A range of poly(methyl methacrylate-co-butyl acrylate), P(MMA-co-BA), copolymers with compositions ranging between 13 and 82 wt% n-butyl acrylate have been mixed with three chlorine containing (56 wt% Cl) polymers: conventional poly(vinyl chloride), (H-T)PVC, chlorinated poly(1,4-butadiene), (H-H)PVC, and chlorinated polyethylene, CPE. The samples which contain the same amount of chlorine differ only in its sequence distribution along the chain. When these were blended with P(MMA-co-BA) random copolymers, the lower critical solution temperature, LCST,was found to increase in the order: CPE< (H-T)PVC< (H-H)PVC Infrared bands attributed to specific intermolecular interactions were identified. The results give a qualitative demonstration of the influence of sequence distribution on the miscibility of some polymer blends.