Controlled Wetting Properties through Heterogeneous Surfaces Containing Two-level Nanofeatures
Journal
ACS Omega
Date
2017.11.15
Abstract
Addressing the direct control of surface wettability has been a significant challenge for a variety
of applications from self-cleaning surfaces to phase-change applications. The surface wettability
has been traditionally modulated by installing surface nanostructures or changing their chemistry.
Among numerous nanofabrication efforts, chemical oxidation method is considered a promising
method since it allows cost-effective, quick, and direct control of the morphologies and chemical
compositions of the grown nanofeatures. Despite the wide applicability of surface oxidation
method, the precise control of wetting behaviors through the growth of nanostructures have yet
to be addressed. Here, we investigate the wetting characteristics of heterogeneous surfaces
which contain two-level features (i.e. nanograsses and nanoflowers) with different petal shapes
and structural chemistry. The difference in growth rates between nanograsses and nanoflowers
creates time-evolving morphology that can be classified by grass-dominated or flower-dominated
regimes, which induce a wide range of water contact angles from 1100 to 200. The following study
systematically quantifies the structural details and chemistry of nanostructures associated with
the wetting characteristics. This investigation of heterogeneous surfaces will pave the way for
selective growth of copper nanostructures and thus a direct control of the surface wetting
properties for use in future copper-based thermal applications.