4D printing of unaligned LCE: a facile approach to print photo mobile polymers

Abstract

Here, we present a novel materials-based strategy that bypasses alignment procedures by integrating ZnO nanoparticles into an LCE ink, enabling a simplified, direct-write 4D printing process. We first demonstrate that ZnO doping significantly enhances the photo-actuation of non-aligned, injected LCE films, confirming the viability of the approach. Applying this strategy, we successfully printed reproducible actuators that exhibit large-amplitude bending and high actuation speeds, with performance comparable to traditionally aligned LCEs. The mechanism behind this enhancement is a synergistic photo-thermal effect; the ZnO nanoparticles increase light absorption via scattering while also dramatically improving the thermal diffusivity of the polymer matrix, leading to a more efficient and rapid mechanical response. By shifting the complexity from the manufacturing process to the material itself, this work offers a scalable pathway towards the rapid fabrication of complex, stimuli-responsive architectures for applications in soft robotics and adaptive systems