Unwinding of ι-carrageenan double helix upon complex formation with polyethylaminophosphazene hydrochloride

• Published in: Polymer Science. Series A Vol. 51; no. 4; pp. 390 - 395
• Main Authors: Grinberg, V. Ya, Burova, T. V., Grinberg, N. V., Usov, A. I., Tur, D. R., Papkov, V. S.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.04.2009
• Subjects: Chemistry; Chemistry and Materials Science; Polymer Sciences; Solutions; Polymer Science Series; Polysaccharide; Double Helix; Polyelectrolyte Complex; Excess Heat Capacity
• ISSN: 0965-545X; 1555-6107
• DOI: 10.1134/S0965545X0904004X

The interaction of poly(ethylaminophosphazene) hydrochloride ( M SD = 3.2 × 10 5 ) with potassium ι-carrageenan ( M w = 2.2 × 10 5 ), which is a linear regular anionic polysaccharide, has been studied by high-sensitivity DSC at pH 3.8 in a 0.15 mol/l solution of KCl. The dependences of temperature, enthalpy, and the cooperativity parameter of the double helix-coil transition of polysaccharide on the concentration ratio of polyphosphazene and polysaccharide have been obtained. The presence of polyphosphazene has no effect on the temperature and cooperativity of transition, whereas the enthalpy of the transition decreases linearly with the content of polyphosphazene and turns to zero at a mass polymer-to-polysaccharide ratio of approximately 1: 1, which corresponds to the equivalent concentrations of polyphosphazene and polysaccharide with respect to charges. Our data indicate that the mixing of poly(ethylaminophosphazene) hydrochloride and potassium ι-carrageenan solutions gives rise to formation of the stoichiometric interpolyelectrolyte complex, in which the polysaccharide loses its ability to form double helix typical of ι-carrageenan in saline solution (0.15 M KCl).