Scientists develop 3D nanomaterial

University of Arkansas chemists announced on Tuesday that they have made nanomaterials accessible as three-dimensional forms by making paper out of titanium oxide nanowires.

The nanopaper can be used as a filter and can withstand heat up to 700°C. It can also be folded by hand, cut with scissors and formed into 3D objects.

While two-dimensional freestanding membranes of nanowires have been available, the scientists said their 3D rendering of thermally stable nanomaterial is a chemistry breakthrough. It will open up the field of nanotechnology to more applications, they added.

The ability to cast the nanopaper into 3D forms will allow the nanomaterial to be used in protective masks and armour, flame-retardant fabric, drug-release capsules and regenerating tissue, the researchers said. The nanopaper could eventually be used to filter bacteria and prevent the spread of pathogens. The application would be similar to the nanowire bar-code system for detecting anthrax.

The researchers also proved the material's use as a low-cost nontoxic photocatalyst — a substance that can regenerate its chemical composition after exposure to light. They did this by comparing the paper's write-erase capability against regular printing paper. A 15-minute exposure to UV irradiation made the water-based ink "disappear".

The nanopaper, while obviously more sophisticated in chemical nature, is actually made from pulp, as is wood-based paper. The scientists figured out a way to make the nanomaterial less brittle and more pliable by playing with "the ratio of water to nanowires in the pulp and the time for drying the nanowire pulp", according to their research paper. The pulp they refer to is made of long nanowires created out of titanium oxide using a hydrothermal heating process.

Details of the nanopaper's development and potential applications appear in a Journal of Physical Chemistry B August article, as well as in an abstract on the University of Arkansas Web site.

The university has applied for a patent on the process and is hoping to license the technology to the commercial industry, according to a University of Arkansas statement.