Work

Spatial Patterning of Tilt Gradients in Liquid Crystal Elastomer Films

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Liquid crystalline elastomers (LCEs) offer programmable mechanical and optical properties driven by nematic director alignment. However, simultaneously achieving localized spatial patterning and control over out-of-plane director tilt remains a significant fabrication challenge, limiting the potential complexity of these materials. Here, we present a scalable, digitally programmable method to spatially pattern tilt gradients in LCE films using digital light projection (DLP) photoalignment. We utilize a two-step process: first establishing a uniform in-plane alignment using polarized light on a standard azo-dye coating, followed by spin coating of a LC monomer layer and localized exposure of unpolarized light. We demonstrate that increasing the energy dose of unpolarized light directly increases the out-of-plane tilt angle. Using Wide-Angle X-ray Scattering (WAXS), we quantify these programmed mesogen orientations, achieving local control from planar configurations to a nearly homeotropic alignment with a tilt angle up to 81.55 ± 1.52°. This localized spatial patterning enables targeted control over in-plane mechanical anisotropy, achieving discrete regions of elastic modulus. Digital image correlation (DIC) was used to demonstrate the strain-shielding effect of these softer domains, effectively isolating stiffer regions from localized strains. Furthermore, by spatially patterning variable tilts in splay-aligned films, we achieved complex three-dimensional (3D) shape-morphing, tuning the actuation radius of curvature from 10.39 ± 0.41 cm down to 2.41 ± 0.26 cm across the length of a single film. By concurrently patterning planar and nonplanar domains within a single exposure, this work overcomes a critical fabrication bottleneck, significantly broadening the design space for LCE-based stretchable electronics and advanced soft actuators.

Source: Macromolecules

DOI: 10.1021/acs.macromol.6c00998