Influence of the linear aromatic density on methylene blue aggregation around polyanions containing sulfonate groups.

The aggregation of methylene blue around different polyelectrolytes is studied by diafiltration, UV-vis, and (1)H NMR spectroscopies. Poly(sodium acrylate-co-sodium maleate) induces the formation of higher-order aggregates, showing a typical polyelectrolyte behavior dominated by long-range electrostatic interactions with the dye which are highly dependent on the ionic strength. Poly(sodium 4-styrenesulfonate) presents a high dispersant ability of methylene blue, showing what we can call a typical polyaromatic-anion behavior characterized by the presence of short-range aromatic-aromatic interactions with the dye which are less dependent on the ionic strength. An intermediate behavior is found for the copolymers poly(sodium 4-styrenesulfonate-co-sodium maleate) at two different comonomer compositions, related to a different probability of the polymers to form and stabilize ion pairs in hydrophobic environments. Their behavior is a function of the linear aromatic density, which is related to the comonomeric structure.

Citation

Ignacio Moreno-Villoslada, César Torres-Gallegos, Rodrigo Araya-Hermosilla, Hiroyuki Nishide. Influence of the linear aromatic density on methylene blue aggregation around polyanions containing sulfonate groups. The journal of physical chemistry. B. 2010 Apr 1;114(12):4151-8

PMID: 20201505

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