By considering the connection sequence of segments in a polymer, a previously developed equation of state was used to correlate the phase behavior of comblike polymer solutions. The equation contains an association term taking into account the hydrogen-bonding interactions between molecules. The effect of segment sequence on the compressibility factor of hard-sphere-chain copolymer fluids is discussed. Vapor-liquid equilibria for mixtures of poly(styrene-co-maleic anhydride) with alkyl side chains of different lengths (C-5, C-12, C-22) and various solvents were correlated with an adjustable interaction energy parameters. It is shown that the model can give results in good agreement with experimental data.