Preparation of uniform and porous polyurea microspheres of large size through interfacial polymerization of toluene diisocyanate in water solution of ethylene diamine

• Highly uniform polyurea (PU) microspheres of size from 400 μm to 750 μm are prepared.
• The process is done by adding toluene diisocyanate (TDI) to a diamine H2O solution.
• The uniformity is achieved with pore size ⩾210 μm of the needle for TDI addition.
• The PU microspheres consist of a coarse shell and a core with macroporous structure.

Uniform and porous polyurea (PU) microspheres of large size, with the diameter between 400 μm and 750 μm, are prepared through interface polymerization by drop-wise addition of toluene diisocyanate (TDI) to an aqueous solution of ethylene diamine (EDA). TDI addition is done through a needle with pore size of 60 μm or larger at constant rate associated with the needle pore size. Effects of the needle pore size for TDI addition, EDA concentration in water and polymerization temperature on the formation of the PU spheres are studied. Results indicate that PU spheres are obtained with varied needle pore size. However, highly uniform PU spheres are achieved only with the needle pore size of 180 μm or larger. In order to get uniform microspheres, polymerization should be carried out at 60–65 °C with EDA/TDI molar ratio kept at 2/21–4/21. Out of these limits, the uniformity of the polymer spheres is deteriorated. Morphology of the microspheres is examined under scanning electron microscope, which shows that the microspheres are consisting of a coarse shell and a core with macroporous structure. The mechanism of the polymerization and PU sphere formation are discussed.

Large, macroporous and highly monodisperse polyurea microspheres of size about 750 μm are prepared through interfacial polymerization by drop-wise addition of toluene diisocyanate into aqueous solution of ethylene diamine.Figure optionsDownload as PowerPoint slide