Graphene oxide-anchored reactive sulfonated copolymer via simple one pot condensation polymerization: proton-conducting solid electrolytes

Abstract

A rapid and efficient post-polymerization functionalization of poly(urea-co-urethane) (PUU) onto the graphene oxide (GO) nanosheets has been developed to produce super-acidic polymer/GO hybrid nanosheets. Thus, the surface of GO nanosheets were functionalized with 3-(triethoxysilyl)propyl isocyanate (TESPIC) from hydroxyl groups to yield isocyanate functionalized graphene oxide nanosheets. Then, sulfonated polymer/GO hybrid nanosheets were prepared by condensation polymerization of isocyanate-terminated pre-polyurea onto isocyanate functionalized graphene oxide nanosheets through the formation of carbamate bonds. FTIR and TGA results indicated that TESPIC modifier agent and poly(urea-co-urethane) were successfully grafted onto the GO nanosheets. The grafting efficiency of poly(urea-co-urethane) polymer onto the GO nanosheets was estimated from TGA thermograms to be 205.9%. Also, sulfonated polymer/GO hybrid nanosheets showed a proton conductivity as high as 3.7 mS cm−1. Modification and morphology of GO nanosheets before and after modification processes were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD).