Ionic Control of Aqueous Film Formation in Methacrylic Acid–Methyl Methacrylate Copolymer via Partial Deprotonation

This study presents a solvent‐free aqueous processing approach for methacrylic acid–methyl methacrylate (MAA: MMA 1:1) copolymer through controlled partial deprotonation with sodium bicarbonate. Increasing the degree of deprotonation from 2.5 to 10 mol% transformed the polymer from a coarse, poorly dispersed material into stable aqueous dispersions capable of forming continuous films. The extent of deprotonation strongly influenced particle size, film appearance, mechanical strength, gloss, and thermal behavior, confirming a direct link between ionic modification and coating performance. Enteric testing showed that low‐to‐moderate deprotonation provided the best balance between aqueous processability and acid resistance. Among the tested systems, MAA‐co‐MMA‐2.5 showed the most reliable performance, maintaining low media uptake in 0.1 M HCl and pH 4.5 buffer media while preserving rapid disintegration at pH 6.8. Pantoprazole tablets coated with the 2.5 mol% formulation showed complete acid resistance and delayed‐release comparable to commercial aqueous and solvent‐based enteric coating systems. Overall, the findings identify 2.5–3.5 mol% deprotonation as an effective formulation window for producing robust aqueous MAA: MMA enteric coatings, offering a practical and environmentally favorable alternative to conventional solvent‐based processing.