Preparation of Poly(Acrylic Acid) Grafted Reduced Graphene Oxide/Polyacrylamide Composite Hydrogels with Good Electronic and Mechanical Properties by in-situ Polymerization

Conductive hydrogels with excellent electronic and mechanical properties are promising materials for flexible sensors. Herein we present a facile method to prepare reduced graphene oxide (rGO)-containing composite hydrogels with suitable electronic and mechanical properties. Poly(acrylic acid) grafted reduced graphene oxide (rGO-g-PAA) was synthesized from GO via a two-step process and then incorporated into chemically crosslinked polyacrylamide (PAM) networks by in-situ polymerization to give rGO-g-PAA/PAM composite hydrogels. The grafted PAA chains on rGO helped produce a stable and homogeneous dispersion of rGO-g-PAA in the PAM in the polymerization process. Hydrogen bonds existed between the grafted PAA chains and the PAM matrix, which not only improved the interfacial interaction between rGO and PAM matrix but also served as sacrificial bonds to dissipate energy. The rGO-g-PAA/PAM composite hydrogels exhibited enhanced tensile properties, rapid self-recovery, satisfactory electrical conductivity and remarkable resistance change upon stretching, all of which means it has the potential to be used as flexible strain sensors.