Estimation of unperturbed chain dimensions of macromolecules from intrinsic viscosity data

An attempt has been made to examine the applicability of the methods, proposed by KAMIDE et al. and STOCKMAYER and FIXMAN, for evaluating the unperturbed chain dimensions of macromolecules from intrinsic viscosity data. In the method of KAMIDE et al., the FLORY's K value is evaluated from the parameters Km and a in the intrinsic viscosity‐molecular weight relation (the KUHN‐MARK‐HOUWINK‐SAKURADA equation) expressed by [η] = Km · Ma, which should be established in two or more solvents for a given series of fractions of a flexible polymer. Namely, the K value can be obtained from an intercept at a = 0.5 of the plots of −log Km + log [1 + 2{(a − 0.5)−1 − 2}−1] against (a − 0.5). STOCKMAYER and FIXMAN proposed a method for evaluating the K value as an intercept at M1/2 = 0 of the [η]/M1/2 vs. M1/2 plots. The K values were calculated by using the two methods for isotactic poly(butene‐1), poly(m‐methyl styrene), poly(p‐methyl styrene), poly(p‐chloro styrene), poly(vinyl acetate), poly(2‐vinyl pyridine), poly(ethyl methacrylate), poly(tetrahydrofuran), poly(acenaphthylene), poly(hexene‐1 sulphone), polyether from bisphenol A and 4.4‐dichlorodiphenyl sulphone, poly(propylene glycol), nylon 66, poly(ethylene terephthalate), chlorinated rubber, p‐chloro styrene/methyl methacrylate copolymer, and amylose acetate. The results of analysis on the intrinsic viscosity data showed that in poor solvents the method of KAMIDE et al. gives similar K values to those obtained by the method of STOCKMAYER and FIXMAN, but in good solvents the former method gives accurate unperturbed dimensions, rather than the latter.