Surface Modification of Polyethersulfone Films for Improved Hydrophilicity and Reduced Solvent Use in Water‐Based Paints

Polyethersulfone (PES) is a significant thermoplastic resin in the surface coating industry due to its high heat resistance, commercial availability, and compatibility with food contact materials. However, PES requires substantial quantities of organic solvents such as N‐methyl‐2‐pyrrolidone (NMP), dimethylformamide (DMF), dichloromethane (DCM), and dimethyl sulfoxide (DMSO) in water‐based paint formulations. To improve sustainability in green chemistry, this study presents the surface modification of PES/DCM films via ultraviolet (UV)‐induced graft polymerization using acrylic acid (AAc) without an external photoinitiator. Grafting was performed under UV exposure (0–90 min), and UV–vis analysis revealed a maximum absorbance at 305 nm with no visible yellowing observed. Improved hydrophilicity was achieved, reducing the contact angle from 83° to 61°. The grafting yield ranged from 2.03% to 6.04%, with FTIR confirming successful modification via the emergence of a carbonyl peak at 1727 cm −1 , most prominent in the D5 sample. TGA analysis indicated high thermal stability with 30% residue at 700 °C, while DSC analysis of the D5 film revealed two distinct glass transition temperatures at 160 °C and 197 °C, verifying the formation of a new copolymer structure.