Abstract
The empirical coefficient B, a measure of polyelectrolyte chain stiffness
was estimated for two types of polycations: chitosans with FA (mote
fraction of N-acetyl-D-glucosamine units) ranging from 0.09 to 0.21
(determined by H-1 NMR method) and poly(diallyldimethylammonium.
chloride) (PDADMAC), in the presence of different counterions (Cl-,
Br-, NO3-, ClO4-). The method relies on the measurements of the intrinsic
viscosity, eta, of polyelectrolyte chains at different solution
ionic strength (1). Thus, the B-parameter shows the response of the
hydrodynamic volume of polyelectrolyte molecules to the salt concentration
in solution (the so-called salt tolerance) referred to the eta
at I = 0.1 M. The temperature coefficient of intrinsic viscosity
of PDADMAC and chitosan was also determined. The comparison of the
B-parameters indicates lower flexibility of chitosan than PDADMAC.
The reasons for this difference are discussed. (C) 2002 Elsevier
Science Ltd. All rights reserved.
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