Preparation And Properties Of The Copolymer And Its Hydrogels With Side-chain Azobenzide

A monomer of acrylamido azobenzene (AAAB) with azobenzide and bond of C=C, was synthesized by p-aminoazobenzene and Acryloyl chloride, and the photoresponse of its solution to the ultraviolet (UV) was studied. A series photopolymers of Poly(Acrylamide-co-acrylamido azobenzene) (P(AAM-co-AAAB)) and their gels were prepared by the radical copolymerization of the monomer AAAB and Acrylamide, and then the copolymer hydrogels of poly(N-isopropylacrylamide -co-acrylamido azobenzene) (P(NIPAAm-co-AAAB)) was prepared too. The structures of the copolymers and its hydrogels were characterized and the properties sunch as photoresponse, equilibrium swelling, and so on, were studied.The results showed that the THF solution of AAAB revealed good photoresponse. When irradiated with UV, the wavelength of the absorption decreased. The absorption of the solution decreased with the increase of the time of UV irradiation. As AAAB, the absorption of the aqueous solution of P(AAM-co-AAAB) decreased gradually with the increasing of ultraviolet radiation time, and increased to the original state after the irradiation. With the increase of AAAB in the copolymer, the photoresponse became more and more remarkably.With the UV irradiation, the P(AAM-co-AAAB) hydrogels began to shrink, the equilibrium swelling volume was decreased. When removing the irradiation, the hydrogels tended to swell, which revealed a good reversibility.Compared with P(AAM-co-AAAB) hydrogels, the P(NIPAAm-co-AAAB) Poly(N-isopropylacrylamide-co-acrylamido azobenzene) hydrogels also exhibited the similar properties to UV irradiation. With the UV irradiation, the P(NIPAAm-co-AAAB) hydrogels began to shrink, the equilibrium swelling ratio was decreased. But when removing the irradiation, the hydrogels tended to swell and the equilibrium swelling rate was increased too, which also had a good reversibility. With the increase of the concentration of the monomer and cross-linking agent, the photoresponse became more and more remarkably. The P(NIPAAm-co-AAAB) hydrogels also exhibited a good temperature-sensitivity. The lower criticial solution temperature(LCST) decreased compare with PNIPAAm hydrogels.