Synthesis and characterization of covalently linked multilayer films prepared in the absence of solvent.

We report the preparation of multilayer organic thin films prepared by sequential vapor-phase coupling of monomers. The reactions were carried out at room temperature and atmospheric pressure. Films prepared using up to six sequential coupling reactions are reported. The following specific vapor-phase reactions were found to be viable: reactions between acid chlorides and both aliphatic and aromatic amine, hydrolysis reactions, anhydride activation, and reactions between anhydrides and primary amines. Homobifunctionalized monomers, such as hexamethylenediamine, react primarily via a single endgroup rather than cross coupling to the reactive surface via both reactive groups. The estimated coverage of the multilayer films is between 36 and 46%. The films were characterized using ellipsometric, contact angle, and spectroscopic measurements.