Three carbazole based building blocks with similar propeller-like steric configuration are designed and synthesized. The polycarbazole networks P-4, 4'-biscarbazolyl-phenyl (P-BCz), P-tetracarbazolyl-p-difluorobenzene (P-TCz) and P-hexacarbazolyl-phenyl (P-HCz) are obtained with high surface areas and uniform ultramicropores. The aggregation morphologies of networks vary from regular spherical particles, ribbon-like structure to large lamellar structure as the number of carbazole increased around the benzene ring. The networks P-TCz, with four carbazole decorating on the benzene ring, have the largest surface area and highest gas uptake ability among the three networks. However, the CO2 and CH4 isosteric enthalpies increased linearly with increasing the number of carbazole. The networks P-HCz with six carbazole show the excellent CO2/N-2 separative capacity (107 at 273 K, and 127 at 298 K), which is among the highest reported about CO2 separation using organic pore networks. Fine designing and tailoring the topological structure of monomer can control the adsorption properties and optimize the gas uptake performance. (C) 2015 Elsevier Ltd. All rights reserved.