High Thermal Conductive Liquid Crystal Elastomer Nanofibers

Liquid crystal elastomers (LCEs), consisting of polymer networks and liquid crystal mesogens, show reversible phase change induced by thermal stimuli. However, the kinetic behavior is limited by the inherently low thermal conductivity of polymers. Transforming amorphous bulk into fiber-like forms enables us to enhance the thermal conductivity by aligning polymer chains. Rigid networks of crosslinked polymer have challenged to fabricate nanofibers of it while the existence of the crosslinks in LCEs is crucial to shape reversible transformation of the elastomers. In this study, hydrodynamic alignment was employed to orient the LCE domains assisted by controlled in-situ crosslinking. A drag force was applied to a suspended individual single polymer fiber anchored to a micro-thermometry device. This process remarkably cuts down the fiber diameter to sub-microns. We observed the highly enhanced thermal conductivity of LCE nanofibers (<100 nm in diameter) which is one order of magnitude higher than that of bulk counterpart. To further elucidate the size-effect on heat transfer in LCE fibers, temperature-dependent analysis was made with various diameters of LCE fibers.