Phosphonium Modification Leads to Ultrapermeable Antibacterial Polyamide Composite Membranes with Unreduced Thickness

Abstract

Water transport rate in network membranes is inversely correlated to thickness, thus superior permeance is achievable with ultrathin membranes prepared by complicated methods circumventing nanofilm weakness and defects. Conferring ultrahigh permeance to easily prepared thicker membranes remains challenging. Here, a tetrakis(hydroxymethyl) phosphonium chloride (THPC) monomer is discovered that enables straightforward modification of polyamide composite membranes. Water permeance of the modified membrane is ≈6 times improved, give rising to permeability (permeance × thickness) one magnitude higher than state‐of‐the‐art polymer nanofiltration membranes. Meanwhile, the membrane exhibits good rejection (RNa2SO4 = 98%) and antibacterial properties under crossflow conditions. THPC modification not only improves membrane hydrophilicity, but also creates additional angstrom‐scale channels in polyamide membranes for unimpeded transport of water. This unique mechanism provides a paradigm shift in facile preparation of ultrapermeable membranes with unreduced thickness for clean water and desalination.

A facile and general method for synthesis of antibiotic-free protein-based hydrogel: Wound dressing for the eradication of drug-resistant bacteria and biofilms

“…According to a previous report [ 35 ], β-[tris(hydroxylmethyl) phosphino] propionic acid (THPP) could react with primary and secondary amines via a Mannich-type reaction to form polypeptide-based biomaterials. Owing to the similarity in structure, THPS has also been considered for Mannich-type reaction with primary and secondary amines, which have been applied to react with polyamides for antibacterial membranes formation [ 36 ]. Therefore, we speculate that amine-rich BSA was also cross-linked with THPS to form hydrogels through the Mannich-type reaction.…”

Solvation‐amination‐synergy that neutralizes interfacially polymerized membranes for ultrahigh selective nanofiltration

“…On the other hand, the content of amino groups determines the balance between amino protonation and carboxyl deprotonation. Due to the differences in their dissociation constants (pK a ), 33,49 the protonation of amino groups is harder than the dissociation of carboxyl groups under the pH range (5.8-7.3), more amino groups are thus needed to balance the dissociation of positively and negatively charged groups (Figure 2B).…”

Electrostatic-modulated interfacial polymerization toward ultra-permselective nanofiltration membranes

“…The combination of technological universality and process designability makes IP attractive for a great number of advanced membrane materials, including polymers ( Jiang et al., 2018 ; Tan et al., 2018 ), supermolecules ( Qin et al., 2017 ), metal-organic frameworks (MOFs) ( Brown et al., 2014 ; Makiura et al., 2010 ), and covalent organic frameworks (COFs) ( Dey et al., 2017 ; Hao et al., 2018 ; Khan et al., 2020 ). Thereinto, the manufacturing of polyamide nanofiltration (NF) membranes represents the large-scale application of IP technology, providing an energy-efficient and sustainable paradigm for water desalination, water softening, and ionic separation ( Peng et al., 2020 ; Werber et al., 2016 ). For a typical IP process, the porous ultrafiltration (UF) membrane is successively immersed in aqueous phase with amine monomer (piperazine, PIP) and organic phase with acyl chloride monomer (trimesoyl chloride, TMC) to form a polyamide membrane spanning tens to hundreds of nanometers thick ( You et al., 2017 ).…”