(458b) Conductive Antifouling Membranes: Preserving Nanoscale Features in Polymers during Laser-Induced Graphene Formation

Membrane-based processes are widely accepted as one of the most promising technologies for water treatment, due to their high energy efficiency and relatively low overall cost compared to other treatment methods. However, membrane-based water treatment requires many additional pre- and post-treatment steps to remove contaminants and maintain membrane effectiveness. In particular, the treatment and prevention of fouling constitutes a large fraction of typical operational costs for membrane separations. One potential approach to combat fouling is to design conductive coatings that can prevent the attachment and growth of biofoulants, both electrostatically and via electrochemical generation of reactive oxygen species. Despite their potential, these conductive membrane coatings are often expensive, requiring additional chemicals and non-scalable methods to produce, e.g. carbon nanotube mats or other graphitic coatings deposited by vacuum filtration.

In this work, we explore the use of laser-induced graphene (LIG) for the creation of conductive ultrafiltration membranes. Porous polyethersulfone (PES) membranes are first treated with alumina using a process called sequential infiltration synthesis (SIS) before being irradiated with an infrared laser. We show that this alumina treatment, which can be scalably performed using roll-to-roll processing, can localize LIG formation to the surface of the membrane, preventing the buried, un-lased areas of PES from melting and losing their porosity during the lasing process. This allows the top-most layer of the PES to be a conductive coating that can be used to electrochemically degrade or remove contaminants (e.g. fouling mitigation). The formation of LIG is verified by scanning electron microscopy and Raman spectroscopy. The conductive layer is also shown to possesses low sheet resistances comparable to carbon nanotube mats, which is important for reducing power consumption in devices. Insight into the mechanism behind the improved stability to melting provided by SIS is provided by thermogravimetric analysis, differential scanning calorimetry, and Fourier-transform infrared spectroscopy. These insights are used to discuss the potential application of this approach to stabilize other materials during thermal cycling, or to create conductive coatings on other polymers.