Surfactant effects on the kinetics of Michael-type addition reaction in reverse emulsion polymeric systems

To ensure patients' safety during vascular surgery involving polymer injection, it Is important to ensure a high degree of control over the gelation rate of the materials to prevent the formation of uncontrolled emboli from shear or dispersion. Through manipulation of factors affecting the kinetics of in situ forming polymeric systems, patients' safety can be maximized. The rate of Michael-Type Addition is known to be affected by the pH of the accompanying solution, as thiols will become nucleophiic thiolates in an aqueous environment. This work evaluates the effect of the addition of 2 and 4 wt % of several common surfactants on the gelation rate of reverse emulsion polymeric systems as a method for augmenting control of in vivo Michael-type addition kinetics. This work shows that both Tween-20 (HLB 16.7) and Pluronic type surfactants (HLB~6,7) stabilize our emulsion, with gelation rates being significantly different in the presence of Pluronic type surfactants (p <0.05). This work has demonstrated the ability of surfactants to promote faster gelation at lower pH by maximizing emulsion stability and reducing cohesion of smaller bubbles, thereby maximizing surface area between the Initiator and the bulk phases.