Shear-Induced Fracture at the Interface of PDMS and a Rigid Slab Modified with Polyelectrolyte Layers

Abstract

We studied the interaction between a surface modified glass prism and a thin film of PDMS (polydimethylsiloxane) elastomer using a shear adhesion test. The glass prism was chemically modified either by depositing a self-assembled silane monolayer (silanization) or by depositing a few layers of polyelectrolytes. The PDMS was modified only with the polyelectrolyte layers (PEL). While the interaction between the chemically modified glass prism and unmodified PDMS (free of any filler additive) is primarily dispersive, some specific interaction prevails when the PEL-modified glass prism contacts a commercial PDMS (i.e., Sylgard® 184) that has silica additives. The surfaces were examined with wettability analysis, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) that established the locus of failure. Water immersion tests show that the adhesion between PDMS and glass is stable under water for a long time when the interfacial interaction is mainly dispersive, whereas it deteriorates rapidly when the interface has a polar character.

Keywords:

• Adhesion
• Biofouling
• Fracture
• Polyelectrolyte
• Under water test

ACKNOWLEDGMENT

This work was supported by the Office of Naval Research (N000140810743 P00001). We thank Jonathan Longley and Chi-Hsiu Lin for carefully reading and correcting the manuscript.

Notes

One of a Collection of papers honoring J. Herbert Waite, the recipient in February 2009 of The Adhesion Society Award for Excellence in Adhesion Science, Sponsored by 3 M.