TechOcular

an insight into technology

Self-cleaning & stain proof coating for fabrics

Chemical scientists have devised a new and arguably better method of coating fabrics with a water-repellent, “self-cleaning” coating.

A number of “super-hydrophobic” coatings have been made before, but a report in the journal Langmuir describes coated fabrics that are far more durable than any other available today.

The trick to creating these more effective and durable coatings was to engineer a multi-layered coating whose layers, when struck with ultra-violet light, bond more firmly to each other and to cotton.

The technique may also be useful when put to use in medical antibacterial coatings.

Super-hydrophobic surfaces have fascinated scientists for years; they are behind the lotus plant’s self-cleaning leaves and the gecko’s super-dry and thus super-sticky feet.

These surfaces are practically impossible to get wet – water just beads on them and dirt and particulates do not stick to them, hence leading to being described as self-cleaning.

The new work hinges on what is known as “layer-by-layer self-assembly”, this basically means dipping a fabric into a solution over and over again to deposit multiple layers on it.

The team from the Australian Future Fibres Research and Innovation Centre at Deakin University made their solution with tiny particles of silica – the same material as sand.

Crucially, they added a few chemical steps to coat the particles with long chemical tails ending in what are known as azido groups.

The team found that layered coatings of the azido-treated nanoparticles were, like many previous attempts, not very durable – a stain-free shirt with such a coating would not survive many washes.

But baked under a source of UV light, the tails on the particles were made to interlink with one another, forming a far tougher structure within and across the layers.

“This technique is simple, but allows forming an [even] coating on irregular [materials] having a complicated surface structure, and it can precisely control the coating thickness,” said Tong Lin, lead author of the work.

Does this mean the end of endless laundry? Most likely not, however it may make our raincoats a little bit more effective in future!