Characteristics of polymer microspheres prepared by radiation-induced polymerization in the presence of organic solvents

Abstract Radiation-induced polymerization of diethylene glycol dimethacrylate (2G) was carried out in methyl orthoformate (MOF) in the range of 25 to −78°C, to obtain the polymeric microspheres. A transparent solution consisting of 2G and MOF showed an emulsified state after irradiation. This means that the colloidal particles of poly(2G)are deposited from monomer solution during the irradiation because of poor solubility. It was confirmed by microscopic observation that the shape of obtained polymer is composed of a complete sphere. The particle size of poly(2G) microsphere obtained by 10 kGy irradiation at temperatures of 25, 0 and −43°C was found to be 1.55±0.54, 1.75±1.09, and 1.76±1.21 μ m, respectively. No formation of the microsphere occurred when irradiated at −78°C. The preparation of poly(2G) microspheres was furter tried using various organic solvents under such conditions as 10 kGy and 25°C. According to this experiment, poly(2G) microspheres of the smallest size were obtained in the presence of ethyl caproate (0.70±0.25 μ m), while the largest size was obtained when tetrahydrofuran was used (8.61±4.21 μ m).