Emulsifiers are materials that keep two substances that would naturally separate bound together. A common emulsion in creams, moisturizers, and lotions is water and oil. Naturally, water and oil separate due to differences in polarity. Water is a super polar substance. The oxygen in H2O has a high electronegativity meaning that the atom attracts bonding pairs of electrons. Therefore, the oxygen pulls on the electrons of the two hydrogen atoms creating a negative charged end (from the oxygen) and a positive charged end (from the hydrogen atoms). On the other end, oil is typically made up of long strands of hydrocarbons. Carbon atoms are much weaker in electronegativity when compared to oxygen, which ultimately makes the oil a non-polar substance. With the principle of “like dissolves like”, the water and oil do not interact but rather separate completely.
So, here are where emulsifiers come in. Emulsifiers have hydrophilic heads (water-loving) and lypophilic tails (oil-loving). The heads bond with water molecules while the tails bond with oil molecules, thus joining the two molecules together.
Common emulsifiers include Borax with Beeswax, Beeswax, BTMS 25%, Carbomer, Cetaryl Alcohol, Emulsifying Wax-NF, Lecithin, PEG-20 Stearate, Propylene Glycol, Silky Emulsifying Wax, Stearyl Alcohol NF, and Polysorbate 80. Below is Polysorbate 80 which shows the two distinct parts of the molecule. The hydrophilic head is characterized by the large number of oxygen atoms (to bond with H2O) while the lypohilic tail is comprised of nonpolar hydrocarbons (to bond with oil).