2, University of Kentucky, Lexington, Kentucky, United States
3, Marine Biological Laboratory, Woods Hole, Massachusetts, United States
The shape anisotropy and enhanced solubility of graphene oxide (GO) in a wide variety of solvents provides the perfect environment to showcase isotropic-to-nematic colloidal phase transitions. As a result, the fluid phase of GO starts to demonstrate properties such as higher viscosity and elasticity compared to the isotropic phase. Thin films of graphene oxide have primarily been fabricated from isotropic phase of GO by processes such as vacuum filtration; which does not attend to manufacturing speeds required by industries. Our research program endeavours to address this issue given the large possibilities in applications ranging from permeable filtration membranes, strategically constructed battery separators, strain sensors, lab-on-chip devices, and supercapacitors.
We have over the years developed quantitative polarized light imaging techniques to quantify fine structure, alignment, texture of the liquid crystalline phases and thin films of GO; which have helped us develop processing-property correlations. We have also shown that large-area GO (13 x 14 cm2) filtration membranes can be produced in < 5 seconds using a high speed gravure printer which have demonstrated molecular sieving properties and suitability in membrane separation processes. Using vinyl-cut stencils and our thin film formation technique various patterns can be produced in flexible, porous, non-porous substrates which can be utilized in applications such as strain sensors & micro-/nano-fluidic components of lab-on-chip devices such as rectifiers and capacitors with enhanced properties. We have also demonstrated that the permeable films GO films can be directly formed over a sulphur cathode in a Li-S battery configuration leading to dramatic improvements in cycle life and capacity.
The scalability and adaptability of our thin film fabrication technique is leading to commercial adaptation and laboratory-to-market translation of products such as nanofiltration membranes.