Poly(dimethylsiloxane)

Catalog	ACM107517-8
CAS	107-51-7
Structure
Description	Poly(dimethylsiloxane) (PDMS), also known as dimethicone, is an organosilicon compound that is widely used as a siloxane based elastomer. It is a hydrophobic material with attractive physical and chemical properties such as elasticity, optical transparency, tunable surface chemistry, and low electrical conductivity.
Synonyms	Octamethyltrisiloxane
IUPAC Name	dimethyl-bis(trimethylsilyloxy)silane
Molecular Weight	236.53
Molecular Formula	[(CH3)3SiO]2Si(CH3)2
Canonical SMILES	C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C
InChI	1S/C8H24O2Si3/c1-11(2,3)9-13(7,8)10-12(4,5)6/h1-8H3
InChI Key	CXQXSVUQTKDNFP-UHFFFAOYSA-N
Boiling Point	153 °C (lit.)
Melting Point	-82 °C (lit.)
Density	0.82 g/mL at 25 °C (lit.)
Solubility	1.44e-07 M;Immiscible with water;Immiscible with alcohol;Miscible with chloroform; soluble in chlorinated hydrocarbons, benzene, toluene, xylene, n-hexane, petroleum spirits, ether, amyl acetate; very slightly soluble in isopropyl alcohol; insoluble in methanol, acetone
Application	Poly(dimethylsiloxane) serves as a versatile compound with a wide range of applications due to its unique chemical properties. It is most commonly used as an antifoaming agent in various industrial processes and consumer products. In the food industry, it effectively prevents foaming and spattering in heated oils and minimizes foam formation during the production of wine, refined sugar, gelatin, and chewing gum. Its role in medical applications is also significant, being used extensively in prostheses like breast implants because of its low toxicity profile, as demonstrated by animal testing. Additionally, when combined with silica gel to form simethicone, it alleviates bloating by reducing gas bubble surface tension in the digestive system, making it a common ingredient in antacids and treatments for infant colic. Overall, poly(dimethylsiloxane) exemplifies the valuable characteristics of silicones, providing practical solutions across various sectors.
Packaging	50 mL in glass bottle
RefractiveIndex	n20/D 1.384 (lit.)
Stability	Stable to heat and ... resistant to most chemical substances, although they are affected by strong acids.
Vapor Pressure	3.34 mmHg
Viscosity	1.0 cSt(25 °C)

Case Study

Development of Flame-Retardant Graphene Derivative/Polydimethylsiloxane Foam Nanocomposites

Cao, Cheng-Fei, et al. Chemical Engineering Journal, 2020, 393, 124724.

Polydimethylsiloxane (PDMS) foams (SiRF) possess inherent mechanical flexibility, non-toxicity, electrical resistance, high-temperature stability, and flame resistance due to their strong Si-O-Si backbone. However, the organic side chains compromise their stability under high heat or flame. This work introduces a facile, green in situ surface assembly method to bond two graphene oxide (GO) derivatives-flakes and nanoribbons (GONRs)-onto SiRF foam surfaces.
Key Findings
· Morphological and structural analysis confirmed the formation of compact GONR or GO coatings on SiRF foam at an ultralow content (~0.10 wt%). These coatings significantly enhanced the foam's mechanical properties and thermal stability.
· Crucially, even at this minimal loading, both GONRs and GO sheets imparted excellent flame resistance. The Limiting Oxygen Index (LOI) increased from ~20.8% (pure SiRF) to 26.7% (SiRF-GONR0.10%) and 27.4% (SiRF-GO0.10%).
· Cone calorimetry tests showed substantial improvements: ~31% (GONR) and ~40% (GO) reduction in peak heat release rate (PHRR), and ~80% (GONR) and ~95% (GO) reduction in total smoke release (TSR).
· Post-burn analysis revealed that while pure SiRF formed a porous silica structure, the nanocomposites developed a protective layer-partly covered silica/rGONR for SiRF-GONR and a well-covered, compact silica/rGO layer for SiRF-GO-effectively inhibiting internal PDMS decomposition.

The Combination of Polydimethylsiloxane-Coated Aluminum Diethylphosphite Enhances Flame Retardancy in Polyamide 6 Materials

Pan, Ying, et al. Journal of Applied Polymer Science, 2020, 137(35), 49027.

The research investigated how a composite material with flame retardant properties behaves when aluminum diethylphosphite (ADP) is encapsulated within polydimethylsiloxane (PDMS) and merged into a polyamide 6 (PA6) matrix.
Modification of PDMS-Coated ADP
To modify ADP, aluminum diethylphosphinate powders were mixed with a chloroform solution containing 2 wt% PDMS prepolymer and 0.2 wt% curing agent for 10 minutes. The modified ADP powders were then filtered and rinsed with chloroform before being dried at 80°C for 2 hours.
Preparation of PA6/PDMS-ADP Composites
The PA6/PDMS-ADP composites were created using the melt-mixing method. Both PDMS-ADP and PA6 were dried at 80°C for 12 hours prior to processing. PA6 was melted at 220°C on a two-roll mixing mill, after which PDMS-ADP powders were added. The mixing was conducted at a roller speed of 100 rpm for 10 minutes. The resulting mixtures were then hot-pressed at a pressure of 10 MPa for 10 minutes to achieve the desired thickness in the samples.
Key Findings
PA6/ADP and PA6/PDMS-ADP composites demonstrate significantly reduced flammability compared to unmodified PA6. Both PA6-1 with 15 wt% ADP and PA6-4 containing 12 wt% PDMS-ADP composites attained UL-94 V-0 certifications during vertical flame tests. Measurements revealed that PA6-1 and PA6-4 reached peak heat release rates of 212 kW/m2 and 192 kW/m2 which showed reductions of 67.3% and 70.4% compared to pure PA6. The results demonstrate that flame-retardant performance of ADP improves when it is coated with PDMS.

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