Mechanical and microstructural characterization of poly(N-isopropylacrylamide) hydrogels and its nanocomposites

Mechanical behavior dependency of the poly(N-isopropylacrylamide) hydrogel related to the amount of initiator, crosslinker, and nanoparticles was investigated. An experimental approach has been undertaken to observe these dependencies and assess the amount of initiator (ammonium persulfate), crosslinker (N, N′-methylene-bisacrylamide), and nanoparticles (graphene oxide) on the macroscopic responses of poly(N-isopropylacrylamide). Different amounts of initiator, crosslinker, and nanoparticle were used to manufacture specimens for the compression test. The specimens were subjected to compressive loading up to breakage to investigate the breaking behavior of poly(N-isopropylacrylamide). The responses of these specimens indicated that the mechanical behavior of poly(N-isopropylacrylamide) was highly nonlinear and depends on these ingredients. The mechanical responses of poly(N-isopropylacrylamide) were simulated using the ideal network model. The simulation results of the mathematical model substantially complied with the experimental data of poly(N-isopropylacrylamide). In addition, a more in-depth microstructural analysis was performed on these specimens. The analysis results allowed us to correlate the dependent amounts of the ingredients on the nonlinear, mechanical behavior of poly(N-isopropylacrylamide).