Driving Deformation, Assembly, and Coupled Motion of Polymers with Light

Ryan Hayward from University of Colorado Boulder

The ability to manipulate materials with light is of interest for controlling untethered vehicles and actuators, as well as for developing active matter systems that exhibit complex emergent dynamics. Our group has recently focused on two main classes of light-addressable polymer composites. In the first case, we employ a platform of temperature-responsive hydrogel nanocomposites adsorbed at air/water interfaces that exhibit a variety of bioinspired non-equilibrium behaviors due to temperature gradients generated by illumination with visible light. Such gradients can induce spatial nonuniformity in both the swelling of the gel, as well as the surface tension, leading to capillary and Marangoni forces between particles that drive self-assembly and a variety of coupled motions. In the second case, we seek to directly translate photon energy into mechanical work through anisotropic deformation of polymers containing aligned crystals of photoisomerizable materials. These include both small molecule crystals grown within polymer matrices, and semi-crystalline polymers containing photo-switchable units in the polymer backbone.