Technology to mimic the color of ‘Queen of the Night’ tulip petals

- Professor Chang-Soo Han of Korea University innovatively realizes the feeling of the color

▲ Glossy and iridescent artificial tulip (micro/nanopattern structures shown in the box on the left bottom).

Queen of the Night is the name of a tulip that has a blackish purple color with glossy and iridescent petals. With its unique color, Queen of the Night has fascinated many artists and tulip-lovers.

A newly developed technology that mimics the color of this tulip is now attracting people’s attention.

Professor Chang-Soo Han of the Department of Mechanical Engineering, Korea University, and his research group have successfully fabricated artificial Queen of the Night tulip petals by preparing a surface featuring unique optical effects by using nanotechnology and applying a dye and micro/nano-patterns to a plastic material.

The natural surfaces of various petals have hierarchical structures, which provide optical effects. A structural color refers to a chromatic color that is dependent upon the structure of an object rather than the actual color of the object itself.

The surfaces of Queen of the Night tulip petals have a hierarchical structure of nano-sized line patterns superimposed on micro-sized line patterns. The resulting surface is glossy and iridescent because of the complex combined effects of light interference, diffraction and scattering. These optical properties attract pollen mediators, such as honey bees, to pollinate the plants.

The micro/nano composite hierarchical structure was fabricated through two processes. To realize the structural color, the research group formed nano-sized line patterns on a polymer substrate surface through soft lithography. Micro-sized patterns were formed after extending the substrate and performing a surface treatment.

The process technology developed by the research group allows control of the period and height of both the nano-sized patterns and the micro-sized patterns. Also remarkable is that the technology allows the surfaces to be fabricated at a low cost and within a short time.

The structural colored polymer film developed by the research group retains its optical properties even in the presence of various motions, including bending, pressing and extending, and thus is appropriate for use as the outermost film of a curved surface.

The result of the present study may open a new market for the film industry by providing glossy and iridescent films that give a luster and color generally unattainable with conventional dye-colored films.

▲ Photograph of tulip’s structural color and magnified petal surface

Professor Han explained the significance of the research, “The present study realized a structural-colored film that exceeds the conventional feeling of color through epoch-making micro/nano composite structure patterning technology. This technology’s expected applications include varied fields, such as smart films, small electronic devices, interior design, and surface painting.”

The result of the present study, supported by the National Research Foundation of Korea, was recently published online in the journal ACS Applied Materials & Interfaces.

- Title of Article: Iridescent and Glossy Effect on Polymer Surface Using Micro-/Nano-hierarchical Structure: Artificial Queen of the Night Tulip Petals

- Authors: Jun Ho Oh (first co-author, Ph. D candidate of Korea University), Ju Yeon Woo (co-author, Professor of Korea University), Sunghwan Jo (co-author, Ph. D candidate of Korea University) and Chang-Soo Han (corresponding author, Professor of Korea University)