Common Name(s): Polysilicone-1,specialty silicone polymer,conditioning silky film-forming

CAS Number: N/a

DESCRIPTION

What It Does: Polysilicone-1 deposits an ultra-thin, flexible conditioning film on skin and hair that dramatically reduces surface friction, provides water-repellent moisture lock-in, protects hair from heat damage and humidity-induced frizz, and delivers the smooth, silky sensory experience that distinguishes premium personal care from basic functional products.

Why It's Used: Formulators choose polysilicone-1 for its unique functional profile that organic emollients cannot replicate: the si-o backbone (bond angle 150° vs c-c 109°) provides exceptional molecular flexibility allowing the silicone polymer to flatten along any surface topology, creating an ultra-conforming film. the surface energy of cured silicone (~20 mn/m) is lower than any organic emollient, providing superior lubricity without the heaviness or comedogenic character of equivalent organic oils. for hair specifically, silicone deposition dramatically reduces the coefficient of friction between hair fibres from ~0.8 (uncoated) to ~0.25 (silicone-coated), providing the detangling and smoothing that defines premium conditioner performance.

How It Works: Polysilicone-1 functions through the si-o siloxane backbone's fundamental physical chemistry: (1) surface deposition — the polymer's backbone flexibility allows it to flatten onto hair and skin surfaces, maximising contact area and van der waals adhesion. the polydimethylsiloxane chain adopts a helical conformation in free solution but extends to near-flat conformation on surfaces, providing maximum coverage per molecule deposited; (2) low surface energy film — the methyl groups surrounding the si-o backbone present an array of non-polar, non-hydrogen-bonding surfaces. the surface energy of ~20 mn/m is lower than water (~72 mn/m) and organic oils (~30–35 mn/m), providing excellent lubricity from the lowest-energy surface; (3) thermal stability — si-o bond energy (105 kcal/mol vs c-c 83 kcal/mol) provides exceptional heat resistance, making dimethicone uniquely suitable as a heat-protectant on hair during blow-drying and flat-ironing up to 230°c; (4) breathability — despite the water-repellent surface, silicone films have sufficient molecular-scale porosity to allow oxygen, co₂, and water vapour transmission from the film's non-crystalline, flexible structure — unlike occlusive waxes that form dense impermeable films.

Typically Found In: Hair conditioners,skin care emollients,heat protectants

TECHNICAL DETAILS

Primary Category: Functional ingredient – emollient

Secondary Functions: Barrier sealing,softening

Application Areas:

Typical Concentration Range: 0.5%–25%

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Plant-derived, synthetic or animal-derived. verify source.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 1/5 – low; formulation-dependent

Sensitivity Concerns: Non-irritating.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Humectants,ceramides,actives as carrier

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Si-o backbone flexibility vs organic polymers: c-c bond angle is fixed at 109.5° (tetrahedral sp3) with restricted rotation, giving organic polymer chains a preferred helical structure that resists lying flat on surfaces. si-o bond angle is 150° with near-free rotation from the longer si-o bond (1.64 å vs c-c 1.54 å) and lower rotational barrier (~0.6 kcal/mol vs c-c ~3 kcal/mol). this 5× lower rotational barrier allows silicone chains to adopt virtually any conformation essentially free of energy cost — enabling the flat, conforming surface adsorption that provides optimal thin-film coverage and explains the silky-smooth feel unobtainable from rigid organic polymer films.

Last Verified: Cosing database,polysilicone-1 silicone film conditioning review

Primary Sources: 2026-03-12