The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiati...The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiation polymerization using Co^60 γ-ray. Their swelling equilibrium data in the media of deionized water, NaCl aqueous solutions and different pH buffer solutions are determined. It appears that lower critical solution temperature （LCST） of the hydrogels will drop with the increase of ionic strength and increase with the rising of acrylamide content, A semi-empirical formula is set up with the experimental results. Moreover, it also indicates that this copolymer is pH-sensitive, which is similar to the homopolymer of PNIPAAm.展开更多
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
基金Project Supported by Science Foundation of Shanghai MunicipalCommission of Science and Technology (Grant No .02DJ14030)
文摘The thermosensitive poly （ N-isopropylacrylamide ） （PNIPAAm） and poly （N-isopropylacrylamide-co-acrylamide） [ poly （NIPAAm-co-AAm） ] hydrogels with different acrylamide molar percentage are prepared by radiation polymerization using Co^60 γ-ray. Their swelling equilibrium data in the media of deionized water, NaCl aqueous solutions and different pH buffer solutions are determined. It appears that lower critical solution temperature （LCST） of the hydrogels will drop with the increase of ionic strength and increase with the rising of acrylamide content, A semi-empirical formula is set up with the experimental results. Moreover, it also indicates that this copolymer is pH-sensitive, which is similar to the homopolymer of PNIPAAm.
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.
