title: Anisotropic wettability on imprinted hierarchical structures.
abstract: 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 degrees to 54 degrees and PS having an anisotropic wettability from 8 degrees to 32 degrees. At the same time, the water contact angle of PMMA and PS can be tuned to nearly 120 degrees 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.
authors.affiliation: Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602.
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Zhang
authors.forename: Hong Yee
authors.initials: HY
authors.lastname: Low