Structure–Property Relationships in 5‐Aminosalicylic Acid‐Functionalized Poly(GMA‐co‐EGDMA) Microspheres: Porosity, Thermal Stability, and Cr(VI) Sorption

Porous poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) microspheres with tunable functionality were synthesized via suspension–emulsion polymerization and subsequently modified with 5‐aminosalicylic acid (ASA). The influence of copolymer composition (GMA:EGDMA = 1:1–5:1) on porosity, surface chemistry, and thermal properties was systematically investigated. Increasing the GMA content led to higher epoxy group density (2.87–5.02 mmol g −1 ) but a pronounced decrease in specific surface area (151–39 m 2 g −1 ), indicating a trade‐off between functionality and porosity. Post‐polymerization modification successfully introduced ASA moieties, as confirmed by FTIR spectroscopy and acid number measurements (14.0–30.9 mg KOH g −1 ), while largely preserving the mesoporous structure. Thermal analysis (TG/DTG and TG–FTIR) demonstrated enhanced thermal stability of ASA‐modified copolymers, attributed to the incorporation of aromatic functionalities and reduced content of thermally labile epoxy groups. The modified materials were evaluated as sorbents for Cr(VI) ions, showing strong pH‐dependent behavior with maximum removal efficiency under acidic conditions. The sorption capacity reached approximately 100 mg g −1 , and the uptake mechanism was governed by electrostatic interactions between protonated surface groups and anionic chromium species. These results demonstrate that ASA‐functionalized poly(GMA‐co‐EGDMA) microspheres are promising materials for selective sorption applications.