Naslov
Complexation, Vesiculation and Precipitation in Mixtures of Carrageenans and Dodecylammonium Chloride

Autori
Vinceković, Marko ; Bujan, Marija

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts / - Brno : Masaryk University, 2005, 98-98

Skup
The 2005 Younger European Chemists Conference

Mjesto i datum
Brno, Češka Republika, 31.08.2005. - 03.09.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
biopolymers; surfactants

Sažetak
Interactions in mixtures of dodecylammonium chloride and anionic polyelectrolytes have been investigated by several methods (surface tension, conductometry, light microscopy, X-ray diffraction, light scattering and microelectrophoretic measurements). Here, we compared three main carrageenan species (κ -, ι - and l-carrageenan) from the point of view of their charge under the concentration conditions from infinite dilution to the phase separation. Complex interactions starting at a very low concentration were accompanied by the formation of a variety of single and coexisting phases. In dilute concentration region differently structured soluble polyelectrolyte-surfactant complexes (PSC) and giant vesicles were found. The increase of carrageenan charge density increased the critical association concentration and reduced the free energy of micelles when bound to carrageenan chains. The electrostatic and hydrphobic interactions, conformation and flexibility of the polyelectrolyte chains and entropy gain due to released carrageenan counterions are main factors governing the soluble PSC's formation. The final size and structure of the complexes depend upon relative magnitudes of these factors. When the surfactant/polyelectrolyte attraction overcomes their solubility, associative phase separation occured. The increase of carrageenan charge shifted the phase separation region towards higher concentration of both components. The X-ray analysis of precipitated phase revealed the lamellar periodicity in mesostructural domains consisting of surfactant bilayers between polyelectrolyte backbones. The ordering of bilayers, interconnecting carrageenan chains, increased with an increase in charge density of carrageenans ; i.e., stronger electrostatic interaction with oppositely charged surfactant induced the formation of more ordered structures. Formation of giant vesicles even at lower carrageenan concentration and structural properties of precipitate revealed lamellar ordering as an important feature of investigated systems.

Izvorni jezik
Engleski

Znanstvena područja
Biotehnologija

POVEZANOST RADA