| Abstract
| - Near-edge X-ray absorption fine structure is used to investigate the temperature dependence of molecularorientation of semifluorinated liquid crystalline (SF-LC) mesogens, which are attached to the modifiedisoprene backbone of (i) a poly(1,2-isoprene) homopolymer and (ii) a diblock copolymer consisting ofpolystyrene and poly(1,2-isoprene) blocks. Our experiments reveal the existence of two temperature regionsin which the surface orientation of the SF-LC mesogens changes abruptly, but even 30 K above the highestsuch temperature region the surface orientation does not become isotropic. The lower temperature surfacetransition for both homopolymer and block copolymer occurs close to the temperature of the bulk homopolymersmectic-B to smectic-A transition and well above the bulk smectic-B to smectic-A transition in the blockcopolymer. It seems to be controlled exclusively by the ordering phenomena originating from the surface.In contrast, the change in the surface organization of the SF-LC mesogens at higher temperatures canbe associated with the bulk LC transition from the smectic-A to the isotropic phase.
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