Polymer blends consisting of poly(styrene-co-4-vinylphenylmethylphenylsilanol) (ST-VPMPS) and poly(n-butyl methacrylate) (PBMA) have been investigated. The experimental results showed that miscible blends were formed when ST-VPMPS copolymers contained 9-56 mol % silanol functional groups. Comparison of the results with poly(styrene-co-4-vinylphenyldimethylsilanol) (ST-VPDMS)/PBMA blends revealed that the miscibility window was shifted to a higher silanol composition in the present system in which a stronger hetero-associated hydrogen bonding interaction was present. The results were discussed in terms of steric shielding and electron-withdrawing effects of the phenyl substituent bound directly to the silicon atom.