Dear All,
I am looking for answer of two questions. Anyone has an idea or a reference about the following questions:
1- Does the size of the polymer (droplet) change in the emulsion polymerization by adding different proportions of water? And can see that clearly by SEM (Scanning electron microscope)
2- How is an emulsion polymerization mechanism for monomer can be in ionic liquids or deep eutectic solvent containing different amount of water?
Kind regards,
Hani
The influence of the proportion of water to monomer does have a significant influence on the droplets! With increasing the amount of water (decreasing the relative proportion of monomer) you are decreasing the probability for collisions of droplets. With decreasing the collision frequency, the drop size, despite the presence of a surface active agent , will be smaller.
Please have a look:
Maaß, S., Paul, N. and Kraume, M., 2012. Influence of the dispersed phase fraction on experimental and predicted drop size distributions in breakage dominated stirred liq-uid-liquid systems, Chemical Engineering Science, 76: 140-153.
Emulsion polymerization is a way of polymerizing hydrophobic, liquid monomers in water, in which they form an emulsion at the initial stage, most generally in the presence of a surfactant.
https://www.sciencedirect.com/topics/chemistry/emulsion-polymerization
You can’t run an SEM in the wet. Freeze-fracture (poor) or cryo-EM (recommended) are the microscopic techniques. Light scattering (DLS, laser diffraction) can be used to measure the size distribution. Altering the concentrations will alter the particle size - this is basic stuff that doesn’t need a reference other than the most basic and simplistic emulsion chemistry textbook.
Dear all, providing you keep in mind the CMC of the emulsifier used, otherwise you will be in a solution polymerization. If there is an effect you can notice it after the accomplishement of the polymerization by measuring the size and its distribution of the polymeric powder. There exists online monitoring polymerization progress reactors but really expensive.
Very important to consider in this situation two interconnected factors are viscosity (dilution) and shear (agitation speed). These have influence on émulsion droplets size. My Regards
The influence of the proportion of water to monomer does have a significant influence on the droplets! With increasing the amount of water (decreasing the relative proportion of monomer) you are decreasing the probability for collisions of droplets. With decreasing the collision frequency, the drop size, despite the presence of a surface active agent , will be smaller.
Please have a look:
Maaß, S., Paul, N. and Kraume, M., 2012. Influence of the dispersed phase fraction on experimental and predicted drop size distributions in breakage dominated stirred liq-uid-liquid systems, Chemical Engineering Science, 76: 140-153.
Hani Khalil Ismail
Ionic liquids usually have two large oppositely charged ions. At room temperature, they are liquids when compared with conventional surfactants sodium dodecyl sulfate, which has a crystalline structure at room temperature. In water, ionic liquids form micelles with, and stabilize the monomer emulsion in water. The polymerization mechanism is the same as with other surfactants. Azeotropic solvent mixtures can reduce the solvophobic interaction of surfactants and impair emulsion polymerization.
Emulsion polymerization technique is commonly applied for the preparation of polymeric latex particles. In this technique, a small amount of water-insoluble monomer is dispersed in water phase, and water-soluble initiators are added into the solution. An appropriate surfactant that shows hydrophobic and hydrophilic feature is used for the stabilization of the emulsion of the monomer in water phase. Surfactant molecules come together and form aggregates also called “micelles.” Then, free radical initiator molecules in water phase migrate into the micelles, and polymerization is initiated. The polymerization kinetics consists of three stages. In the first stage, monomers diffuse from droplet into micelles and polymerization starts to form polymeric particles. Second stage corresponds to growth of polymeric particles by propagation. During this stage, the monomer concentration inside the polymeric particles and number of polymeric particles remain almost constant. In the final stage, the rate of the polymerization decreases, and no monomer droplets are observed. The remaining monomers in the particles are polymerized. The size distribution of the obtained latex particles varies from 50 to 700 nm depending on the polymerization conditions.
The size of the polymer (droplet) change in the emulsion polymerization by adding different proportions of water.With decreasing the collision frequency, the drop size, despite the presence of a surface active agent , will be smaller.The rate of the polymerization decreases, and no monomer droplets are observed. The size distribution of the obtained particles varies. It from depends on the polymerization conditions.
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