Materials that change shape in response to light (photo-responsive materials) have many applications, including micro-mechanical systems. Liquid crystal systems are useful in creating photo-responsive materials because they possess long-range order that helps amplifying the microscopic deformation (in this case, the light-activated trans-cis isomerization of azobenzene) into a macroscopic deformation of the entire material. The azobenzene-containing monomer, disperse red 1 acrylate (DR1 acrylate), was introduced to a one-pot literature-based liquid crystal elastomer (LCE) platform that produces monodomain LCEs in a two step process: an initial thiol-acrylate crosslinking and then a photo-crosslinking step. Solvent leaching shows that the DR1 acrylate successfully covalently attached to the other LCE. The LCE was photo-cured in monodomain alignment by mechanically stretching it (up to 200% strain) and photo-crosslinking intentionally excess acrylate groups with UV light (365 nm). Efforts are underway to build an Arduino-based tensile-strength tester (universal testing machine) to measure the repeatability of the synthesis from batch to batch. Upon irradiation with a laser pointer (450 nm), monodomain material bends towards the light source with enough force to move small objects. (Polydomain material does not appear to bend towards the light source). When the light is removed, the material returns to its original position.

Synthesizing and measuring the properties of an azobenzene-based photo-responsive liquid crystal elastomer

2019 Fall National Meeting

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