New pH and temperature-sensitive hydrogels have been synthesized throug h copolymerization of anionic acrylate polyurethane prepolymer (P(U)) and N -isopropyl acrylamide (NIPAAm) under various feed ratios.Single glass...New pH and temperature-sensitive hydrogels have been synthesized throug h copolymerization of anionic acrylate polyurethane prepolymer (P(U)) and N -isopropyl acrylamide (NIPAAm) under various feed ratios.Single glass transitio n t emperature was noticed from the DSC curves of the dried hydrogels,indicating of good miscibility between the two components.The pH sensitivity was much affecte d by the composition of the hydrogels and a lowest swelling degree was shown in hydrogel H4 with P(U)/NIPAAm feed ratio of 1/1.Hydrogel H4 also possessed low er critical solution temperature (LCST) of about 27℃ at both pH11 and pH7 sol utions.In the equilibrium hydrogel,most of the absorbed water was freezable wa ter with its content little affected by the hydrogel composition.Furthermore,t he gel strength was improved with incorporating more P(U) chains into the hydrog el.展开更多
The pH-sensitive copolymer hydrogels were prepared with the monomers of acrylic acid and N-vinyl-2-pyrrolidone based on gamma radiation technique. The morphology of the hydrogels was monitored by using scanning electr...The pH-sensitive copolymer hydrogels were prepared with the monomers of acrylic acid and N-vinyl-2-pyrrolidone based on gamma radiation technique. The morphology of the hydrogels was monitored by using scanning electron microscope. The influence of absorbed dose, monomer composition and concentration on the swelling ratio (SR) of the hydrogels were investigated in detail. The effect of pH and temperature of the swelling medium on the swelling behavior of the hydrogels were also examined. The results show that the SR of the copolymer hydrogels decreases with the monomer concentration and absorbed dose increasing. The copolymer hydrogels show a better pH-sensitive behavior. In alkaline solution, the SR of the hydrogels is much higher than in acid solution.展开更多
文摘New pH and temperature-sensitive hydrogels have been synthesized throug h copolymerization of anionic acrylate polyurethane prepolymer (P(U)) and N -isopropyl acrylamide (NIPAAm) under various feed ratios.Single glass transitio n t emperature was noticed from the DSC curves of the dried hydrogels,indicating of good miscibility between the two components.The pH sensitivity was much affecte d by the composition of the hydrogels and a lowest swelling degree was shown in hydrogel H4 with P(U)/NIPAAm feed ratio of 1/1.Hydrogel H4 also possessed low er critical solution temperature (LCST) of about 27℃ at both pH11 and pH7 sol utions.In the equilibrium hydrogel,most of the absorbed water was freezable wa ter with its content little affected by the hydrogel composition.Furthermore,t he gel strength was improved with incorporating more P(U) chains into the hydrog el.
基金Natural Science Foundation of Henan Province (0611023900)
文摘The pH-sensitive copolymer hydrogels were prepared with the monomers of acrylic acid and N-vinyl-2-pyrrolidone based on gamma radiation technique. The morphology of the hydrogels was monitored by using scanning electron microscope. The influence of absorbed dose, monomer composition and concentration on the swelling ratio (SR) of the hydrogels were investigated in detail. The effect of pH and temperature of the swelling medium on the swelling behavior of the hydrogels were also examined. The results show that the SR of the copolymer hydrogels decreases with the monomer concentration and absorbed dose increasing. The copolymer hydrogels show a better pH-sensitive behavior. In alkaline solution, the SR of the hydrogels is much higher than in acid solution.
