Inverse emulsion polymerization means that the water-soluble monomers (such as acrylic acid, acrylamide) are dissolved in water phase first, then the water soluble monomer I is dispersed in the oil phase and formed oil lotion lotion under the presence of oil in water emulsifier by means of the strong shearing effect of mechanical agitation. Finally, a reaction of polymerization is initiated under the action of oil soluble initiator.
The main advantages of inverse emulsion polymerization are mild reaction conditions, stable reaction process and less side reaction lotion. Lotion is beneficial to industrial production. The product prepared by the reaction has high solid content and excellent solubility.
The main disadvantage of inverse emulsion polymerization is that lotion of organic solvents is inevitable when lotion is prepared by inverse emulsion polymerization, and it is not suitable for environmental protection. Moreover, the electrolyte resistance of products is still greatly improved.
The mechanism of inverse emulsion polymerization is more complicated. At the beginning of reaction, monomer droplets and micelles exist simultaneously, and initiators dissolve and decompose in lotion, resulting in free radicals. Because the diameter of the single body fluid droplet is several orders of magnitude larger than that of the micelle, the specific surface area of the single body fluid droplet is much smaller than that of the micelle, and the radius of curvature of the micelle is very small. Therefore, the arrangement of emulsifier molecules on the surface of the micelle and in the single body fluid droplet is very different, which leads to great differences in the thermodynamic distribution of the monomer. Therefore, when the system is heated, the free radicals distributed in the continuous phase and interface are easier to enter the micelle, Initiate monomer polymerization in micelles, which is called micellar nucleation.
The technology of preparing thickeners by inverse emulsion polymerization has been quite skillful. Many foreign companies, such as Basf Inc, Dow Chemical Corporation, 3V of Italy, etc., have successfully prepared thickeners with good performance by using inverse emulsion polymerization in Shenyang University of Chemical Technology and Qingdao Institute of Chemical Industry. However, the common problem is the poor electrolyte resistance. The current research mainly focuses on further improving the electrolyte resistance of thickeners by introducing some functional monomers into polymerization
