EPR Spin Probe Study of Molecular Mobility and Structure of Aqueous Solutions and Gels of Polydiphenylenesulfophthalide

• Published in: Applied magnetic resonance 2015-12, Vol.46 (12), p.1409-1420
• Main Authors: Wasserman, L. A., Barashkova, I. I., Vasil’ev, V. G., Papkov, V. S., Salazkin, S. N., Wasserman, A. M.
• Format: Article
• Language: English
• Subjects: Aggregates; Aqueous solutions; Atoms and Molecules in Strong Fields; Electron paramagnetic resonance; Ethanol; Gels; Hemodialysis; Hydrophobicity; Hydroxides; Investigations; Laser Matter Interaction; Molecular structure; Nanoparticles; Organic Chemistry; Photon correlation spectroscopy; Physical Chemistry; Physics; Physics and Astronomy; Polymers; Polystyrene resins; Resonance scattering; Salt; Solid State Physics; Spectroscopy/Spectrometry; Spectrum analysis
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-015-0702-3

The sizes and local mobility of nano-sized aggregates formed in aqueous solutions of polydiphenylenesulfophthalide before and after its treatment with alkali metal hydroxides were determined by the method of electron paramagnetic resonance (EPR) spectroscopy and the method of dynamic light scattering. Nano-aggregates possess a dense hydrophobic core whose local mobility is commensurable with the local mobility of solid polystyrene. The solubility of these aggregates is explained by the presence of hydrophilic groups (lyophilizing corona) in their outer layer. The hydrophobic core of nano-aggregates is not uniform; it contains a significant amount of less ordered (“defect”) regions. This is confirmed by the superposition of EPR spectra of spin probes. Dense non-uniform structures of aggregates are formed in diluted solutions and maintain their integrity during gel formation as the concentration of solution increases.