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Personal Profile
Voxel‐by‐voxel molecular programming of smart structures
Liquid crystalline elastomers (LCEs) are distinguished among stimuli-responsive materials due to their ability to reversibly generate large strains (up to 400% shrinkage) and actuation stresses (100’s kPa, exceed those produced by natural muscle) from molecular order–disorder transitions of the long-range orientational order in the macromolecular network. Actuation can be induced using a range of stimuli, including heat, light, and solvent. Blueprinting spatially heterogeneous molecular patterns to direct the large work potential is a compelling feature of the LCE. This allows for their utilization in actuators across length scales ranging from the micrometer to the macroscopic scale. Previous strategies for stimuli-responsive materials (LCEs in particular) mostly require mechanical programming (stretching, bending, or extruding the material), or command surfaces. Furthermore, current fabrication approaches are unable to access this 3D design space, limited to flat geometries or 2.5-dimensional geometries fabricated in molds. Thus, the ability to build (scalable) 3D freeforms with arbitrarily voxelated LC ordering remains elusive.
In this project, we proposed a novel framework for voxel-by-voxel indexing of the molecular order in 3D free-forms (geometrically complex structures) is realized with magnetically assisted additive manufacturing of liquid crystalline polymers. I studied the mechanism of magnetically controlling the molecular orientation and characterized the effect of different components of the composition concentration on the magnetic susceptibility and the elastic constants.
The versatility of this framework was illustrated by making light-responsive topographies, heat-responsive structures that generate Gaussian curvatures from flat geometries, a multi-responsive robotic manipulator (can be controlled using heat and/or light), and bioinspired falling seed with controllable flight dynamics.
I further exploited the combination of anisotropic magnetic susceptibility of the liquid crystalline monomers in a re-orientable magnetic field and spatially-selective photo-polymerization to independently define molecular orientation in light and/or heat responsive multi-material elements, which are additively incorporated into 3D free-forms, at scales ranging from the micro- to the macroscale.
Future work....
Publication & Patent
In progress
Tabrizi, M., Babaei, M., Martinez, A., Clement, J. A., Gao, J., Ware, T.H. and Shankar, M.R., Three-dimensional Blueprinting of Molecular Patterns in Liquid Crystalline Elastomers.
Ph.D.
