Preparation of graphene/poly(p-phenylenebenzobisoxazole) composite fibers based on simultaneous zwitterion coating and chemical reduction of graphene oxide at room temperature

Zwitterion-coated reduced graphene oxide (rGO) was used in fabricating graphene/PBO composite fibers via in situ polymerization. The zwitterionic 1 : 1 adducts were formed by two monomers of PBO and they could be crystallized using rGO sheets as templates. Covalent bonds could be formed between GO and 4,6-diaminoresorcinol dihydrochloride (DAR center dot 2HCl, a monomer for PBO) with GO being reduced simultaneously at room temperature. The structure of rGO sheets was well characterized and a mechanism including nucleophilic addition and E1 dehydration was proposed. Zwitterions could precipitate out from water rapidly and yet dissolve in PPA easily. Thereby, rGO sheets could be homogeneously dispersed in the PBO matrix as zwitterions dissolve and polymerize. By adjusting the feeding of zwitterion-coated rGO sheets, various composites with 0.1-3.0 wt% GO sheets incorporated were obtained. With very low rGO sheet content, both the mechanical properties and thermal stability of rGO/PBO fibers increased remarkably.