Microemulsion (ME)
MEs are water based formulations with a very small emulsified droplet size; this makes the formulation transparent.
They are thermodynamically stable over a wide temperature range due to this very fine droplet size, usually between 0.01 and 0.05 μm. Therefore in contrast to other emulsion systems, where the oil droplets can slowly coalesce causing phase separation, in ME formulations this does not occur.
Benefits
- Thermodynamically stable therefore have increased shelf life
- Low solvent level
- Easy to transport and store
- High flash point and safe handling
- Improved bioefficacy due to the solubilisation of the active ingredient in the micro droplets
- Low viscosity; so easier to handle
Limitations
- Low active ingredient content
- Require high surfactant level to form
The Formulator's Toolbox (Full Version)
Recommended products for ME
Anionic surfactants are required in an ME formulation to form a spontaneous emulsion. Due to the overall charge on an anionic emulsifier it provides additional electrostatic stabilisation.
Atlox™ 4838B
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Atlox Metasperse™ 500L
Zephrym™ 3300B
The combination of a low and high HLB non-ionic surfactant is recommended to provide steric stabilisation at the emulsion interface.
Tween™ 22
Tween™ 23
Tween™ 24
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Atlas™ G-5002L
Atlox™ 4916
Atlox™ 4914
Atplus 310 is a single product, emulsifier package. Its novel blend makes formulating an ME relatively easy and simple as blending ratios of the emulsifiers have already been predetermined. Microemulsions do not normally form in high electrolyte conditions. This is due to the disruption that electrolytes cause to steric stabilisation and the shielding effect to electrostatic repulsion between droplets. Atplus 310 however, is designed to overcome this problem and allows the formation of high electrolyte microemulsions.
Atplus™ 310
Our extensive range of phosphate esters gives the formulator a high degree of flexibility in their formulation design of microemulsions. When combined with other surfactants such as sarcosinates, they can provide stable microemulsion systems in very challenging conditions. As with the combination of non-ionic surfactants, it is important to consider pairing a phosphate ester with high solubility in your target aqueous system, along with a phosphate ester with high solubility in your target oil system.
Atlox™ AL-3382
Multitrope™ 1214
In an ME formulation, the active ingredient must be fully soluble in the carrier solvent. If the active ingredient is solid, it will need to be dissolved in a solvent first. Croda’s Seatons Natural Oil range are 100% natural and renewable, making them great options for crop care formulations.
Atlox™ Solvall™ BDE-1
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Seatons refined linseed oil
Seatons refined rapeseed oil
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Seatons refined soyabean oil
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