Activated Poly(hydromethylsiloxane)s as Novel Adhesion Promoters for Metallic Surfaces

A poly(hydromethylsiloxane) (PHMS) was bound to aluminum, copper and steel surfaces via activation with cis-[PtCl₂(PhCH [dbnd] CH₂)₂] in solution at room temperature. The attached polymer promotes the adhesion to two-component silicone resins where the curing process is based on catalytic hydrosilylation of olefins. In lap-shear or peel tests, cohesive failure was always observed. An example shows that the adhesive joint withstood boiling water for 200 h without considerable loss of adhesive strength. It is suggested that a small fraction of the olefinic component of the resin, e.g., a poly(dimethylsiloxane) containing some olefinic groups, is also connected with the attached PHMS via catalytic hydrosilylation, thus binding the silicone resin to the surface via the PHMS layer.