(725a) Development of Membranes with Special Wettability for a Solar-Driven Water Desalination Scheme

Creating reentrant structures on flexible and porous substrates poses a significant challenge to the scalable fabrication of omniphobic membranes. Designing such membranes requires control over the surface topography and chemistry of the interfacial domains. Here, we present a semi-continuous bottom-up polymerization approach–based on initiated chemical vapor deposition–that allows for creating interfaces with the desired chemical and structural properties. By adjusting the free radical polymerization rate and controlling the dynamics and growth mechanism in our process, we assembled desired reentrant structures on a variety of porous substrates, making their surface superhydrophobic. Subsequently, by depositing a conformal thin film of low surface-energy polymer on the assembled structures, we further improve the non-wetting properties of the membranes, rendering them omniphobic. The developed method was applied to a variety of substrates, and variations of the method were developed to create Janus hydrophilic/omniphobic membranes. Here, we demonstrate the versatility of the developed scheme and create a vapor gap on a microfluidic channel, constructing a water separation module. The fabricated modules were tested for desalination of a saline feed water and the feasibility of constructing a stand-alone solar-driven desalination module was evaluated. Additionally, we developed a representative two dimensional model of the system. The result of our simulations indicates that the module can provide a specific water production rate of 10 L/m² per hour at a specific energy consumption of 3 Kwh/m³.