One step fabrication of polymeric ratchet structures of diverse tilting angles

Abstract

Asymmetric micro/nano structures in nature provide diverse multifunctional properties including directional water transport, light transmission and adhesion. Due to these intriguing features, the fabrication of an anisotropic surface has been extensively studied as a broad research area. Herein, we present a novel strategy to fabricate asymmetric ratchet-like polymeric structures with various tilting angles by using photo-polymerization and controlling light refraction. We used a prism array that allows directional light transmission through the refraction on one face of it. To construct symmetric ratchets by negating the refraction effect in a specific area, we filled the region of the array with a refractive index matching liquid. To make a ratchet structure with a higher tilting angle, we used two films of the designed prism arrays to refract twice. Furthermore, we demonstrate one step fabrication of ratchet structures with tilting angles of 0°, 24.4° and 49.7° through the combination of the refractive index matching method and double-refraction on two layers of prism arrays.