Synthesis And Photochromism Study Of Chitosan Containing Spiropyran Of Spirooxazine

Part I. The review on research and development of the spiropyran and spirooxazineThe photochromic process, the advantages, and the optical information memory principle of photochromic material were reviewed in this paper, especially the research development of spiropyran and spirooxazine. Photochromic materials have attracted much attention recently because of their potential utility in various high-tech applications, such as optical filters, optical switches, high-density optical data storage , displays, non-linear optics and other molecular devices. The initial colourless form with orthogonal planes of the two parts of the molecule suffered C-0 bond breaking of the pyran or oxazine ring after UV irradiation. The plannar coloured form which is a mixture of the isomers with strong bands in the visible region because of the newly formed delocalized p-electron conjugation, and vice versa by visible light or heat. The influences of the substituent and media, the reaction mechanism were reviewed to the spiropyrans and spirooxazines. And then, the research development > the properties and the applications of polymer having spiropyran or spirooxazine were described.Part II. The synthesis and structural characterization of the spiropyrans and spirooxazinesThe synthetic crafts which were simple, convenient and economical had been designed and developed, based on the systematical consulation of the literature documents. Scores of middle compounds and 14 target compounds were synthesized, and the structures of them were confirmed by means of elemental analysis, IR , ~1H NMR., ~13C NMR.Part III. The synthesis and photochromic study of the chitosan containing spiropyran or spirooxazineThe research development the properties and the applications of chitosan were reviewed briefly in this paper. The polymer containing spiropyran or spirooxazine side groups and the film doped photochromic monomers were designed to do firstly.The evidences and structural characterizations of these esters of chitosan andspiropyran ,spirooxazine had been determined by means of FTIR spectroscopy, X-ray diffraction analysis, thermogravimetric analysis /differential thermal analysis (TG-DTA), scanning electron microscopy (SEM).The photochromic properties such as the absorpting spectra, fatigue resistance, thermal stability, etc. were investigated by UV. Spiropyran was a negative solvatochromic dye,i.e. with increasing solvent polarity,the absorption band underwent a hypsochromic(or blue) shift. Introduction of electron-donating group or electron-withdrawing group in the indoline moiety of the spiropyran can achieve a blue shift or a red shift, but the spirooxazine showed conversely.Photochromic polymers are materials of significant scientic technological interest. Solid films of spiro compounds are interesting since they have applications as optical memory media. As a rule, photochemical reaction were retarded by a polymer matrix, as compared with liquid.This effect was usually attributed to the steric hindrance of the reactions by the polymeric medium. So it was shown that the rate of the merocyanine conversion was significzntlly lower than that of monomer in solvent. The kinetics of decoloration didn't show first-order behavior as in solution, but exhibited birefringence. These monomers complexed with carboxymethyl chitosan could conform J-aggregate on UV irriation because of the red-shit of the absorption band, and they had not some good fatigue resistence and stablitiy.