Light-triggered thermal conductivity switching in azobenzene polymers

Significance Heat is carried as diffusion of vibrational modes in insulating polymers, a process that is highly dependent on the macromolecular ordering of a polymer. As a result, changes in macromolecular ordering have potential to significantly change the thermal transport property of a polymer. Here, we design and synthesize a thermally switchable azobenzene polymer that exhibits a reversible crystal-to-liquid transition in response to UV and visible light. By driving a transition between the planar (trans ) and nonplanar (cis ) conformational states of azobenzene moieties attached to the polymer, we modulate interchain π-π bonding, resulting in fast and reversible thermal and structural transitions. This work unravels the pathway of crystal-to-liquid transitions of the azobenzene polymer and the resulting thermal and physical property changes.