c-Perpendicular Orientation of Poly(-lactide) Films

Poly(-lactide) (PLLA) films, even of high thickness, exhibiting co-crystalline and crystalline alpha phases with their chain axes preferentially perpendicular to the film plane (c(perpendicular to) orientation) have been obtained. This c(perpendicular to) orientation, unprecedented for PLLA films, can be achieved by the crystallization of amorphous films as induced by low-temperature sorption of molecules being suitable as guests of PLLA co-crystalline forms, such as N,N-dimethylformamide, cyclopentanone or 1,3-dioxolane. This kind of orientation is shown and quantified by two-dimensional wide-angle X-ray diffraction (2D-WAXD) patterns, as taken with the X-ray beam parallel to the film plane (EDGE patterns), which present all the hk0 arcs centered on the meridian. PLLA alpha-form films, as obtained by low-temperature guest-induced crystallization, also exhibit high transparency, being not far from those of the starting amorphous films.

Automated summary

This study achieves perpendicular orientation of PLLA films through low-temperature sorption of molecules suitable as guests of PLLA co-crystalline forms, demonstrating high transparency.