Investigation of Polyimidesiloxanes for Use as Adhesives by Electron Spectroscopy for Chemical Analysis |
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Authors: | Hengzhong Zhuang Joseph A. Gardella Jr. Joseph A. Incavo Sergio Rojstaczer Jerold C. Rosenfeld |
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Affiliation: | 1. Department of Chemistry , State University of New York at Buffalo , Buffalo, NY, 14260, USA;2. Occidental Chemical Corporation , 2801 Long Road, Grand Island, NY, 14072, USA |
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Abstract: | Angle-dependent electron spectroscopy for chemical analysis (ESCA) was used to examine the air facing surface (20–100 Å thick) composition of polyimidesiloxanes with different processing variations, and of varying polydimethylsiloxane (PDMS) content and block length (number of PDMS repeat unit varies from 1 to 9). Polyimide was clearly detected (due to the nitrogen content) in the 20–100 Å surface regions. This shows that a small amount of PDMS and short PDMS segment lengths in polyimidesiloxanes give a surface region with both PDMS and polyimide present. The surface composition, particularly that in the ca. 100 Å region, was correlated to the peel strength of polyimidesiloxane melt pressed to a metal substrate. Our results suggest that both PDMS and polyimide are essential components to rendering a needed peel strength. PDMS, having a good diffusive ability, readily reaches the substrate upon being pressed, achieving intimate contact, while imide groups interact with the substrate, presumably through chemical bonding; these two factors act synergistically to result in a high peel strength. In addition, the interaction mechanism and the failure mechanism involved in bonding polyimidesiloxane and metal substrate were also elucidated based on the ESCA results. |
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Keywords: | Angle-dependent ESCA polyimidesiloxane adhesion relationship between peel strength and surface composition |
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