| With the rapid development of bio-medical technology,the potential application of polymer hydrogels have been discovered in this filed gradually.Whereas,there are few theoretical research reports related to the gel property,sol-gel transition mechanism and reversal performance of polymer hydrogels.It seems important to focus on the polymer hydrogel response type,the sol-gel transition and the reversibility performance.Meanwhile,it can provide better theoretical support for the design and applications of polymer hydrogels.In this article,the triblock copolymer composite hydrogel named PEP-AG(P(NIPAMco-n-BA)-PEG-P(NIPAM-co-n-BA)-AG)was used as the research model.Concretely,the polyethylene glycol(PEG)worked as the hydrophilic segment,n-butyl acrylate(nBA)worked as the hydrophobic monomer and N-isopropyl acrylamide(NIPAM)worked as thermosensitivity monomer.The PEP hydrogel was prepared by Reversible AdditionFragmentation Chain Transfer Polymerization(RAFT),and the sol-gel behavior of hydrogel was researched by adjusting the molecular weight of polymer PEP and the concentration of silver in the inorganic nanomaterial(AG).It is proved that the molecular weight of the polymer PEP not only affect the sol-gel process of hydrogel(i.e.the higher the molecular weight of the polymer PEP,the lower the sol-gel transition temperature),but also affect the reversibility of hydrogel.When the molecular weight polymer PEP reaches the 20500 Da(the degree of polymerization about PNIPAM above 150),the loading of the silver content radio in AG exceeds 49%(i.e.,the concentration of Ag in the PEP-AG composite hydrogel dispersion above 2.45 mg/m L),and this phenomenon will lead to irreversible denaturation of this hydrogel.It can be concluded that the irreversibility of the PEP-AG composite hydrogel is determined by the molecular weight of the polymer PEP and the silver content in the AG.Furthermore,in order to study other factors about the reversibility of composite hydrogel,we compared diblock copolymer hydrogel EP(PEG-(NIPAM-co-n-BA))with the triblock copolymer hydrogel PEP,and it showed that the number of blocks also has an effect on the reversibility of hydrogels. |
