Oligomeric ethylene-glycol brush functionalized graphene oxide with exceptional interfacial properties for versatile applications

Graphene oxide (GO) has continued to prompt fantastic discoveries and applications; however, the highly extended two-dimensional pi-conjugation of pristine graphene sheets leads to the aggregation of GO sheets in strong brine, which impairs the applications of GO. In this work GO with covalently-bound oligomeric ethyl-ene-glycol brushes (termed as GOC) was prepared using graphite oxide as a raw material. The synthesized GOC was investigated by a holistic combination of experimental characterizations and molecular dynamic simula-tions. Our results showed that GOC behaves like a highly anisotropic colloid that well dispersed in various organic solvents, and retained high dispersion stability in strong brine even after storage at high temperature (e. g, 90 celcius). The GOC can sharply decrease surface tension after reaching a very low threshold concentration of 0.04 mg/mL; on account of that, it successfully generated water-in-oil Pickering emulsions with an internal water content of as high as 90 vol%. The GOC also functions as a liquid crystal at the oil-water interface without the need of external assistances/stimuli. We envisage that the prepared multifunctional GOC materials will stimulate a broad range of its applications when exceptional interfacial properties are required such as in the field of food, cosmetics, and petroleum industries.

Automated summary

This research focuses on improving the dispersion of graphene oxide (GO) to prepare a highly anisotropic GO material (GOC) that can disperse well in various organic solvents and maintain high dispersion stability in strong brine. The GOC can significantly reduce surface tension, generate water-in-oil Pickering emulsions with high water content, and exhibit liquid crystal behavior at the oil-water interface without external stimuli.