Strategies for covalently reticulated polymer multilayers

The past decade has seen a growing need for robust organic coating technologies in various fields going from biotechnology, sensing and electronic devices to membrane design. Polyelectrolyte multilayers constitute a major and versatile tool in this respect. Yet, these films usually suffer from chemical and mechanical weakness. Improvement of the chemical and mechanical stability of multilayer films can be brought about by covalent reticulation between the constituent polymers. Three main routes were developed for this purpose: post-reticulation after film buildup, step-by-step reticulation during film buildup and recently one-pot film construction. This review summarizes these main strategies with emphasis on the mechanisms of the chemical reactions used.