On the spectrum of cosmetic phenyl silicones,
Trimethyl Pentaphenyl Trisiloxane (TPPT) represents the ceiling of phenyl density—not a polydisperse mixture but a single molecule locked at C₃₃H₃₄O₂Si₃ (MW 546.9) (CAS 28855-11-0 / 3390-61-2, listed in
Inventory of Existing Cosmetics Ingredients in China 2021, No. 05761). As luxury lip gloss pursues "water-light translucency," hair oils demand "mirror-shine," and clear antiperspirants trend toward "non-whitening suspension," a
colorless to pale-yellow clear, 175 cSt, closed-cup flash >101℃, 60-month shelf-life high-phenyl silicone emerges as the optical anchor reconstructing interfacial reflection.
Addressing this "defined-structure high-phenyl" slot,
Anhui IOTA Silicone Oil Co., Ltd. (IOTA) releases
High Refractive Cosmetic Phenyl Silicone Fluid IOTA 21555. Defined by core parameters—
Ph₃Si–O–SiPh₂–O–SiPh₃ variant, phenyl/Si ratio 1.67, short-chain siloxane non-greasy—it carries the triple attributes of
"nD 1.58-level optical gain + non-polymeric batch consistency + non-oily cold-process," domestically benchmarking
DOWSIL PH-1555 HRI / DC 555 Cosmetic Fluid, bridging makeup, hair care, skincare, and antiperspirant scenarios.
Molecular Architecture: C₃₃H₃₄O₂Si₃ Five-Phenyl Defined-Structure Optics
IOTA 21555 is 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane:
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Phenyl Density Limit: Five phenyls grafted onto three silicon atoms (avg. 1.67 Ph/Si)—the highest phenyl/silicon ratio among commercial phenyl silicones. Benzene π-electron polarization pushes refractive index naturally to 1.5775-1.5800, +0.12 vs DC556 (nD~1.46) and +0.08 vs IOTA 54 (nD~1.50), approaching optical adhesive territory.
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Defined Small Molecule (Non-Polymeric): No polydispersity, high purity, minimal batch-to-batch nD/viscosity drift—enables "optical metering" in formulation: +1% brightening, +5% mirror-shine, highly reproducible.
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Siloxane Backbone for Skin Feel: Trisiloxane short-chain, 175 cSt at 25℃, fast spreading, thin film, non-comedogenic; lighter than IOTA 54 (400 cSt), no "silicone-heavy" sensation.
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Oxidation & Thermal Stability: Phenyl conjugation absorbs UV, siloxane backbone resists oxidation; open-cup flash 243℃, closed-cup >101℃; stable at 80℃ emulsification without yellowing; clear AP/deo resists haze during long-term storage.
Performance Leap: From "Brightening" to "Optical Reconstruction"
Across makeup, hair care, skincare, and antiperspirant contexts, 21555 reconstructs interfacial reflection:
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Makeup Highlight & Chroma: Lip gloss/lip oil 3-10%—water-light edges, central mirror-shine; foundation 1-5%—soft-focus pore blurring, enhanced pigment loading; eyeshadow—crease-free film, metallic depth.
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Hair Mirror-Shine: Hair oil/conditioner 1-5%—high-nD silicone film over cuticles elevates reflectance; "wet-look" on dark hair, "salon-highlight" on brown tones; non-yellowing vs amino silicones, non-tacky.
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Skincare Soft-Focus Spread: Creams/serums 1-3%—reduces greasy feel, lifts gloss and spreadability, rich yet non-oily skin feel.
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Clear Antiperspirant Suspension: Oil-phase carrier stabilizing actives/aerosols; transparent non-whitening film; dry silky skin after application.
Cosmetic formulators read 21555 plainly: it is the domestic isomorphic of
DC 555 / DOWSIL PH-1555 HRI—five-phenyl trisiloxane defined structure, nD 1.58-level, 175 cSt, 60-month shelf—numbers aligned with import specs. The value is not a new molecule but folding "makeup highlight, hair mirror-shine, clear antiperspirant" into one bucket of pale-yellow clarity, giving color houses and personal care plants a swap when DC 555 lead times wobble.
