Synopsis:
Graphene and graphitic oxide are among the most hotly researched materials in physics and materials science during the past four years. Efforts to fabricate large-scale films of graphene and graphene oxide are immensely interesting to the scientific community, as the potential for large-scale production would facilitate their use in devices and composites that harness their unique electrical and mechanical properties. My group has developed a straightforward method to form centimeter-sized films of graphene oxide whose microstructure and physical properties can be tuned. This can give rise to tunable hydrophobic and hydrophilic graphene oxide films. The different microstructures engender distinct surface wetting behavior. We also demonstrate how freestanding films can be fabricated to facilitate their transfer to arbitrary substrates. The techniques suggest a path by which graphene could be deployed in technologically beneficial applications.
Major Achievement:
Tunable morphology of electrophoretically deposited graphene films yields specific surface wettability.
Publicity:
Detailed Discussion:
Colloidal graphene is a rapidly emerging, immensely interesting material whose large-scale production would facilitate its employment in applications as diverse as transparent conductors to micro-resonators and antifogging coatings. Challenges, inherent to the use of colloidal graphene to fabricate films and coatings, include control over the deposition site, the dimension of the films, and the arrangement of the graphene sheets within the deposit. Our research has discovered a straightforward method to produce centimeter-sized films of graphene oxide whose microstructure is controlled, in part, by tuning the pH of the aqueous suspension from which they are deposited. We also found that films of graphene can be made freestanding (Figure ), which aids their transfer to arbitrary substrates and, hence, their integration into devices. The freestanding nanoparticle film technique is very similar to the method described earlier in this research summary. One unique finding from this work, however, was that different microstructures within the graphene sheets engender distinct surface wetting behaviors (both hydrophobicity and hydrophilicity). We are continuing our activities in this area and predict that the distinct surface wetting characteristics may have technological implications in functional coating applications. Further, the capability of making freestanding films may result in the deployment of these flexible, translucent, high-surface-area films display screens and energy storage devices. The use of EPD, as well, may facilitate their integration into manufacturing, when combined with techniques like roll-to-roll production.
Reference Articles:
a. S.A. Hasan, J.L. Rigueur, R.R. Harl, A.J. Krejci, I. Gonzalo-Juan, B.R. Rogers, and J.H. Dickerson, Transferable Graphene Oxide Films with Tunable Microstructures, ACS Nano 4, 7367, 2010.