This morning, for instance, I had a request from someone looking for help with dissolving polyethylene oxide (PEO) in ethanol. I've dissolved it in water plenty of times, but that can actually be difficult because PEO is readily soluble in water at room temperature. Unless you are adding at an extremely slow rate, it will clump up and form "snots" that will never disperse. But if you adjust the temperature, either by adding ice to the water, or by boiling the water (actually 90 oC is hot enough), you can dump the PEO pretty quickly. Then let it warm/cool to room temp and away you go. The ice slows down the dissolution rate which prevents clumping, while the hot water is actually not capable of dissolving the PEO - it is merely getting dispersed quite well - so that upon cooling you have a clump free solution.
But back to the literature. I had no idea if the same tricks could work with ethanol, so I googled "PEO ethanol solubility" and this was at the top of the results. From the abstract, the paper looked spot on, but as expected, it was behind the dreaded pay-per-view firewall.
But I didn't let that stop me. I copied the article title into the Google Scholar search bar and - oh happy day - saw this:
Why go through a firewall when you can quickly do an end run?
I passed all of this onto the requester in short order. And in case you are curious, it appears that the heat dissolution technique will work in ethanol, but when the solution cools the polymer starts to crystallize out creating a paste. That's all the more I'll say at this point, in order to respect the privacy of the requester.
(All of this reminds me that I need to update the "Free Access to Research in the Polymer Literature" page that you can access on the left hand side of the blog.)
1 comment:
pay-per-view firewall... :-P
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