Studies On Synthesis And Properties Of Spiropyran Hydroxypropyl Cellulose

As the most abundant and renewable resources in the nature, Cellulose has so many advantages, such as low price, storage stability, biodegradable and biocompatibility, nontoxic and no immunogenicity etc. So this green resources has attracted widespread attention.In this thesis, Cellulose derivatives (SP-HPC) containing different contents of spiropyran moieties were synthesized by the esterification reaction between hydroxypropyl cellulose (HPC) and 3-(3’,3’-Dimethyl-6-nitrospiro[chromene-2,2’-indolin]-1’-yl) propranoic acid (SPCOOH), using DCC/DMAP as catalyst in tetrahydrofuran (THF). The structure of SP-HPC was characterized by 1H-NMR, FT-IR, TGA. The degree of substitution of SP group in SP-HPC increased with lifting the adding weight of SPCOOH. Photochromism of the SP-HPC was investigated in THF, and this solution showed rapid reversible UV-light stimuli response, also it can show colourless and upon intervals UV irradiation and dark conditions reversibly. The color of SP-HPC solution in THF changed from colourless to modena after UV irradiation, After the solution was in dark, its color changed again to colourless.SP-HPC can be self-assemble into spherical micelles in water and be characterized by DLS, TEM, SEM. The micelles size increased with the increasing of the polymer concentration and the degree of substitution of SP groups. The micelles also showed stimuli response to UV-light. Under UV irradiation, spiropyran groups in the micelles stacked more tightly through a transition from loop-locked state to ring opening structure, the size of the micelles become smaller and the distribution of micelles particle size become narrow.The photochromism of the SP-HPC solid membrance was characterized by UV-vis spectra. SP-HPC films showed reversibly photochromic properties, but the transfer speed fiom MC to SP in dark was more slower than that from SP to MC by uptaking energy. The wetting properities of the solid membrances were investigated using the contact angle meter. The contact angle of the SP-HPC is strongly depend on the configuration changing of spiropyran groups on the solid membrances surface, which relates with photoisomerization ring opening and closing of the spiropyran groups in SP-HPCs. The change of the water contact angle of the solid membrance depends on the Dsp and the higher DSsp can lead to a smaller variation of the water contact angle during the UV irradiation and dark conditions.