Synthesis And Characterization Of High-performance Poly(Magnesium Acrylate) Based Hydrogel

Poly(magnesium acrylate)is a kind of hydrogel material with excellent mechanical properties and thermal aging resistance.However,poor water-absorption,water-retention and repeated water-absorption capacity limit its application in agriculture-water conservation,and construction materials and other fields.Synthesizing poly(magnesium acrylate)composite hydrogel through dually cross-linked network structure and semi-interpenetrating network structure can not only improve its mechanical properties,but also obtain hydrogels with excellent water-absorption and water-retention ability.In this paper,magnesium acrylate was used as monomer with sodium persulfate-sodium thiosulfate as the redox initiation system to prepare poly(magnesium acrylate)hydrogel by free radical polymerization.Then the preparation process was optimized:magnesium acrylate 40wt%,sodium persulfate 0.25wt%,initiator/reductant ratio 1:1.Furthermore,the self-healing property of poly(magnesium acrylate)(PAMgA)was studied.The results showed that tensile property of this hydrogel could be restored to 60%of original version after 12h recovery.On this basis,using sodium acrylate as a comonomer and N,N'-methylenebisacrylamide(MBA)as a covalent crosslinking agent,poly(magnesium acrylate-co-sodium acrylate)(PAMgA/PASA)dually cross-linked hydrogels were prepared.Then the microstructure,water-absorption ability,water-retention capacity and mechanical properties of hydrogels were studied.The results revealed that with the addition of MBA,magnesium acrylate and sodium acrylate formed a dually cross-linked hydrogel.The interaction of ionic coordination and covalent bond made the fracture surface of hydrogel material rough and the ability of maintaining network structure during the drying process was improved.When the amount of sodium acrylate was 20wt%and the amount of MBA was 0.4wt%,the swelling ratio of this copolymerized hydrogel was increased by 400%,the water-retention capacity after 12h drying increased by 100%and elongation increased by 70%compared with PAMgA hydrogel.At the same time,after repeated drying-swelling cycle,the swelling ratio of this copolymerized hydrogel was maintained as high as 300%.In addition,using polyvinyl alcohol(PVA)as a semi-interpenetrating network component,the poly(magnesium acrylate)/polyvinyl alcohol(PAMgA/PVA)composite hydrogels were prepared by aqueous solution polymerization and the optimal amount of PVA was obtained in the study.The results showed that with the addition of PVA,SIPN structure was obtained and the water-absorption,water-retention,mechanical property and self-healing property of composite hydrogels were significantly improved.The hydrogel prepared under optimal amount of PVA had a swelling ratio of increased 90%,water-retention capacity increased 30%,tensile strength increased nearly 200%,elongation increased nearly 100%and self-healing efficiency increased by nearly 20%.