Tailoring crosslinking networks to fabricate photocurable polyurethane acrylate (PUA) dielectric elastomer with balanced electromechanical performance

The trade-off between high dielectric permittivity and low Young's modulus is always a challenge for fabricating high-performance polyurethane acylate (PUA) based dielectric elastomers (DEs). In this work, networks with scattered crosslinking points (type-I) and domains of concentrated crosslinking points (type-II) that being prepared by different functional telechelic ends, were mainly introduced into the photocured PUA elastomers. As the increasing of chain length between crosslinking points ( N e ), the Young's modulus ( Y ) of the PUA was restrained below 1.2 MPa while the elongation at break ( E B ) markedly increased. Compared to type-I network, a longer N e in type-II network can lower the overall crosslinking density, which endows the materials with a relatively low Y (ca. 0.83 MPa) and a large E B (389%). In addition, the concentrated crosslinking points in type-II network enhanced the polarization effect between entangled long chains and crosslinking domains, which further upraised the dielectric permittivity of the elastomer up to 74.17 @ 10 3  Hz. The actuation strain of the PUA elastomer with type II network can reach utmost 13.88% @ 45.41 V∙μm −1 without any pre-strain. This work offers a new strategy to fabricate photocurable dielectric elastomer actuators (DEAs) with balanced electromechanical performance.