Delamination between Functionalized Silicon Surfaces (Experimental and Applied Mechanics)

The paper describes the development of an experiment with associated analysis to determine the toughness of a molecular adhesive formed by bringing together two functionalized silicon surfaces. Si (111) surfaces were coated with amine and carboxy-terminated self-assembled monolayers (SAMs). The areal density of these termini was varied in order to modulate the bonding interactions between the two surfaces. The silicon beams were pressed together to form miniature laminated beam beam specimens and then fractured in high vacuum using a specially developed fracture tester. Normal crack opening displacements were measured using infra red crack opening interferometry.

The fracture toughness of the specimens was measured as a function of the areal density of bonds. Traction-separation laws were extracted from the measurements of crack opening displacements. Interesting differences are being noted in mode 1 and mixed-mode in these highly controlled experiments.

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