Preparation And Characterization Of Poly(N,N-dimethyl Acrylamide)/Graphene Double Crosslinked Nanocomposite Hydrogels

This study aims to prepare a composite hydrogel by using nanoparticles as reinforcing materials and constructing double crosslinked structure inside the network.Compared with the low-conductivity graphene oxide as a nano-filler to construct a nanocomposite hydrogel,it is undoubtedly more advantageous to directly select graphene with more excellent properties such as light,electricity,heat and mechanics.However,it is difficult to uniformly disperse the pristine graphene in a polar solvent such as water,which is a major obstacle to its effective application.In order to solve this problem,this paper prepared a new type of initiator containing pyrene group（pybACVA）from the molecular design point of view,using N,N-dimethyl acrylamide（DMAA）as a reactive monomer and graphene dispersant.The pyrene group of pybACVA and graphene adsorb the initiator on the graphene sheet layer byπ-πaction and initiate polymerization of the monomer,which promotes the graphene sheet layer to function as a physical crosslinking point.In addition,in order to further enhance the strength of the hydrogel,a new type of poly（N,N-dimethylacrylamide/graphene）double-crosslinking nanocomposite hydrogel was prepared by adding a small amount of N,N’-methylenebisacrylamide（BIS）as the chemical crosslinking point.The specific preparation process is as follows:First,pybACVA is obtained by esterification reaction,and then blended with graphene to adsorb each other.The solvent,water content and concentration of pybACVA were optimized by TGA test.The optimal adsorption capacity of pybACVA on graphene was 21.62 wt%.Raman and other tests have demonstrated the interaction between graphene and the initiator,thus indicating the successful preparation of GR-pybACVA.After adding GR-pybACVA to the DMAA monomer to prepare the PDMAA/graphene double crosslinked nanocomposite hydrogel by in-situ polymerization.The prepared hydrogels were subjected to rheological tests to optimize the optimum content of each component,showing that the optimal amounts of Ammonium persulfate（APS）,graphene and BIS were 0.7 wt%,0.7 wt%and 0.1 wt%,respectively.Infrared,Raman,SEM and other components and morphology tests showed that there was an interaction between graphene and pybCAVA in the gel state,indicating that the gel was successfully prepared.In addition,the novel nanocomposite hydrogel has good mechanical properties(the tensile strength of PA_0.7G_0.7B_0.07H is 36±1.3 kPa,the elongation at break is 892±23%,and the compressive strength is 519±12 kPa),and still have good transient resilience after multiple stretching and compression cycles.The gel also had good swelling properties(the water content and the swelling ratio of the equilibrium swelling of PA_0.7G_0.7B_0.1H were 539%and 6.69,respectively).At the same time,its conductivity is also significantly improved.The conductivity of PA_0.7G_0.7B_0.1H hydrogel and aerogel added with GR-pybACVA is 2.2×10^-3S/m and31.3×10^-99 S/m,respectively.Compared with pure polymer gel,it increased by 1.65times and 54 times respectively.These excellent properties make it possible to apply in medical biological cell culture and other fields,and have broad development prospects.