Anisotropic Wettability on Imprinted Hierarchical Structures

• Published in: Langmuir Vol. 23; no. 14; pp. 7793 - 7798
• Main Authors: Zhang, Fengxiang, Low, Hong Yee
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.07.2007
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Surface physical chemistry; Water; Lithography; Device; Methyl methacrylate polymer; Contact angle; Orientation; Surface structure; Chemistry; Wettability; Sequential; Micrometer; Styrene polymer; Liquid flow
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la700293y

A series of two-level hierarchical structures on polystyrene (PS) and poly(methyl methacrylate) (PMMA) were fabricated using sequential nanoimprinting lithography (NIL). The hierarchical structures consist of micrometer and sub-micrometer scale grating imprinted with varying orientations. Through water contact angle measurements, these surface hierarchical structures showed a wide range of anisotropic wettabilities on PMMA and PS, with PMMA having an anisotropic wettability from 6° to 54° and PS having an anisotropic wettability from 8° to 32°. At the same time, the water contact angle of PMMA and PS can be tuned to nearly 120° without modifying the surface chemistry. A tunable anisotropic wettability is beneficial for applications where controlling the direction of liquid flow is important, such as in microfluidic devices.