Self‐Assembled Nanoparticles Based Fabrication of Gecko Foot‐Hair‐Inspired Polymer Nanofibers

Abstract

Wafer‐scale polymer nanofabrillar structures have been fabricated using the combination of colloidal nanolithography, deep‐silicon etching, and nanomolding to mimic the nanostructure of gecko foot‐hairs. The artificial surface features densely packed polymeric nanofibrils with super‐hydrophobic, water‐repellent, and “easy‐to‐clean” characteristics. The lateral dimension of the nanofibrils is as small as 250 nm and an aspect‐ratio as high as 10:1 has been achieved without lateral collapse between neighboring fibrils. The method allows both fabrication of synthetic structures over a large area and direct integration of a flexible membrane to assist the array of nanofibrils in making intimate contact with uneven surfaces. A single nanofibril exhibits a mean adhesive force ranging from (0.91 ± 0.34) nN to (1.35 ± 0.37) nN. In the macroscopic scale, the nanostructured surface can adhere firmly to a smooth glass substrate and inherits the in‐use, self‐cleaning property of the setal nanostructures found in gecko lamellae.

Sliding-induced adhesion of stiff polymer microfibre arrays. I. Macroscale behaviour

“…Multiwalled carbon nanotubes (MWCNT; Zhao et al 2006;Ge et al 2007) and low aspect ratio (length/ diameterZ0.5-10) hard polymer stalks (Geim et al 2003) demonstrated tensile adhesion but they require high normal compressive preload. Kustandi et al (2007) have recently demonstrated 0.7 N cm K2 tensile adhesion with preload pressure of 1 N cm K2 using 10 : 1 aspect ratio hard polymer fibres (Ew2.8 GPa).…”

Recent advances in gecko adhesion and friction mechanisms and development of gecko-inspired dry adhesive surfaces

“…A combination of lithography and the two-step molding process is now also widely used for fabricating hierarchical fibrillar surfaces [37, 110−112]. Deep reactive ion etching [113], self-assembly [114], anodic oxidation [113], angled etching, and mechanical yielding techniques or methods [37, 115−117] have also been explored to fabricate templates of gecko-inspired dry adhesive surfaces.…”

“…A selection of materials for gecko-inspired adhesives, such as polymide [89,106], PVS [25,74], PDMS [99,106,108,126], poly(methyl methacrylate) (PMMA) [115], polyurethane [109][110]113], polystyrene (PS) [105,114], silicon rubber [127], polypropylene [128], and polyethylene has also been considered [122]. It is proposed that polyurethane with a low Young's modulus can generate strong adhesion because the polar groups contribute to the enhancement of the adhesion; thus, this material may be suitable for gecko-inspired adhesives [129].…”

Biomimetic self-cleaning surfaces: synthesis, mechanism and applications

“…Various strategies have been formulated to synthesize gecko feet-like surfaces from different materials including silicones [75], CNTs [76 -79], poly(methyl methacrylate) [80], polyurethane acrylate [81], polydimethylsiloxane (PDMS) [82] and more [83][84][85][86]. The successful fabrication of gecko-inspired functional materials requires the combination of the physical, chemical and biological principles.…”