Micro-focus X-ray scanning on layers of smectic superstructures

The investigated main chain poly(ester imide)s (PEI) form smectic layers with different superstructures due to a nanophase separation of the rigid mesogens and flexible spacers, which give rise to X-ray reflections in the small angle region (2θ =1-6°; d=2-8 nm). The novel micro-focus X-ray scanning technique at the beamline ID13 (ESRF, France) enables a visualisation of the local orientation of smectic layers in different morphologies such as bâtonnets and spherulites. Previous investigations of the spherulites formed from PEI by optical and electron microscopy, and SAXS indicated a negative birefringence and a lamellar internal structure. The particular feature of these spherulites is their internal smectic layer structure. The present X-ray scanning experiments reveal a radial arrangement of the smectic layers within the spherulite. Furthermore, the micro-beam scanning experiments provide maps of the molecular orientation in different smectic LC-textures. The internal S_C-order of a single bâtonnet (10 * 90 µm) could be examined.