Ammonium Acryloyldimethyl Taurate/Beheneth-25 Methacrylate Crosspolymer — INCI reference

What it is

Ammonium Acryloyldimethyl Taurate/Beheneth-25 Methacrylate Crosspolymer is a pre-neutralized, hydrophobically modified sulfonic acid copolymer available as a white powder. It is the INCI name for Aristoflex HMB, a rheology modifier manufactured by Clariant. The polymer combines a water-soluble AMPS (acrylamido methyl propane sulfonate) backbone with hydrophobic beheneth-25 methacrylate side chains, enabling it to stabilize oil-in-water emulsions through a combination of electrostatic and steric mechanisms without requiring traditional emulsifiers. At 1% concentration in water it achieves approximately 53,600 cP viscosity. It is cold-processable, UV-stable, electrolyte-tolerant, and functions across pH 4–9. It is used in creams, lotions, gels, hair styling products, color cosmetics, and sun protection formulations. It imparts a soft, non-sticky, silky skin feel.

Safety & warnings

The CIR Expert Panel assessed acryloyldimethyltaurate polymers and found them safe as used in cosmetics. Sensitization risk is low owing to large molecular size and negligible skin penetration. Irritancy is low; a related acrylates/beheneth-25 methacrylate copolymer showed slight skin irritation in rabbit studies. Residual acrylamide monomer should be limited to 0.1 mg/kg in leave-on products per EU guidelines. The polymer may release ammonia at pH above 9.0. EWG Skin Deep scores this ingredient at 3 (moderate concern band), primarily reflecting data gaps rather than demonstrated hazard.

Origin & sourcing

Fully synthetic origin. Produced by free-radical crosslinking copolymerization of ammonium 2-acrylamido-2-methylpropanesulfonate (AMPS monomer) with beheneth-25 methacrylate, a PEG ether of behenyl alcohol. The resulting crosslinked network is pre-neutralized to the ammonium salt form before drying to a powder. No plant- or animal-derived raw materials are used; the product is vegan and Halal certified.

History

Aristoflex HMB was developed by Clariant (formerly Hoechst / Süd-Chemie) as a hydrophobically modified variant of the AMPS polymer family. The CIR Expert Panel completed a safety assessment of acryloyldimethyltaurate polymers in 2016, concluding the ingredient class is safe as used in cosmetics. The ingredient appears on the EU CosIng inventory and is registered for use in China.

Questions everyone asks

What does Ammonium Acryloyldimethyl Taurate/Beheneth-25 Methacrylate Crosspolymer do in a sunscreen?

It acts as a rheology modifier and emulsion stabilizer, thickening the formula into a smooth cream or gel texture and helping keep UV-filter particles evenly suspended without the need for conventional emulsifiers.

Is this ingredient the same as Aristoflex HMB?

Yes. Aristoflex HMB is the trade name for this polymer, manufactured by Clariant. The INCI name fully describes its chemical composition.

Is it safe for sensitive skin?

The CIR Expert Panel concluded the ingredient is safe as used. Its large molecular size limits skin penetration, keeping sensitization and irritation risk low. It is rated suitable for normal, dry, oily, and sensitive skin types.

Does it require heat to incorporate into a formula?

No. Aristoflex HMB is cold-processable and pre-neutralized, meaning it can be dispersed and activated in water at room temperature, simplifying manufacturing.