Update:
Emulsion Polymers can be defined as dispersions of polymeric particles of about 100 – 1000 nm size in an aqueous disper...
Emulsion Polymers can be defined as dispersions of polymeric particles of about 100 – 1000 nm size in an aqueous dispersion media. They are polymer dispersions, by technical terms, and often also referred to as “polymer emulsions”, “dispersions” or “polymer latex”.
Physically they fall into the category of colloidal systems.
- Colloids are the microscopical dispersion of one substance into another of which it is not (or little) soluble in.
- These systems are characterized by high internal interface areas and specific physico-chemical properties derived thereof.
Due to the high surface area, all colloidal systems are meta-stable. The laws of physics drive them to reduce that area which leads to coagulation.
In technical systems, stabilizers are used to mitigate this natural tendency and to keep the systems in the colloidal state until usage.
Examples for naturally formed colloids are milk, fog, mist or clouds, smoke, blood and the natural rubber latex from the Amazonian rubber tree (Hevea brasiliensis), which stands at the origin of this industry. Since its first industrial application in the early 20th century, emulsion polymerization developed to be one of the most versatile polymerization techniques in the polymers industry.
Polymer emulsions are primary dispersions, which means that the polymer and the colloid are formed in one step. Dispersing already made polymers into an aqueous medium forms secondary polymer dispersions. Commercial examples are wax dispersions. This step requires:
- A high-energy intake to create small enough particles, and
- Often high amount of stabilizers to keep the microscopic particles separated.
Technically important and Emulsion Polymers. Here, we are focusing on the latter.
How Emulsion Polymers are Made
Emulsion Polymers formed by free-radical polymerization of monomers emulsified into water. has a specific mechanism and kinetics, which makes it different from many other polymerization techniques.
Organic monomers are emulsified under the aid of stabilizers into water that serves as a continuous matrix.
- The addition of radical-forming initiators to the aqueous phase starts the polymerization, which happens outside of the monomer droplets (this would make suspension polymerization instead!).
- But in the aqueous phase, monomer micelles or monomer swollen polymer particles, depend on mechanism and phase of the process.
The monomer droplets just serve as a reservoir from which monomer molecules are delivered. With this mechanism, very high degrees of polymerization can be achieved at high-solids content, whilst the overall viscosity of the system stays within reasonable terms for processing.
This process results in a dispersion of about 50 – 60% solid polymer particles in the aqueous matrix.
For many applications, this dispersion is ready-to-use without further expensive separation and cleaning steps. In other cases, the polymer emulsion is precipitated or spray-dried to form a re-dispersible polymer powder (RDP).
From an application point of view, polymer emulsions are waterborne systems.
- Waterborne systems are based on water – not organic solvent – as the main carrier.
- They found increasing interest over the past decades due to their favorable profile in terms of emission control.
Therefore, emulsions polymers are amongst the fastest-growing categories of specialty chemicals in the world.
If you have interested to learn more, please contact Ms.Lin Yang.
Thanks & Best regards,
Lin Yang(Ms.)
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ZHEJIANG RUICO ADVANCED MATERIALS CO., LTD.(STOCK NO.: 873233)
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No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China
+86 (572)
2903236
+86 (572)
2905222
+86 15088303595
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