Reactive Multilayers and Coatings Fabricated by Spray Assembly: Influence of Polymer Structure and Process Parameters on Multiscale Structure and Interfacial Properties

We report new alternating and simultaneous spray-based approaches to the assembly of thin films and chemically reactive polymer coatings using azlactone- and amine-containing building blocks. Our results reveal the impacts of both polymer structure (e.g., the presence or absence of hydrolyzed azlactone groups) and other spray-process parameters (e.g., number of cycles, elimination of rinses, and changes in spray rate) on key aspects of film growth and morphology that are relevant to potential applications of these reactive materials. Manipulation of these parameters permits rapid and automated fabrication of uniform and continuous coatings that are either (i) thin and optically transparent or (ii) thicker and optically opaque, with varying and useful levels of nano- and microscale roughness and porosity. These coatings also present both unreacted azlactone and amine functionality, allowing facile postfabrication functionalization using amine-based nucleophiles and/or electrophilic amine-reactive species. These combinations of control over physical and chemical features permit facile tuning of interfacial properties and chemical patterning to design soft material coatings with useful properties, including extreme wetting and slippery antifouling behaviors. These spray-based methods are fast, efficient, and amenable to coating substrates of arbitrary shape and size. The approaches reported here should thus help guide the development of new processes for the fabrication of these reactive materials that can be implemented at scale or as elements of commercial or industrial processes.