- The use of copper(I)-catalyzed "click" reactions of azides and alkynes for covalent layer-by-layer grafting on polyethylene is described. Water-soluble poly(N-alkylacrylamide) copolymers that contain pendant azide or alkyne groups that can be thermally separated from aqueous solutions were used to alternately "click" together azide and alkyne polymers via 1,2,3-triazole formation onto a prefunctionalized alkyne-containing surface. The layer-by-layer self-assembly process proceeds under ambient conditions and was followed by ATR-IR spectroscopy using control reactions to show that azide groups and copper catalysis are required for the assembly process. Post-graft functionalization of the hyperbranched assembly is used to demonstrate that the functional interfaces so formed can be further derivatized for other functions. 2007 American Chemical Society.