Surface characteristics of water-repellent polyelectrolyte multilayer films containing various silica contents

• Published in: Thin solid films 2009-07, Vol.517 (17), p.5001-5005
• Main Authors: Jindasuwan, S., Nimittrakoolchai, O., Sujaridworakun, P., Jinawath, S., Supothina, S.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Silica; Structure and morphology; thickness; Superhydrophobicity; Surface energy; Surface roughness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Water-repellent
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2009.03.116

Water-repellent films were dip-coated onto glass substrate by mimicking a unique surface feature of the lotus leaf by a layer-by-layer deposition of polyelectrolyte, followed by SiO 2 particle to modify surface roughness, and finally a semifluorinated silane to lower the surface energy. Two types of the SiO 2, a fine-sized Aerosil ® 200 and a coarse-sized Aeroperl ® 300/30, were employed at various contents to modify the films' surface roughness. SEM and AFM analysis revealed that the Aerosil ® 200 had more uniform deposition onto the etched polyelectrolyte layer due to its very fined size while the Aeroperl ® 300/30 had less uniform deposition due to its coarser size. In both cases, higher SiO 2 content in the films led to more surface roughness and more hydrophobicity, although the effect was not dramatic in the case of Aerosil ® 200. The films containing the Aerosil ® 200 had very high contact angles of 167–175°and very low surface energy of 0.03–0.51 mJ m − 2 , while the films containing the Aeroperl ® 300/30 had lower contact angles of 132–154°and higher surface energy of 3.07–11.29 mJ m − 2 .