Self cleaning systems

Studies on adhesion might have started a century ago, but today its coming to us in all the unusual and ‘magical’ forms seeming as though materials and their surfaces have a life of their own! Ralk Blosseys progress article in Nature starts with a quote of Oscar Wilde who once exclaimed and i quote – ‘We live , I regret to say, in an age of surfaces’. Whatever philosophical dimensions that statement had is not something i am familiar with but the only thing we could replace in that statement is ‘regret’. Today its our good fortune that we are getting so see tiles and textiles which can clean themselves (a boon to students in hostels who crib about scrubbing clothes every weekend!), all thanks to the ‘re’discovery of superhydrophobicity in lotus leaves. The only slight Indian connection is that lotus is revered as a ‘god level’ flower in hindu scriptures, and till today is worshipped in many homes, for its ability to clean itslef in the dirt of the pond in which it thrives.  Ever since studies on adhesion began, there has been confusion about whether it is a rough or smooth surface which helps maintain a system clean. Now its known that both superhydrophobocity (the act of repelling water with a contact angle exceeding 150 degress)  and its opposite effect of  superhydrophilicity (complete wetting with almost 0 degree contact angle) can help achieve the same goal, though in different circumstances.  Here’s a brilliant example of how ideas can fuel both scientific research and commercial usage at the same time! Heres a link to the article i particularly enjoyed reading: http://www.sciam.com/article.cfm?id=self-cleaning-materials

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About jayabhat

Research student, Dept of Materials Engg, IISc, Bangalore
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