▎ 摘　　要

NOVELTY - Graphite powder is added to round bottom flask, concentrated sulfuric acid, potassium permanganate and sodium nitrate are added, hydrogen peroxide is added, and stirred, to obtain pure graphene oxide. The obtained product, refined starch and cellulose are added to caprolactam acid ionic liquid, mixed, polylactic acid dissolved in chloroform is added, and cast, to obtain composite film (f1). The resultant product is immersed in polyethyleneimine solution, dried, resultant film is immersed in graphene oxide suspension, and dried, to obtain graphene-based biodegradable composite film. USE - Preparation of graphene-based biodegradable composite film used in garden field. ADVANTAGE - The method enables preparation of graphene-based biodegradable composite film having excellent mechanical property, thermal stability and biocompatibility. DETAILED DESCRIPTION - 1-5 g Graphite powder is added to a round bottom flask, 98% concentrated sulfuric acid, potassium permanganate and sodium nitrate are sequentially added, ice-cooled, heat-preserved for 4-6 hours, heated to room temperature, stirred for 2 hours, deionized water is added, heated to 60-80 degrees C, stirred for 2 hours, hydrogen peroxide is added, stirred at room temperature for 24 hours, centrifuged, and washed with dilute hydrochloric acid and deionized water 2-3 times, to obtain pure graphene oxide. The obtained product is added to deionized water, and ultrasonically processed for 5-8 hours, to obtain graphene oxide suspension with concentration of 1.5 mg/ml. 10-20 Pts. wt. refined starch, 20-30 pts. wt. cellulose and 5-10 pts. wt. graphene oxide suspension are added to 50-100 pts. wt. caprolactam acid ionic liquid, and stirred at 60-70 degrees C for 1-3 hours, to obtain solution (A). 30-40 Pts. wt. polylactic acid dissolved in chloroform is added to resultant solution (A), and stirred, to obtain mixed solution (B). The mixed solution (B) is poured into a mold, cast for 16 hours, dried in an oven at 30-50 degrees C for 12-72 hours, and cooled to room temperature, to obtain composite film (f1). The obtained film is washed with solution of ethanol/water in a volume ratio of 1:5, and then with deionized water, the resultant product is immersed in polyethyleneimine solution for 1-2 hours, dried, treated with 5% dilute hydrochloric acid and deionized water, and dried, to obtain pretreated composite film (f1). The resultant film is immersed in graphene oxide suspension for 10-30 minutes, dried at room temperature, washed with deionized water, dried, immersed in 1 mg/ml solution of polyethyleneimine for 10-30 minutes, dried at room temperature, washed with deionized water, and dried, to obtain graphene-based biodegradable composite film.