Enhanced organic solvent nanofiltration of aligned Kevlar composite membrane by incorporated with amino-polystyrene nanospheres

Abstract

Kevlar aramid nanofibers (KANF) are formed by the nanoscale structure of poly (paraphenylene terephthalamide) chains and are the emerging candidate for organic solvent permeation. However, the KANF membranes have a highly ordered and compact structure with few nanofluidic channels, resulting in low-efficiency solvent transport and undesirable membrane filtration. Here, the aligned composite membranes were fabricated by assembling the amino-polystyrene nanospheres (APN) into the KANF matrix and finally obtained a series of the APN@KANF membranes. These APN disrupted the KANF chain packing and increased the fractional free volume (from 27.7 to 35.6%). The ethanol permeance of the APN@KANF membrane was six times higher than the KANF membrane and maintained its rejection performance. Experiments and molecular simulations indicated that these APN increased the pore interconnectivity, which enhanced solvent permeability and molecular sieving. In addition, these highly stable and rigid resulting APN@KANF composite membranes could be used in extreme polar aprotic and nonpolar environmental conditions. This work highlights a promising application of the APN@KANF membranes in organic solvent nanofiltration.