Thermosensitive Shape-Changing Polymers

LCE were characterized by the switching rate, which is a measure of the time interval between stimulation and actuation. In thermally-stimulated LCE the switching rate depended on the heat transfer from the surface to the bulk of the material. In contrast, in LCE based on ferroelectric mesogens, faster switching 

A biaxial shape-changing effect had been realized in SmC elastomers [132]. These LCEs displayed shrinkage (expansion) because of the smectic-isotropic (isotropic-smectic) transformation and shear deformation because of the tilting in the smectic phases. This behavior, which required a macroscopic C2 symmetry of the LC domains, had already been theoretically postulated in the mid 1990s [139]. However, creation of the monodomain samples was an experimental challenge. One approach to obtain monodomain samples having the required symmetry applied a prepolymerization procedure, a first deformation process for the orientation of the 

As the SCC of LCE depended on the size of the LC domains, which was usually in the micrometer range, it was researched whether SCC could be realized for nanoscale shaped bodies [144]. In MCLP nanoparticles based on the nematic main chain polyether l-(4-hydroxy-4 -biphenyl)-2-(4-hydroxyphenyl)butaneandin other LC main-chain moieties a shape change between ellipsoids and spheres could be observed. This effect was only observed if the particle size in these polymer systems was below a critical size. This size related effect resulted from an quasi-equilibrium between the intrinsic shape of the entangled MCLP and the thermodynamically most stable form in the isotropic phase, the sphere [144]. 

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