New fluid-repellent paper discovered
Researchers in the US have created a new type of paper that repels almost any liquid – including water and oil.
By applying a chemical coating and creating new surface patterns at the nanometre and micron scale, the Gerogia Tech team was able to reproduce the same repellent effect in the paper that is observed in the leaves of the lotus plant.
This changes the paper from an absorbent material to one which repels all fluids.
"Paper is a very heterogeneous material composed of fibres with different sizes, different lengths and a non-circular cross-section," said Dennis Hess, a professor in the Georgia Tech School of Chemical and Biomolecular Engineering. "We believe this is the first time that a superamphiphobic surface – one that repels all fluids – has been created on a flexible, traditional and heterogeneous material like paper."
According to Hess, the paper can be produced from standard softwood and hardwood fibres.
The researchers started out by breaking up cellulose fibres into even smaller structures using a mechanical grinding process. The fibres were then pressed in the presence of water before additional processing was carried out with the chemical butanol.
Butanol was added to inhibit the hydrogen bonding that normally takes place between cellulose fibres, affording the scientists better control of the spacing.
So far, the paper has only been produced in samples roughly 4in in size, but the researchers are confident that the process can be scaled up.
As well as enabling improved packaging materials, they believe it could be used as the foundation for a new generation of inexpensive biomedical diagnostics.
