Electrostatic-modulated interfacial polymerization toward ultra-permselective nanofiltration membranes

Xinda You,Ke Xiao,Hong Wu,Yafei Li,Runlai Li,Jinqiu Yuan,Runnan Zhang,Zhiming Zhang,Xu Liang,Jianliang Shen,Zhongyi Jiang

doi:10.1016/j.isci.2021.102369

Abstract

SummaryInterfacial polymerization (IP) is a platform technology for ultrathin membranes. However, most efforts in regulating the IP process have been focused on short-range H-bond interaction, often leading to low-permselective membranes. Herein, we report an electrostatic-modulated interfacial polymerization (eIP) via supercharged phosphate-rich substrates toward ultra-permselective polyamide membranes. Phytate, a natural strongly charged organophosphate, confers high-density long-range electrostatic attraction to aqueous monomers and affords tunable charge density by flexible metal-organophosphate coordination. The electrostatic attraction spatially enriches amine monomers and temporally decelerates their diffusion into organic phase to be polymerized with acyl chloride monomers, triggering membrane sealing and inhibiting membrane growth, thus generating polyamide membranes with reduced thickness and enhanced cross-linking. The optimized nearly 10-nm-thick and highly cross-linked polyamide membrane displays superior water permeance and ionic selectivity. This eIP approach is applicable to the majority of conventional IP processes and can be extended to fabricate a variety of advanced membranes from polymers, supermolecules, and organic framework materials.

Highlights

Interfacial polymerization (IP) is a platform technology for fabricating ultrathin membranes by confining chemical reactions at the immiscible biphasic interface (Wang et al, 2020)
Most efforts in regulating the IP process have been focused on shortrange H-bond interaction, often leading to low-permselective membranes
The electrostatic attraction spatially enriches amine monomers and temporally decelerates their diffusion into organic phase to be polymerized with acyl chloride monomers, triggering membrane sealing and inhibiting membrane growth, generating polyamide membranes with reduced thickness and enhanced cross-linking

Summary

Introduction

Interfacial polymerization (IP) is a platform technology for fabricating ultrathin membranes by confining chemical reactions at the immiscible biphasic interface (Wang et al, 2020). Ever thinner synthetic membrane approaching an 8-nmthick cell membrane with short mass transport pathway can harvest high permeability (Hao et al, 2018; Jiang et al, 2018; Karan et al, 2015; Li et al, 2020; Yuan et al, 2019), and sufficient cross-linking is essential for generating high permselectivity (Liang et al, 2020). The too fast polymerization reaction rate of the IP process hampers the precise structural manipulation of polyamide membranes with 10-nm-scale thickness and high cross-linking degree (Freger, 2003)

Results

Discussion

Conclusion