Hyperbolic Spirals as Surface Structures in Thin Layers

When thin layers of 4-chloro-3-methylphenol and a copolymer of methyl(methacrylate) and maleic acid dissolved in acetone are dried by solvent evaporation, various surface structures appear. Besides linear surface deformations that can ramify like fractals, spirals of the hyperbolic type have been found. The surface structures are due to crystallization processes and flows caused by surface tension differences. The spirals are surface elevations with grooves on both sides as shown by surface profile measurements by means of a microscope interferometer. The addition of surfactants reduces the structure formation. A large surfactant concentration prevents the structure formation.