Researchers Develop Self-Cleaning Clothes

Ponca City, We Love You writes "Researchers at Monash University, in Australia, have found a process to coat natural fibers such as wool, silk, and hemp that will automatically remove food, grime, and even red-wine stains by coating their fibers with titanium dioxide nanocrystals, which break down food and dirt in sunlight. Titanium dioxide is a strong photocatalyst and in the presence of ultraviolet light and water vapor, it forms hydroxyl radicals, which oxidize, or decompose, organic matter. "These nanocrystals cannot decompose wool and are harmless to skin," says organic chemist and nanomaterials researcher Walid Daoud. Titanium dioxide can also destroy pathogens such as bacteria in the presence of sunlight by breaking down the cell walls of the microorganisms making self-cleaning fabrics especially useful in hospitals and other medical settings."

Re:Safe on the body, but inside the body?

[tim_darklighter]

Titanium dioxide is non-toxic. You'll just poop it out.

Re:Life span of garment?

[BytePusher]

"Titanium dioxide is a strong photocatalyst" meaning it's not used up in the process. It breaks water into an -OH and an H, which in turn clean your clothing. Basically, it'll produce bleach vapor from water vapor when sunlight is hitting it.

This might make business SCENTS and CENTS...

[davidsyes]

But, it doesn't seem to make SENSE to me...

http://www.osha.gov/SLTC/healthguidelines/titaniumdioxide/recognition.html [osha.gov]
Search down to:

HEALTH HAZARD INFORMATION

http://www.theorganicmakeupcompany.com/CA/titaniumdioxide.asp [theorganic...ompany.com]

"Titanium dioxide has a variety of uses, as it is odorless and absorbent. This mineral can be found in many products, ranging from paint to food to cosmetics. In cosmetics, it serves several purposes. It is a white pigment, an opacifier and a sunscreen. Concern has arisen from studies that have pointed to titanium dioxide as a carcinogen and photocatalyst, thus creating fear in consumers."

"The MSDS states that titanium dioxide can cause some lung fibrosis at fifty times the nuisance dust, defined by the US Department of Labor as 15 mg/m cubed (OSHA) or 10 mg/m cubed (ACGIH Threshold Limit Value). The ACGIH states that titanium dioxide is "not classifiable as a human carcinogen". Symptoms of chronic overexposure to titanium dioxide in an industrial setting, according to the MSDS, include a "slight increase in lung tumour incidence in lab rats". It also states "when titanium dioxide was fed to rats/mice in a carcinogen bioassay, it was not carcinogenic". The NIOSH declares that at 5000 mg/m cubed there was slight lung fibrosis, concluding that this substance was carcinogenic in rats."

http://www.ccohs.ca/headlines/text186.html [ccohs.ca]

OK, I know the first slam upon me will be the lack of concentration of the TiO2, the means of entry, and so on, but STILL...

Re:Two questions

[tim_darklighter]

1) Ideally no. If the coating is thick enough, light should not be able to get through and start the degradation of the fabric/dyes. This assumes that all fibers are similarly (and thus perfectly) coated. I could see cheaper coating processes leading to quicker bleaching. 2) This is similar to your first question. Only light + catalyst = degradation, so as long as the coating is uniform and thick enough to keep light from penetrating too far, it should be safe.

Headlines

[pete-classic]

Feb. '08 - Researchers Develop Self-Cleaning Clothes
June '09 - Startup "Washtec" Sells First Self-Cleaning Clothes
Oct. '09 - Old Navy, Nike, UnderArmour License Self-Cleaning Fabric Technology
Nov. '12 - Self-Cleaning Apparel Set to Overtake Ordinary Clothing Sales this Holiday
July '13 - Self-Cleaning Clothes Linked to Cancer, Impotence, Schizophrenia
Aug. '13 - Self-Cleaning Clothes Health Study Flawed
Nov. '13 - Self-Cleaning Clothes: The Killer in your Closet
Nov. '13 - SCCs do Pose Some Risk, Scientists Say
Dec. '13 - SCC Risks Exaggerated, Study Finds
Feb. '14 - Old Navy pulls SCCs from Shelves
June '14 - Newer, Safer, SCC Technology Developed

Re:self-cleaning and self-destructing?

[evanbd]

Cotton is basically cellulose, which is chemically highly inert (it's a strong structure, and it arranges itself with all the chemically interesting bits on the inside of a spiral, so the attacking chemicals have trouble getting to them). Hydroxyl radicals aren't going to be enough to attack it agressively (though they might very slowly). This will be chemically similar to (not the same as) peroxide based bleaches, which are relatively mild (especially compared to chlorine bleach).

I don't know specifically about the other fibers, but many natural fibers are chemically resistant, so I'm not surprised they say it works with wool and other things as well.

Re:This might make business SCENTS and CENTS...

[Quadraginta]

Any very fine mineral dust you inhale in large quantities -- and 5.0 grams per cubic meter is unbelievably dusty, like blowing a whole pack of chalk to smithereens in your office -- will cause the symptoms described in both the OSHA document and the more problematic document you cite from people who want to scare you into buying their (more expensive) "natural" products.

All particles with sharp edges, i.e. that come from minerals, irritate the delicate tissue lining your lungs if you inhale it. TiO2 is no different in this regard than, say, SiO2 -- plain old sand -- that you might inhale if you were around blasting or power sanding operations all day. (Google "silicosis.")

Furthermore, your lungs are built like lobster traps from the point of view of inhaled superfine particles: it's easy to get in, but very difficult to get out. This is why in the upper region of the respiratory tract, you have mucus that traps inhaled larger particles and cilia that beat constantly to flush them up and out, plus a cough reflex to expel the scum. But you can't have these things in the deep tissue of the lungs, because that surface area is needed for gas exchange.

So if you inhale very fine dust, it just stays in your lungs pretty much forever, jiggling around and rubbing on things, irritating them. Your body may decide to wall it off with scar tissue if it's irritating enough, which is the "fibrosis" mentioned. It's even possible if it's sufficiently irritating, like the very sharp particles of asbestos fibers, that it can stimulate lung cancer. For all we know, the only reason people get lung cancer in the large numbers they do is because, sooner or later, everyone's lungs fill up with irritating particles of all manner and description and the chronic irritation causes tumors. Unfortunately, the only way to eliminate the threat of inhaled fine dust completely is to never breathe without a heavy fine-filtering face mask.

Insofar as these clothes are concerned, the primary question would be: how is this very fine dust going to be generated? I mean, inhaling very fine silica (SiO2) dust is dangerous in exactly the same way, but you don't refuse to go to the beach or rock-climbing because you know the rock and sand has no reason to suddenly pulverize itself and become superfine dangerous dust. So how would fibers coated with TiO2 get pulverized and generate super fine dust? Don't say the motion of wearing the clothes, either, because you need much more force than this. Walking on the sand at the beach doesn't pulverize the sand particles and generated dangerous superfine silica dust, after all.

The Man in the White Suit

[ajm]

Ealing comedy (think Lavender Hill Mob, Lady Killers, Passport to Pimlico) from 1951. http://www.imdb.com/title/tt0044876/ [imdb.com]

Re:Totally off topic

[commodoresloat]

And here's an image of her [wikimedia.org] that's a bit more telling....

Re: Wait a cotton pickin minute?

[blueg3]

There's actually a pretty subtle distinction here. "Superbugs" are caused by the overuse or misuse of antibiotic medicines -- chemical agents that selectively kill bacteria and other germs. Less-subtle techniques, like most antiseptics, are much tougher to develop a mechanism for avoiding, so topical antiseptics like soap and bleach stand no real chance of becoming ineffective germ-killers. (They're also not selective, and so doing something like ingesting them is not feasible.) While putting antibiotics into products unnecessarily increases the risk of developing an antibiotic-resistant bacterial strain, this isn't the case for an antiseptic (like what is produced by TiO2).

Life imitates art

[ardent99]

There was a great movie about this subject made in the 50's called "The Man in the White Suit", with Alec Guinness. In the movie, a scientist invents a fabric that repels dirt and doesn't wear out. After initially being heralded as a hero, all the vested interests (pun unintended) in the world's textile and clothing industries think it will mean the end for them, and they want him dead. The movie might take on renewed relevance...

http://en.wikipedia.org/wiki/The_Man_in_the_White_Suit [wikipedia.org]
http://www.imdb.com/title/tt0044876/ [imdb.com]

Already done

[whoever57]

It was done in 1951 [imdb.com].
What's that you say, it was only a story? Perhaps it was and perhaps it predicted the outcome (not good for the inventor).

Re:self-cleaning and self-destructing?

[uberhobo_one]

No fabric is resistant to hydroxyl radicals. It's just about the most potent oxidant out there, and can make short work of cellulose. It works fast, too. In fact, there are industrial processes that utilize hydroxyl radicals to degrade the lignin in wood pulp for use in paper. Just about the only way to protect your clothes from hydroxyl radicals would be to coat them in Teflon, but then you wouldn't have to worry about stains anyway.

Re:This might make business SCENTS and CENTS...

[Anonymous Coward]

been a researcher in this very field as well, I would have to say the results are abit over-hyped at the moment. Also the toxicity of the nanoparticles so close to the body is not well understood at all as Titanium dioxide under UV can also attack cells. Hell it attacks everything organic...including the wool over time

Not really suprising

[EmbeddedJanitor]

Part of dying is to break down or "open up" the proteins or whatever in the fibres so that they can take up the dyes. If you don't do this the dye just washes off. This same process will also break down some other materials, including many stains, allowing them to be washed away.

Protein based fibres (wool, feathers, silk etc) require different treatment than plant based fibres(cotton, hemp etc) because there's a need to "open up" different types of cells.

For protein based dying (in a home/craft situation) it is common to use vinegar. Vinegar is also one of your great grandmother's go-to household cleaners.