Maleic acid-alt-styrene copolymer as compatibilizer for poly(ethylene oxide)-poly(styrene) blends

Abstract

Maleic acid-alt-styrene (MAaS) copolymer with number-average molecular weight M̄n = 2500 was used as a compatibilizer in blends of poly(ethylene oxide) (PEO) and poly(styrene) (PS). PEO with weight-average molecular weight M̄w = 105 (PEO100) and two PS samples with M̄w = 9×104 and 4×105, respectively (PS90 and PS400, respectively) were used. A depression of the melting temperature Tm of PEO in blends containing MAaS relative to pure PEO and PEO/PS blends was observed. The melting enthalpy ΔHm for the PEO/PS blends containing MAaS was lower than those of pure PEO and PEO/PS blends without compatibilizer. The crystallization kinetics of PEO and the blends were studied by differential scanning calorimetry (DSC) at different crystallization temperatures Tc. Flory-Huggins interaction parameters χ12 for the blends were estimated. Their values are in good agreement with those obtained for similar systems and suggest that the free energy of mixing ΔGmix should be negative. Polarized optical mi