Enhancement of Glass Ionomer Cements Through Polycarboxylic Acid Modification with Alkylenoic Acid Spacers

This study investigated the effects of alkylenoic acid spacers (3-butenoic acid [VA], 4-pentenoic acid [PA], and 5-hexenoic acid [HA]) on the properties of modified polycarboxylic acids (PCAs) and their glass ionomer cements (GICs). Modified PCAs were synthesized with varying alkylenoic acid concentrations (4–15 mol%) and analyzed using FT-IR, 1H-NMR, gel permeation chromatography, and differential scanning calorimetry. Mechanical properties of the resulting GICs were evaluated through flexural strength (FS), flexural modulus (FM), and compressive strength (CS) tests, with microstructural analysis conducted via scanning electron microscopy. Results showed that alkylenoic acids effectively modified PCA structures while maintaining stable molecular weight distributions (PDI < 2). Increasing alkylenoic acid content reduced the glass transition temperature, with optimal mechanical properties observed at 12 mol%. PCA-VA exhibited the highest flexural strength (52.29 MPa, 23.1% increase) and flexural modulus (16.30 GPa). PA-modified GICs demonstrated superior matrix cohesion and interfacial bonding. In summary, alkylenoic acids showed potential, particularly VA at 12 mol%, to enhance GIC mechanical properties without compromising structural integrity, offering an option for developing advanced dental materials suitable for high-stress applications.