Polydimethylsiloxane
Systematic name	Polydimethylsiloxane
Other names	PDMS, dimethicone, E900
Chemical formula	(CH3)3SiO[SiO(CH3)2]nSi(CH3)3
Density	965 kg/m3
Melting point	xx.x °C
Boiling point	xx.x °C
Glass transition temperature	-125 °C
CAS number	[63148-62-9]
Disclaimer and references

Polydimethylsiloxane (PDMS) is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties. It is optically clear, and is generally considered to be inert, non-toxic and non-flammable. PDMS has been assigned CAS number 63148-62-9, and is occasionally called dimethicone. It is one of several types of silicone oil. Image File history File links PDMS.png‎ Polydimethylsiloxane (PDMS), created by Arthuralbano 02:49, 20 October 2006 (UTC), using Chemdraw Ultra from Cambridgesoft Corporation. ... Image File history File links Download high-resolution version (1000x673, 207 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Polydimethylsiloxane ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... A material’s glass transition temperature, Tg, is the temperature below which molecules have little relative mobility. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... Benzene An organic compound is any member of a large class of chemical compounds whose molecules contain carbon, with the exception of carbides, carbonates, carbon oxides and elementary carbon. ... Polymer is a term used to describe large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. ... Rheology is the study of the deformation and flow of matter. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences and alloys. ... Silicone caulking can be used as a basic sealant against water and air penetration. ...

Chemistry

The chemical formula for PDMS is (H₃C)[SiO(CH₃)₂]_nSi(CH₃)₃, where n is the number of repeating monomer [SiO(CH₃)₂] units. Industrial synthesis can begin from dimethylchlorosilane and water by the following net reaction: A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... Chlorosilanes are a group of reactive, chlorine-containing chemical compounds, related to silane and used in many chemical processes. ... Water is a tasteless, odorless substance that is essential to all known forms of life and is known as the universal solvent. ...

n [Si(CH₃)₂Cl₂] + n [H₂O] → [Si(CH₃)₂O]_n + 2n HCl

During polymerization, this reaction evolves potentially hazardous hydrogen chloride gas. For medical uses, a process was developed where the chlorine atoms in the silane precursor were replaced with acetate groups, so that the reaction product of the final curing process is nontoxic acetic acid (vinegar). As a side effect, the curing process is also much slower in this case. This is the chemistry used in consumer applications, such as silicone caulk and adhesives. R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. ... For a description of caulking in computer game creation, refer to caulking (computer games) Caulking is a process used in the sealing of the seams in wooden boats and making them watertight. ... An adhesive is a compound that adheres or bonds two items together. ...

Silane precursors with more acid-forming groups and fewer methyl groups, such as methyltrichlorosilane, can be used to introduce branches or cross-links in the polymer chain. Ideally, each molecule of such a compound becomes a branch point. This can be used to produce hard silicone resins. Similarly, precursors with three methyl groups can be used to limit molecular weight, since each such molecule has only one reactive site and so forms the end of a siloxane chain. Vulcanization is an example of cross-linking. ... Silicone resins is a type of silicone material which is formed by branched, and cage-like oligosiloxanes with the general formula of RnSiXmOy, where R is a non reactive substituent, usually Me or Ph, and X is a functional group H, OH, Cl or OR. These groups are further condensed...

The polymer is manufactured in multiple viscosities, ranging from a thin pourable liquid (when n is very low), to a thick rubbery semi-solid (when n is very high). PDMS molecules have quite flexible polymer backbones (or chains) due to their siloxane linkages, which are analogous to the ether linkages used to impart rubberiness to polyurethanes. Such flexible chains become loosely entangled when molecular weight is high, which results in PDMS having an unusually high level of viscoelasticity. The pitch drop experiment at the University of Queensland. ... In chemistry, a molecule is an aggregate of at least two atoms in a definite arrangement held together by special forces. ... Ether is the general name for a class of chemical compounds which contain an ether group — an oxygen atom connected to two (substituted) alkyl groups. ... A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... A viscoelastic material is one in which: hysteresis is seen in the stress-strain curve. ...

Mechanical properties

PDMS is viscoelastic, meaning that at long flow times (or high temperatures), it acts like a viscous liquid, similar to honey. However at short flow times (or low temperatures) it acts like an elastic solid, similar to rubber. In other words, if you leave some PDMS on a surface overnight (long flow time), it will flow to cover the surface and mold to any surface imperfections. However if you roll the same PDMS into a sphere and throw it onto the same surface (short flow time), it will bounce like a rubber ball. Viscosity is a measure of the resistance of a fluid to deformation under shear stress. ... A liquid will usually assume the shape of its container. ... Look up Elastic in Wiktionary, the free dictionary. ... In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ...

Hardened PDMS cylinder on the glass of a stereomicroscope light.

Although the viscoelastic properties of PDMS can be intuitively observed using the simple experiment described above, they can be more accurately measured using dynamic mechanical analysis. This involves using a specialized instrument to determine the material's flow characteristics over a wide range of temperatures, flow rates, and deformations. Because of PDMS's chemical stability, it is often used as a calibration fluid for this type of experiment. Image File history File linksMetadata PDMS-cylindertje_onder_stereomicroscoop. ... Image File history File linksMetadata PDMS-cylindertje_onder_stereomicroscoop. ... ... Dynamic mechanical analysis (DMA) or dynamic mechanical thermal analysis (DMTA) is a technique used to study and characterize materials. ...

The shear modulus of PDMS varies with preparation conditions, but is typically in the range of 100 kPa to 3 MPa. The loss tangent is very low (). In materials science, shear modulus S, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain: S = shear stress/shear strain = (F/A)/Φ. Another commonly accepted symbol is G. Shear modulus is usually measured in ksi (kips per square... In physics, the dissipation factor is a measure of the rate of loss of power of a mechanical mode, such as an oscillation, in a dissipative system. ...

Applications

Many people are indirectly familiar with PDMS because it is the primary component in Silly Putty, to which PDMS imparts its characteristic viscoelastic properties. The rubbery, vinegary-smelling silicone caulks, adhesives, and aquarium sealants are also well-known. PDMS is also used as a component in silicone grease and other silicone based lubricants, as well as in defoaming agents, damping fluids, heat transfer fluids, cosmetics, hair conditioner and other applications. PDMS has also been used as a filler fluid in breast implants, although this practice has decreased somewhat, due to safety concerns. It continues to be used in knuckle replacement implants, with good results. It has been suggested that Thinking Putty be merged into this article or section. ... Silicone grease is a waterproof grease made by combining a silicone oil, with a thickener. ... It has been suggested that this article or section be merged into Lubrication. ... In thermal science, heat transfer is the passage of thermal energy from a hot to a cold body. ... The examples and perspective in this article or section may not represent a worldwide view. ... A breast implant is a prosthesis used to enlarge the size of a womans breasts (known as breast augmentation) for cosmetic reasons, to reconstruct the breast (e. ...

Activated dimethicone, a mixture of polydimethylsiloxanes and silicon dioxide (sometimes called simethicone), is used in over-the-counter drug as an anti-foaming agent and carminative. R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Simethicone, is an oral antifoaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract. ... An antifoaming agent is a food ingredient intended to curb effusion or effervescence in preparation or serving. ... A carminative, also known as carminativum ( plural: carminativa), is a medicinal drug with antispasmodic activity that is used against cramps of the digestive tract in combination with flatulence. ...

As a food additive, it has the E number E900 and is used as an anti-foaming agent and an anti-caking agent. Food additives are substances added to food to preserve flavour or improve its taste and appearance. ... For the mathematical constant see: E (mathematical constant). ... An antifoaming agent is a food ingredient intended to curb effusion or effervescence in preparation or serving. ... Anticaking agents are used in such things as table salt to keep the product from forming lumps, making it better for packaging, transport and for the consumer. ...

PDMS is commonly used as a stamp resin in the procedure of soft lithography, making it one of the most common materials used for flow delivery in microfluidics chips. Figure 1 - Inking a stamp. ... Microfluidics deals with the behavior, precise control and manipulation of microliter and nanoliter volumes of fluids. ...

PDMS can be cross-linked into networks and is a commonly used system for studying the elasticity of polymer networks. Vulcanization is an example of cross-linking. ...

External links

• Link page to external chemical sources.