Thanks to their permissibility of vapor transmitting and resistance to water penetration, hydrophilic-hydrophobic membranes (HHMs) are a critical factor in so many applications. Current strategies focus on electrospinning hybrid layers from two different hydrophilic-hydrophobic polymers. Here, we report a new generation of HHMs by electrospinning one layer of pH-switchable polymers followed by a simple post-treatment. In doing so, a hydrophobic poly(methyl methacrylate)-co-poly(N,N-diethylaminoethylmethacrylate) (PMMA-co-PDEAEMA) membrane is fabricated using the electrospinning method. Then, hydrochloric acid (HCl) vapor is used to convert one face of the membrane to a hydrophilic state. Field emission-scanning electron microscopy, drop test, water contact angle (WCA), moisture management test (MMT), tensile strength, water vapor permeability (WVP), air permeability (AP), and cytotoxicity test were used to characterize the obtained membrane. The results show that by HCl vapor exposure, one side of the membrane gets successfully converted into a hydrophilic state, with the other side still remaining hydrophobic. The drop test and the WCA test showed that the optimal exposure time is only 5 min. This trigger has a small effect on the morphology and, subsequently, on water and air permeability as well as on the mechanical behavior of the membrane. This new generation of membranes can have applications in protective clothing and wound dressing.