Chemical Properties
colourless liquid with a viscosity, The polydimethylsiloxane materials are excellent examples of silicones because of their chemical properties and widespread industrial use. They can be manufactured as gels, resins, fluids, or elastomers, depending on the cross-linking characteristics. Toxicity testing using polydimethylsiloxane compounds on animals has found little, if any, harmful effects associated with chronic exposure. These tests include oral dosing and teratogenicity testing (Cutler et al., 1974; Kennedy et al., 1976). Human health effects associated with silicone implants have been reported. Polydimethylsiloxane is the most prevalent silicone used medically and has been incorporated into many prostheses, including breast implants.
Uses
Silicones are polymeric materials having silicon and oxygen on their composition. They are largely inert compounds usually heat-resistant, nonstick, and rubberlike. Polydimethylsiloxane (PDMS, molecular formula (C2H6OSi)n, density 965 kg/m3, boiling point: < 200℃, shear modulus between 100 kPa and 3 MPa, loss tangent less than 0.001) is a viscoelastic polymer (elastomer). PDMS is widely used in microfluidic technology thanks to some of its unique properties: it is low cost, nontoxic, chemically resistant, and stable against humidity and temperature variations. PDMS also presents low interfacial energy, which allows it to avoid chemical interactions with other polymers and solutions in the microfluidic channels. After polymerization and cross-linking, solid PDMS presents hydrophobic surface. A treatment using plasma oxidation is frequently used to alter the surface chemistry by adding silanol (SiOH) groups to the surface terminations and make the surface hydrophilic (wettable). PDMS is usually used as sealant, structural microchannel material or elastomer stamping matrix in soft lithography techniques like microcontact printing and micromolding.
Uses
Poly(dimethylsiloxane) is an antifoaming agent used in fats and oils. It prevents foaming and spattering when oils are heated and prevents foam formation during the manufacture of wine, refined sugar, gelatin, and chewing gum. It is also termed methyl polysilicone and methyl silicone.
brand name
Gas-X (Novartis); Mylanta Gas Relief (Johnson & Johnson-Merck Consumer); Mylicon Infant’s Drops (Johnson & Johnson-Merck Consumer); Sentry Simethicone (Witco); Sentry Simethicone Emulsion (Witco).
General Description
Colorless odorless liquid, Floats on water.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
Poly(dimethylsiloxane) is a weak reducing agent.
Health Hazard
Contact of liquid with eyes may cause temporary discomfort. Does not irritate skin. Harmless when ingested.
Pharmaceutical Applications
Simethicone is a mixture of poly(dimethyl siloxane) and silica gel, known for their antifoaming properties. It is an orally administered suspension containing polysiloxanes and silicon dioxide. It is an antifoaming agent and is used to reduce bloating by decreasing the surface tension in bubbles. Excessive formation of gas bubbles in the stomach and intestines can be painful and can also be of hindrance for any ultrasound examination. Simethicone can be found in antacids and in suspensions given to babies against colic.
Biochem/physiol Actions
Dimethylpolysiloxane is a silicon-based organic polymer, inert and non-toxic. It is applicable in the pharmaceutical, food, and cosmetic industry. Dimethylpolysiloxane is excreted unchanged unaltered in the faeces and is non-mutagenic.
