Spatially resolved infrared microspectroscopy is used in conjunction with the contact method to conduct in situ diffusion experiments of photocured polymer-dispersed liquid crystals (LCs). The system analyzed consists of a low-molecular-weight liquid crystal (E7) diffusing into
a photopolymerizable monomer (NOA65). The measured concentration profiles were generated by monitoring the hydroxyl band of the monomer as a function of time and spatial position. The diffusion coefficients were calculated from least-squares fitting of the data. The system followed Fick's
second law of diffusion. The diffusion coefficient for this system is (1.97 ± 0.2)(10-8) cm2/s. The morphology of the system after polymerization exhibited three distinct regions: nematic LC molecularly mixed in the cross-linked network of the polymer, nematic
LC droplet gradient in the polymer matrix, and polymer fibers scattered in the continuous nematic LC.
Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106
Publication date: November 1, 1996
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