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Programmable 2D and 3D Liquid Crystal Elastomers
Liquid crystal elastomers (LCEs) are a class of materials that straddle the boundary between liquids and solids. A striking feature of LCEs is their reversible shape transformation at both micro- and macroscopic scales, which can be controlled by strategically arranging molecular orientations. Although much progress has been made since their discovery over 30 years ago, the conventional cross-linking technique used to join the polymer chains of LCEs has mostly been used to manufacture 2D films; few studies have focused on using this standard approach to manufacture 3D-shaped LCEs.
This technology comprises a novel fabrication process that can be used to fabricate 2D- and 3D-shaped LCEs at both the macro- and microscale. After the chemical synthesis of liquid crystal oligomers (which are chains of repeating units called monomers), the approach involves a facile two-step UV curing process. A key aspect to this method is that the LCE is mechanically programmed before the final UV curing step by simply stretching or pressing it into the desired shape, which is then ‘remembered’ by the material. LCEs produced using this process exhibit reversible shape transformations when chemical or thermal stimuli are applied. Thus, this technology paves the way to several applications that require shape-programable materials.
Technology Features, Specifications and Advantages
This technology utilizes a two-step process to produce 2D and 3D LCEs with a variety of shapes and programmable mechanical properties.
- LCEs are first synthesized via step-growth polymerization to obtain the oligomers. The oligomers are partially cured by UV to generate polydomain LCEs to undergo mechanically programming.
- Mechanical programming techniques such as pressing, stretching, embossing, and UV printing, allow for the creation of arbitrary shapes adjusted to each application. The LCE alignment is locked in by additional and complete UV curing.
The shape of LCEs prepared using this approach can be reversibly altered by simply modifying its temperature or chemical environment.
The proposed technology paves the way for a great variety of potential applications that could use shape-programable, and thermally and chemically responsive materials.
Examples include (but are not limited to) :
- Soft actuators
- Flexible devices
- Medicine and artificial muscles
- Smart coatings
- Simple and similar to conventional, well-established techniques for producing LCEs
- Does not require the use of a solvent and can be done at room temperature
- Applicable for both 2D and 3D LCEs in the large- or microscale
- Complex shapes and patterned materials with tailored responses to thermal and chemical stimuli can be developed