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An investigation of the radial distribution of the counterions of a synthetic rodlike polyelectrolyte in aqueous solution is presented. The cationic polyelectrolyte used here has a poly(p-phenylene) backbone. For typical molecular weights the macroion comprises approximately one persistence length (ca. 20 nm) and effects of finite stiffness may be disregarded. Each repeating unit bears four charges which leads to a charge parameter of xi = 6.65. The distribution of the iodide counterions around this highly charged macroion is studied by small-angle X-ray scattering (SAXS) in dilute aqueous solution. These investigations are supplemented by measurements using anomalous small-angle X-ray scattering (ASAXS) that furnishes additional information about the contrast of the macroion. Data taken at high scattering angles give indication for contributions caused by the longitudinal fluctuations of the counterions. After correction for this effect the experimental results are compared to intensities calculated by use of the Poisson-Boltzmann (PB)-cell model. It is found that the PB-cell model describes the corrected data at intermediate and high scattering angles. Deviations at low scattering angle are attributed to the mutual interaction of the rod-like polyelectrolyte that can be described in terms of an effective structure factor. Data taken at lowest scattering angles point to a weak attraction between the rod-like macroions.

We present a study of the clustering counterion of iodine counterions around a cationic rodlike polyelectrolyte in aqueous solution. The novel synthetic polyelectrolyte used here has a poly( p -phenylene) backbone and can be considered as rodlike in good approximation. The correlation of the counterions with the macroion in aqueous solution is determined by small-angle x-ray scattering which is mainly sensitive to the I¯ counterions. The measured intensities agree with the prediction of the Poisson-Boltzmann cell model if radius of the macroion is treated as an adjustable parameter. The small value of radius of the macroion found here shows that the cell model underestimates the correlation of the counterions to the macroion.

Lignin is an abundant polyphenol biopolymeric material chemically functionalisable to act as flame retardant in polymers.

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