GROWTH AND STRUCTURE OF SPHERULITES IN POLYMER-DISPERSED LIQUID-CRYSTALS FABRICATED BY PHOTOPOLYMERIZATION-INDUCED PHASE-SEPARATION

Spherulites appear during the formation of a polymer-dispersed liquid crystal (PDLC) under cel tain fabrication conditions. High UV irradian ce results in a sample dominated by liquid crystal droplets while low UV irradiation results in the growth of sperulites, possibly because t he latter condition creates fewer droplets, which is preferable for sp herulitic growth. Spherulites that are nucleated adjacent to each othe r maintain their circular shape during growth until they make contact with each other, and then form a straight line boundary while maintain ing radial growth. Direct observation of the inner aspect of PDLCs by means of Nomarsky differential interference microscopy and scanning el ectron microscopy (SEM) has revealed that the three-dimensional struct ure of a spherulite is plate like and that the boundary line seen in p olarization microscopy contains no structure within the resin matrix, indicating that the body of a spherulite consists mainly of liquid cry stal. A model of merging spherulites is proposed in this paper.