Complexation of cellulose nanocrystals and amine monomer for improved interfacial polymerization of nanofiltration membrane

Thin film composite (TFC) polyamide membranes prepared by the interfacial polymerization (IP) of reactive monomers are widely utilized for desalination. However, the trade-off between the permeability and selectivity of TFC membranes limits further improvements in separation performance. In this study, the complexation of amine monomers with cellulose nanocrystals (CNC) and subsequent deposition on a substrate for the IP reaction was employed to modify the polymerization process and the resulting interlayered-thin film nanocomposite (iTFN) membrane structure. This method can optimize the amine loading and distribution for the IP reaction, and CNC with favorable functional groups can limit the release and diffusion behavior of the amine monomer, resulting in a crumpled membrane structure with a retained continuous polymer network. The optimized membrane had a three-fold higher water permeance than the pristine membrane without compromising salt rejection performance. This study provides a strategy for regulating the monomer distribution and reaction at the IP interface for improved performance.