The miscibility behavior of dextran (Dx) with synthesized functional binary poly(citraconic anhydride-acrylamide) (poly(CA-alt-AAm) and ternary poly(citraconic anhydride-acrylamide-vinyl acetate) (poly(CA-co-AAm-co-VA) copolymers was investigated in dilute aqueous solutions by viscometry and in a solid state by Fourier transform infrared (FTIR) spectroscopy. The relative viscosities of each polymer and their blends with Dx/related copolymer ratios of 20 : 80, 50 : 50, and 80 : 20 were measured at body temperature, 37 degrees C, in bidistilled and deionized water. Starting with the classical Huggins equation, results of the viscosity measurements of each parent polymer and their blends were interpreted in terms of miscibility parameters: Delta k, Delta b, alpha, beta, Delta beta, and mu. Based on the sign convention used with these criteria, the miscibility between Dx and related copolymers was found to increase with the weight fraction of Dx in the blends and with the number of AAm units in the copolymer composition. From FTIR spectral analysis, supporting results were achieved that explained the interactions between Dx and the copolymers. Miscibility behavior was also investigated theoretically with Askadskii's miscibility criterion, and the theoretical calculations provided strong evidence supporting the experimental results. (c) 2006 Wiley Periodicals, Inc.