Polymers of intrinsic microporosity (PIMs) are attractive materials and have drawn increasing attention in separation membranes. Here carboxy groups 'are introduced to improve hydrophilicity of the PIMs membranes for pervaporation dehydration of ethylene glycol (EG). The resulting carboxylated PIM-1 (cPIM-1) membranes have adjustable carboxylation degree of up to 0.94. Carboxylation produces many small diffusion channels and greatly improves the membrane hydrophilicity that increases linearly with the carboxylation degree. The membranes show excellent pervaporation performances that depend on the membrane hydrophilicity. The fluxes and permeance greatly increase and likewise the separation factor and water selectivity linearly increase with the hydrophilicity. Compared with other membranes, the cPlM-1 membranes show the high flux. Typically, the cPIM-1 membrane with the carboxylation degree of 0.94 has a total permeation flux of 13.68 kg mu m m(-2)11(-1) and separation factor of,75.92 in the dehydration of the 80 wt% EG mixture at 30 degrees C. The cPIM-1 presents a wide application in the pervaporation dehydration of organics. (C) 2016 Elsevier B.V. All rights reserved.