Layer-by-Layer Preparation of Ormosil Nanomaterial for Amphiphobic Surfaces ^†

Surfaces with special wetting properties are still in the attention of researchers, especially due to the numerous industrial applications, for example corrosion protection materials, anti-caking, anti-soiling, separations, etc. [1]. Many methods have been developed for creating coating materials for surface modification, in order to obtain superhydrophobic or superhydrophilic properties. Obtaining surfaces that efficiently repel both polar (water) and non-polar liquids, respectively, with amphiphobic properties is another great challenge. In the present work, a simple multi-step method to produce amphiphobic coatings on cellulosic substrate is proposed, combining the layer-by-layer deposition of nanoparticles and polymeric films, with the final step of fluorination of the coatings.

Zinc oxide and silica nanoparticles were studied as nanopowders to produce the suitable roughness of the coating materials. ZnO and SiO₂ nanoparticles have been prepared by simple hydrothermal route. Tuning the reaction conditions in both cases, nanoparticles with various sizes of nanocrystallites and different shapes have been obtained. As model solid substrates commercially available paper and cotton fabric were studied. The surface of the paper and textile samples was activated by deposition of polymeric films from natural polyelectrolyte Chitosan. Further steps involve the deposition of NPs layers, followed by the deposition of a fluorosilane derivative, as main reagent to ensure hydrophobization of the surface. The obtained films were characterized by using FTIR, SEM, and colorimetric measurements.

Hybrid coatings materials were obtained with various degrees of roughness and optical properties. The samples of paper and cotton fabrics exhibited high liquid repellency to water, oily phases with lower surface tension, showing contact angles of 150° and 135°, respectively. The coatings based on SiO₂ NPs show increased transparency and produced minimum visual changes to the original surface.

On both substrates, investigated filmogenic material were deposited by the layer-by-layer technique, using polyelectrolytes and various types of nanoparticles. The micro and nanoscale 3D morphology and external coating with very low surface energy results in good amphiphobic properties, either on paper or cotton materials. The addition of hydrotalcite into polyamide should provide the nanocomposite materials with improved bulk and surface properties, which in turn, can find applications in an industry, which requires materials with high performances.