NMR CHARACTERIZATION OF LIQUID-CRYSTAL POLYMER INTERACTIONS IN POLYMER-DISPERSED LIQUID-CRYSTALS

Solid-state nuclear magnetic resonance (NMR) and optical microscopy ha ve been used to study liquid crystal-polymer interactions in polymer-d ispersed liquid crystals (PDLCs) composed of the E7 liquid crystal mix ture and poly(n-butyl methacrylate) or poly(isobutyl methacrylate). As previously reported, the droplets adopt a bipolar configuration in th e PDLCs using poly(n-butyl methacrylate) as the matrix material and a radial configuration in those using poly(isobutyl methacrylate). The N MR signals from the E7 cannot be detected in the bulk state by using m agic angle spinning and cross-polarization because of its liquid-like properties, The E7 and the polymer signals are only weakly cross-polar ized in 60:40 E7/poly(n-butyl methacrylate) PDLCs but are strongly cro ss-polarized in the PDLCs with poly(isobutyl methacrylate), We suggest that the differences are due to a change in the surface-anchoring con ditions and that Nh IR spectroscopy may provide a molecular-level prob e of the forces that control droplet configuration and the electro-opt ical properties of these materials.