Fabricating Janus Membranes via Physicochemical Selective Chemical Vapor
Deposition
Abstract
Membranes with asymmetric wettability-Janus membranes-have recently
received considerable attention for a variety of critical applications.
Nonetheless, the current methods for making such membranes are still
challenging. Here, we report on a simple approach to introduce
asymmetric wettability into hydrophilic porous domains. Our approach is
based on the physicochemical-selective deposition of
polytetrafluoroethylene (PTFE) on hydrophilic polymeric substrates. The
physicochemical inhibition was achieved through prefilling the
substrates with glycerol, containing a known amount of free radical
inhibitors. We showed that the glycerol/inhibitor mixture hinders the
deposition of PTFE within the membrane pores. As a result, the surface
of the substrates remains open and porous. The fabricated Janus
membranes show stable wetting-resistant properties, evaluated through
sessile drop contact angle measurements and direct contact membrane
distillation (DCMD).