COMPOSITION AND TEMPERATURE-DEPENDENCE OF THE SEGMENTAL INTERACTION PARAMETER IN STATISTICAL COPOLYMER HOMOPOLYMER BLENDS

The polymer blend system of deuterated polystyrene (PS(D)) and a stati stical copolymer poly(cyclohexyl acrylate-stat-n-butyl methacrylate) ( P(CHA(1-x)-stat-nBMA(x))) was investigated by small-angle neutron scat tering (SANS) and neutron reflectometry (NR). The Flory-Huggins-Staver man interaction parameter chi was determined as a function of temperat ure and copolymer composition in the one- and two-phase regions by SAN S and NR, respectively. By a combination of both methods compatible an d incompatible blends could be investigated. It is shown that theoreti cal treatments of the two regimes are consistent. The phase diagram is calculated where a snitching from an upper critical solution temperat ure to a lower critical temperature behavior is predicted.