The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of tem...The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of temperature and pH in aqueous solutions. It was shown that controlled alteration of the hydrogel phase transition temperature can be achieved by changing their composition and pH of the environment. Increase in content of hydrophilic allylamine from 10 to 60 wt% in monomer mixture causes a shift of the phase transition temperature from 35oC to 47oC. Hydrogels with N-isopropylacrylamide/allylamine hydrochloride mass ratio of 3:2 show the highest pH-response. Values of average molecular weight between polymer cross-links, , and Flory parameter, χ, were calculated using temperature dependences of the equilibrium swelling of the synthesized hydrogel.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
文摘The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of temperature and pH in aqueous solutions. It was shown that controlled alteration of the hydrogel phase transition temperature can be achieved by changing their composition and pH of the environment. Increase in content of hydrophilic allylamine from 10 to 60 wt% in monomer mixture causes a shift of the phase transition temperature from 35oC to 47oC. Hydrogels with N-isopropylacrylamide/allylamine hydrochloride mass ratio of 3:2 show the highest pH-response. Values of average molecular weight between polymer cross-links, , and Flory parameter, χ, were calculated using temperature dependences of the equilibrium swelling of the synthesized hydrogel.
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.
