Fabrication of Self-Standing Inorganic-Organic Composite Films at a Miscible Interface by "Soft Spray" Technique

Membranes have extensive applications in catalysis, separation, antimicrobial activities, and sensing. However, developing a simple and environmentally friendly method for preparing membranes remains challenging. Here, we report a novel strategy for fabricating self-standing inorganic-organic composite films at the miscible liquid/liquid interface using a soft spray technique. Specifically, metal salt solutions are sprayed onto the interface between an alkaline poly(vinyl alcohol) (PVA) solution to form heterogeneous metal hydroxide/PVA composite films with PVA as the supporting substrate. The preparation method is simple, easy to manipulate, environmentally friendly, and resource-efficient. It has been extended to prepare metal phosphate/PVA, metal carbonate/PVA, and metal sulfide/PVA composite films. Notably, the copper hydroxide/PVA (Cu(OH)₂/PVA) composite films exhibit exceptional tensile strength (19.0 MPa) and remarkable antimicrobial properties (99.9%). This simple soft spray-assisted technique provides a novel approach for fabricating miscible interface composite films.