Although grain size was even well and the inorganics particle of the nano- size where grain size is controlled precisely in the organic solvent reached the point where it can by synthesis, because the fatty acid of the long chain has adsorbed into the particle surface in that inorganics particle, it was difficult to obtain the inorganics particle of the nano- size where dispersion in the polar solvent is obstructed, furthermore this surface coating substitutes disperses in the polar solvent. In the inactive solvent which the inorganics particle which was covered with the fatty acid is dispersed, adding temporary incrustant such as thio malic acid, it substitutes the fatty acid coating of the particle first with this temporary incrustant coating, it disperses the inorganics particle which was covered next with this temporary incrustant to the polar solvent, adds polar solvent detachable incrustant such as citric acid in this dispersed liquid, obtain the various surface coating inorganics particles which from the inorganics particle which was covered with the fatty acid by substituting the temporary incrustant coating which covers the inorganics particle with this polar solvent detachable incrustant, are dispersed in the polar solventIt reached the point where it is possible.粒子サイズがよく揃い粒径が精密に制御されたナノサイズの無機物粒子が有機溶媒中での合成によって得られるようになったものの、その無機物粒子には長鎖の脂肪酸が粒子表面に吸着しているため極性溶媒中での分散が阻害されており、しかもこの表面被覆を置換して極性溶媒中で分散するナノサイズの無機物粒子を得ることが困難であった。脂肪酸で被覆された無機物粒子が分散している非極性溶媒中に、チオリンゴ酸などの一時被覆物質を添加して粒子の脂肪酸被覆をまずこの一時被覆物質被覆で置換し、次にこの一時被覆物質で被覆された無機物粒子を極性溶媒に分散し、この分散液にクエン酸などの極性溶媒分散性被覆物質を添加し、無機物粒子を被覆している一時被覆物質被覆をこの極性溶媒分散性被覆物質で置換することによって、脂肪酸で被覆された無機物粒子から極性溶媒中で分散するさまざまな表面被覆無機物粒子を得ることができるようになった。
