Solvent‐Assisted 4D Programming and Reprogramming of Liquid Crystalline Organogels

Abstract

Encoding molecular ordering during liquid crystalline network (LCN) formation endows preprogrammed but fixed shape morphing in response to external stimuli. The incorporation of dynamic covalent bonds enables shape reprogramming but also permanently alters the network structures. Here, an entropic approach that can program complex shapes via directed solvent evaporation from an isotropic LCN organogel is discoursed. Different shapes can be erased and reprogrammed from the same LCN on demand depending on the modes of deformation of the organogel during solvent evaporation. The ability to decouple network synthesis and molecular alignment relaxes the requirements to LCN chemistry and alignment methods, allowing for the realization of a variety of origami/kirigami structures and 4D shape morphing of LCNs printed from the digital light processing technique with unattainable spatial and temporal controls.

Photothermal-Driven Liquid Crystal Elastomers: Materials, Alignment and Applications

“…Jin et al [41] designed another way to orientate LCE with a stretching force. They added a certain proportion of solvent to the liquid crystal precursor to prepare a fully crosslinked isotropic liquid crystal oil gel; once the solvent evaporates, the liquid crystal oil gels will be oriented according to the direction of stress applied to it.…”

Combining printing and nanoparticle assembly: Methodology and application of nanoparticle patterning

“…Materials are mainly divided into categories according to the deformation driving force of the structures, namely, heat (for example, shape memory polymers [SMPs]), 102 light (e.g., photoresponsive polymers), 93 , 103 electric fields (e.g., carbon nanotube), 104 , 105 , 106 magnetic fields (e.g., Fe 3 O 4 and FeO), 107 , 108 and reactants (e.g., polyacrylic acid, poly(n-isopropylacrylamide), and polyvinyl alcohol). 109 , 110 , 111 Although the technology is in its infancy, 4D printed technology combined with NP assembly can serve as an effective method for constructing stimuli-responsive microstructures for reversible and two-way self-assemblies. 112 This section briefly discusses the application and development prospects of nanoassembly and 4D printing under different stimuli, such as thermal, magnetic, and reactants.…”

“…The patterns were deformed and assembled into pyramids, jellyfish, snails, and other shapes at one step above the glass transition temperature and were restored after heating, realizing pixelated memory deformation assembly. 111 …”

“…fabricated fully aligned mesomorphic structures using SLA-printed liquid crystal elastomers. 111 Toluene was used to change the crosslinking degree of the structure and to control the assembly process of the mesomorphic arrangement. The prepared structure exhibited high stability and could switch between temporary and fixed structures.…”

Thermally Driven Self-Rotation of a Hollow Torus Motor

“…In recent years, based on various stimuli-responsive materials including thermally responsive polymer materials [ 26 , 27 ], liquid crystal elastomers (LCEs) [ 28 , 29 , 30 , 31 ], dielectric elastomer [ 32 , 33 , 34 , 35 ], hydrogels [ 36 , 37 ], and ion gels [ 38 , 39 ], a wealth of self-excited motion modes have been proposed, such as rolling [ 40 , 41 ], vibration [ 24 , 31 , 40 , 41 ], torsion [ 41 , 42 ], stretching and shrinking [ 10 , 40 , 43 ], swinging [ 44 ], buckling [ 45 , 46 ], jumping [ 47 , 48 , 49 ], rotation [ 25 , 28 ], eversion or inversion [ 27 , 50 ], expansion and contraction [ 51 , 52 ], swimming [ 53 ] and even group behavior of several coupled self-excited oscillators [ 54 ]. The self-oscillating system is usually accompanied with damping dissipation, and its motion is a non-equilibrium dissipation process.…”