Preparation and Properties of Poly N-isopropylacrylamide/Polyacrylic Acid Hydrogels
When the external environment changes,the physical or chemical properties of environment-sensitive hydrogels will change accordingly,and most hydrogels have a simple response to the environment.Poly N-isopropylacrylamide/polyacrylic acid hydrogels prepared with acrylic acid(AA)and N-isopropylacrylamide(NIPAm)as raw materials can respond to both temperature and pH.Poly N-isopropylacrylamide/polyacrylic acid hydrogel was prepared by one-pot method.By adjusting the neutralization of acrylic acid,the ratio of acrylic acid(AA)and N-isopropylacrylamide(NIPAm)monomers,and the dosage of crosslinking agent N,N′methylene bisacrylyl(BIS)and initiator potassium persulfate(KPS),the effects on the water absorption and tensile properties of the hydrogels were studied,and the response of the prepared poly N-isopropylacrylamide/polyacrylic acid hydrogels to temperature and pH were investigated.The experimental results showed that when the neutral degree was 125%,n(NIPAm)∶ n(AA)= 0.3 ∶ 1,the mass fraction of BIS was 0.5%,and the mass fraction of KPS was 1%,the hydrogel had the highest swelling rate and certain elasticity,and the water absorption rate reached 179.73 g/g at room temperature.The hydrogel shrinked in an acidic buffer(pH value=3).When the pH value of the buffer was greater than 3,the hydrogel swelled and had a sensitive and reversible pH response.At the same time,the hydrogel had both heat shrinkage and temperature sensitivity.
polyacrylic acidpoly(N-isopropylacrylamide)hydrogelpH value
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