Charge-modified particles and methods of making the same

A method of making charge-modified particles, the method comprising:

• providing an aqueous mixture of inorganic particles and surfactant;
• adding at least one hydrophobic free-radically polymerizable monomer and a free-radically polymerizable substituted benzotriazole phenol the aqueous mixture to form a free-radically polymerizable mixture, wherein at least a portion of the at least one hydrophobic free-radically polymerizable monomer is disposed in a surfactant bilayer that is disposed on the particles;
• adding a free-radical initiator to the free-radically polymerizable mixture thereby polymerizing at least a portion of the hydrophobic free-radically polymerizable monomer to form the charge-modified particles, each comprising the inorganic core and a shell surrounding the inorganic core, wherein the shell comprises a copolymer comprising monomeric units corresponding to the at least one hydrophobic free-radically polymerizable monomer and the free-radically polymerizable substituted benzotriazole phenol;
• and
• converting at least a portion of the monomeric units corresponding to the free-radically polymerizable substituted benzotriazole phenol into a substituted benzotriazolylphenolate salt.