Simulating the Response of Liquid Crystalline Elastomer Microposts to Light

Liquid crystalline elastomers (LCEs) represent a realizable physical system that can exhibit a large, non-linear response to an environmental stimulus. By adding light-sensitive moieties to the mesogens responsible for liquid crystalline order, one can create elastomers that will change shape in response to ultraviolet light. This provides a basis for a “write once, read many times” (WORM) memory. Information is encoded in an array of LCE microposts through a magnetic field during cross-linking, and then read out by introducing a light source. The system will return to its initial state upon removal of the stimulus, allowing the reading process to be repeated without altering the system. We developed a finite element simulation code to study components of such a system. Using our simulation method, we can predict the micropost deflection as a function of the preset nematic director and the incident angle of the light. We make comparisons to available experimental results and describe new findings that reveal how light can be used regulate the structure of an array of multiple, interacting LCE microposts. These studies point to new ways of utilizing the LCE arrays for technological applications.