3D Printing of Liquid Crystal Elastomeric Actuators with Spatially Programed Nematic Order

Abstract

Liquid crystal elastomers (LCEs) are soft materials capable of large, reversible shape changes, which may find potential application as artificial muscles, soft robots, and dynamic functional architectures. Here, the design and additive manufacturing of LCE actuators (LCEAs) with spatially programed nematic order that exhibit large, reversible, and repeatable contraction with high specific work capacity are reported. First, a photopolymerizable, solvent-free, main-chain LCE ink is created via aza-Michael addition with the appropriate viscoelastic properties for 3D printing. Next, high operating temperature direct ink writing of LCE inks is used to align their mesogen domains along the direction of the print path. To demonstrate the power of this additive manufacturing approach, shape-morphing LCEA architectures are fabricated, which undergo reversible planar-to-3D and 3D-to-3D' transformations on demand, that can lift significantly more weight than other LCEAs reported to date.

Hierarchical cellular scaffolds fabricated via direct foam writing using gelled colloidal particle‐stabilized foams as the ink

“…10,11 During such printing process, viscoelastic inks are squeezed out of the nozzles to form filamentary struts and finally become various patterns according to the prescribed motion of nozzles. 18 However, most of the printing process are light-based, and their foam inks usually have intricate constituents which must hybrid with preceramic resins [19][20][21][22] or photopolymerizable organics [23][24][25][26] to facilitate gelation during printing. Nowadays various inks which span as diverse as hydrogels, 14 viscoelastic polymer, 15 and elastomers 16 have been successfully proposed for DIW method.…”

Spontaneous Alignment of Graphene Oxide in Hydrogel during 3D Printing for Multistimuli‐Responsive Actuation

“…The apparent viscosity of the GO/SA ink obviously drops along with the increase of the shear rates. Notably, the shear rate at the nozzle is usually orders of magnitude higher than that of the flow in other parts, indicating that the ink at the nozzle can be extruded . Besides, the GO/SA ink becomes viscous with increasing GO content.…”

Liquid Crystal Templates Combined with Photolithography Enable Synthesis of Chiral Twisted Polymeric Microparticles

“…The route for the synthesis of liquid crystal elastomer microparticles involves the polymerization of single component or multicomponent mixtures of reactive mesogens with mono‐ or diacrylate reactive groups . These studies employed methods such as replica molding, emulsion polymerization, dispersion polymerization, 3D printing, inkjet printing, and microfluidic to maintain desired shapes of the microparticles for specific purposes ranging from soft robotics, micropumps, artificial muscles, or sensors . Recently, it has been shown that low molecular weight non‐reactive LCs can also be used for the templated synthesis of polymeric materials.…”