Most outdoors people would know: There’s nothing worse than keeping dry on the outside with a water proof jacket, but getting wet on the inside through sweat and condensation.
Well, the good news is that a team of researchers at Deakin University, led by Associate Professor Tong Lin, has developed a waterproof coating for fabric that allows water to travel through it in one direction only.
Associate Professor Lin says that the coated fabric, when used to make a waterproof jacket, would not only provide an effective barrier to rain from the outside, but would be able to remove sweat and condensation from the inside.
“This would have multiple applications for the military, sportswear and general leisure wear,” he said.
Dr Hongxia Wang, an Alfred Deakin Postdoctoral Fellow who is the key researcher to work on this project, explained the process:
“To get this effect, we coat polyester fabric with a sol-gel solution, using a dip coating process, leaving a layer of TiO2 and hybrid silica with hydrophobic hexadecyl and 3-thiol propyl groups easily forming through the fabric.
“One side of the fabric is then treated with strong UV radiation. The TiO2 catalyses a reaction that causes the hydrophobic groups to become hydrophilic. “
Hydrophilic, from the Greek hydros (water) and philia (bonding) refer to the physical property of a molecule that can transiently bond with water through hydrogen bonding.
Associate Professor Lin said the effect of the UV light diminishes as it passes through the fabric, creating a gradient, leaving the side that is not irradiated hydrophobic.
“Water dropped on to the hydrophobic side passes quickly through to the hydrophilic side,” he said.
“The direction can only be reversed when much extra pressure is applied.
“Previous approaches using knitting can achieve moisture-wicking fabrics, for example, layered knitted structures. The approach is only suitable for relatively thick multi-layer knitted fabrics.
“It is not suitable for single layer fabrics, nor is it suitable for the commonly used woven fabric structures like shirts. Also, wicking is a reversible phenomenon, but unidirectional water-transfer is not.”
Associate Professor Lin said the next stage of the research would involve clarifying the mechanism of water transport, as this is not yet clear.
“We do believe however, it is related to the porous morphology of the fabric, its hydrophobicity/hydrophility profile and the surface electrostatic charges,” he said.
While not ready yet for release on the commercial market, Associate Professor Lin believes it won’t be too much longer before, much to the relief of all sorts of outdoor adventurers, the new products will available to the public.