Photocrosslinkable liquid crystal main-chain polymers: Thin films and electrospinning

For mechanical actuators, a response to external stimuli is required. Main-chain liquid crystal elastomers (MCLCEs) show high response to changes in temperature especially in the vicinity of a phase transition. Most of these crosslinked materials were synthesized in a one-step reaction which leads to a macroscopically aligned elastomer. Up to now only macroscopic samples have been prepared. We are presenting a new approach which allows us to prepare thin films as well as aligned fibers. First a liquid crystalline main-chain polymer with a photoactive moiety was synthesized, which was oriented by a mechanical field and photocrosslinked. The thin films show exceptional mechanical properties such as large temperature-dependent changes in length and a nonlinear stress-strain relation. To obtain fibers, we used the electrospinning process from solution with in situ UV curing. We obtained crosslinked fibers with a uniform alignment of the nematic director. {graphics}