Encapsulation of carboxyl polymer on the surface of nanometer calcium carbonate

Nanometer calcium carbonate has important applications in the field of polymer modification. However, its hydrophilic nature leads to poor compatibility with polymer, for which, surface modification is often necessary. In this study, nanometer calcium carbonate was encapsulated with carboxyl styrene-butadiene rubber latex or carboxyl terminated polybutadiene by direct mixing with the dilution of polymer. Obtained particles were characterized by Soxhlet extraction, FT-IR, TEM and sedimentation experiment. The results show that the encapsulation of either polymer on the surface of nanometer calcium carbonate was successfully achieved. Optimum loading amount of polymer is 13%, corresponding to encapsulation ratio of 11% and 6.8%, and encapsulation efficiency of 85% and 52%, respectively. After the encapsulation, the shape of nanometer calcium carbonate particles changes from polyhedral to approximately round. Surface character of particles becomes from hydrophilic to hydrophobic, and the dispersibility of particles in hydrophobic solvent gets improved.