Applications of the sol-gel process for the preparation of photochromic information-recording materials: synthesis, properties, mechanisms

David Levy*, Shlomo Einhorn, David Avnir

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

161 Scopus citations

Abstract

The preparation and properties of two types of photochromic materials based on room-temperature trapping of spiropyranes in modified silicon oxide matrices are described. The sol-gel process was employed for this purpose by polymerizing ethyltriethoxysilane in the presence of the photochromic dyes. When the system reaches the xerogel stage a material with normal photochromic behavior (colorless converted to colored) is obtained. When the sol-gel process was employed with a 4 1 mixture of tetramethoxysilane/polydimethylsiloxanes (with molecular weights in the range 162-43 600), materials with reversed photochromism (colored to colorless) were obtained. The difference between the normal and reversed photochromism is explained in terms of the differences in the cage properties within which the dye is trapped, namely low polarity in the former and higher polarity in the latter. Whereas polymerization of tetraalkoxysilanes provides photochromic materials with temporary activity, the two modifications described here provide long-acting materials. The added flexibility of the matrix achieved by these new synthetic procedures is the direct cause for this property. We demonstrate the feasibility of the potential use of such composite materials as information-recording and information-processing materials.

Original languageEnglish
Pages (from-to)137-145
Number of pages9
JournalJournal of Non-Crystalline Solids
Volume113
Issue number2-3
DOIs
StatePublished - 4 Dec 1989

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