Synthesis and dielectric characterization of poly[acrylonitrile-co-acrylamide-co-(acrylic acid)] terpolymer gels

✍ Scribed by David Shiaw-Guang Hu; Yow-Shi Lin

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 558 KB
• Volume: 195
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1994.021951110

✦ Synopsis

Abstract

The acidic hydrolysis of polyacrylonitrile, stabilization and thermal gelation in mixed solvents were sequentially carried out to yield a variety of terpolymer gels made up of 58,5 to 89,4 mol‐% units of acrylonitrile, 10,2 to 39,2 mol‐% acrylamide and 0,4 to 2,3 mol‐% acrylic acid. The posthydrolysis stabilization at temperature below 0°C was shown to induce chemical conversion from acrylonitrile to acrylamide, that is more pronounced for a certain range of initial acrylamide contents than others as evidenced by the kinetic analysis using ^1^H NMR and base titration. The dielectric relaxation measurements on swollen gels show three relaxation transitions, α, β and γ in decreasing order of temperature, over −150 to 0°C. The β‐transition, due to the segmental motion of the polymer, is the least distinct of the three. The β‐ and γ‐transitions in decreasing order of temperature are associated with the cooperative motion of polar groups with water and glass transition of water, respectively, as judged from the activation energy and temperature of relaxation. The β‐relaxation was shown to be strongly influenced by the type of swelling solvent in the gel, water contents and chemical composition of the gel. Furthermore, the Cole‐Cole plots in the region of the β‐relaxation were constructed to demonstrate the role of morphology in the dielectric behaviour of hydrogels.