What it is
Hydrogenated styrene/isoprene copolymer is a synthetic elastomeric polymer made from styrene and isoprene monomers that is then hydrogenated for stability. It thickens and gels oil phases and forms a flexible film, which helps anchor pigments and other ingredients onto the skin. It is frequently used in stick formats and other anhydrous products to provide structure and a cohesive, wear-resistant feel.
Safety & warnings
As a large, inert synthetic polymer, it is generally considered non-irritating and is not absorbed into the skin. It is used as a structuring agent rather than an active ingredient.
Origin & sourcing
It is a fully synthetic petrochemical-derived polymer produced by polymerizing styrene and isoprene and then hydrogenating the chains.
Questions everyone asks
Why is this polymer used in sunscreen sticks?
It thickens and structures the oil phase and forms a flexible film, helping the product hold its shape and adhere evenly to skin.
Is it a natural ingredient?
No, it is a synthetic polymer made from styrene and isoprene that is then hydrogenated for greater stability.