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We present a computational and experimental study of the in-plane heat transfer behavior of a coiled multi-walled carbon nanotube (MWCNT) yarn. The surface temperature of the MWCNT yarn in contact with the high-temperature wire is measured to verify that the thermal conductivity in the radial direction (TCRD) of the coiled MWCNT yarn is high enough to be captured by a thermal imaging camera. A significant change in the TCRD is observed under mechanical strain in particular. Furthermore, the in-plane heat flow of MWCNTs is studied using molecular dynamics simulations. The results confirm that the structural deformation of interstitial spaces between MWCNTs during mechanical loading is a key factor in explaining the heat transfer paths generated by the thermal vibrations of carbon atoms. It is also confirmed that the change in TCRD is reduced owing to an increase in the radial buckling strength of the yarn comprising MWCNTs of a smaller diameter. The TCRD change is crucial in MWCNT-yarn applications such as twistron energy harvesters.

Azobenzene-containing crosslinked liquid crystalline polymer (CLCP) exhibits macroscopic deformation through irradiation with light, and recently, carbon nanotubes (CNTs) were inserted to improve the efficiency of the photo-mechanical energy conversion. We conducted molecular dynamics simulations to study the effects of the arrangement of the single-walled CNT (SWCNT) and photo-isomerization of the photochromic moieties on the opto-mechanical properties of the composite. We characterized the composites in terms of the interfacial shear strength (IFSS), photostrain, and elastic modulus according to the isomerization ratio. The SWCNT-CLCP composite enables 19–29% larger photostrain and 20–41% higher modulus compared to those of neat azo-PRP. As the angle between the CNT axis and the nematic director increases, mechanical reinforcing effect decreases. Nevertheless, the applicable photo-shrinkage increases because more space for polymer diffusion is made by the nematic defects in the interphase. The isomerization of azobenzene weakens the interfacial adhesion due to the decrease in the π-π interaction. However, changes in the elastic stiffness of the composite can be modulated by adjusting the arrangement between the SWCNT and matrix. These results provide insight into the mechanism of changes in the interfacial and opto-mechanical properties of the CNT-PRP composite caused by photo-isomerization and the mechanical design of a photo-responsive actuator.