Synthesis, adsorption and aggregation properties of new saccharide-cationic surfactants

A novel saccharide-cationic surfactants containing a quaternary ammonium as cation and saccharide-amide as nonion N,N-dimethyl-N-[3-(gluconamide/lactobionamide)]propyl-N-alkylammonium bromides (CnDGPB and CnDLPB, where n represents hydrocarbon chain lengths of 8, 10, 12, and 14) were designed and synthesized. Their surface activities, adsorption, and aggregation behavior in aqueous solution were investigated by surface tension, conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Surface tension measurement was used to derive surface adsorption properties such as adsorption efficiency (pC20), the (CMC/C20) ratio, maximal surface excess concentration (Γmax), and minimum surface area per molecule (Amin) at the air–water interface. From the results of temperature dependent conductivity measurements we could obtain the degree of counterion binding (β), and the thermodynamic parameters such as standard free energy ( Δ G m i c 0 ), enthalpy ( Δ H m i c 0 ), and entropy ( Δ S m i c 0 ) of aggregation. DLS and TEM analysis of C14DGPB aqueous solutions revealed the morphology of molecular self-assembles.