Molecular Crystals and Liquid Crystals, Vol.526, 1-9, 2010
A Wide-Range Controlling of Optical and Morphological Parameters of PDLC Samples via the Intensity of Curing Light
The phase separation kinetics and morphology of polymer dispersed liquid crystals (PDLCs) formed from the nematic liquid crystal (LC) E7 and pre-polymeric composition NOA65 via the photoinduced phase separation in a wide intensity range of actinic UV light (I = 0.5-40mW/cm(2)) are investigated. The phase separation process was monitored by measuring transmittance kinetics of the composite layers, while the morphology was observed by polarized optical microscopy. Increase of curing light intensity dramatically influenced the phase separation kinetics and final structure of PDLC samples. Reduction of light intensity below 2 mWcm(-2) resulted in transition from the conventional PDLC morphology of fine monodispersed LC droplets (with a droplet diameter d similar to 1 mu m) to the morphology of large LC domains (d similar to 10 mu m) of irregular shape. The realized transition extends the field of PDLC morphologies of E7-NOA65 composites and thus the field of their potential applications.