There’s a new cotton fabric that will self-clean when exposed to sunlight. From the Dec. 14, 2011 news item on Nanowerk,
Mingce Long and Deyong Wu say their fabric uses a coating made from a compound of titanium dioxide, the white material used in everything from white paint to foods to sunscreen lotions. Titanium dioxide breaks down dirt and kills microbes when exposed to some types of light. It already has found uses in self-cleaning windows, kitchen and bathroom tiles, odor-free socks and other products. Self-cleaning cotton fabrics have been made in the past, the authors note, but they self-clean thoroughly only when exposed to ultraviolet rays. So they set out to develop a new cotton fabric that cleans itself when exposed to ordinary sunlight.
Their report describes cotton fabric coated with nanoparticles made from a compound of titanium dioxide and nitrogen. They show that fabric coated with the material removes an orange dye stain when exposed to sunlight. Further dispersing nanoparticles composed of silver and iodine accelerates the discoloration process. The coating remains intact after washing and drying.
It’s nice to see that the coating doesn’t wash or dry off easily. Long’s and Wu’s report appears in the ACS [American Chemical Society] Applied Materials & Interfaces (“Realizing Visible-Light-Induced Self-Cleaning Property of Cotton through Coating N-TiO2 Film and Loading AgI Particles”). Mingce Long is from the School of Environmental Science and Engineering, Shanghai Jiao Tong University, China and Deyong Wu is from the School of Chemical and Environmental Engineering, Hubei University for Nationalities, China.
Dexter Johnson of the Nanoclast blog on the IEEE website (Institute of Electrical and Electronics Engineers) notes this in his Dec. 22, 2011 posting,
… This is not just cotton treated with TiO2 but cotton treated with a mix of silver iodide (Agl) along with Nitrogen (N)-TiO2. This combination increased the photocatalytic activities of the material.
So, this is what I find so infuriating about coverage of nanotechnology. Couldn’t someone (besides me) have said that researchers had found a way of improving the photocatalytic performance of TiO2 in textiles so as to make their self-cleaning properties X times better than previous methods?
There you have it from an engineer who’s been the nanotech scene for quite some time. The concept of coating a textile with nanoscale titanium dioxide so it self-cleans is not new; the discovery in this case is a refinement which increased the photocatalytic properties of the textile in question.