Hypercrosslinked Microporous Polymer Membranes from an Interfacial Friedel–Crafts Alkylation for Nanofiltration ^†

Comprehensive Summary Hypercrosslinked polymers (HCPs) from Friedel–Crafts alkylation have attracted significant attention as promising materials for adsorption and separation due to their abundant porosity, low cost, ease of preparation, and excellent stability. Here, we fabricated a series of composite membranes coated with continuous HCP layers on polyvinylidene fluoride (PVDF) film substrates, using various aromatic monomers as building blocks via an external braiding method. Different HCP structures were constructed by tuning the number of crosslinking sites on the monomers and their structural rigidity, and their effects on organic dye separation were systematically investigated. Benefiting from both physical size sieving and electrostatic effects, the prepared biphenyl‐based membranes can effectively block anionic dyes, such as methyl blue, Congo red, Eriochrome black T and methyl orange, achieving a rejection rate exceeding 99% and a water flux of up to 30.2 L·m –2 ·h –1 ·bar –1 . This study presents an efficient method to uniformly grow hypercrosslinked functional HCP layers on substrate membranes via interfacial polymerization, offering a versatile and straightforward approach to fabricating nanofiltration membranes for the treatment of organic pollutants.