incorporated into the crosslinked polymeric nanoparticle matrix by means of a modified miniemulsion polymerization process. The rate of ring closure reaction of photochromic dye was retarded by virtue of crosslink reaction, which is expected to control the free volume surrounding photochromic moiety and provide a passivating microenvironment to repell outside surroundings interference.The photoswitchable fluorescent nanohybrids based on spirobenzopyran were fabricated in the same way, in which hydrophobic spirobenzopyran and the matched fluorescent dyes are covalently attached to polymer chains and noncovalently embedded in the nanoscale crosslinked polymeric matrix, respectively. The obtained nanohybrids have exhibited superior fluorescent photoswitchable performance due to the efficient photoinduced intermo -lecular energy transfer, and the thermal stability of photomerocyanine has been improved. This has shown the potent application for photocontrolled nanoswitches.