Structure and morphology of poly(ethylene)-block-isotactic poly(propylene) di-block copolymers

A study on the structure and morphology of crystalline di-block copolymers (BCP), composed of stereoregular crystallizable polyolefins is presented. In particular, we report a structural characterization of di-block copolymers formed by crystalline PE block linked to crystalline isotactic polypropylene (iPP) block of different block lengths. The dependence of the thin film BCP morphology on the sequential crystallization from the phase separated melt of the crystallizable blocks has been investigated. The BCPs have been epitaxially crystallized onto crystals of a substrate to achieve a better control over the crystallization. Ordered nanostructures where the two blocks are organized in separated alternating lamellar domains guided by the orientation of the crystalline lamellae are obtained. We demonstrate that, tuning the block length and using a specific substrate, it is possible to control the crystallization process and obtain large-sized, well-oriented lamellar microstructures with long range order achieved over the area in contact with the crystalline substrate. Possible applications of these nanostructures are discussed.