[Mitch]

Sometimes in lab there will be an interesting result that would be good for fellow scientists to know but is not worth even considering publishing. In that spirit, I bring you random science fact. In the course of experiments, it became prudent to determine whether Rhodamine B will stain an apparatus made out of PEEK (polyetheretherketone), which is a rather good chemical resistant material. I prepared a 1M Rhodamine B solution in DI water (not all Rhodamine B dissolved by the way) and spun it in an apparatus completely made out of PEEK in conjunction with my undergrad colleagues.

PEEK

PEEK's chemical structure is shown above.

Rhodamine B did appear to stain PEEK, where the PEEK had been poorly machined and there were small grooves for Rhodamine B to collect in. Cleaning with a 1M HCl solution and some intense elbow grease action cleaned the Rhodamine B off the PEEK very well. However, the crazyglue that was used to piece together some of the PEEK pieces were permanently stained and no amount of HCl seemed to be able to remove the stain.

This has been a Random Science Fact...

Mitch

[excimer]

That's interesting. Is it possible that the HCl is partially hydrolyzing the polymer and allowing the rhodamine to attack it? Or maybe it's just aromatic enough to the point where rhodamine can embed itself in nicely?

[Mitch]

I would doubt there are any chemical reactions going on between the PEEK and rhodamine B. My hypothesis is that the micro lacerations that the rhodamine embeded itself into, once filled, became too difficult for HCl to get into and solubilize the contents within. Just as cleaning under your fingernails can be difficult, even though soap shouldn't have any trouble solubilizing the dirt within.

[Goodie]

Hey Mitch,

Thanks again for writing down and sending that molecular formula for polyethertherketone.  (C19H12O3)n.  If anyone else is scouring the web for it (and it is no where to be found), here it is. 

Good luck to all!

Thanks again!!!