Role of architecture and molecular weight in the formation of tailor-made ultrathin multilayers using dendritic macromolecules and click chemistry.

Vestberg, R.; Malkoch, M.; Kade, M.; Wu, P.; Fokin, V.V.; Sharpless, K.B.; Drockenmuller, E.; Hawker, C.J.;
J. Polym. Sci., Polym. Chem.;
45, 2835-2846.

The high efficiency and mild reaction conditions associated with the Cu(I) catalyzed cycloaddition of azides and alkynes were exploited for the covalent layer-by-layer synthesis of dendritic thin films on silicon wafers. The preparation of azide and alkyne-terminated dendrimers based on bisMPA was accomplished by a divergent strategy; combinations of these monodisperse building blocks from the 2nd to the 5th generation were used for construction of the thin films. The layer-by-layer self assembly process proceeds under ambient conditions and was monitored by ellipsometry, XPS, and ATR-IR, which showed extremely regular growth of the dendritic thin films. Film thickness could be accurately controlled by both the size/generation number of the dendrimers as well as the number of layers. In comparison with linear analogues, the growth of the dendritic films was significantly more controlled and defect-free with each layer being thinner than the corresponding films prepared from the isomeric linear polymers, demonstrating the well-defined, three-dimensional nature of the dendritic architecture.