Easy clean plastic coatings

C&I Issue 17, 2009

A coating that needs only water to remove oil has been developed by a team at Purdue University, Indiana, US. ‘You add water, and the oil just comes right off like magic,’ said lead researcher Jeffrey Youngblood. ‘These are eco-friendly coatings – environmentally “green” in the sense that they eliminate the need for harsh detergents and solvents in settings ranging from home kitchens to industrial machine shops that must contend with heavy oil spills.’

The coatings have a bottom layer of polyethylene glycol, which attracts water, and a top layer that prevents the passage of oil, and can be applied to glass, plastics, fabrics and a wide range of other materials. Any oil on the surface of the coating can be removed by wiping with water. The coatings can also be used as antifogging coatings for windscreens and spectacles.

The solvent soluble coatings were produced by the copolymerisation of perfluorinated end-cap polyethylene glycol (f-PEG) amphiphilic macromers with a variety of comonomers. The f-PEG component has previously been shown to be stimuli-responsive, showing both oleophobic and hydrophilic behaviour, according to Youngblood. The proportion of the comonomer was varied to determine the minimum level of surface activity needed to produce the self-cleaning characteristics.

Meanwhile, another group of researchers has been examining the use of depth profile X-ray photoelectron spectroscopy to examine the performance of antireflective and antismudge coatings, applied to the screens of consumer electronics products such as mobile phones and mp3 players. Steven Carlo, from C3 Consulting, Maryland, US, said that the structure and mechanisms of these coatings, generally based on perfluoroalkyl ethers with layers of silica and aluminium, are poorly understood and this new approach could determine the composition and chemistry to facilitate the development of improved coatings.

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