Monodispersed phenyl-capped tetraaniline was added to the poly(amic acid) at different ratio, then the mixture was mixed with ultrasonic for 15h .

• （2）将苯封端苯胺四聚体以不同比例混入聚酰胺酸中，超声15h混匀，再将混合物刮到玻璃板上，然后逐段升温得到梯度膜。