Abstract:
Liquid crystalline elastomers (LCEs) are widely recognized for their exceptional promise as actuating materials. Under external stimuli, LCEs exhibit dramatic shape and/or optical changes that can be utilized in aerospace, optics, and medicine. Of specific interest is how processing and structure dictate the distinctive, nonlinear mechanical deformation of these materials. By controlling LCE processing, we can program specific curvature and deformation profiles. Here, we present a methodology to realize surface-templated, homeotropic orientation in LCE films, leading to omnidirectional nonlinear mechanical deformation. To further leverage this behavior, we use inkjet printing as an additive manufacturing tool to localize discrete regions of homeotropic and planar orientation within a monolithic LCE element. Localized control of self-assembly and molecular orientation, combined with structural design methods, yields functional materials with a continuous composition but discontinuous mechanical deformation. This approach completely eliminates material-material interfaces, which are a common source of mechanical failure. Building upon this work, we also developed a method to spatially control the alignment tilt angle continuously from planar to homeotropic using light. Finally, as we transitioned from 2D sheets to complex 3D architectures via hot direct ink writing (DIW), we investigated how processing conditions affect the resulting polymer chemistry, mechanics, and ultimately, actuation performance. Overall, this work enables the creation of tailored functional monoliths and architectures with novel, tunable macroscopic properties (such as negative Poisson's ratios) for applications including flexible hybrid electronics and robust, shock-absorbing materials.

Bio:
Dr. Anesia Auguste is a Research Materials Engineer at the Air Force Research Laboratory (AFRL). She began her career at AFRL as a National Research Council (NRC) Postdoctoral Fellow, working under the direction of Dr. Timothy White. Dr. Auguste earned her Ph.D. in Polymer Science and Engineering from the University of Massachusetts Amherst in 2016, following her B.S. in Materials Science and Engineering from the University of Florida. She has received several honors and awards including: LUCI Fellowship (2024); NRC postdoctoral fellowship (2016); NSF Graduate Research Fellowship (2011); GEM Fellowship (2010); and Northeast Alliance for Graduate Education and the Professoriate Fellowship (2010, 2015).