Seed Emulsion Polymerization

Seed emulsion polymerization technology is another important method for preparing functional emulsions. In the past one or two decades, the development and application of new emulsion polymerization processes and technologies have been very active. Extensive research has been conducted on the reaction kinetics and mathematical models of emulsion polymerization, achieving considerable and fruitful progress.

Microemulsion Polymerization

The concept of microemulsions was first proposed by Hoar and Schulman in 1943. Unlike traditional W/O and O/W, microemulsions can also adopt many other textured structures, such as spherical, columnar, and layered structures. A crucial property of microemulsions is that they are isotropic and thermodynamically stable systems; as long as the composition and temperature remain constant, the system will not aggregate.

Fine Emulsion Polymerization

Fine emulsion polymerization refers to emulsions with monomer droplets only 100–400 nm in size (submicron). Its main components are water, emulsifiers, and water-insoluble long-chain aliphatic hydrocarbons (alcohols) as co-emulsifiers. Because the monomer droplets are dispersed at the submicron level, their surface area is large, making it easier to capture free radicals. Therefore, the main reaction site is the submicron-sized monomer droplet dispersion phase. The presence of long-chain aliphatic hydrocarbons creates a robust interfacial layer between the dispersed phase and submicron-sized monomer droplets, formed by the emulsifier and the long-chain aliphatic hydrocarbon (alcohol). This layer prevents collisions and aggregation of monomer droplets and particles. Simultaneously, the water insolubility of the long-chain aliphatic hydrocarbon (alcohol) also inhibits the interdiffusion of monomers between droplets. Such emulsions are easily predictable and controllable.

Non-aqueous emulsions: Non-aqueous emulsions are emulsions obtained by polymerizing vinyl monomers in a solvent that dissolves monomers but not polymers, using the polymer dissolved in that solvent as a stabilizer. Non-aqueous emulsions allow solvent-based polymers to be obtained in high-degree-of-polymerization, high-concentration forms. Furthermore, they can significantly improve the water and alkali resistance of the emulsion.