Oriented perylene incorporated optically anisotropic 2D silica films

Abstract

Controlling the assembly of molecules in thin films is essential for developing functional materials for sensitive and smart coatings. Highly oriented heterogeneous and optically anisotropic 2D silica films were prepared at the liquid–liquid interface using octadecylsilane and perylenesilane as starting materials. The film formation involved the organization of molecules assisted by van der Waals interactions and network formation from silica polymerization. All films were fully characterized using a wide range of instruments. Wetting behavior of the thin film was established using contact angle measurement. The octadecylsilica (O-Si) film showed a water contact angle of ∼107° on the hydrophobic side and ∼70° on the hydrophilic side. The films prepared from perylenesilane (P-Si) and mixtures of perylenesilane and octadecylsilane (PO_x-Si) through hydrolysis, were fully characterized and showed higher contact angle than the O-Si films. As expected, an increase in the concentration of octadecylsilane in PO_x-Si film led to the disruption of the π–π stacking of perylene groups, followed by changes in optical properties of the film, which were established using spectroscopic techniques. Such bifunctional anisotropic films can be used for creating interesting functional coatings on different substrates.