Poly(methylhydrosiloxane)
[CAS# 63148-57-2]

Identification

• Classification: Food additive >> Defoamer
• Name: Poly(methylhydrosiloxane)
• Molecular Formula: C₃H₉OSi^.(CH₄OSi)_n^.C₃H₉Si
• Molecular Weight: 1700-3200
• CAS Registry Number: 63148-57-2
• EC Number: 613-152-3
• SMILES: [Si](C)(C)(C)C.[Si](O)(C)(C)C.[SiH](O)(C)C

Properties

• Density: 1.006 g/mL (25 ºC)
• Refractive index: 1.398

Safety Data

• Safety Description: S23;S24/25

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319

Discovory and Applicatios

Poly(methylhydrosiloxane), often abbreviated as PMHS, is a type of organosilicon polymer consisting of a backbone of alternating silicon-oxygen (Si-O) bonds with methyl groups (CH3) and hydride (Si-H) groups attached to the silicon atoms. This polymer has garnered significant attention due to its unique properties, which include high flexibility, low surface tension, and excellent hydrophobicity. The discovery of poly(methylhydrosiloxane) is a result of research into the development of silicone-based materials, which began in the early 20th century. Silicones, a broad class of synthetic polymers made from silicon, oxygen, carbon, and hydrogen, were first synthesized by researchers such as Frederick Kipping in the 1930s. Over time, poly(methylhydrosiloxane) emerged as a notable material due to its versatility and unique chemical properties.

The primary method for the synthesis of poly(methylhydrosiloxane) involves the polymerization of methylhydrosiloxane monomers, typically initiated by a catalyst such as platinum, which facilitates the formation of Si-O-Si linkages. The polymerization process leads to the creation of long chains of siloxane units, each incorporating both methyl and hydride groups. The structure of PMHS imparts unique physical characteristics, including a low viscosity when in its liquid state, making it useful for a variety of industrial applications. The polymer’s flexible backbone also allows for significant customization of its properties by adjusting the molecular weight or introducing other functional groups.

Poly(methylhydrosiloxane) has numerous applications across various industries, including the automotive, cosmetics, and pharmaceutical sectors, among others. One of the key applications of PMHS is as a silicone resin, used in coatings and sealants. Its ability to form hydrophobic surfaces makes it particularly useful in creating water-resistant and moisture-repellent coatings. PMHS is commonly used in the automotive industry for the manufacturing of gaskets, seals, and other components that require resistance to moisture and high temperatures. Additionally, PMHS is incorporated into silicone elastomers, which are employed in applications requiring high-temperature stability and durability, such as in medical devices and electronics.

In the cosmetics industry, poly(methylhydrosiloxane) serves as a key ingredient in skin care products, hair care products, and cosmetics formulations. Its lightweight, non-greasy nature allows it to provide a smooth and silky feel when applied to the skin or hair. It also acts as an emollient, helping to reduce the appearance of wrinkles by forming a protective barrier on the skin that retains moisture. PMHS is found in a variety of cosmetic products, including moisturizers, serums, and hair conditioning treatments, due to its ability to impart a soft and glossy finish.

In the pharmaceutical industry, poly(methylhydrosiloxane) is used in controlled drug delivery systems, particularly in the formulation of hydrophobic drug carriers. Its hydrophobic nature allows it to encapsulate drugs in a way that improves their solubility and bioavailability. PMHS can be used to create micro- or nanoparticles that facilitate the targeted delivery of drugs to specific areas of the body, offering significant advantages in terms of efficacy and safety. Additionally, PMHS has been studied for use in surgical implants, where its biocompatibility and flexibility are beneficial.

Poly(methylhydrosiloxane) is also employed in chemical synthesis as a hydrosilating agent in reactions involving organic compounds, such as in the synthesis of various silanes and siloxanes. Its reactivity with organic compounds containing unsaturated bonds makes it an ideal reagent for hydrosilylation reactions, which are key processes in the synthesis of many organosilicon compounds. These reactions are widely used in the production of various specialty chemicals, including surfactants, adhesives, and sealants.

Another significant application of PMHS is in the field of electronics. The material is used as a dielectric material in capacitors, insulators, and coatings for electronic components due to its excellent insulating properties and resistance to high temperatures. It is also employed in the production of electronic devices that require a stable and durable material to protect sensitive components from moisture, dirt, and other environmental factors.

In conclusion, poly(methylhydrosiloxane) is a versatile and valuable material with a wide range of applications across multiple industries. Its unique properties, including hydrophobicity, flexibility, and low viscosity, make it a useful component in coatings, cosmetics, pharmaceuticals, and electronics. As research into its potential applications continues, poly(methylhydrosiloxane) is likely to remain an important substance in the development of innovative products and materials.