Velocity Sedimentation and Intrinsic Viscosity Analysis of Polystyrene Standards with a Wide Range of Molar Masses
-
Pavlov, George M.; Perevyazko, Igor; Schubert, Ulrich S.
- Abstract:
- Analytical ultracentrifugation is one of the key methods among the molecular hydrodynamic
methods of polymer science, biophysics, and colloid science. The aim of this work is to
demonstrate the possibilities of a modern instrument, the Beckman XLI Analytical Ultracentrifuge,
coupled with the now available software for the molecular characterization of
synthetic polymers. For this purpose the classical system polystyrene in methyl ethylketone
was investigated. The samples of low polydispersity index were studied in a 1 000-fold interval
of molar mass values. The exhaustive analysis of such hydrodynamic values as velocity
sedimentation coefficient, frictional ratio, concentration Gralen coefficient, and intrinsic
viscosity, was done. The values of partial specific volume, refractive index increment, and
hydrodynamic invariants were also determined and discussed. The estimation of the statistical
segment length (or persistent length) of polystyrene chains was made taking into
account the intrachain excluded volume and draining effects (Gray–Bloomfield–Hearst
theory). The obtained experimental data and results of its analysis allow the conclusion that
the method of velocity sedimentation, coupled
with the numerical solution of the Lamm
equation, represents a powerful absolute characterization
method for molar mass determination
of flexible polymers of low polydispersity in relatively
poor solvent.
- Year:
- 2010
- Type of Publication:
- Article
- Journal:
- Macromolecular Chemistry and Physics
- Volume:
- 211
- Pages:
- 1298 - 1310