架橋促進による高分子ミクロフェアの合成と形成のメカニズム  [in Japanese] Formation of Polymer Microspheres Promoted by Cross-Linking Reaction  [in Japanese]

Monodisperse microspheres of poly (diethylene glycol dimethacrylate) with diameter in the size range 0.4-4.8 μm particle were prepared by the radiation-induced polymerization. Effects of solvent viscosity and monomer solubility were investigated for various kind of solvents. The number of the nuclei, produced in the early stage of the polymerization, was found to be constant during the polymerization. The nuclei grow to be monodisperse polymer particles without aggregation. This is attributed to the low mobility of the growing polymer particle. The monomer concentration strongly affected the conversion and the shape of the microspheres. The particles were obtained in the range from 2 to 24 vol % of 2G monomer. The effective concentration for the preparation of monodisperse microspheres is around 10 vol %. Higher monomer concentrations up to 24 vol % gave rough surface particles. Considering of the effects on the number of microspheres in the solution, the authors introduced the inhibiting region, where one microsphere disturbs the existence of another microsphere, and tried to explain the mechanism of the microsphere growth. The competition between the propagation and the cross-linking reactions is balanced to give the microspheres.