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Dielectric spectroscopic characterization of a weak‐acid polystyrene colloid
Author(s) -
Su Lao Sou,
Jayasuriya Sunil,
Fitch Robert M.
Publication year - 1993
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990300214
Subject(s) - counterion , colloid , dielectric , polystyrene , surface charge , ionic strength , analytical chemistry (journal) , charge density , dielectric spectroscopy , phase (matter) , materials science , chemistry , ionic bonding , relaxation (psychology) , aqueous solution , chemical physics , ion , chromatography , polymer , organic chemistry , social psychology , psychology , physics , optoelectronics , quantum mechanics , electrode , electrochemistry
A commercially available aqueous polystyrene colloid with surface ‐COOH groups was purified by exhaustive dialysis. This was then investigated for dielectric frequency response in the low frequency domain (0.01‐100 Hz), as a function of pH, ionic strength and the chemical nature of the counterions in the electrical double layer. In previous work on strong‐acid (sulfonate) colloids it had been shown that a plot of the imaginary part of the complex impedance as a function of the real part gave semicircles whose radii were a direct function of the surface charge density. In this work, surface charge is a function of pH. The degree of counterion binding was a function of hydrated ion size, as determined from an analysis of titration data and ionic strength of the continuous phase, which in turn was determined from the phase angle and the characteristic relaxation frequency. Dielectric spectroscopy is thus a powerful non‐invasive tool for quantitative analysis of the properties of the electrical double layer in these systems.