  Liquid crystalline elastomers (LCEs) are shape-changing materials that
exhibit large deformations in response to applied stimuli. Local control of the
orientation of LCEs spatially directs the deformation of these materials to
realize spontaneous shape change in response to stimuli. Prior approaches to
shape programming in LCEs utilize patterning techniques that involve the
detailed inscription of spatially varying nematic fields to produce sheets.
These patterned sheets deform into elaborate geometries with complex Gaussian
curvatures. Here, we present an alternative approach to realize shape-morphing
in LCEs where spatial patterning of the crosslink density locally regulates the
material deformation magnitude on either side of a prescribed interface curve.
We also present a simple mathematical model describing the behavior of these
materials. Further experiments coupled with the mathematical model demonstrate
the control of the sign of Gaussian curvature, which is used in combination
with heat transfer effects to design LCEs that self-clean as a result of
temperature-dependent actuation properties.
