Muscle-Inspired Super-Flexible Phase Change Materials with Programmable Deformation for Photothermal Actuation

Abstract

Phase change materials (PCMs) with remarkable latent heat storage/release capacity have demonstrated prominent advantages in energy conservation and efficient thermal management. Nevertheless, simultaneously achieving high thermal energy storage capacity, excellent toughness, and flexibility in PCMs is a significant challenge for programmable deformations when used in complex environmental scenarios. A flexible PCM is reported with programmable deformation constructed through a three-dimensional (3D) dynamic cross-linked network. This approach has culminated in the development of homogeneously cross-linked and self-supporting polyurethane-based solid-solid PCM with graphene enhancement, which exhibits exceptional properties of high latent heat storage/release capacity (∆H_m = 105.3 J g⁻¹, ∆H_c = 105.0 J g⁻¹), high toughness (ε = 1543%, σ = 19.2 MPa), excellent flexibility, and shape memory behavior (R_r = 90.3%). Notably, when subjected to photothermal stimulation, it can lift objects weighing more than 2620 times their weight, presenting a working density of 1330 kJ m⁻³. This flexible PCM, which simultaneously possesses a high latent capacity and photothermal-driven performance, opens a new pathway for artificial muscles or soft robots with the requirements for energy conservation and thermal management in complex scenarios.