Characterization of model branched polymers by multi-detector SEC in good and theta solvents

Well-defined linear and branched polystyrenes with complex architectures (regular combs and centipedes) were characterized via on-line size exclusion chromatography (SEC), in the good solvent tetrahydrofuran and the theta solvent trans-decalin, in order to measure their radii of gyration (R-g), hydrodynamic radii (R-H), and intrinsic viscosities. Various measures of the sizes of these macromolecules were plotted as a function of the retention volume (V-R) in order to examine the validity of different universal calibration strategies for SEC. Hydrodynamic-based calibration curves were found to be universal, whereas a plot of log R-g versus V-R did not yield universal curves in either solvent. These findings are consistent with previously published data for linear and branched Polymers in thermodynamically good solvents. In addition, good solvent data were used to derive values of the epsilon parameter relating radius of gyration-based and intrinsic viscosity-based chain shrinkage factors. Values of about 0.9 were found for both regular combs and centipedes.