Investigation of mechanical and thermal properties of poly(N-isopropylacrylamide) hydrogels containing graphene oxide

In this study, we have prepared poly(N-isopropylacrylamide) (PNIPAm) hydrogel containing graphene oxide (GO) by a simple mixing of a solution containing the monomers and aqueous GO through radical polymerization. Mechanical property of the PNIPAm/GO was investigated by measuring storage modulus using a rheometer. PNIPAm containing 3 wt% of GO showed the highest storage modulus among the samples of various GO contents. In this GO content, the exfoliated GO sheets were well dispersed in the hydrogel matrix, enhacing the mechanical property of the hydrogel. We found that the dense porous structure consisted of small channels was formed in the PNIPAm containing 3 wt% of GO. The storage moduli of the PNIPAm/GO hydrogels were rapidly increased near the lower critical solution temperature of the PNIPAm during heating. We concluded that the mechanical property of PNIPAm/GO was closely related to the porous structure of the hydrogels that was affected by the dispersion state of GO in the matrix.