| This article is based on the photoisomerization property of azobenzene. Azobenzene molecules were applied in the main chain of azo polymers, photoresponsive hydrogels were prepared, and the photoresponsive behaviors of hydrogels were studied. The main work is shown as follows.(1)Firstly, main-chain azo polymers were made of 4,4'-dihydroxy-azobenzene (DHAB), polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI) with more molar weight than DHAB and PEG. Then, main-chain azo polymers were chemically crosslinked by polyhydroxy ?-cyclodextrin (?-CD) and the hydroel was prepared. The relationship between water absorption and modulus with the content of azobenzene added in hydrogel was studied. Under ultraviolet irradiation, the water absorption of hydrogel decreased and the modulus of hydrogel increased accordingly. The change rate of water absorption has a close relationship with the hydrophility of the azo polymers. Dried azo polymers could change their shapes when they were irradiated under ultraviolet.(2)Then, azobenzene-4,4'-dicarbonyl dichloride(AZO-DC) was synthesized and reacted with PEG to get polymers with good hydrophility, and hydrogels with large water absorption were prepared by free radical reaction. Hydrogels showed a relatively slow response rate under 365 nm ultraviolet light source. The principle that influences the rate of water absorption change was found based on the photoresponsive behaviors of hydrogels. The key points and the influence factors in preparation process were proposed, which has a guiding significance. |
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