Miniemulsioonpolümerisatsioon

Miniemulsioonpolümerisatsioon is a polymerization technique that involves creating a miniemulsion of monomers, which are then polymerized within the dispersed monomer droplets. A miniemulsion is a thermodynamically unstable dispersion of oil-in-water droplets, typically ranging in size from 50 to 500 nanometers. These droplets are stabilized by a combination of a hydrophobic compound and a surfactant. The hydrophobic compound, often a long-chain alkane or wax, is crucial for preventing droplet coalescence and Ostwald ripening, phenomena that are common in conventional emulsions and can lead to broader particle size distributions or larger particles.

The process begins with the preparation of the miniemulsion. This involves dissolving a monomer and a hydrophobic agent in a continuous aqueous phase containing a surfactant. High-shear mixing, such as sonication or high-pressure homogenization, is then applied to break down the larger oil droplets into the desired miniemulsion size range. Once the miniemulsion is formed, a water-soluble initiator is added to the aqueous phase. Upon heating, the initiator decomposes, generating radicals that diffuse into the monomer droplets and initiate polymerization. The polymerization proceeds within these individual monomer droplets, which act as miniature batch reactors, leading to the formation of polymer particles with a narrow particle size distribution. This technique offers control over particle size, morphology, and composition, making it suitable for producing various polymeric materials, including latexes, nanoparticles, and nanocapsules for applications in coatings, adhesives, drug delivery, and more.