Preparation of Monodisperse Melamine-Formaldehyde Microspheres via Dispersed Polycondensation

摘要

We have successfully synthesized relatively monodisperse and cross-linked melamine-formaldehyde(M-F)microspheres by dispersed polycondensation and subsequent pH adjustment with serum replacement cleaning.The average particle sizes(D_w:weight-average and D_n number-average),the polydispersity index(D_v/D_n),the number of particles N_p,and the gel content of the M-F microspheres were observed by varying the pH,the surfactant concentration,and the polymerization temperature.We observed that both the pH and the polymerization temperature were predominant factors in determining D_n and N_p,but the effect that the temperature and pH had on the gel content(> 94% for all samples)was negligible.The exponents of the slopes of plots of N_p versus pH and surfactant concentration were-10 and 0.6,respectively.Particle nucleation and growth were achieved within short periods;the incessant coagulation occurred even in the presence of surfactants.