Tony O’Lenick asks industry expert Valerio Vergani of AKOTT Italia: What is the difference between a polar oil and a nonpolar oil?
In making emulsions, one uses water and oil. Water is a compound (CAS number 7732-18-5). Oil, however, is a term that describes a material that is both hydrophobic (water-hating) and oleophilic (oil-loving). Oil, unlike water, is not one compound but a vast variety of compounds.
The term oil includes hydrocarbons, triglycerides, esters, fatty alcohols and oil soluble silicones (alkyl dimethicone). Since silicone fluids are insoluble in oil and water, they are siliphilic and are in a class by themselves. Additionally, oils can be classified by the source from which they are derived such as petrochemical or natural; animal or vegetable. Oils can be solid or liquid and unsaturation and branching will increase their liquidity. They are important materials in cosmetic formulation and often are used as vehicles and emollients.
One of the most interesting ways to divide oils into type is to consider polarity of the oil. Nonpolar oils are hydrocarbons. They lack an electronegative element like oxygen, which results in their typical hydrocarbon feel.
Polar oils contain heteroatoms that differ in electronegativity. This results in a dipole moment. Typical polar oils are fatty alcohols, esters and triglycerides. While they are still water insoluble and oil-loving, these oils have unique characteristics due to their polar nature. They require higher HLB emulsifiers to make stable emulsions, they dissolve materials that are insoluble in nonpolar oils, and they provide unique properties when compared with nonpolar oils such as mineral oil.
Polar oils have unique and often improved cosmetic aesthetics. They also have improved pigment wetting and grinding properties, spreadability, skin feel, emolliency, hydratation and are often easily biodegradedable. The formulator is encouraged to explore the range of polar oils available when beginning formulations.