title: The interactions of ι-carrageenan with cationic surfactants in aqueous solutions.
abstract: The interactions between the anionic polymer ι-carrageenan (IC) and the cationic surfactants 1-dodecyl-3-methylimidazolium bromide (C12mimBr), dodecyltrimethylammonium bromide (DTAB) and ethyl-α,ω-bis(dodecyldimethylammonium)dibromide (12-2-12) have been studied by fluorimetry and isothermal titration calorimetry. Our experimental results showed that at a low surfactant concentration, the monomers adsorbed on the IC chains through the electrostatic attraction, followed by the formation of induced micelles on the IC chains through the hydrophobic interaction until the IC chains are saturated by surfactant molecules; after that the added surfactant formed free micelles in the solution. A pseudo-phase-equilibrium thermodynamic model was proposed to explain the experimental results and to understand the mechanisms of the interactions in these three systems. Moreover, the salt effect on the interactions was investigated and found that it changed the critical concentrations but not the interaction mechanism.
authors.affiliation: School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China. shenwg@ecust.edu.cn.
authors.forename: Tianxiang
authors.initials: T
authors.lastname: Yin
authors.forename: Miao
authors.initials: M
authors.lastname: Qin
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Peizhu
authors.initials: P
authors.lastname: Zheng
authors.forename: Dashuang
authors.initials: D
authors.lastname: Fan
authors.forename: Weiguo
authors.initials: W
authors.lastname: Shen