# Postfunctionalization of PAN Membranes via UV-Grafting of Charged and Zwitterionic Polymer Brushes

## TL;DR

This paper introduces a UV-grafting method to improve PAN membranes for water purification by reducing fouling and enhancing dye adsorption.

## Contribution

A sustainable UV-grafting process is developed to modify PAN membranes with charged and zwitterionic polymer brushes.

## Key findings

- Modified membranes showed improved fouling resistance and dye adsorption capabilities.
- Some grafted polymers exhibited antibacterial properties according to microbiological tests.
- Characterization techniques confirmed successful surface modification and functionalization.

## Abstract

Polyacrylonitrile (PAN) membranes are widely used for
water purification,
but their susceptibility to fouling limits efficiency and lifespan.
In this study, a sustainable and efficient UV-grafting process was
employed to modify PAN membranes. Cationic and zwitterionic vinylbenzene-
and methacrylate-based monomers, including ammonium, ammonium alcohol, N-oxide, carboxybetaine, sulfobetaine, and phosphobetaine
groups, were used to graft polymers from the membrane surface using
photoinitiators such as phenylbis­(2,4,6-trimethylbenzoyl)­phosphine
oxide (BAPO) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate
(LAP). The modified membranes were characterized using FTIR, SEM-EDX,
AFM, ζ potential analysis, permeability testing, molecular weight
cutoff measurements, dye adsorption assays, porosity, and pore size
analysis. Microbiological evaluation following a modified ASTM E2149-20
protocol revealed antibacterial properties for some of the grafted
polymers. These findings demonstrate the potential of postfunctionalized
PAN membranes for the adsorption of dyes and to mitigate fouling,
both are important factors for water treatment.