Chitosan strongly interacts with sulfated surfactants, forming water- insoluble and structured complexes over a wide range of concentrations and mixing ratios [67,69,76,101,102] (see Fig. 3). The interaction with so- dium dodecyl sulfate was investigated in detail, as it represents a model system for chitosan/anionic surfactants. Its binding is a cooperative pro- cess, with the Satake–Yang model (Eq. (1)) being a good approximation of the adsorption process. Wei and Hudson systematically investigated the effect of the degree of acetylation of chitosan (Mw = 190–400 kDa, DA = 0.08–0.24) on the interactions with SDS at pH = 4.2 [38]. From the description of the binding isotherms with the Satake–Yang model (Eq. (1)) the authors concluded that an increase in DA decreases the cooperativity of the binding process, as a consequence of the increased spacing among the surfactant tails. The increase in DA does not affect the non-cooperative binding constant, i.e., the vertical surfactant/ glucosammonium interaction. Furthermore, the authors found that an increase in ionic strength decreases the binding constant K but not the cooperativity of the process. This indicates the electrostatic nature of the vertical interaction and the hydrophobic origin of the cooperativity. The same results were confirmed by calorimetric and potentiometric
Chitosan strongly interacts with sulfated surfactants, forming water- insoluble and structured complexes over a wide range of concentrations and mixing ratios [67,69,76,101,102] (see Fig. 3). The interaction with so- dium dodecyl sulfate was investigated in detail, as it represents a model system for chitosan/anionic surfactants. Its binding is a cooperative pro- cess, with the Satake–Yang model (Eq. (1)) being a good approximation of the adsorption process. Wei and Hudson systematically investigated the effect of the degree of acetylation of chitosan (Mw = 190–400 kDa, DA = 0.08–0.24) on the interactions with SDS at pH = 4.2 [38]. From the description of the binding isotherms with the Satake–Yang model (Eq. (1)) the authors concluded that an increase in DA decreases the cooperativity of the binding process, as a consequence of the increased spacing among the surfactant tails. The increase in DA does not affect the non-cooperative binding constant, i.e., the vertical surfactant/ glucosammonium interaction. Furthermore, the authors found that an increase in ionic strength decreases the binding constant K but not the cooperativity of the process. This indicates the electrostatic nature of the vertical interaction and the hydrophobic origin of the cooperativity. The same results were confirmed by calorimetric and potentiometric
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