Controlling the asymmetry of densified and porous hybrid coatings based on vapor sublimation and deposition

Abstract

Interface coating technology is important to render altered surface properties for materials while replacing undesired original properties. We herein introduce an asymmetric and hybrid coating comprising controlled structural and chemical properties in one coating layer synthesized in simple steps by a vapor-phase sublimation and deposition process. The synthesis of the hybrid coating is based on acknowledging that the adsorption-limited and diffusion-limited polymerization of poly (p-chloro-xylylene) is shown to vary the final coating form factor into a densified thin film and porous structure of poly (p-chloro-xylylene), respectively. The current study enables the manipulation of the two mechanisms at the solid/vapor interface by utilizing ice templates on material substrates with confined and designable configurations as well as locations, and the proposed fabrication process produces asymmetric and hybrid coatings in one transformation step from the arranged ice templates to the substrates. Demonstrations of such advanced hybrid coatings include side-by-side and/or layer-by-layer arrangement of dense/porous films of poly (p-chloro-xylylene) in horizontal and vertical layouts, as well as particulate and organized structural configurations to address the dense/porous combination, and finally, combined structural and chemical properties with define compartments in one coating layer. Most importantly, these hybrid coatings are synthesized utilizing simple mechanisms in simple steps regardless of the complication of the design of the asymmetry configuration, and the fabrication process uses environmentally-friendly water as a template together with the subsequent dry and clean vapor-phase sublimation and deposition process, in which no solvent, initiator, or catalyst is needed. The proposed hybrid coating technology is expected to attract unlimited applications across multidisciplinary fields in materials science.