Application of long chain amine activator in conventional acrylic bone cement

A long chain acid derivative bearing an aromatic tertiary amine group, 4-N,N-dimethylaminobenzyl laurate (DML), which acts as an activator for the curing of acrylic cements at low temperature, has been synthesized and characterized to reduce the biological adverse effects usually associated with the classical activator N,N-dimethyl-4-toluidine (DMT). The effectiveness of the activator was tested on commercial formulations (e.g., Palacos R) and on experimental bone cements based on poly (methyl methacrylate) by using different benzoyl peroxide/amine molar ratios. The exotherms of polymerization were followed at three different temperatures: 25, 30, and 37 degrees C. The DML activator was found to be more sensitive to temperature than the corresponding DMT. DML provided exotherms of polymerization with decreasing peak temperatures and increasing setting times without impairing the mechanical properties. Residual monomer content was analyzed in a range of activator concentrations by keeping the benzoyl peroxide concentration constant. In all cases the residual monomer content was lower than 5%, indicating its good efficiency in the benzoyl peroxide initiated polymerization.