Molecular morphology and molecular weight affect the properties of surfactants

2019-09-29 08:38:33

The structure of surfactant is composed of hydrophilic group and hydrophilic group. The hydrophilicity and hydrophilicity of molecule, the morphology and molecular weight of molecule affect the properties of surfactant.

1) The higher the HLB of surfactant, the higher the hydrophilicity.

2) The influence of hydrophobic groups: hydrophobic action of hydrophobic groups reduces the surface tension and affects the formation of micelles.

3) The influence of hydrophilic groups: the hydrophilic groups of surfactants will affect their solubility, thus further affecting the formation of micelles. The higher the solubility, the higher the critical micelle concentration. At the same time, different hydrophilic groups have different sensitivity to temperature and the properties affected by temperature.

4) The influence of molecular morphology: the relative position of hydrophilic group and the branching of hydrophilic group, when the hydrophilic group is between the molecules, the wettability of surfactant is stronger than that at the end of the molecule; the surfactant with branching structure has better wettability and permeability, but better decontamination.

5) The influence of molecular weight: surfactants with larger molecular weight are washed, dispersed and emulsified, while surfactants with smaller molecular weight have better wetting and penetrating effect.

6) Solubility of surfactants: The lower the Krafft point of ionic surfactants and some non-ionic surfactants, the better the solubility. For most non-ionic surfactants, when the temperature is higher than the cloud point, grouping will occur, and many properties and effects will decrease.

7) Safety, mildness and toxicity of surfactants: non-ionic and amphoteric < anionic 8="" span=">.

The solubility of ionic surfactants increases with the increase of temperature. When a certain temperature is reached, the solubility of ionic surfactants will suddenly increase rapidly. This transition temperature is called Kraff point. During the heating process of a certain concentration of surfactant solution, the temperature point at which the surfactant suddenly precipitates and makes the solution turbid is called the cloud point.