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).