Interfacial Polymerization at a Nonaqueous Acid Interface for the Fabrication of Structurally Unusual Polymer Thin Films

Interfacial polymerization represents one of the most widely employed methods for fabricating polymeric thin films and membranes. However, conventional approaches are largely restricted to water-compatible reactions occurring at the interface between aqueous and organic phases. To address this limitation and expand the chemical versatility of interfacial polymerization, we introduce a method to synthesize polymer thin films at the interface of a nonaqueous acid, facilitated by anionic surfactants. The selective interfacial polymerization results from the elevated monomer concentration at the interfacial region, driven by electrostatic interactions between interfacially adsorbed anionic surfactants and protonated, positively charged monomers. Various acid-promoted reactions, such as ether condensation, phenol condensation, aldol cyclotrimerization, and imidazole condensation were tested and validated using this method. A wide variety of monomers, such as polyols, polyphenols, acetyl-functionalized aromatics, and the combination of aromatic 1,2-disubstituted amines and dianhydrides were successfully converted into unconventional thin films at the acid interface. Thin film composite membranes were also fabricated using this method and exerted good performance and durability in organic solvent nanofiltration.