Important factors for silane adhesion promoter efficacy: surface coverage, functionality and chain length

• Published in: Journal of adhesion science and technology Vol. 18; no. 13; pp. 1497 - 1516
• Main Authors: Jenkins, M. L., Dauskardt, R. H., Bravman, J. C.
• Format: Journal Article
• Language: English
• Published: Leiden Taylor & Francis Group 01-01-2004; Brill
• Subjects: AMMONIA CATALYST; Applied sciences; BENZOCYCLOBUTENE; CHAIN LENGTH; Compounding ingredients; CONTACT ANGLE; Exact sciences and technology; HYDROLYSIS; Miscellaneous; Polymer industry, paints, wood; SILANES; SURFACE COVERAGE; Technology of polymers; X-RAY PHOTOELECTRON SPECTROSCOPY (XPS); Performance evaluation; Silanes; Structure effect; ammonia catalyst; Adhesivity; Molecular structure; Chain length; Organic silane; contact angle; Experimental study; surface coverage; Coupling agent; Hydrolysis; benzocyclobutene; Medium effect; Silicon oxides; X-ray photoelectron spectroscopy (XPS); Surface properties; Kinetics; Cyclobutene derivative polymer
• ISSN: 0169-4243; 1568-5616
• DOI: 10.1163/1568561042411268

The effects of an ammonia-based catalyst, surface coverage, organofunctional group and chain length on silane adhesion promoter efficacy were examined at a benzocyclobutene (BCB)/silicon dioxide interface with silanes of varying functionality and chain length. Fracture-mechanics-based
techniques, and X-ray photoelectron spectroscopy and contact-angle measurements were used to quantify the adhesion energy and silane surface coverage, respectively. Inclusion of a propylamine catalyst in silane solutions was found to affect both silane surface coverage and the resulting adhesion
energy. However, in the absence of the catalyst comparable results were obtained with hydrolysis times in excess of 1 h. Only a weak dependence of adhesion energy on silane surface coverage was observed. After adhesion energy results for silanes with varying organofunctional group were normalized
for differences in surface coverage, only the vinylfunctional silane was found to enhance adhesion of BCB to silicon dioxide, due to interaction of the vinylfunctional group with BCB during cure. A trend of increasing adhesion energy with increasing chain length was observed for CH
3
-terminated
silanes (2 ≥ n ≥ 18), while an opposite trend of decreasing adhesion energy with increasing chain length was found for vinyl-terminated silanes (2 ≥ n ≥ 22). The results are compared to existing models of polymer chain entanglement.