Characteristic ratio Polyacrylics

For another synthetic ( conventional") vinyl polyelectrolyte, sodium polyacrylate, Takahashi and Nagasawa (42) have measured the intrinsic viscosity of a number of fractions under G conditions (1.056 N NaBr at 15° C) and report 11.0 as the characteristic ratio value of that polymer [using the value 0 — 2.87 10 for the universal parameter in equation (1)]. Both the polyvinylsulfonate and polyacrylate samples used by Eisenberg and Woodside and by Takahashi and Nagasawa were however of the conventional type, and thus composed of chains of unknown tacticity. This fact makes it more difficult to compare the experimental values with those dedudble from theories based on... 

The unperturbed average dimensions of polyacrylate chains would thus be only slightly dependent upon ionic strength, the characteristic ratio, value at 15° ranging from about 11 to 13 going from... 

The characteristic complex composition corresponds to the ratio 2 COOH-groups 1 amine molecule which does not depend on the structure of the amine residue. As it is shown in (75) with low molecular dicarboxylic acids - malonic (MA) and glutaric (GA) the main reason for non stoichiometrical complex composition is the formation of intramolecular H-bonds. MA forms stable intramolecular H-bonds whereas GA is not able to form them but at the same time it is the best structure model for the section of the polyacrylic acid chain between two carboxylic groups. The analysis of IR spectra shows that MA forms characteristic complexes of the same composition as PAA does whereas both COOH groups in GA can react giving either or 2 1 and 1 1 complexes. 

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