Open sensu shaped graphene oxide and modern carbon nanomaterials in translucent hydrophobic and omniphobic surfaces – Insight into wetting mechanisms

Abstract

Thermal feathering of modern carbon nanomaterials (CNM), among them single walled carbon nanohorns (SWCNH) and carbon nanoonions (CNO), in polyethylene (PE) is applied to produce new durable, transparent hydrophobic, superhydrophobic and omniphobic surfaces. To increase SWCNH reactivity, they were converted into open sensu shaped graphene oxide (OSSGO). Next omniphobicity was introduced by fluorination. New superhydrophobic and hydrophobic translucent surfaces were deeply characterized by using spectroscopic methods, tribological analysis and contact angle (CA) measurements. Thermal feathering and fluorination by perfluorooctyl trichlorosilane (PFOTS) led to creation of grafted polysiloxanes and the attachment of fluorine-containing chains. The analysis of the Zisman plots, the adhesion tension vs. surface tension plots, CA and roll-off and hysteresis measurements results, together with Molecular Dynamics simulations, allowed to explain wetting mechanisms and the derivation on the adhesion tension vs. surface tension of liquids plots, suggesting surface freezing under the droplet as a new potential cause. Some new correlations describing the process of wetting are also discussed and explained. Fluorination creates translucent surfaces, and thus obtained materials can be used for red color filtering in self-cleaning coatings invisible for flying insects, which are a source of biological pollution of electronics that emit light in the open air at night.