Paper Authors, left to right: Xuesong Li, Jinho An, Rod Ruoff, Sungjin Park, Sung Jin An, Richard Piner and Aruna Velamakanni.
A team at The University of Texas at Austin has developed a general method for creating dispersed and chemically modified graphene sheets in a wide variety of organic solvents, opening the door for the widespread use of colloidal suspensions for a host of important applications. Colloidal suspensions are used in paper-making, paints, inks, formulations in the food industry, biomedical industry, and in many other applications as well.
Scanning electron microscopy (SEM) image of the cross-section of Highly Reduced Graphene Oxide (HRG) 'paper' material
Graphene, a one atom-thick carbon-based material
Graphene is a unique atom-thick carbon-based material that has exceptional physical and chemical properties. It has elicited wide-spread interest in many applications:
- superior composite materials that are high-specific stiffness and strength,
- nanoelectronics for logic, memory and interconnects,
- as transparent and electrically conductive films for image display and solar photovoltaic devices,
- in energy storage devices such as batteries and ultracapacitors,
- in thermal management
- and other applications.
Many of these applications require dispersion of graphene, or chemically modified graphene, in solvents. Some possible uses are coating thin films of graphene as is done in paper-making, paint, and deposition of ink.
HRG 'paper' material, diameter 3.7 centimeters, 10 microns thick.
Research into colloidal suspension of graphene
“A part of our research group is studying how to readily make colloidal dispersions of graphenes in a wide variety of solvents from water to various organic solvents. The solvents and the chemical functionalization of the graphene, and thus how the graphene disperses or doesn't disperse, has allowed us to develop important rules for the research and technology communities,” according to Professor Rodney Ruoff, Cockrell Family Regents Chair, Department of Mechanical Engineering and the Texas Materials Institute, at The University of Texas at Austin.
“By using solubility parameters, which are ubiquitously used in industry to understand which solvents are likely to dissolve certain materials or to create good colloids, we have been able to develop a set of solubility parameters for chemically-modified graphenes. We believe that this approach will be exceptionally useful in the colloidal suspensions of graphene sheets,” Ruoff added.
Publications
The paper “Colloidal Suspensions of Highly Reduced Graphene Oxide in a Wide Variety of Organic Solvents” that was recently published on-line in Nano Letters (available as an "ACS ASAP" article) was authored by Sungin Park, Jinho An, Inhwa Jung, Richard D. Piner, Sung Jin An, Xuesong Li, Aruna Velamakanni, and Rodney S. Ruoff, all of the Department of Mechanical Engineering at The University of Texas at Austin.
Park and Ruoff have also contributed an article on “Chemical methods for the production of graphenes” that appeared in the March 29 issue of Nature Nanotechnology. This is an extensive review of various methods of making graphene through chemical methods, which also discusses colloidal suspensions of graphenes and how they are made.
Colloidal suspensions of HRG sheets in a wide variety of organic solvents, Volume ration of added solvents: DMF:water = 90;9;1, Added solvents from left: DMF, ethanol, acetone, THF, DMSO, NMP, acetonitrile, 1,2- dichlorobenzene, diethylether, and toluene. (DMF=N,N-Dimethylformamide, THF=tetrahydrofuran, DMSO=dimethyl sulfoxide, NMP=N-Methyl-2-pyrrolidone). All photos by Jinho An and Sungjin Park.
