Microcalorimetric evidence of hydrophobic interactions between hydrophobically modified cationic polysaccharides and surfactants of the same charge

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Guangyue Bai (Author) Other; Jose A M Catita (Author) Other; Marieta Nichifor (Author) Other; Margarida Bastos (Author) FCUP

Journal

Title: Journal of Physical Chemistry B

Vol. 111

Pages: 11453-11462

ISSN: 1520-6106

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 24 Citations

Scopus - 26 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-004-6VN

DOI: 10.1021/jp073530r

Abstract (EN): We synthesized and characterized a series of new polymers-hydrophobically modified cationic polysaccharides-based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-alkylammonium chloride groups randomly distributed along the polymer backbone. These polymers are good candidates for studying the hydrophobic effect on polymer/surfactant association. In previous papers we reported their interactions with oppositely charged surfactants. For further insight into the relative importance of the hydrophobic interaction in the association process now we studied the thermodynamics of the interaction of these hydrophobically modified polymers with surfactants of the same charge (DMRX/C(n)TAC) by isothermal titration calorimetry (ITC). In order to try to discriminate the solution behavior of these polymer/surfactant systems, we analyzed separately the interaction of unmodified dextran with ionic surfactants and the interactions between the corresponding cationic surfactants. The interaction enthalpies for DMRX/C(n)TAC systems were derived from a proposed thermodynamic model with equations that describe the polymer-surfactant interactions. The thermodynamic parameters for the DMRX/C(n)TAC aggregation process as well as surfactant micellization in the presence of the polymer were also calculated. From all the results we were able to ascertain the effect on the interactions of changing the alkyl chain length of the polyelectrolyte pendant groups or the surfactant. The importance of the polymer aggregation state on the mechanism of interaction was also addressed.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10