Molecular weight scaling in critical polymer solutions

In this letter me address the long-standing controversy which originated fr om differences between the experimental and theoretical values of the scali ng exponent (n) for the critical amplitude xi(0) of the correlation length in polymer solutions. Using small-angle neutron scattering me examine the d ependence of xi(0) on polymer molecular weight in polystyrene-methylcyclohe xane-d(14) solutions. We find that the experimental values of n(cr) = 0.195 +/- 0.010 in the critical region of phase demixing as well as n(mf) = 0.25 5 +/- 0.009 in the mean-field domain around the Theta temperature agree wit h the predictions of scaling theory (n(cr) = 0.185, n(mf) = 0.25).