Synt Hesis Of Monodisperse, Highly Cross-Linked, Functional PMMA Microspheres By Dispersion Polymerization

Monodisperse, Highly Cross-Linked Poly(MMA-EGDMA) microspheres were prepared by dispersion polymerization using ethanol-water as solvent, polyvinylpyrrolidone (PVP) as steric stabilizer,2,2’-azobisizobutyronitrile (AIBN) as initiator, and ethylene glycol dimethacrylate as cross-linking agent.In the improved batch dispersion polymerization, the solvent mixture consisted of ethanol and water, EGDMA and MMA were quickly added after the nucleation stage, which can obtain cross-linked PMMA microspheres with cross-linking agent concentration of1.4wt%based on MMA. The average size of cross-linked PMMA microspheres is5.3μm and polydispersity index is1.02.In the semicontinuous addition dispersion polymerization, the solvent mixture consisted of ethanol and water, EGDMA and MMA were continuously added after the nucleation stage, which can obtain cross-linked PMMA microspheres with cross-linking agent concentration of70wt%based on MMA. The influence factors on the size and size distribution of Poly (MMA-EGDMA) were investigated. Moreover, the relationship between particle size and molecular weight was investigated and the polymerization kinetics was investigated in different initiator concentration and cross-linking agent concentration. Through the properties characterization, it is found that the microspheres with excellent solvent resistance and thermal stability and the insoluble matter content reached the maximum of96.6%.Monodisperse Highly Cross-Linked PMMA microspheres with hydroxyl group or amide group on surface were prepared by semicontinuous addition dispersion polymerization using hydrophilic hydroxyethyl methylacrylate and acrylamide as reactive monomer. The experimental results show that with the increase of the dosages of hydrophilic monomer, the hydrophilicity of microspheres increased.