Preparation method of biopolymer surfactant

The invention discloses a preparation method of a biopolymer surfactant, and belongs to the technical field of bioengineering. The biopolymer surfactant disclosed by the invention is prepared by performing esterification reaction on biopolymer oil-displacing agent sphingosine glue WL with different molecular weights and octenyl succinic anhydride (OSA) according to different proportions, and the polymer surfactant not only has the viscosity of a polymer, but also has the surface activity of the surfactant; the effect that one agent has two purposes can be achieved. A series of polymer surfactant samples with different properties are prepared according to the method, compared with sphingosine gel WL, the viscosity of each sample is improved to different degrees, and compared with sphingosine gel WL2, the viscosity of WL2-OSA-1 is improved by 103.98%; when the concentration is 1mg/mL, the viscosity of the WL1-OSA-1 polymer surfactant can reach 27.59 mPa.s, and the emulsifying activity reaches 18.52 m < 2 >/g; t