Influence of polymolecularity on the second virial coefficient of polymers, 2

Scaling theory is applied to derive expressions describing the influence of polymolecularity on the second virial coefficient, A 2 , as obtained from osmotic pressure and light scattering measurements. Numerical values of polymolecularity correction factors are calculated for Schulz-Zimm and logarithmic normal distributions of the molecular weight, different qualities of the solvent and several ratios of the weight-average and the number-average molecular weights R w /R n . It is found that in the equation A 2 = K A2 .M av aA the weight-average molecular weight is a good approximation for M av if A 2 is measured via light scattering, while the number-average molecular weight can be inserted for M av if A 2 stems from osmotic pressure measurements.