| abstract |
The present invention relates to a polymer ball having a radius R, the polymer comprising from 0.3% to 20% by weight, based on the weight of the polymer, polymerized units of one or more multifunctional vinyl monomers and % to 99.7% by weight, based on the weight of the polymer, of polymerized units of one or more monofunctional vinyl monomers. According to the invention: (a) the polymerized units of multifunctional vinyl monomer have a radial distribution factor MR of 0.9 to 1.1, and (b) some of the vinyl groups in the polymerized units of polyvinyl monomer do not have reacted, and the unreacted vinyl groups have a radial distribution factor VR of 2.5 or higher. |