A new type of waterproofing and antifouling/fogging materials has been developed by Swansea University scientists in the Energy Safety Research Institute (ESRI). This material could replace the expensive and hazardous materials that are currently in use.

According to Swansea University and ESRI, this new material is non-toxic, economical and just as effective as the dangerous waterproofing and antifouling materials currently in our ecosystem. This is a new class of nanomaterials that has tunable wettability. The material can be applied onto a surface via spray- or spin-coating.

The chemical functionality of the material can change a surface from superhydrophilic (water wetting) to superhydrophobic (water-repelling). It will also add a texture to the surface that it is put on, regardless of substrate.

This is a schematic of the functionalization of the nanoparticles along with photographic images of the water droplets on spray-coated microscope slides. An environmentally friendly superhydrophobic coating to superhydrophilic coating for antifogging and antifouling according to scientists at Swansea University. (Shirin Alexander Swansea University)

Wafaa Al-Shatty, a master student at ESRI at Swansea University Bay Campus, was in charge of fabrication and testing of low to high surface energy. She synthesized aluminum oxide nanoparticles by using hydrocarbon linear and branched carboxylic acids. This demonstrates that hydrophobicity can be tuned easily, based on the chemical functionality. Her research shows that subtle changes to the organic chain can enable the control of surface wettability, roughness, surface energy and the ability of the nanoparticles to behave as surface active agents.

Hydrophobicity and hydrophilicity are reinforced by roughness. When nanoparticles with methoxy functionality show high surface energy they develop superhydrophilicity attributes. Branched hydrocarbons reduce the surface energy. Branched chains are the first defense against water, along with the roughness of the surface. These are both caused by nanoparticles. The combination of these two attributes minimizes surface contact with the water droplets. This allows the water to slide off of the surface.

A material must have a water contact angle, the angle where the surface of the water meets the material, larger than 150 degrees in order to be considered superhydrophobic. Superhydrophilic surfaces have water contact angles lower than ten degrees.

The relationship between the superhydrophobic and superhydrophilic materials and the oil stability and interfacial tension at the oil/water boundary with instructive yielding insights could benefit greater efficiency in the recovery of oil through enhanced oil recovery methods. This new material would have a wide array of uses and would take a step towards creating an eco-friendly solution in a no-so-ecofriendly industry.

The paper on this material was published in the American Chemical Society journal ACS Omega. Coauthors of this paper were Wafaa Al-Shatty, Alex Lord, Shirin Alexander and Andrew Barron.