A novel two step method has been developed for the preparation of anisotropic polymer particles using soap‐free emulsion polymerization in the presence of the reactive silane coupling agent 3‐methacryloxypropyltrimethoxysilane (MPTMS). In the first step, seed polymer particles were prepared in the presence of MPTMS in water. In the second step, another polymerization was conducted in the presence of the seed particles, which induced anisotropic protrusion of polymer from the seed particles. The two step method is applicable to the preparation of anisotropic polymer particles containing inorganic particles such as silica. Silica particles inside the anisotropic polymer particles were dissolved with hydrofluoric acid, which created hollow polymer particles with anisotropy.
