The new type of efficient pervaporative separation hybrid materials based on cellulose acetate propionate (CAP) and doped with 1-methyl-3-(4-vinylbenzyl)-1H-imidazol-3-ium chloride polymerizable ionic liquid (PIL) monomers (12.3-44.4 wt%) were elaborated for dehydration of propan-2-ol. Broad material and physicochemical characterization of membranes was performed including assessment of physicochemical, equilibrium, transport, and separation properties. Incorporation of PIL results in the plasticization of CAP based membranes. Additionally, with increasing loading of PIL from 12.3 to 44.4 wt% values of thickness-normalized Pervaporation Separation Index (PSIN) increase 1.6-2.4 times comparing to unloaded membrane (pure CAP). The distance parameters calculated on the base of the Hansen's solubility parameters were additionally employed to interpret swelling and pervaporative properties of membranes as well as to discuss interactions between solvents and prepared membranes. Lower value of distance parameter between pristine CAP and ethanol corresponds to the highest molar swelling degree of CAP based membranes. Swelling of CAP-PIL membranes in contact with water, ethanol, and propan-2-ol increased with of the increasing PIL content due to the hydrophilic character of ionic liquid. The gathered data provided insight into the potential applicability of the novel hybrid separation materials for pervaporative separation of liquid-liquid mixtures.