Re: [Aroid-l] lotus effect with Colocasia fallax

From: Theodore Held <oppenhauser2001 at gmail.com> on 2011.01.16 at 21:09:12(21758) David, I have no idea whether or not individual Pistia hairs are coated with some form of wax or whether the wetting by water of an individual hair is simply poor enough to provide a bridge for the droplet surface over to the next surface hair, which bridging prevents wicking of the water down into the hairy structure. This would be a good research topic: Dry some Pistia leaves and see what is extracted (meaning dissolved by some liquid, ordinarily followed by gentle drying to investigate the residual - Steve Lucas was right to insist on technical terms being defined) by solvent (hexane or toluene would be good solvent candidates for wax) and if it is indeed a waxy substance. If no one has done this I'll do it myself and report back to this forum. Another thing that might be of interest to aroiders is that the net result of Pistia hydrophobicity (which merely means its reluctance to be wetted by water, typically observed as a tendency for water on a hydrophobic surface to "bead up" into discrete droplets) is the extreme buoyancy of the species. Try to submerge one of these plants and it's almost like you are trying to submerge an air bubble. It is curious to me how insubstantial a Pistia leaf is. It looks big, but when compacted and dried there is almost nothing left. Much of the apparent volume is simply air. Ted Held +More Detroit. On Thu, Jan 13, 2011 at 7:53 AM, david bröderbauer wrote: > Hi Ted, > > Pistia is in fact a very beautiful example for a water-repellent surface. It > has to be kept in mind - as you mention - that it generates this > superhydrophobic effect with hairs (not with papillate cells like in Nelu mbo > or Colocasia) that are covered with wax. So, the term 'lotus-effect' > describes the syndrom of superhydrophobicity (which means that the contact > angle of a water droplet is at least 150°), but there are different > structures within the Araceae and other plant families, that produce this > effect. > > David Broederbauer > >> Date: Wed, 12 Jan 2011 13:04:17 -0500 >> From: oppenhauser2001@gmail.com >> To: aroid-l@www.gizmoworks.com >> Subject: Re: [Aroid-l] lotus effect with Colocasia fallax >> >> Geneviève, >> >> The lotus effect is quite common in my experience. It has been getting >> a lot of attention in the popular press lately and there are a number >> of academic studies of the phenomenon using nano materials. A Google >> search will turn up many hits. >> >> One of the best displays can be seen on the humble aroid Pistia. >> Leaves of Pistia will support quite a large water droplet with no >> wetting of the leaf surface that supports the hairs. >> >> Ted Held. >> Detroit >> >> 2011/1/11 Geneviève Ferry : >> > Dear aroiders , >> > >> > Today, three students came looking leaves Colocasia fallax to understa nd >> > the >> > phenomenon of superhydrobicity (lotus effect). >> > Do you have information on this phenomenon? >> > (Experience, etc. ....) >> > >> > Thank you for your help. >> > >> > Best wishes , >> > >> > Geneviève Ferry >> > _______________________________________________ >> > Aroid-L mailing list >> > Aroid-L@www.gizmoworks.com >> > http://www.gizmoworks.com/mailman/listinfo/aroid-l >> > >> > >> _______________________________________________ >> Aroid-L mailing list >> Aroid-L@www.gizmoworks.com >> http://www.gizmoworks.com/mailman/listinfo/aroid-l > > _______________________________________________ > Aroid-L mailing list > Aroid-L@www.gizmoworks.com > http://www.gizmoworks.com/mailman/listinfo/aroid-l > > _______________________________________________ Aroid-L mailing list Aroid-L@www.gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

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