Chain Folding in EBEE Semicrystalline Diblock Copolymers

摘要

X-ray pole figure analysis and small angle x-ray scattering were used todetermine the lattice unit cell orientation with respect to the lamellar microstructure for semicrystalline diblock copolymers of ethylene-co-butylene-b-ethylethylene (EBEE). The x-ray data indicate that the orientation of the crystallized EB chains is perpendicular to the lamellar normals, unlike the chain cry folding which has been observed in semicrystalline homopolymers and proposed for semicrystalline diblock copolymers where the crystallized chains align roughly parallel to the lamellar normals. The unusual chain folding observed for EBEE is attributed to the influence of topological constraints in the EB blocks which crystallize with the amorphous lamellar microdomains present in the heterogeneous melt phase of the block copolymers.