Effect of Pluronic block copolymers on aqueous dispersions of graphene oxide

The effect of Pluronic block copolymers F127 and P123 on aqueous dispersions of graphene oxide (GO) was studied. The combination of optical microscopy, rheometry, scanning electron microscopy and X-ray diffractometry studies indicated that the introduction of Pluronics F127 and P123 could markedly change the dispersion, flow and processing behaviors of GO in water. Interestingly, the ordered-lamellar-structure composite tapes were easily fabricated by casting the GO/F127 dispersions through a doctor blade method while they were not obtained by casting the GO/P123 dispersions. The study on the intercalation structure of GO composite tapes suggested that the ordered lamellar structure of GO/F127 composite tapes originated from the anchor-buoy-type adsorption of F127 on the GO surface. In the anchor-buoy-type configuration, long ethylene oxide (EO) segments of F127 were extended out into water to form a hydration protection layer, which effectively prevented the aggregation of GO sheets. Instead, the protective effect was weaker for P123 due to its very short EO segments, and the phase-separated dispersions were present with higher GO content.