A series of miscible linear and star poly(methyl methacrylate) (PMMA)/phenolic blends with different compositions have been prepared. T(g)s of both systems are negative derivation from the average values, implying that the self-association interaction is stronger than the inter-association interaction between linear or star PMMA with phenolic. The proton spin-lattice relaxation time in the rotating frame (T-1rho(H)) determined by high resolution solid state C-13 NMR indicates single composition dependent T-1rho(H) from all blends, implying a good miscibility with chain dynamics on a scale of 1-2 nm. However, T(1rho)(H)s of star PMMA/phenolic blends are relatively smaller than those of linear PMMA/phenolic blends, implying that the degree of homogeneity of star PMMA/phenolic blends is higher than those of linear PMMA/phenolic blends. According to FT-IR analyses, the above results can be rationalized that the hydrogen-bonding interaction of the star PMMA/phenolic blends is greater than the corresponding linear PMMA/phenolic blends. (C) 2004 Elsevier Ltd. All rights reserved.