Polyelectrolyte complexes. V. Solid-state properties of some polycation/azo dye complexes controlled by the dye structure

Abstract

The solid-state properties of some polycation/azo dye complexes according to the dye structure were studied in this work. One polycation contained about 95 mol % N,N-dimethyl-2-hydroxypropyleneammonium chloride units in the backbone (PCA5), and eight azo dyes, different in either the number of sulfonic groups or their distribution, were used as opposite components. The selected azo dyes were as Crystal Scarlet, Congo Red, Crocein Scarlet MOO, Ponceau SS, Amaranth, Ponceau S, Direct Blue 1, and Direct Red 80. Information on the compensation degree of the oppositely charges was obtained by the elemental analysis of the solid-state polycation/dye complexes (the experimental contents of chlorine, nitrogen, and sulfur were compared with the calculated values). Differential scanning calorimetry was employed to probe the strength of the intermolecular interactions in the PCA5/dye complexes. Wide-angle X-ray diffraction was used to assess the supramolecular order of the solid-state complexes. The physical properties of the PCA5/azo dye complexes (the complex stoichiometry, glass-transition temperature, decomposition temperature, and degree of supramolecular order) were influenced mainly by the dye structure but also by the polycation concentration and the presence of NaCl. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 264–272, 2003