Why do Tween surfactants form cloud spots

Tween (or polysorbate) is a nonionic surfactant, smelly, warm and slightly bitter, and is part of a series of polyoxyethylene sorbitol fatty acid esters. Widely used as emulsifier and solubilizer of oil substances. Polysorbate is generally considered to be non-toxic and non-irritating. According to WHO assessment, according to the total polysorbate calculation, the daily intake can be as high as 25mg/kg body weight.

Cloud point is a characteristic constant of nonionic surfactants, which is affected by the molecular structure of the surfactant and co-existing substances. The aqueous solution of surfactant will appear turbidity with the increase of temperature, and the surfactant will change from completely dissolved to partially dissolved, and the temperature at the time of transformation is the turbidity point temperature. Turbidity point (CP) is a very important physical parameter for the phase separation temperature of nonionic surfactant (NS) homogeneous micelle solution.

In summary, all non-ionic surfactants have cloud points, and the Tween series is a non-ionic surfactant.