|I will be attending the Discovery Channel Young
Scientist Challenge in Washington, DC from
October 14-20 as one of 40 students chosen
nationally to compete for over $100,000 in
prizes. In preparation for a number of science
challenges that I will be participating in, one
of the skills that I need to possess is to be
able to separate polymers of differing densities.
Despite researching online, in books, with
teachers, I have been unable to find a specific
method to be able to do so. Again, my question
is regarding separating polymers of differing
I don't think fractional precipitation will
separate polymers of different densities.
However, density gradient columns can do
this....such columns exist for common polymers
such as polyester,probably for other polymers as well.
One way to distinguish between water soluble
polymers of different densities is to place them
on a test tube that contains a discontinuous
sucrose density gradient which is prepared by
layering successive decreasing sucrose density
solutions upon one another. The polymer sample is
then placed at the top of the tube and
centrifuged. Each polymer will go to the sucrose
layer that best matches its density.
principle a similar method could be applied to
polymers that are non water soluble by using a
gradient of organic solvents
for separation of water soluble charged polymers
by their molecular weight is gel electrophoresis.
Here a mixture of polymers is placed on a gel and
an electric current is applied. Low molecular
weight move faster through the gel than high
molecular weight polymers.
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