Enabling and Localizing Omnidirectional Nonlinear Deformation in Liquid Crystalline Elastomers

• Published in: Advanced materials (Weinheim) Vol. 30; no. 35; pp. e1802438 - n/a
• Main Authors: Auguste, Anesia D., Ward, Jeremy W., Hardin, James O., Kowalski, Benjamin A., Guin, Tyler C., Berrigan, J. Daniel, White, Timothy J.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 29.08.2018
• Subjects: Catastrophic events; Continuity (mathematics); Crystal structure; Crystallinity; Deformation; Deformation mechanisms; Elastomers; Electronic devices; flexible devices; Inkjet printing; liquid crystal elastomers; Liquid crystals; Materials science; nonlinear mechanics; Nonlinear response; Nonlinearity; Orientation; Poisson's ratio; self‐assembly; self-assembly; liquid crystal elastomers; nonlinear mechanics; flexible devices
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201802438

Liquid crystalline elastomers (LCEs) are widely recognized for their exceptional promise as actuating materials. Here, the comparatively less celebrated but also compelling nonlinear response of these materials to mechanical load is examined. Prior examinations of planarly aligned LCEs exhibit unidirectional nonlinear deformation to mechanical loads. A methodology is presented to realize surface‐templated homeotropic orientation in LCEs and omnidirectional nonlinearity in mechanical deformation. Inkjet printing of the homeotropic alignment surface localizes regions of homeotropic and planar orientation within a monolithic LCE element. The local control of the self‐assembly and orientation of the LCE, when subject to rational design, yield functional materials continuous in composition with discontinuous mechanical deformation. The variation in mechanical deformation in the film can enable the realization of nontrivial performance. For example, a patterned LCE is prepared and shown to exhibit a near‐zero Poisson's ratio. Further, it is demonstrated that the local control of deformation can enable the fabrication of rugged, flexible electronic devices. An additively manufactured device withstands complex mechanical deformations that would normally cause catastrophic failure. The synthesis of liquid crystal elastomers (LCEs) in the homeotropic orientation enables omnidirectional nonlinearity in mechanical deformation. Locally directing the self‐assembly of the orientation of the LCEs generates films of continuous composition but spatially distinguished mechanical responses. Local control of the mechanical deformation of the LCEs has functional benefits in realizing near‐zero Poisson's ratio or by ruggedizing flexible electronic devices.