New miscible blend systems comprised of poly(4-vinyl phenol) (PVPh) and a homologous series of polyesters of different CH2/CO ratios (from 4.5 to 7) was discovered. Miscibility has been confirmed using differential scanning calorimetry, Fourier-transformed infrared spectroscopy, and scanning electron microscopy. The PVPh/polyesters blends investigated exhibited a single composition-dependent glass transition and homogeneous phase morphology, and they similarly exhibited a cusp in the T-g-composition relationships. This work further extended the range of aliphatic polyesters that are known to be miscible with PVPh. The Flory-Huggins interaction parameter (chi(12)) or energy density (B) obtained from analysis of melting point depression for PVPh/PEAz and PVPh/PHS blends are of negative values. More interestingly, the specific interactions in the PVPh/polyester blends change with the corresponding different structures in the polyester component. For the PVPh/PHS blend whose polyester constituent possesses a lower carbonyl density in the main chain (average CH2/CO ratio = 7) the energy density B was found to be -1.17 cal cm(-3). This value is significantly lower than those for either the PVPh/PEAz (CH2/CO = 4.5) blend system (B = -7.72 cal cm(-3)). Miscibility, specific interactions, and peculiar T-g-composition relationships in the blends of PVPh with selected homologous polyesters are discussed. (C) 2004 Elsevier Ltd. All rights reserved.