Blends of poly(acrylic acid) (PAA) and poly(p-vinylphenol) (PVPh) were prepared from N,N-dimethylformamide (DMF) and ethanol solutions. The DMF-cast blends exhibited single T-g's, as shown by modulated differential scanning calorimetry, whereas the ethanol-cast blends had double T-g's. Fourier transform infrared spectroscopy showed that there was a specific interaction between PAA and PVPh in the DMF-cast blends. The single-T-g blends cast from DMF showed single-exponential decay behavior for the proton spin-lattice relaxation in both the laboratory frame and the rotating frame, indicating that the two polymers mixed intimately on a scale of 2-3 nm. (C) 2003 Wiley Periodicals, Inc.