Encoding Gaussian curvature in glassy and elastomeric liquid crystal solids.
We describe shape transitions of thin, solid nematic sheets with smooth, preprogrammed, in-plane director fields patterned across the surface causing spatially inhomogeneous local deformations. A metric description of the local deformations is used to study the intrinsic geometry of the resulting surfaces upon exposure to stimuli such as light and heat. We highlight specific patterns that encode constant Gaussian curvature of prescribed sign and magnitude. We present the first experimental results for such programmed solids, and they qualitatively support theory for both positive and negative Gaussian curvature morphing from flat sheets on stimulation by light or heat. We review logarithmic spiral patterns that generate cone/anti-cone surfaces, and introduce spiral director fields that encode non-localized positive and negative Gaussian curvature on punctured discs, including spherical caps and spherical spindles. Conditions are derived where these cap-like, photomechanically responsive regions can be anchored in inert substrates by designing solutions that ensure compatibility with the geometric constraints imposed by the surrounding media. This integration of such materials is a precondition for their exploitation in new devices. Finally, we consider the radial extension of such director fields to larger sheets using nematic textures defined on annular domains.
Department of Engineering , University of Cambridge , Cambridge CB2 1PZ, UK.
Cyrus
C
Mostajeran
Cavendish Laboratory , University of Cambridge , 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK.
Mark
0000-0003-3172-0265
M
Warner
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433, USA; Department of Bioengineering, The University of Texas at Dallas, 800 W Campbell Road, Richardson, TX 75080, USA.
Taylor H
TH
Ware
Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base , OH 45433, USA.
Timothy J
TJ
White
curvature; elastomers; nematic; solids