Click chemistry in materials synthesis. III. Metal-adhesive polymers from Cu(I)-catalyzed azide-alkyne cycloaddition

1,2,3‐Triazole‐based polymers generated from the Cu(I)‐catalyzed cycloaddition between multivalent azides and acetylenes are effective adhesive materials for metal surfaces. The adhesive capacities of candidate mixtures of azide and alkyne components were measured by a modified peel test, using a customized adhesive tester. A particularly effective tetravalent alkyne and trivalent azide combination was identified, giving exceptional strength that matches or exceeds the best commercial formulations. The addition of Cu catalyst was found to be important for the synthesis of stronger adhesive polymers when cured at room temperature. Heating also accelerated curing rates, but the maximum adhesive strengths achieved at both room temperature and high temperature were the same, suggesting that crosslinking reaches the same advanced point in all cases. Polytriazoles also form adhesives to aluminum, but copper is bound more effectively, presumably because active Cu(I) ions may be leached from the surface to promote crosslinking and adhesion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5182–5189, 2007 Mixtures of polyvalent azides and alkynes in contact with metallic copper surfaces produce metal‐adhesive crosslinked polymers. The process can be speeded by the addition of copper salts to increase the concentration of catalytic Cu(I) ions. The strength of these materials was assayed in a peel test, leading to the discovery of the triazide + tetra‐alkyne mixture shown here as the most effective combination identified to date. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]