Phase separation dynamics of a polymer dispersed liquid crystal

Phase separation in a polymer dispersed liquid crystal (PDLC), consisting of a main chain liquid crystal (E7) and polymethyl methacrylate (PMMA), was studied by means of light scattering and optical microscopy. The PMMA/E7 mixture exhibits an upper critical solution temperature (UCST), overlapping with a nematic-isotropic transition of the E7 liquid crystal. Several temperature quenches were undertaken by rapidly transferring the 60/40 PMMA/E7 from a single phase (95°C) to an unstable region (25, 35 and 45°C) and by subsequently monitoring the time-evolution of scattering profiles. The time-evolution of structure factor reveals a cross-over of a kinetic exponent from -0.33 to -0.6 or larger slopes at a shallower temperature quench. Multiple droplets appear under a polarized microscopic investigation. Concurrently, nematic disclinations develop within the droplets and annihilation occurs as droplets coalesce