Carbopol

Carbopol refers to a family of high molecular weight, crosslinked polyacrylic acid polymers developed by BF Goodrich and marketed under the Carbopol trademark by Lubrizol. These polymers act as thickening, suspending, emulsifying, and stabilizing agents in cosmetics, personal care products, and pharmaceutical formulations. They are commonly used as rheology modifiers to adjust viscosity and provide texture.

In water, carbopol particles swell; when the polymer is neutralized with a base such as triethanolamine or sodium hydroxide, the carboxyl groups ionize and the network forms a gel. The resulting gels are highly viscous and display shear-thinning (pseudoplastic) behavior, allowing easy spreading while resisting flow at rest. Typical usage ranges from about 0.1% to 2% depending on grade and desired texture.

Preparation and use: Powdered Carbopol is dispersed slowly in water with high-shear mixing to prevent clumping, then hydrated and neutralized to produce gels. Formulations may require pH adjustment to 6–8 and can be destabilized by electrolytes, significant shifts in pH, or certain surfactants, especially cationic ones. They can be incompatible with strong bases or acids that degrade the polymer.

Grades: Multiple grades exist (e.g., Carbopol 934, 940, 980, with newer Ultrez or permanently crosslinked variants), offering different particle sizes, clarity, and viscosity ranges to suit emulsions, creams, gels, and suspensions.

Safety and regulation: Carbopol polymers are widely used in cosmetics and pharmaceuticals and are considered safe for external use at standard concentrations. They are not absorbed in the body and are generally non-irritating, though skin sensitization is possible at high exposures. Storage is in dry, sealed conditions.