Self-cross-linked 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP) polymers with tailored pore size distribution (PSD) and average pore width (W-avg) were synthesized via the Friedel-Crafts reaction in 1,2-dichloroethane (DCE) with reactive (benzene) or non-reactive (hexane and cyclohexane) co-solvents. Compared to using only DCE, W-avg increases (up to 450%) with increasing benzene:DCE ratio due to decreases in cross-linking degree. Hexane and cyclohexane induce phase separation and co-solvent trapping in developing polymers, changing PSD and W-avg without altering cross-linking degree. Findings provide a simple technique to synthesize hyper-cross-linked polymers with user-defined PSDs. (C) 2018 Elsevier Ltd. All rights reserved.