Common Name(s): Polyurea crosspolymer-1,crosslinked polyacrylate network,carbomer-class rheology modifier

CAS Number: N/a

DESCRIPTION

What It Does: Polyurea crosspolymer-1 thickens aqueous formulations into stable transparent gels, suspends particles (pigments, exfoliants, actives) in gel matrices, provides the elegant spreading and 'breaking' feel of premium serum textures, and creates a film on skin during application that provides a smooth, non-tacky finish. its shear-thinning rheology means it flows easily when pumped or spread but immediately rebuilds gel structure at rest.

Why It's Used: Formulators choose polyurea crosspolymer-1 as the cornerstone thickening technology for serums, gel moisturisers, and clear toners because of its exceptional efficiency — 0.1–0.5% provides the same viscosity as 2–5% of natural gums, enabling clear, light formulations with minimal ingredient loading. the crosslinked architecture provides yield stress (gel strength threshold before flow begins) that stabilises suspended particles and prevents sedimentation in physical spf sunscreens, face masks with microbeads, and vitamin c powder formulations. the carbomer gel also provides optimal release kinetics for actives — the swollen polymer network retards diffusion, providing controlled release of water-soluble actives from the gel matrix during application.

How It Works: Polyurea crosspolymer-1 works through neutralisation-driven polymer coil expansion: the polyacrylic acid polymer consists of carboxylic acid groups (–cooh, pka 4.5–5.5) distributed along a crosslinked backbone. in the unneutralised state (ph <4), –cooh groups are protonated and the polymer chains coil compactly from hydrogen-bonding interactions — low viscosity. when base (naoh, tea, amp) is added raising ph above pka, –cooh groups ionise to –coo⁻ — the like-charge electrostatic repulsion between adjacent –coo⁻ groups forces the polymer chains to expand dramatically (100–1000× volume increase). above the chain overlap concentration c* (typically 0.1–0.5% for crosslinked carbomers), the expanded chains form an entangled viscoelastic network providing gel viscosity, yield stress, and transparent clarity. the crosslinks (typically divinyl glycol or pentaerythritol allyl ether) prevent the expanded chains from fully dissolving while maintaining the swollen gel architecture — the crosslink density controls gel strength and molecular weight between crosslinks determines elasticity vs viscosity balance.

Typically Found In: Gel serums,transparent formulas,particle suspension

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: 0.1%–2%

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Carbomer yield stress suspension mechanism: carbomer gels have a yield stress τ_y (~1–50 pa depending on concentration and crosslink density). for a particle to sediment, the gravitational force on it must exceed τ_y × particle cross-section area. for a 50 μm particle of density 1.2 g/cm³, gravitational force ≈ 3×10⁻⁸ n. carbomer gels at 0.5% provide τ_y ≈ 10 pa × area ≈ 2×10⁻⁸ n suspension force — barely sufficient. at 1%, τ_y ≈ 50 pa providing 10⁻⁷ n suspension force — robust. this quantitative balance between particle gravitational force and polymer yield stress is why formulating physical sunscreen suspensions requires matching carbomer concentration to particle size and density.

Last Verified: Cosing database,carbomer neutralisation gel mechanism review

Primary Sources: 2026-03-12