Syntheses And Properties Of Ionic Driving Hydrogels And Photosensitive Hydrogels With Spiropyrane

This study was concentrated about stimuli-responsive hydrogels. Hydrogels driven by ionic coacervation and contained spiropyrane were successfully synthesized separately. A rheometer with the parallel plate geometry (25 mm diameter) was used to investigate the properties and response of the hydrogels in different circumstances.For one thing, a cation triblock copolymer functionalized with guanidinium was synthesized by oxyanion-initiated polymerization, and characterized by 1H NMR spectra. Hydrogels were formed by mixing the aqueous solutions of both cation and natural anion polymers. The studies of the hydrogels in this part contained many aspects like below:(1) The resultants of oxyanion-initiated polymerized P(AGE-EG-AGE) with four different initiators were studied. (2) Two processes for preparing gunidinium functionalized ABA cation copolymer were compared, and a thiol functionalized guanidinium which could be used in thiol-ene reaction was first designed and prepared, improving the transformation rate. Syntheses were characterized by 1H NMR. (3) Sodium alginate (SA) and sodium ligninsulfonate hydrogels both combined with guanidinium functionalized copolymer were first prepared, and the mechanical properties responses to polymer concentration, ionic ratio, salt concentration were investigated by dynamic mechanical spectroscopy. The results showed that, G' increased with the increasing polymer concentration, but decreased with the increasing salt concentration. SA hydrogel was destroyed in NaCl solution of 0.5M, but SLS hydrogel was still formed in NaCl solution even of 1M. Also, G' of SLS hydrogel was greater then that of SA hydrogel at the same water content of the two hydrogels. Besides, G' increased with the increasing ratio of anion polymer, but decreased at the ratio of 4:1 in the ionic ratio study.For the other thing, a photosensitive acrylamide (AM) hydrogel contained spiropyrane and crosslinked by POSS was prepared in this study. FTIR and 1H NMR were used for characterization. At the same time, the swelling ratio and the mechanical properties were measured. It showed that, the swelling ratio increased but G' decreased with increasing time of UV irradiation. It was reversible above under visible light. While guanidinium copolymer was added to the hydrogel before formed, the opposite results were showed. It was proved that, there was an interaction between spiropyrane and guanidinium under UV light.