Preparation of pH-sensitive particles by membrane contactor

In this work, pH-sensitive particles are synthesized using a membrane contactor technique. The polymer (Eudragit (R) L100 or Eudragit (R) E 100) is dissolved in water at a set pH and is then passed through the pores of a membrane into a continuous phase of a different pH. Contact with the continuous phase causes the pH-sensitive polymer to precipitate. The final particle size distribution (PSD) using this membrane contactor technique is compared to that of a similar batch process. The influence of the different parameters of the process (pressure, cross-flow velocity, concentration of polymer and temperature) on the PSD are studied. The results allow analysis of the different forces controlling the formation of droplets at the membrane pores. (C) 2007 Elsevier B.V. All rights reserved.