Thin-film composite membranes with programmable in-plane heterostructure for high degree-of-freedom performance control

Ultra-efficient membrane separation technologies are needed to reduce the cost of molecular separations. However, the two-dimensional isotropy of conventional selective membrane limits the freedom for deep optimization of separation process. In addition, the membrane separation properties, e.g. permeability, are difficult to be accurately pre-determined according to actual needs of applications, because membrane fabrication is largely empirical and lacks highly-controllable structure variable. Herein, we develop a novel thin-film composite membrane with high controllability, where two kinds of polyamides differing in structural and physicochemical properties are integrated into a unity according to pre-designed proportion and distribution, by generating heterogeneous polymerization interface with the help of inkjet printing. The separation performance of the heterostructure (HS) membranes show function relationships with the fabrication parameters (the essence is the ratio of different structures). The separation properties of every point (micron scale) of membrane can be individually managed. Thus, the HS design not only enables programmable, pre-determined membrane separation properties, but also opens the door to controlling their spatial distribution within membrane plane. Furthermore, the membrane with gradient permeability is proposed to solve the problem of flux imbalance within membrane elements, showing the great potential of the HS design in ultra-efficient membrane separation process. • A novel TFC membrane featuring in-plane heterostructure (HS) is developed. • The HS design allows fabrication of membranes with programmable, predetermined water permeance. • Independent control of separation properties anywhere within membrane plane is achieved. • TFC HS membrane with gradient permeability is proposed to solve imbalance of flux within membrane elements.