Superhydrophobic surfaces, characterized by a water contact angle of greater than 150º, have attracted considerable interest for applications in self-cleaning products and microfluidic drag reduction. However, aging-deterioration of superhydrophobicity over time is a major obstacle that hinders the practical application of artificial superhydrophobic surfaces. Here we try to fabricate a non-aging hydrophobic/superhydrophobic surface.

Super hydrophobic surfaces are processed by etching pillars on silicon wafer by lithography technique and Bosch process. These etched silicon pillars are then covered by a hydrophobic thin polymer film to make it superhydrophobic. Bell labs first fabricated and named these silicon pillars (in nanometer size) with hydrophobic coatings as “nanograss”.

These superhydrophobic surfaces age in extremely oxidative environment, water and humidity. We anticipate that to demonstrate an approach that includes suitable deposition technique and conditions that could be applied for fabrication of non-ageing hydrophobic surfaces that could then be extended to the superhydrophobic surfaces. Various characterization techniques like XPS, FTIR, SEM, and AFM are being used to study the mechanical stability and chemical robustness of the film.

Further we also study the reliability of other monolayers deposited by vapour phase deposition and supercritical fluid deposition techniques. Currently we are working on with FOTS monolayers deposited with vapour phase and chlorosilanes with supercritical fluids.

Selected Publications

• "Factors Influencing Adhesion of Fluorocarbon (FC) Thin Film on Silicon Substrate", Arun Kumar Gnanappa, Orla Slattery, Frank Peters, Cian O' Murchu, Cian O' Mathuna, J A. Taylor, Tom N. Krupenkin, Robert Fahey, Thin films 2006, Singapore 11-16 Dec 2006.
• "Factors Influencing Adhesion of Fluorocarbon (FC) Thin Film on Silicon Substrate", Arun Kumar Gnanappa, Orla Slattery, Frank Peters, Cian O' Murchu, Cian O' Mathuna, J A. Taylor, Tom N. Krupenkin, Robert Fahey, Thin Solid Films (In press)

Contacts:

Orla Slattery, Orla.slattery@tyndall.ie | Arun Kumar Gnanappa, arun.kumar@tyndall.ie