Multi-functional Janus membranes, with opposing properties on each side, can act as on-off gates for controlled release, switchable permeation or directional transport of macromolecules. Janus membranes with poly (methylacrylic acid-co-ethylene glycol dimethacrylate), p(MAA-co-EGDMA), and poly (4-vinylpyridine-co-ethylene glycol dimethacrylate), p(4VP-co-EGDMA), polymer coatings on opposite sides are prepared by initiated chemical vapor deposition (iCVD) technique. Conformality of the coatings on the pore openings can be controlled by changing the ratio of the partial pressure (P-m) to the saturation pressure (P-sat) of the monomer and at P-m/P-sat values of 0.20-0.24, keyhole shapes can be obtained. The keyhole shape of the polymer at the pore openings allows closing of the pores upon swelling of the polymer due to a change in the pH of the environment. The Janus membranes are used for protein gating by successfully blocking the permeation of a model protein, bovine serum albumin (BSA). The membranes can take in, store and release the BSA molecules on demand by controlling the open/close states of the pores on the opposite sides individually.