Gel-melting method for preparation of organically modified siloxane low-melting glasses
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Masahide Takahashi Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Japan; and PRESTO, Japan Science and Technology Agency, Saitama 332-0012, Japan
Yomei Tokuda, and Toshinobu Yoko Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Japan (Received 15 September 2004; accepted 7 February 2005)
Softening or melting behavior of the organically-modified siloxane hybrid gels and glasses in the system of RSiO3/2 and R2SiO2/2 (R: methyl and phenyl) has been investigated to obtain a new family of low-melting glasses. The RSiO3/2 and RSiO3/2–R2SiO2/2 gels showed softening temperatures around 50–100 °C. The softening temperature of RSiO3/2 single-component glasses, which were obtained by melting the corresponding gels at a temperature above the softening temperature, increased by heat-treatment at 200 °C, and finally showed no softening behavior. On the other hand, in the PhSiO3/2–Ph2SiO2/2 binary glasses, the softening temperatures showed a tendency to saturate after longer heat treatment over 200 h. These facts indicate that the present organically modified siloxane system will be a potential candidate for the low-melting glass. I. INTRODUCTION
Low-melting glasses are one of the most important materials indispensable to advanced electronics technology. For example, they are used as insulating, bonding, and passivation materials of a variety of electronics parts. The most widely used low-melting glass material is leadcontaining glasses.1–3 However, alternative materials free from lead or other pollutant elements are widely explored.4–7 On the other hand, high-speed and large capacity information technology has been realized with an optical networking system. In more advanced information and communication technology, the high-performance devices, which possibly utilize nonlinear optical materials,8–10 are required to process the information signal. Although low-melting glasses containing optically functional organic molecules are expected to be promising candidates for such applications, it is difficult to obtain glasses with high figure-of-merit because the solubility of organics, especially non-polar molecules, is very low in the presently available lead glasses.11,12 It is known that organically modified polysiloxanes, such as polysilsesquioxane, exhibit a reflow characteristic.13–18 The microlens arrays can be formed by the post
II. EXPERIMENTAL
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2005.0151 1234
http://journals.cambridge.org
heat treatment of the patterned phenyl polysilsesquioxane thin films in the same way as photoresist technology.19–22 The optical anisotropy of the matrix containing electrically or optically aligned polar molecules such as azobenzene DR1 can be fixed by quenching after the poling at a temperature higher than its softening point.23 It is clear that the organic functional group attached to the silicon atom acts as a network terminator, leading to a decrease in the network dimensions. If the t
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