Direct covalent bond formation between materials using copper(i)-catalyzed azide alkyne cycloaddition reactions

Abstract

Copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) reactions have been used to prepare organic molecules and polymeric materials, however direct adhesion between polymeric materials and between polymeric and inorganic materials via irreversible reactions has not been reported, except for reversible adhesion using some reversible reactions. Herein we realize direct adhesion of materials using the CuAAC reaction in which a poly(acrylamide) gel (pAAm gel) modified with a pendent terminal ethynyl group (E-gel) selectively adheres to the pAAm gel with a pendent azide group (Az-gel). The E-gel selectively bonds to a glass substrate whose surface is modified with the azide groups, but the adhesion strength depends on the ratio of the functional groups. These results indicate that direct adhesion using the CuAAC reaction should be applicable to various environments regardless of the materials' quality.