Preparation of Photo-curable 3-Arm Star-shape Polyacid-based Glass-ionomers via Aqueous ATRP

A photo-curable 3-arm starshape polyacrylic acid was synthesized via aqueous atom-transfer radical polymerization (ATRP), followed by tethering with 2isocyanatoethyl methacrylate. The purified polymer was used to formulate with water, comonomer and Fuji II LC filler to form a photocurable glass-ionomer cement. Compressive strength (CS) was used for evaluation. The effects of MW, comonomer, filler powder/polymer liquid (P/L) ratio and aging on CS were investigated. All the specimens were conditioned in distilled water at 37 o C for 24 h prior to testing. Although the ATRP reaction was run at room temperature in the presence of water, it was extremely fast with significant exotherm generation and the 90 % conversion was achieved only at 10 min. The effects of MW and comonomer on CS were significant. It was found that the MBA-containing cement exhibited much higher CS than the HEMAcontaining cement due to salt-bridge contribution of the MBA. Increasing P/L ratio increased CS. In the course of aging, the novel cement showed a continuous increase in yield strength, ultimate strength and modulus in compression within 30 days, indicating that a salt-bridge formation is a gradual process for this system. Keywords—antibacterial 3-Arm star-shape polyacrylic acid; aqueous ATRP synthesis; glassionomer cement; compressive strength