ABSTRACT
Most of methods used for the preparation of CA pseudolatices are based on the direct emulsification approach. Because most solvents for CA are either slightly or completely miscible with water, binary solvent systems in which one solvent is water immiscible and the other water miscible are usually used to prepare CA emulsions. Seminoff and Zenter [15] dissolved CA in a 1:1 mixture of methylene chloride :methanol and then emulsified the solution in water using 0.1 % sodium lauryl sulfate as an emulsifying agent. Ultrasonication followed by removal of the solvent produced a pseudolatex. A similar method was used by Bodmeier and Chen [16] to prepare a 10% CA pseudolatex with a particle size in the range between 250 and 300 jum. They dissolved the polymer in a 9:1 ratio of methylene chloride:methanol solvent and then emulsified the resulting solution in water using 0.5% sodium lauryl sulfate. Microfluidization, instead of ultrasonication, was used to reduce the particle size. Studies show that the stability of the homogenized emulsion is greatly dependent on the amount of solvent partitioned into the aqueous phase. In general, high concentrations of solvent in water cause either surfactant desorption or Ostwald ripening of the polymer and, consequently, result in the instability of the dispersion [14].
