Abstract
The grafting of polyesters onto ultrafine inorganic particles, such as silica, titanium oxide, and ferrite, by use of potassium carboxylate (COOK) groups introduced onto the surface was investigated. The introduction of COOK groups onto the surface was achieved by the neutralization of acid anhydride groups, which were introduced by the reaction of 4‐trimethoxysilyltetra‐hydrophthalic anhydride with hydroxy groups on the surface: the amount of COOK groups introduced onto the surface of silica, titanium oxide, and ferrite was estimated to be 1.92, 0.94, and 0.62 mmol/g, respectively. It was found that the anionic ring‐opening copolymerization of epoxides with cyclic acid anhydrides is initiated by COOK groups introduced onto the surface. In the polymerization, polyester formed was effectively grafted onto the surface based on the propagation of the polymer from COOK groups on the surface: the percentage of grafting of polyester from chloromethyloxirane and phthalic anhydride onto silica, titanium oxide, and ferrite reached to 118.3, 82.1, and 7.5%, respectively. The rate of the polymerization and percentage of grafting increased with an increase in COOK group content of the ultrafine particles. The grafting of polyester onto these particles was confirmed by infrared spectroscopy. Polyester‐grafted ultrafine particles produced a stable colloidal dispersion in organic solvent.