Silicone Oils and Fluids — PDMS, Amino, Hydroxy, Methyl-Hydrogen, Vinyl, Cyclic, Phenyl Grades

Overview

Silicone oils — linear or cyclic polysiloxanes with a siloxane backbone (–Si–O–Si–O–) and methyl, hydrogen, or organofunctional side groups — are the workhorse fluids of cosmetic, textile, silicone rubber, automotive, and coating formulation. The property combination has no organic equivalent:

• Thermal stability — most grades −50°C to +200°C continuous; phenyl-modified to +300°C
• Surface activity — low surface tension (20–22 mN/m for PDMS) enables wetting, slip, defoaming
• Chemical inertness — siloxane backbone unreactive to acids / bases / oxidants; side groups can be functionalised
• Biocompatibility — low irritation; many grades FDA-approved for cosmetics
• Lubricity — viscosity tunable across 4 orders of magnitude without solidification

East Materials supplies seven silicone fluid families covering major industrial use cases, viscosity 5 cSt (cyclomethicone D5) to 100,000 cSt (damping fluid). Every batch is REACH-registered (with appropriate SVHC documentation for D4/D5), tested for viscosity, density, refractive index, and volatiles. Functional equivalents to Dow Corning DC200 / DC PMX, Wacker AK / V / BS, Shin-Etsu KF, and Momentive Silwet series at 35–50% landed-cost discount.

For silicone rubber compounding fillers see HJSIL® Fumed Silica; for paint formulation context see Coatings hub.

The 7 Silicone Fluid Families

1. Polydimethylsiloxane (PDMS) — non-reactive dimethyl

Linear silicone with trimethylsilyl end caps, viscosity 5 → 100,000 cSt continuum. The most-used silicone in industry.

• Structure: (CH₃)₃SiO–[Si(CH₃)₂O]ₙ–Si(CH₃)₃ · CAS 63148-62-9 (some viscosity ranges 9006-65-9)
• Reference: Dow DC200, Wacker AK, Shin-Etsu KF-96
• Common viscosities (cSt): 5, 10, 50, 100, 200, 350, 500, 1000, 5000, 10000, 30000, 60000, 100000
• Use: defoamer base, release agent, lubricant, hydraulic damping, polish, cosmetic emollient, silicone rubber base precursor

2. Amino-Functional Silicone

Linear PDMS with primary/secondary amine side groups; amine anchors to cellulose, protein, and synthetic fibre surfaces for durable softening.

• Structure: PDMS + [Si(CH₃)(CH₂CH₂CH₂NHCH₂CH₂NH₂)O] pendants · CAS 71750-80-6 (amodimethicone)
• Reference: Dow DC929 / Silastic AM, Wacker FZ-3196, Momentive SF1708
• Spec: amine value 0.3–1.2 mg KOH/g, viscosity 500–3000 cSt
• Use: textile softeners (20+ wash-cycle durability vs 2–3 for non-functional), hair conditioner microemulsion 0.5–2%, automotive leather softener

3. Hydroxy-Terminated Silicone (Silanol-Terminated PDMS)

Linear PDMS with –OH end groups instead of methyl. The terminal silanol is the reactive site for condensation-cure silicone rubber, sealants, and adhesives.

• Structure: HO–[Si(CH₃)₂O]ₙ–H · CAS 70131-67-8
• Reference: Dow Silres / Genesee Polymers GP-1, Wacker E series
• Spec: OH 0.05–4.0%, viscosity 750–80,000 cSt
• Use: RTV-1 acetoxy / alkoxy silicone sealant base polymer; many RTV-2 silicone moulds. 750 cSt for low-viscosity RTV-2 moulds → 80,000 cSt for HCR mill-compoundable

4. Methyl Hydrogen Silicone (PMHS / Polymethylhydrosiloxane)

Linear polysiloxane with Si–H side groups on every silicon. Si–H is the reactive crosslinker for addition-cure silicone rubber via hydrosilylation with vinyl-PDMS.

• Structure: (CH₃)₃SiO–[Si(H)(CH₃)O]ₙ–Si(CH₃)₃ · CAS 63148-57-2
• Reference: Dow OFX-1107, Wacker M series, Momentive Y-17056
• Spec: Si–H 6–16 mol/kg (some 30–50% Si–H copolymer for slower crosslinking), viscosity 5–100 cSt
• Use: addition-cure silicone rubber crosslinker; textile DWR water-repellent (Si–H hydrolyses to silanol on fibre, then condenses to hydrophobic film); pigment surface treatment; leather hydrophobic finish

⚠️ Critical handling: PMHS releases hydrogen gas in presence of strong base or moisture at >50°C. Dry storage <30°C, closed-system handling. Do not seal containers if subjected to elevated temperature during transit.

5. Vinyl-Terminated Silicone (V-PDMS)

Linear PDMS with vinyl end groups, the reactive site for addition-cure (hydrosilylation) with PMHS under platinum catalysis. Base polymer of LSR and addition-cure RTV-2.

• Structure: CH₂=CH–Si(CH₃)₂O–[Si(CH₃)₂O]ₙ–Si(CH₃)₂–CH=CH₂ · CAS 68083-19-2
• Reference: Gelest DMS-V31/V35, Dow XIAMETER PMX-200V, Wacker V200/V1000
• Spec: vinyl 0.05–0.5 mmol/g, viscosity 100–100,000 cSt
• Use: LSR injection moulding (medical, baby care, automotive seals), addition-cure RTV-2 (resin-casting moulds), electronic encapsulants. Typical formulation 100 V-PDMS : 5 PMHS : 0.01 Pt catalyst. Grade differentiated by viscosity (flow + crosslink density) and vinyl content (hardness)

6. Cyclomethicone (Cyclic Silicone, D4 / D5 / D6)

Volatile cyclic polysiloxanes used as carrier fluids in personal care. Evaporates after application leaving actives on skin/hair surface.

• Structure: cyclic [Si(CH₃)₂O]ₙ, n = 4 (D4) / 5 (D5) / 6 (D6) · CAS D4 556-67-2, D5 541-02-6, D6 540-97-6
• Reference: Dow XIAMETER 244 / 245 / 246, Wacker AK Volatile, Shin-Etsu KF-994 / 995
• Spec: purity ≥99%, BP D4 = 175°C, D5 = 211°C, D6 = 245°C; viscosity 2.5–7.0 cSt
• Use: hair care (shampoo, conditioner, leave-in spray) — smooth slip + clean evaporation; cosmetic foundation, deodorant; "dry-touch" emollient

⚠️ Regulatory: D4 = REACH SVHC since 2018, D5 added 2024. EU rinse-off cosmetics still permit ≤0.1% D5; leave-on restricted. Check current EU REACH / ECHA guidance before specifying.

7. Phenyl-Modified Silicone

PDMS with phenyl side groups replacing some methyl. Improves high-temp stability (continuous use to 300°C), oxidative stability, and refractive index (matches glass for optical adhesive).

• Structure: PDMS + [Si(C₆H₅)(CH₃)O] or [Si(C₆H₅)₂O] pendants · CAS 63148-58-3
• Reference: Dow 510 fluid, Wacker AP series, Shin-Etsu KF-50
• Spec: phenyl 5–50 mol%, refractive index 1.430–1.580, viscosity 50–10,000 cSt
• Use: high-temp heat-transfer fluid; optical adhesive (LED encapsulation); plasticiser in high-temp silicone rubber. Specified at the high-end of thermal applications

8. Modified Silicone Fluids (Alkyl / Polyether / Carboxyl / Epoxy)

PDMS with specific organic modifications for specialty use:

• Alkyl-modified (octyl / cetyl / stearyl side groups) — emulsifier-free cosmetic, hair conditioner active
• Polyether-modified (PEG / PPG side groups) — paint slip / leveling additive, waterborne coating wetting agent
• Carboxyl-functional — textile DWR crosslink partner
• Epoxy-functional — adhesion promoter in silicone-organic resin hybrids
• Trimethyl Hydrogen Hybrid (T-PMHS) — lower Si–H, slower cure for skin-curing formulations

Applications and Formulation Guidance

Procurement, Storage, and QC

Packaging, MOQ, and lead time:

Storage: PDMS / modified — ambient, 24 mo sealed. Hydroxy-terminated — dry storage <25°C, 18 mo. PMHS — dry <25°C, away from heat and base, 12 mo. Vinyl-terminated — ambient, 24 mo. Cyclomethicones — tight-sealed, away from open flame, 24 mo.

QC documentation (every batch CoA includes):

• Kinematic viscosity at 25°C — ASTM D445
• Density at 25°C — ASTM D4052
• Refractive index at 25°C — ASTM D1218
• Volatile content (105°C × 3 hr for non-volatile; GC quantification for D5/D6 in cyclomethicones)
• Functional content (amine value / OH content / Si–H content / vinyl content for functional grades — ASTM titration)
• Heavy metals (Pb / As / Cd / Hg) for cosmetic and food-contact grades

Regulatory: PDMS / amino / modified — REACH-registered. Hydroxy-terminated / vinyl / PMHS — REACH-registered via UK/EU Only Representative. D4 / D5 — REACH SVHC, restricted documentation required.

Specification Table — All Silicone Fluid Families

Selection Guide

FAQ

Can East Materials silicone fluids be used in cosmetic / food-contact applications?

Yes for most grades. PDMS, cyclomethicones D5/D6, and amino silicones have FDA 21 CFR 175.300 compliance pathway for indirect food contact. Cosmetic-grade documentation (heavy metals < pharmacopoeia limits, BHT not added, microbial bioburden) is available for PDMS, D5, and amino silicone on contract supply. D4 is REACH SVHC and is restricted — we recommend D5 or D6 as substitutes (note D5 is also SVHC-listed since 2024).

How do I switch from Dow Corning DC200 / Wacker AK to East Materials PDMS?

Direct 1:1 substitution by viscosity grade. Independent testing shows East Materials PDMS 350 cSt matches Dow DC200 350 cSt within ±5% on viscosity, density, refractive index, and surface tension. Common reformulation watch-outs: (1) defoamer formulations may require adjustment for slightly different silica-PDMS interaction; (2) cosmetic formulations should be re-microbial-tested when switching suppliers (industry standard).

What's the difference between PDMS and hydroxy-terminated PDMS?

PDMS has –CH₃ end groups (chemically inert). Hydroxy-terminated PDMS has –OH (silanol) end groups (reactive). Use PDMS for non-reactive applications (defoamer, mould release, hair care emollient). Use hydroxy-terminated PDMS for reactive applications (silicone sealant base polymer, condensation-cure silicone rubber). NOT interchangeable.

How do I handle PMHS (methyl hydrogen silicone) safely?

PMHS contains Si–H bonds that release hydrogen gas in presence of strong base or water at >50°C. Storage: tight-sealed, dry, below 30°C, away from heat sources. Production: closed-system batch reactors with inert gas blanket. Avoid: caustic soda, ammonia, strong amines. Personnel: full skin and eye protection. SDS includes specific safety guidance — request before first order.

Is D5 cyclomethicone subject to EU regulation?

Yes. D4 is REACH SVHC since 2018; D5 was added as REACH SVHC in 2024. EU rinse-off cosmetic products still permit D5 at ≤0.1%; leave-on cosmetic products (foundation, deodorant, hair spray) face escalating restrictions. Manufacturers should track current ECHA guidance. East Materials supplies D5 with appropriate certification, but end-use compliance burden rests with the formulator.

What is the typical lead time and MOQ?

Standard grades (PDMS / amino / modified): 3–5 weeks FOB Shanghai, MOQ 200 L (one drum). Specialty (hydroxy-terminated / vinyl-terminated / PMHS): 4–6 weeks, MOQ 200 L. Cyclomethicones: 3–4 weeks, MOQ 25 L (premium D5 / D6). Container shipments are available across blended grades — order 8 weeks ahead for confirmed delivery.

Related & Sister Sites

• HJSIL® Fumed Silica — silica reinforcement and rheology additive used with silicone fluids.
• MEGEL® Silica Aerogel — for silicone-binder thermal-insulation coating slurries.
• HMMAT® Matting Agents — matting silica often combined with silicone slip additives.
• Coatings Application Hub — for silicone oil as coating additive.
• For silicone curing catalysts (DBTDL, T-12, dioctyltin, platinum) that go with hydroxy- and vinyl-terminated silicones, see chemzip.com/products/silicone-curing-catalysts/. For silane coupling agents (KH-550 etc.) as substrate adhesion promoters, see chemzip.com/products/silane-couplers/. For silicone-rubber-compatible refractory and high-temperature applications, see thermaleast.com.