Photothermally Responsive Liquid Crystalline Elastomer/Carbon Nanotube Nanocomposite Actuators with Orthogonal Light-Driven Actuation and Reprogrammability

Abstract

This study presents photothermally responsive liquid crystalline elastomer (LCE)/multiwalled carbon nanotube (MWCNT) nanocomposites that enable light-only actuation, self-healing, and reprogramming without thermal treatment. The nanocomposites are fabricated by dispersing MWCNTs using a main-chain mesogenic liquid crystalline oligomer containing disulfide bonds (SS-oligomer) and embedding them in an allyl selenide-containing main-chain LCE (LCE_Se) matrix. Notably, polymerization, monodomain generation, self-healing, and actuation of the prepared LCE_Se/MWCNT nanocomposite occur solely under light irradiation. The MWCNTs in the nanocomposite serve as photothermal agents. They enable actuation through NIR light irradiation and exhibit outstanding properties, including 1.5 MPa actuation stress, 60% actuation strain (Δε), >400% failure strain, 308.3 kJ m^–3 work capacity, heating to 200 °C under light irradiation, and only 13% loss of Δε after 100 NIR light on/off cycles. The allyl selenide linkages enable dynamic exchange reactions (DER) through UV (or visible) light irradiation, which facilitates self-healing and reprogrammability. In particular, the orthogonality between the thermal actuation (driven by photothermal effects under NIR or visible light) and DER (triggered by UV light) ensures stable, fatigue-resistant operation. These combined features establish the LCE_Se/MWCNT nanocomposites as a versatile platform for adaptive materials capable of complex motions such as cantilever bending, lateral locomotion on water surfaces, and bipedal walking.