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Original scientific paper

Hydrodynamic Properties of Short NaPMA in Excess Salt: a Dynamic Light Scattering Study

Sabina Haber-Pohlmeier ; ITMC, Technical University Aachen, Aachen, Germany
Andreas Pohlmeier ; ICG 4, Research Center Jülich, Jülich, Germany


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Abstract

Diffusion of short poly(methacrylic acid) (Na-PMA, M = 6600 g/mol) in aqueous solution has
been investigated by means of dynamic light scattering at different scattering angles, ionic
strengths, pH, and polymer concentrations in the pH range between 2.1 and 8.2. At pH = 2.14,
only one fast relaxation mode was observed whereas at higher pH-values a fast and a slow
mode could be determined. Whereas the slow mode is due to collective diffusion of polyelectrolyte
domains, the fast mode at a sufficiently high ionic strength (I > 0.1 mol/L) is caused by
the diffusion of single polyelectrolyte chains. From the dependence on the polymer concentration,
self-diffusion coefficients at infinite dilution, the corresponding hydrodynamic radii, and
second virial coefficients were determined and discussed. It was concluded that PMA exists as
a random coil in excess electrolyte solution in the whole pH range, although a slight stretching
was observed for pH > 4.

Keywords

poly(methacrylic acid); PMA; dynamic light scattering; DLS; diffusion; polyelectrolyte

Hrčak ID:

18667

URI

https://hrcak.srce.hr/18667

Publication date:

30.11.2007.

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