[Tim]

Hi!

I would be very happy if someone could explain to me a few things regarding the
2nd virial coeffient, A2. My question concerns the determination of molar mass for large polysaccharides e.g. a starch derivative (Mw ca 10^7 g/mol) using static light scattering (MALS). Is it possible to neglect the 2nd virial coeffient in the calculations of the molar mass (based upon the experimental light scattering data) ? What would be a correct estimate of the A2-coefficient for a dilute concentration of let´s say 0.1 - 0.05 %(w/w) of such a polymer in an aqueous solution?

Thanks.

Tim.

 

[ericandrews]

Hi Tim, any luck with your problem so far ?

[ericandrews]

To get an estimate have you tried a zimm plot ? It will give you estimates of Mw, Rg & A2 with no need of other references. The slope of the the theta=0 line is equal to 2A_2/const.

Reference:
Polymer Solutions,  chapter 2 thermodynamics of polymer solutions.