Dimethylsilanediol is a chemical compound, diol monomer, monomeric unit of polydimethylsiloxane, consisting of 99.9 % dimethylsilanediol and oligomers (1).

Dimethylsilanediol is an organosilicon compound widely used in the cosmetic industry for its moisturizing, regenerative, and antioxidant properties. It belongs to the silane family and is primarily used as a conditioning and protective agent in skincare and haircare products. Due to its ability to enhance skin elasticity and strengthen hair, it is a valuable ingredient in many personal care formulations.

Chemical Composition and Structure
Dimethylsilanediol has a silicon-based chemical structure with two methyl groups attached to a silicon atom and two hydroxyl groups (OH). This structure enables the compound to bind with water, improving hydration and offering antioxidant properties. Silicon, a key component of Dimethylsilanediol, is known for its role in maintaining the integrity of connective tissues, supporting skin regeneration, and strengthening hair.

Physical Properties
Dimethylsilanediol is typically a clear, colorless liquid that is water-soluble and easily incorporated into skincare and haircare formulations. Its film-forming and conditioning properties make it ideal for enhancing the texture and protection of both skin and hair.

Production Process
Dimethylsilanediol is synthesized through chemical reactions involving organosilicon compounds. This process results in a highly pure compound suitable for use in cosmetic and personal care products. It is then stabilized to ensure long shelf life and optimal performance in formulations.

Applications

• Skincare: Dimethylsilanediol is used in creams, serums, and lotions to improve hydration and provide antioxidant benefits. It helps strengthen the skin barrier, improve elasticity, and reduce visible signs of aging.

• Haircare: In shampoos, conditioners, and hair masks, Dimethylsilanediol strengthens the hair fiber, preventing breakage and enhancing shine and softness.

• Cosmetic Products: Used as a conditioning and protective agent, it improves the texture of various formulations, ensuring smooth application and a silky feel.

Health and Safety Considerations

Safety in Use
Dimethylsilanediol is considered safe for use in cosmetic products. It is generally well-tolerated by both skin and hair, and it is not known to cause irritation or sensitization. Its moisturizing and protective properties make it suitable for a wide range of skin types, including sensitive skin.

Allergic Reactions
Allergic reactions to Dimethylsilanediol are rare. However, as with any cosmetic ingredient, a patch test is recommended before using new products, especially for individuals with particularly sensitive skin.

Toxicity and Carcinogenicity
There is no evidence that Dimethylsilanediol is toxic or carcinogenic. It is widely used in cosmetic products and is considered safe at recommended concentrations. Safety studies have confirmed that it does not pose significant health risks to humans.

Environmental and Safety Considerations
Dimethylsilanediol is a biodegradable compound and does not pose significant environmental risks. As part of the silane family, it degrades easily under natural environmental conditions, minimizing its ecological impact.

Regulatory Status
Dimethylsilanediol is approved for use in cosmetics by regulatory bodies such as the European Union and the Food and Drug Administration (FDA) in the United States. It is considered safe for use in a wide range of skincare and haircare formulations.

Safety

Despite the concerns of some in the press about soil pollution by Dimethylsilanediol, the scientific literature has downgraded the problem by showing that degradation is slow and under field conditions as predicted by laboratory experiments (2). Recently found in the ISS space station in a wet zone.

For more information:

Dimethylsilanediol studies

Typical commercial product characteristics Dimethylsilanediol

Appearance	White to Off-white Solid
Boiling Point	122.2ºC at 760mmHg
Flash Point	27.7°C
Density	0.998g/cm3
Loss on drying	≤2.0%
Sulphated ash	≤0.5%/g
Water	≤1.0%
Heavy metals	Heavy metals
Impurities	≤0.5%
Purity	≥99.0%
PSA	40.46000
Vapor Pressure	6.73mmHg at 25°C
Refraction Index	1.414
Storage	-86°C,
Safety

• Molecular Formula  C₂H₈O₂Si
• Molecular Weight     92.17
• Exact Mass   92.02940
• CAS  1066-42-8
• UNII    
• EC Number   213-915-7
• DSSTox Substance ID  DTXSID001019098
• IUPAC  dihydroxy(dimethyl)silane
• InChI=1S/C2H8O2Si/c1-5(2,3)4/h3-4H,1-2H3  
• InChl Key      XCLIHDJZGPCUBT-UHFFFAOYSA-N
• SMILES   C[Si](C)(O)O
• MDL number  MFCD19441445
• PubChem Substance ID    
• ChEBI  23816

Synonyms

• Silanediol, dimethyl-
• Dihydroxydimethylsilane
• dihydroxy(dimethyl)silane

References_________________________________________________________________________

(1) Sabourin CL, Carpenter JC, Leib TK, Spivack JL. Biodegradation of dimethylsilanediol in soils. Appl Environ Microbiol. 1996 Dec;62(12):4352-60. doi: 10.1128/aem.62.12.4352-4360.1996.

Abstract. The biodegradation potential of [14C]dimethylsilanediol, the monomer unit of polydimethylsiloxane, in soils was investigated. Dimethylsilanediol was found to be biodegraded in all of the tested soils, as monitored by the production of 14CO2. When 2-propanol was added to the soil as a carbon source in addition to [14C]dimethylsilanediol, the production of 14CO2 increased. A method for the selection of primary substrates that support cometabolic degradation of a target compound was developed. By this method, the activity observed in the soils was successfully transferred to liquid culture. A fungus, Fusarium oxysporum Schlechtendahl, and a bacterium, an Arthrobacter species, were isolated from two different soils, and both microorganisms were able to cometabolize [14C]dimethylsilanediol to 14CO2 in liquid culture. In addition, the Arthrobacter sp. that was isolated grew on dimethylsulfone, and we believe that this is the first reported instance of a microorganism using dimethylsulfone as its primary carbon source. Previous evidence has shown that polydimethylsiloxane is hydrolyzed in soil to the monomer, dimethylsilanediol. Now, biodegradation of dimethylsilanediol in soil has been demonstrated.

(2) Lehmann RG, Miller JR, Kozerski GE. Degradation of silicone polymer in a field soil under natural conditions. Chemosphere. 2000 Sep;41(5):743-9. doi: 10.1016/s0045-6535(99)00430-0. 

Abstract. Silicone polymers (PDMS = polydimethylsiloxane) are used in numerous consumer and industrial products. Our previous work showed that they will degrade in soil under laboratory conditions. This paper investigates PDMS degradation in the field. Four soil plots (each 2.44 m x 2.44 m) in Michigan were sprayed in May, 1997, with aqueous emulsion to achieve nominal soil PDMS concentrations of 0 (control), 215 (low), 430 (medium), and 860 (high) microg/g. Over the following summer, soil cores (0-5 and 5-10 cm) were collected every two weeks and analyzed for decrease in-total soil PDMS, and decrease in molecular weight of remaining PDMS. PDMS concentrations decreased 50% in 4.5, 5.3, and 9.6 weeks for the low, medium, and high treatments, respectively. Degradation rates were 0.26 (low), 0.44 (medium), and 0.44 (high) g PDMS/m2 day, indicating that degradation capacity of the soil was exceeded by the High treatment. Dimethylsilanediol (DMSD), the main degradation product, was detected in most samples at <5% of original PDMS. This is consistent with laboratory data showing biodegradation and volatilization of DMSD. Deeper sampling (to 20 cm) found only trace amounts of DMSD, and minor downward movement of the polymer. Respraying and subsequent analysis of one plot with a medium treatment in late August showed slow PDMS degradation during the cool, wet fall, followed by a 40% decrease over winter and extensive degradation during the summer of 1998. The study thus shows that PDMS will degrade under field conditions as predicted from laboratory experiments.