| Here we obtained highly uniform sized crosslinking polyurea microspheres in the mixedsolvent of water and acetone through precipitation polymerization using isophoronediisocyanate and polyamine as monomers. The influences of crosslinking agents, monomerloading, the ratio of water/acetone, polymerization temperature and the dosage of crosslinkingagent on the morphology, yield and particle size of microspheres were studied. Themicrospheres were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) andscan electronic microscope (SEM) and so on.Monodisperse polyurea microspheres were synthesized with their number-averagediameters ranging from1.087μm to3.450μm and particle size distribution between1.006and1.054by tuning polymerization conditions, and microsphere yield up to83wt%.Specially, the monodispersity of microsphere is the best with triethylenetetramine (TETA) ascross-linking agent, the mass ratio of water/acetone being30/70,35/65and40/60, andmonomer loading of2wt%at polymerization temperature of30and40℃.Cross-linking agents improve the rate of polymerization largely, and it was demonstratedthat crosslinked microspheres are more resistant of acid and other organic agents thanmicrospheres prepared without polyamine. Three polyamines diethylenetriamine (DETA),TETA, and tetraethylenepentamine (TEPA), were use in this work. Spheres were smaller withincreasing functional group of polyamines. Microspheres yield was improved and particlediameters became decreasing as the mass ratio of water/acetone rose. Polymerizationtemperature would impact particle sizes and rate of reaction obviously but not the yields ofthe microspheres. Particle sizes decreased when temperature varied from20℃to50℃andincreased from50℃to70℃.It was demonstrated that degree of crosslinking of microspheres was affected by ratio ofH2O/acetone and content of polyamine through Soxhlet extraction, and it was higher withincreased ratio of H2O/acetone, and lower with decreased content of cross-linking agent. |
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