Polymer–TiO2 composite nanorattles via RAFT‐mediated emulsion polymerization

In this work, successful synthesis of polymer nanorattles containing titanium dioxide pigment particles in the centers of air voids is reported. The method used amphiphilic macro‐RAFT copolymers as stabilizers for pigment dispersion and the subsequent encapsulation of the pigment with polymer. The particles were first encapsulated by a water swellable hydrophilic layer, followed by a hard hydrophobic layer. Nanorattles were formed by swelling of hydrophilic polymer layers on the surface of the encapsulated pigment particles in a basic solution at elevated temperature. After swelling, the outer hard polymer shell was crosslinked to improve its strength. Air void sizes of the nanorattles were found to be controlled by swelling time, temperature, and the hydrophilic polymer layer thickness.