The formation of “inverted” core-shell latexes



It has been found that when hydrophobic monomers are polymerized in the presence of highly hydrophilic polymer seed particles, the second-stage hydrophobic polymers form cores surrounded by the first-stage hydrophilic polymers, resulting in “inverted” core-shell latexes. The formation of core-shell morphology by this inversion process has been found to be dependent on the hydrophilicity and molecular weight of the first-stage hydrophilic polymers and the extent of phase separation between the two polymers involved. Particle morphology has been examined by electron microscopy, surface acid titration, alkali swelling of particles, and surface reactivity.