Mixed monolayers of poly (ε-caprolactone) grafting O-sulfonated chitosan with cholesterol

O-sulfonated chitosan-graft-poly(e-caprolactone)(HSCS-g-PCL)was synthesiz-ed and the structure of it was characterized by FT-IR,1 H NMR and EA.The properties of mixed monolayers of HSCS-g-PCL and cholesterol were studied.Experimental results indicated that when cholesterol was added,theπ-A isotherms of the HSCS-g-PCL monolayer turned from expand type into condensation type and had obvious LE-LC phase transition.As the cholesterol molar ratio increased,collapse pressure and the limiting molecular area of mixed monolayers decreased,meanwhile maximum compression modulus increased.The value ofΔGexcchanged from an repulsive interaction to an attractive interaction between HSCS-g-PCL and cholesterol with a critical point when cholesterol molar ration was 0.6.When molar ratio of cholesterol was 0.8,ΔGexcof mixed monolayers was minimum and the mixed monolayer was the most stable.