Structure, growth, and morphology in para nitroaniline dispersed polymethyl methacrylate guest-host NLO composites

The structure, growth, and morphology of composite films made by dispersing para nitroaniline (PNA) in poly(methyl methacrylate) (PMMA) was investigat ed with respect to different crystallization methods, composition, and appl ication of electric field. The wide-angle X-ray diffraction scans showed la rge variations in intensity of different reflections, especially the Okl wi th composition and in the presence of an electric field. In addition, it al so showed the occurrence of a new crystalline structure, possibly due to co mplex formation between PNA and PMMA. The presence of this complex was furt her confirmed by infrared spectroscopy and thermal analysis. In a certain r ange of composition (30 to 40 % PNA), spherulitic morphology was observed, which otherwise consisted of needle-shaped crystals dispersed in amorphous matrix. The transparency of these films also depended strongly on the cryst allization conditions, and highly transparent films could be obtained, even at high PNA content by application of electric field. These various result s could be explained on the basis of the intermolecular interaction between PNA and PMMA, as well as preferential growth direction and orientation of the PNA crystals. (C) 1999 John Wiley & Sons, Inc.