3. Results and discussion
The fabrication process of the composite film is illustrated inFig. 1 . First, MMT colloid was obtained after sonication of MMT in water,[34] then mixed with PAAS solution. The resulting glue has a brown color, and no precipitation is generated because of the interaction between them, especially the interaction of hydrogen bond. Finally, the glue was poured onto the PI film fixed by the flange ring and put into the temperature-controlled oven. At lower temperature, MMT nanosheets adhered to PAAS gradually precipitated to the bottom under the action of gravity (because of the large aspect ratio of MMT) and were well arranged in a “flat lay” manner. thermal imidization was completed to obtain the final composite film.