Colloidal particle sols, methods for preparing and curable film-forming compositions containing the same

A method of preparing a sol of particles suspended in an organic medium comprising:

• a) providing a suspension of particles in an aqueous medium;
• b) adding a first organic liquid compatible with the aqueous medium to form an admixture;
• c) reacting the particles in the admixture with a first modifying compound, wherein the first modifying compound comprises a group that does not react with the particles and a functional group capable of reacting with functional groups on the particles;
• d) reacting the particles with a second modifying compound, wherein the second modifying compound is different from the first and comprises a hydrophobic group and a functional group capable of reacting with functional groups on the particles;
• and
• e) adding a second organic liquid compatible with the liquid portion of the admixture either before or after the particles are reacted with the second modifying compound, wherein the second organic liquid is different from the first organic liquid used in step b);
• wherein when the second organic liquid is added to the admixture before the particles are reacted with the second modifying compound, the admixture is maintained at a temperature and pressure and for a time sufficient to substantially remove the water and the first organic liquid added in step b) before reacting the particles with the second modifying compound.