Preparation And Stabilization Of Emulsifier-Free Macromolecule Nanoparticle Latex And The Mechanism Of Emulsifier-free Polymerization

The latexes obtained by emulsifier-free emulsion polymerization show good adhesion and water-resistant properties and are characterized by having a narrow size distribution and 'clear' surface. They had been widely applied in biological systems.Emulsifier-free macromolecule nanoparticle latex can be obtained by conventional heating method but the reaction takes more time and the particle size distribution is wide in comprision with those obtained by microwave heating method. So in this paper, the monodisperse emulsifier-free macromolcule nanoparticle latex is obtained by the use of microwave radiation under ambient pressure. The suitable condition for the preparation of such latex is discussed through analyzing the factors such as the kind and content of monomer, cosolvent, initiator and the temperature of the reaction. The stability testing of the synthesized latex such as the storage stability at normal or low temperature and the stability to electrolyte is done.The particle formation mechanism of emulsifier-free macromolecule nanoparticles under microwave radiation is discussed through analyzing several kinds of factors affecting the emulsifier-free polymerization and the data or phenomena obtained during the polymerization such as the curve of the conversion vs. time, the curve of the transparency of the system vs. time, the hydrodynamic radius and its distribution during the polymerization. It is considered that both the homogeneous nucleation and the micelle nucleation exist in acetone-water medium or in methanol-water system. Furthermore, the nucleation will happen several times during the polymerization.