Pseudopeptidic Polymer Microsphere-Filled Liquid Crystals as High-Performance Light-Scattering Switches

We, herein, report the fabrication of light-scattering switches from polymer microsphere-filled liquid crystals (PFLCs) using pseudopeptidic bottlebrush polymers. A simple method of precipitation of a polymer using the 4-cyano-4′-pentylbiphenyl (5CB) nonsolvent is employed for the preparation of PFLC devices. For this, a series of phenylalanine (Phe)-based bottlebrush polymers having different chain lengths are synthesized by ring-opening metathesis polymerization (ROMP) using the Grubbs second-generation ruthenium catalyst and used in a nematic liquid crystal (LC) matrix. The developed PFLC devices are well-characterized using various ultramicroscopic techniques such as field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM). For the first time, the effect of the molecular weight of a polymer on electro-optic (E-O) properties of PFLC is investigated. PFLCs show significant differences in microsphere size, required operating voltage, transmittance, contrast ratio (CR ratio), memory effect, and switching speed upon subtle variation of the dopant polymer units. Overall, we demonstrated that the chain length of a polymer plays a crucial role in controlling the performance of PFLC devices. The presented methodology offers promising possibilities for the fabrication of PFLC-based switchable scattering devices with improved performance for optoelectronic applications.