Preparation of polyurethane microspheres via dispersion polycondensation using poly(1,4-isoprene)-block-poly(ethylene oxide) as steric stabilizer

A novel dispersion polymerization of a diisocyanate and a diol for the preparation of spherical polyurethane particles is reported. An amphiphilic block copolymer, namely, poly(1,4-isoprene)-block-poly(ethylene oxide) was used as a steric stabilizer. Monodisperse spherical particles were obtained in the size range from 0.2 to 2.0 μm. The polyurethane particle formation was dependent on the concentration of the steric stabilizer, the block segment molecular weight and the nature of dispersion medium. The polyurethane particles were stabilized by a mechanism involving physical adsorption of the steric stabilizer on the surface of the growing particle