Tuning Adhesion through 3D Mesogen Alignment in Liquid Crystalline Elastomers.
Journal Article
Overview
abstract
Adhesives that harness anisotropy in molecular orientation can generate direction-dependent bonding and release. Such materials provide pathways to tailor the adhesive response through geometry, with implications in soft robotics, wearable systems, and reconfigurable interfaces. To realize these advanced functionalities, it is crucial to better understand and control the factors that govern the adhesive anisotropy. We prepared liquid crystalline elastomer (LCEs) with planar parallel, planar orthogonal, homeotropic, and isotropic orientations to systematically evaluate how the mesogen orientation affects peel and shear adhesion. While planar LCEs exhibit classic directional anisotropy, homeotropic alignment activates a distinct out-of-plane nonlinear viscoelastic deformation axis. This deformation allows mesogens to reorient and dissipate energy under the shear. Accordingly, LCE adhesives aligned in the homeotropic orientation show superior energy dissipation at low deformation rates and conformal adaptation to surface asperities. Functionally, this uniquely positions homeotropic LCEs to maintain or even enhance adhesion on rough substrates; a challenging and technologically important surface condition for pressure-sensitive adhesives (PSAs).
