Abstract: The interfacial activity of polymeric surfactants based on carboxy methyl cellulose with Daqing crude oil was studied by dynamic laser scattering, environmental scanning electron microscope, spinning drop interfacial tensiometer and surface tensiometer. The results show that polymeric surfactants based on CMChave same excellent surface(interfacial) activity as low molecular weight surfactants. The surface tension of 0.5% copolymer aqueous solution is 28—35 mN/m, the interfacial tension(IFT) with Daqing crude oil is 10^-1—10 mN/m. And IFTdecreases sharply after alkali is added into polymeric surfactant solutions. At the appropriate conditions, IFTof some systems reach 10^-3 mN/m. The studies on equal-alkane model show, the standpoints that the action of alkali and acid components in crude oil leads to the lowest IFTare not perfect yet. The analyses by ESEMand dynamic laser scattering indicate that the micelles of polymeric surfactants disaggregate by adding alkali into solution, which leads to decrease size of micelles. And the number of mono-molecules also goes up. These changes contribute polymeric surfactants to move to and arrange in the interface of oil/water, which is the main reason of the decreasing of IFTto the lowest value.

Key words: Polymeric surfactant, Carboxy methyl cellulose, Ultra-low interfacial tension