Looking for low MW sodium polystyrene sulfonate (PSS)

[Pittman]

Folks, I am looking for low MW (<20 kD) sodium polystyrene sulfonate (PSS) for coating nanoparticles. The widely availble molecular weight is 70 kD, but with this molecular weight, dialysis cannot be used for purification. The ideal MW should be less than 20 kD. I know about the suppliers of GPC standards, but these standerds are too expensive ($300 per gram), besides, we do not need highly monodisperse polymer. Ideally, we would like to simply buy it and not synthesize it as we do not have characterization capabilites. I will appreciate any suggestions. Thanks.

 

[Demon3]

This page lists "8827 Styrene Sulfonic Acid, Sodium Salt Polymer Low M.Wt. [9080-79-9] "

http://store.net-thing.net/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=Monomer&Category_Code=2

You might call them and ask how low is low. They list medium and high as well so there's some hope.

A crude trick you might try is to take the 70 000 mwt, make a concentrated (viscous) solution of it in water and then beat it to death with a high speed mixer. This breaks down the molecular weight by chopping the large chains which are too slow to get out of the way of the blade. I have done this before. Not sure if 70 000 is high enough for this to work though. You can take a gel of high mwt PEO (PEG) in water and shop the long chains down in a couple on minutes. When done you no longer have a gel but an easy flowing solution.


There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell

 

[Pittman]

I called the monomer-polymer company, their low MW PSS is 25 k, with polydispersity of 3, 250 g for 50 bucks. We may use it, the MW distribution is kind of broad. I think for now, we will buy a GPC standard and use it in our current study, although it is expensive, and in the future, we will make low MW PSS from low MW polystyrene by sulfonation. Low MW polystyrene is quite common. Thank you for your tips, I highly appreciate your input.

 

[Demon3]

Hello. Glad to have helped! If I were you I would consider buying the PS sulfonate as the price was low and then purifying it to lower the polydispersity a little. That is easily done. You just dissolve it in water and add a non solvent that's miscible with water (i.e. methanol, ethanol, acetone) and the high molecular weight fraction will precipitate first. In this way you can precipitate mwt fractions (of narrower polydispersity) and use that for your work. I believe that will be easier, cheaper and more effective than sulfonating polystyrene which is nasty chemistry and you are not sure to sulfonate every benzene unit and not always in the para position.


There is not any memory with less satisfaction than the memory of some temptation we resisted.
- James Branch Cabell