In the present study, the relationship between the permeable properties of stimuli-responsive gating membranes and the structural properties of surface-grafted polymers was investigated. The grafting initiation rate and the resultant characteristics of the grafted polymers were altered by controlling the grafting temperature in acid-assisted plasma-induced graft polymerization. The grafted polymers were isolated from the membranes to investigate their structural properties, including molecular weight and grafting density. The molecular weights of the grafted polymers were sufficiently high to fill the pore in the polymer swollen state. Therefore, the grafting density is strongly associated with the open/close gating performance of the membranes. A higher grafting density enhances both the pore-close and pore-open performances, while a lower grafting density impairs both open and close performances. The hydrodynamic dimensions and the structures of the grafted polymers, as well as membrane pore size, were considered when investigating the underlying mechanism of this applicative phenomenon.