Styrene/Isoprene Copolymer

Styrene/Isoprene Copolymer 1
AKA: Styrene-Isoprene Copolymer
Synthetic
Occlusive
Clean
Benzene, ethenyl-, polymer with 2-methyl-1,3-butadiene
CAS #
25038-32-8
Form
Liquid
State
Solid
Functions
Film Forming
Creates a physical seal on skin to lock moisture in and keep irritants out. The "slugging" ingredient — barrier protection.
Opacifying
Creates Protective Barrier
Adds Opacity
Reduces Inflammation
Locks In Moisture
Wound Healing
Creates protective layer
Creates creamy opacity
Traditional Use
A synthetic polymer developed in the 20th century combining styrene and isoprene monomers. Used in cosmetics as a film-forming agent without traditional historical precedent.
EWG
1
CIR
Safe as used
Pregnancy
Caution
CIR Safety Findings
medical-approval
all-shades-safe
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: CosIng · EWG · CIR