Two new pyrene-cored covalent organic polymers (COPs), CK-COP-1 and CK-COP-2, were synthesized via the one-step polymerization of two thiophene-based isomers, 1,3,6,8-tetra(thiophene-2-yl) pyrene (L-1) and 1,3,6,8-tetra(thiophene-3-yl) pyrene (L-2). The resulting pyrene-cored COPs exhibit rather different surface areas of 54 m(2) g(-1) and 615 m(2) g(-1) for CK-COP-1 and CK-COP-2, respectively. The CO2 uptake capacities of CK-COP-1 and CK-COP-2 also show different values of 2.85 and 9.73 wt % at 273 K, respectively. Furthermore, CK-COP-2 offers not only a larger CO2 adsorption capacity but also a better CO2/CH4 selectivity at 273 K compared with CK-COP-1. CK-COP-1 and CK-COP-2 also exhibit considerable differences in their photophysical property. The different structure and properties of CK-COPs could be attributed to the isomer effect of their corresponding thiophene-based monomers. (C) 2017 Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc.