From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Mon May 26 2003 - 07:45:12 MDT
On Mon, 26 May 2003, Brett Paatsch wrote:
> Robert, it is my understanding that there are still some severe limits
> on the length to which nanotubes can be produced, any idea of what
> this might be at present and what the limiting factor(s) are in producing
> these to longer lengths?
It is my impression that there are now companies claiming they are
up to milli-meter (mm) lengths (whereas before I think we were talking
sub-micro-meter (mu-m) lengths. Gina might know more.
With something like 40+ companies working on the problems (growing
longer tubes, larger volumes, decreased costs) there has to be
some progress in these areas.
> Also, when it comes to nanotubes as potential hollow containers or
> short "pipes" what sorts of hollow diametres have been produced?
I believe that we are talking a range of diameters in the 10's of nm.
I'm reasonably sure that a group at Berkeley demonstrated a tube
within a tube (a structure which could be used as a molecular bearing).
> do you know offhand if say a double strand of dna could be
> contained in the hollow within a constructible nanotube?
I am reasonably certain one could package DNA within an intermediate
diameter nanotube. The diameters of the smallest nanotubes might
make things a bit tight. Now how you get the DNA *into* or out of
the tube -- that's something I think you would have to talk to
Siegfried & Roy about.
Interestingly I believe as one decreases the diameter of nanotubes
one increases the stress on the covalent bonds (i.e. they are at
angles they do not "prefer"). This is a very specific problem
for the construction of some types of nanotech "diamondoid" materials
and is discussed in Nanosystems and I think to a lesser extent
briefly in Nanomedicine. But it is *not* a new problem to organic
chemistry (Google on "synthesis of cubane",
e.g. http://www.chem.ox.ac.uk/dhtml/default.html
for example).
Robert
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