Background

The oleophobic–hydrophilic capabilities of surfaces are ranked according to their switching parameter, the measured difference in static contact angle of oil and water droplets resting on the surface.

Scientists at Durham University have developed a new range of solvent cast polymer coatings exhibiting the highest switching parameters of any known materials as well as exhibiting ultra-fast switching speeds.

Technology Overview

Anti-fog and self-cleaning surfaces

Smooth copolymer–fluorosurfactant complex films are found to produce optically transparent surfaces with fast switching behavior. Equilibration of high oil contact angle (hexadecane = 80°) and low water contact angle (<10°) occurs within 10 s of droplet impact . The extremely low water contact angles are highly desirable for anti-fogging applications.

Oil-water separation technologies

Due to the frequency of off-shore oil spillages and the expansion of fracking, the separation of oil and water remains an important and unmet challenge for the oil industry. The favoured option of using filters with oleophobic–hydrophilic surfaces, where the oil-based contaminants are repelled and water passes through, have so far failed to make it into widespread usage. Commercial adoption has been constrained by a series of known limitations of available film materials:

It can take several minutes for water to penetrate through a fluorinated top layer, resulting in a surface that is initially hydrophobic
Materials often exhibit an inadequate level of oil repellence
Production may involve multi-step processes, such as pulsed plasma deposition, that are unsuitable for many applications

The new surface coatings overcome these key limitations opening up a new route for rapid commercial implementation. When sprayed as a single step process on to a steel mesh we have recorded separation efficiencies exceeding 98%.

Benefits

Anti-fogging:

Extremely low contact angle
Ultra fast switching (<10s)

Oil water separation:

Higher separation efficiency (>98%)
Faster filtration of oil/water mixtures
Ultra fast switching (<10s)
One step process

Antibacterial:

Not only separates oil from water but also kills water-borne bacteria very successfully.
Kills at least 99.9% of E Coli and Staphylococcus bacteria in the water.

State of Development

Further development work has been undertaken to refine a single step application process and to optimise the technology for anti-fog and self-cleaning or oil–water separation applications. The technology is summarised in the following publications: ACS Appl. Mater. Interfaces 2014, 6, 7504−7511 and Colloids and Surfaces A 560 (2019) 352–359.

Opportunity

Durham University is seeking expressions of interest form suitably positioned industry partners to take forward the commercial development of a novel range of polymer surface coatings exhibiting significantly enhanced capabilities over currently available materials used in anti-fogging, self-cleaning surfaces and in oil and water separation.

Ultra-Fast Oleophobic–Hydrophilic Switching Surfaces

Patents

IP Status

Seeking