Graphite oxide sheet, now referred to as graphene oxide (GO), is the product of chemical oxidation and exfoliation of graphite powders that was first synthesized over a century ago. Interest in this old material has resurged in recent years, especially after the discovery of graphene, as GO is considered a promising precursor for the bulk production of graphene-based materials. GO sheets are single atomic layers that can readily extend up to tens of microns in lateral dimension. Therefore, their structure bridges the typical length scales of both chemistry and materials science. GO can be viewed as an unconventional type of soft material as it carries the characteristics of polymers, colloids, membranes, and as highlighted in this review, amphiphiles. GO has long been considered hydrophilic due to its excellent water dispersity, however, our recent work revealed that GO sheets are actually amphiphilic with an edge-to-center distribution of hydrophilic and hydrophobic domains. Thus, GO can adhere to interfaces and lower interfacial energy, acting as surfactant. This new property insight helps to better understand GO's solution properties which can inspire novel material assembly and processing methods such as for fabricating thin films with controllable microstructures and separating GO sheets of different sizes. In addition, GO can be used as a surfactant sheet to emulsify organic solvents with water and disperse insoluble materials such as graphite and carbon nanotubes (CNTs) in water, which opens up opportunities for creating functional hybrid materials of graphene and other p-conjugated systems.
Bibliographical noteFunding Information:
This work was primarily supported by the National Science Foundation (CAREER DMR 0955612). Additional supports were provided by the Initiative for Sustainability and Energy at Northwestern (ISEN), the Northwestern Nanoscale Science and Engineering Center (NSF EEC 0647560), the Northwestern Materials Research Science and Engineering Center (NSF DMR-0520513) and the Sony Corporation. L.J.C. is a NSF graduate research fellow. We thank Y. Wa, Prof. K. R. Shull, Z. Zhang, J. H. Huang, Prof. C. W. Chu, and Prof. C. Sun for collaboration in some of the works presented in this review.
- Graphene oxide
- Langmuir-Blodgett technique
ASJC Scopus subject areas
- Chemical Engineering(all)