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 (M) over bar (n) = 2500 was used as a compatibilizer in blends of poly(ethylene oxide) (PEO) and poly(styrene) (PS). PEO with weight-average molecular weight (M) over bar (w) = 10(5) (PEO100) and two PS samples with (M) over bar (w) = 9 x 10(4) and 4 x 10(5), respectively (PS90 and PS400, respectively) were used. A depression of the melting temperature T-m of PEO in blends containing MAaS relative to pure PEO and PEO/PS blends was observed. The melting enthalpy DeltaH(m) 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 crystalization temperatures T-c. Flory-Huggins interaction parameters chi (12) 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 DeltaG(mix) should be negative. Polarized optical microscopy shows differences in the macroscopic homogeneity of the blends containing compatibilizer that could be attributed to a compatibilization process.