Determination of the Flory−Huggins Interaction Parameter of Styrene and 4-Vinylpyridine Using Copolymer Blends of Poly(styrene-co-4-vinylpyridine) and Polystyrene

On the basis of the experimentally determined phase behavior in blends of polystyrene and random copolymers of styrene and 4-vinylpyridine, i.e., P(S x - co -4VP 1 - x )/PS, the Flory−Huggins interaction parameter is demonstrated to satisfy 0.30 < χ S,4VP ≤ 0.35. This value is substantially smaller than reported before. To corroborate our results, a similar study was performed using 2-vinylpyridine leading to 0.09 < χ S,2VP ≤ 0.11, in excellent agreement with the well-established value of χ S,2VP = 0.1.