Microwave Dielectric Study of an Oligomeric Electrolyte Gelator by Time Domain Reflectometry

• Published in: The journal of physical chemistry. B 2009-07, Vol.113 (30), p.10112-10116
• Main Authors: Kundu, Shyamal Kumar, Yagihara, Shin, Yoshida, Masaru, Shibayama, Mitsuhiro
• Format: Article
• Language: English
• Subjects: B: Macromolecules, Soft Matter; Electric Impedance; Electrolytes - chemistry; Gels; Microwaves; Polymers - chemistry; Spectrum Analysis; Time Factors; Water - chemistry
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp901043h

The dynamics of water molecules in aqueous solutions of an oligomeric electrolyte gelator, poly[pyridinium-1,4-diyliminocarbonyl-1,4-phenylene-methylene chloride] (1-Cl) was characterized by microwave dielectric measurements using the time domain reflectometry method. The dielectric dispersion and absorption curves related to the orientational motion of water molecules were described by the Cole−Cole equation. Discontinuities were observed in the concentration dependence of the dielectric relaxation strength, Δεh, as well as in the Cole−Cole parameter, βh. These discontinuities were observed between the samples with concentrations of 6 and 7 g/L 1-Cl/water, which correspond to a change in the transparency. Such a discontinuity corresponds to the observation of the critical concentration of gelation. The interaction between water and 1-Cl molecules was discussed from the τh−βh diagram. As 1-Cl carries an amide group, it could be expected that 1-Cl may interact hydrophilically with water, but the present result suggests that 1-Cl interact hydrophobically with water.