TY - JOUR
T1 - Applications of the sol-gel process for the preparation of photochromic information-recording materials
T2 - synthesis, properties, mechanisms
AU - Levy, David
AU - Einhorn, Shlomo
AU - Avnir, David
PY - 1989/12/4
Y1 - 1989/12/4
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0024961453&partnerID=8YFLogxK
U2 - 10.1016/0022-3093(89)90004-5
DO - 10.1016/0022-3093(89)90004-5
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AN - SCOPUS:0024961453
SN - 0022-3093
VL - 113
SP - 137
EP - 145
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
IS - 2-3
ER -