Structure and morphology of sol-gel prepared polymer-ceramic composite thin films

• Published in: Polymer (Guilford) Vol. 34; no. 22; pp. 4607 - 4612
• Main Authors: Embs, Frank W., Thomas, Edwin L., Wung, Chichang J., Prasad, Paras N.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1993; Elsevier
• Subjects: Applied sciences; Chemical modifications; Chemical reactions and properties; composites; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; poly( p-phenylene vinylene); sol-gel; composites; poly( p-phenylene vinylene); sol-gel; Composite film; Third harmonic; Non linear optics; Non linear optical susceptibility; Experimental study; Silica; Chemical modification; Phenylene(vinylene) polymer; Sol gel process; Optical properties; Morphology; Preparation; Electrical conductor; Optical attenuation
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(93)90691-3

Poly( p-phenylene vinylene) (PPV)-silica composite thin films were prepared via the sol-gel process incorporating a water-soluble PPV precursor. After solvent evaporation, the spin-coated or quiescently cast films were cured and the PPV precursor and the silica sol were completely converted into the PPV-silica composites. Quiescently cast films show an improved wave-guiding behaviour with a χ 3 value only slightly smaller than pure PPV films. Their structure consists of a nanophase-separated morphology composed of amorphous silica and paracrystalline PPV. Small-angle X-ray scattering and bright field transmission electron microscopy images indicate a random arrangement of the nanoscale domains with average domain size of approximately 4 nm. In contrast, spin-coated films show clusters and cluster-cluster aggregates approximately 100 nm in diameter. The clusters consist of particulate silica and pores, each about 3 nm in size, with the PPV contained in the pores and between the clusters. The observed morphologies are related to film preparation conditions in terms of sol-gel processing, taking the presence of the polymer into account.