The invention provides a
polyimide multilayer
composite membrane material as well as a preparation method and application thereof, and belongs to the technical field of
gas separation. According to the method, through
collaborative design of a functional support layer, a gradient MOF layer and an ultrathin selection layer structure, the problems of support layer pore seepage, MOF agglomeration, weak
interface bonding and the like in an existing
composite membrane material are solved. The preparation method comprises the following steps: firstly, carrying out electrostatic
spinning on a
polyamide acid glue solution, and synchronously introducing
dopamine by adopting a chemical imidization method to prepare a functionalized
polyimide fiber membrane containing hydroxyl and amino on the surface, so that the
mechanical property of a supporting layer and the MOF anchoring capability are remarkably improved; growing MOF
layers with different particle sizes on the surface of the
fiber membrane by regulating and controlling the
concentration gradient of ligand /
metal salt and the reaction time, and passivating through a
silane coupling agent after each step of growth so as to avoid heterogeneous
nucleation and construct a gradient structure; after the MOF gradient layer is subjected to Ar
plasma pretreatment to introduce hydroxyl, the ultrathin
polyamide selection layer is formed by utilizing
interfacial polymerization of
fluorine-containing
acyl chloride and a macrocyclic amine
monomer, and the ultrathin
polyamide selection layer is suitable for
gas separation work.