Rapid Synthesis of Nanoporous Conformal Coatings via Plasma-Enhanced Sequential Infiltration of a Polymer Template

Nanoporous conformal coating is an important class of materials for electrocatalysis, water purification, antireflective coatings, etc. Common synthesis methods of porous films often require harsh conditions (high temperature and high plasma power) or specific substrate materials. Here, we report a plasma-enhanced sequential infiltration synthesis (PE SIS) as a new platform toward deposition of nanoporous inorganic films. PE SIS is based on oxygen-plasma-induced rapid conversion of metal precursors selectively adsorbed in a block-copolymer template. Porosity and thickness of resulting materials can be easily controlled by characteristics of the template. PE SIS is conducted under gentle conditions, and can be applied to a broad range of substrates, including water-sensitive surfaces. PE SIS offers adventurous rapid infiltration with improved ability to obtain highly interconnected porous alumina films with thicknesses up to 5 μm. We show that full infiltration of the polar domain of the polymer template can be achieved upon initial exposure to TMA, followed by its oxygen-plasma-induced conversion into a functional material. Since different types of plasma (such as oxygen, nitrogen, hydrogen, etc.) induce conversion of a broad range of metal precursors, PE SIS opens a new approach for synthesis of highly porous materials with various elemental compositions and stoichiometries.