The coupling of the orientational order of the liquid crystal mesogens with the polymer network is stable up to the isotropic phase transition temperature. At the liquid crystalline to isotropic phase transformation temperature, the liquid crystalline network becomes isotropic and behaves like a conventional rubber with a corresponding change in the dimensions of the entire network. However, because the of orientation order and anisotropic nature of the LC component, the network contracts along the director axis. For nematic side chain LCEs the change of length is around 40%, while for main chain LCEs, this change can be on the order of 500%. The speed of the contraction is determined by thermal heat conductivity of the network, not by material transport processes. A schematic diagram of the change in dimension for a hybrid main-chain / side chain system is shown below to the left. Ref: Wermter & Finkelmann LCE as artificial muscles ePolymers 13 2001
Side chain LCE prepared through photo-polymerization of acrylate mesogens. Please click on the image to enlarge for a detailed explanation. Materials available from the facility of this type include photo-sensitive polymer networks (Ikeda) and vapor sensitive LCE (Broer).
Side chain LCE prepared via hydrosilylation reaction of vinyl mesogen with methyl-hydrosiloxane polymer. Materials of this type available from the facility include LCE films developed by either H. Finkelmann's group or R. Zentel's group. Please click on image to expand for more detailed information.