Analysis of the expansion behavior of poly(methyl methacrylate) chains in n-butyl chloride by the scaled reduced temperature parameter

Expansion behavior of poly(methyl methacrylate) (PMMA) chains of high molecular weights dissolved in n-butyl chloride(BC) was investigated near the theta temperature (Theta=41.8 degrees C) by means of viscometry and laser light scattering. The expansion factor alpha, the universal ratio of the radius of gyration R-G to the effective hydrodynamic radius R-H, and Kraemer coefficient k(K) were analyzed in terms of the scaled reduced temperature parameter tau /tau(C), where tau=(T-Theta)/Theta, tau(C)=(Theta-T-C)/T-C, which was derived from the Flory equation for the expansion factor and the Schultz-Flory equation for the critical solution temperature T-C. The above-mentioned quantities for PMMA samples of two different molecular weights have shown the universality as the solvent power is increased, when plotted as a function of the tau/ tau(C) parameter. Especially, the R-G/R-H ratio was obtained as 1.26 at the Theta temperature, and 1.45 at tau/tau(C)=5.5. These agreed well with the values from the renormalization group theory. However the expansion factor of the intrinsic viscosity, alpha(eta)(3), was found to be rather close to alpha(H)(3), which was different from Weill's theoretical prediction of alpha(eta)(3)=alpha(S)(2) alpha(H), where alpha(S) and alpha(H) mean the expansion factors of R-G and R-H, respectively.