Problems Dissolving PEO

[Will Edmonds]

Based on a paper I read, I am trying to create model viscoelastic fluids by
dissolving polyethylene oxide (Mw = 2M) in aqueous solutions of polyethylene
glycol (Mw = 8000). The weight percent of PEG in the solvent is 37.5 and
the weight percent of PEO I am trying to achieve is 0.2. The PEG will
readily dissolve in the water, but when I add PEO very little dissolves.
The result is a cloudy suspension of undissolved polymer in the solvent,
even after days of gentle mixing. I have tried chilling the PEG solvent
before adding PEO, and I have tried heating the solvent prior to adding PEO.
Neither method has worked. I am still playing with variables, but I am
curious if anyone has any suggestions about how to resolve this issue. In
addition after about one month, the PEG in the solvent solution precipitates
resulting in another cloudy suspension. Any ideas or suggestions will be
greatly appreciated!

[John Spevacek]

Temperature is your friend. Either cool the water with ice prior to
mixing, or boil the water mix then cool.

The PEO dissolves readily in room temperature water - too readily. It
starts to swell, get sticky and the other particles stick to it making a
clumpy mess. The cold water prevents this by slowing down the
dissolution rate until all the particles are dispersed.

PEO is insoluble in water above ~ 90 C, so it's the same idea. Disperse
it first in these conditions and then let is dissolve.

The above ideas are tried and true for straight water. The PEG may force
a change, but my gut says no. The other option would be to dissolve the
PEO first in water then add the PEG.

John
--
"Writing is God's way to show you how sloppy your thinking is."

Opinions expressed herein are my own and may not represent those of my employer.

[culi...@gmail.com]

Hi
I'm trying to dissolve polyethylene glycol (3350) into water to get a gel.
But i can't get it . How do i get the gel?