Poly(methylhydrosiloxane)

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Cat Number

CHE63148572

CAS Number

63148-57-2

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CAS Number

63148-57-2

EINECS

613-152-3

Storage

Room temperature

Synonyms

hydroxy(dimethyl)silane,hydroxy(trimethyl)silane,tetramethylsilane

Molecular Formula

(CH4OSi)n

Molecular Weight

1700-3200

Smiles

C[SiH](O[Si](C)(C)C)O[Si](C)(C)C

Relative Density

1.006

Standard

REACH

General Description

Poly(methylhydrosiloxane), a multi-functional, high molecular weight silicone compound, is a colorless, free-flowing liquid with a unique combination of favorable properties: it is non-toxic, physiologically inert, and highly stable in hydrocarbon solvents. Poly(methylhydrosiloxane) has found applications as a green, low-cost, and safe alternative to toxic silanes in the fields of industrial surface modification and complex organic synthesis.

Mechanism of Action

Active silicon-hydrogen bonds within the polymer backbone are the source of Poly(methylhydrosiloxane)'s reactivity and enable its use as a mild and efficient hydride donor for the controlled transfer of hydrides to reducible functional groups or metal centers in the presence of metal catalysts or nucleophilic activators. It can also be catalytically cross-linked at low temperatures to form a stable, hydrophobic siloxane network, and is thus an ideal cross-linking agent for superior moisture resistance and reinforcement.

Application

Poly(methylhydrosiloxane) is a green reductant for the reduction of esters to alcohols, phosphine oxides to phosphines, and for the reductive amination to prepare amines. In addition, it is used in industrial material science as the precursor to waterproof membranes, water-repellent and anti-fouling coatings for textiles, ceramics, glass, natural stone, and as an anti-yellowing agent for heat vulcanized silicone rubber. It is also a key ingredient in the production of mold release agents, as a stabilizer of polyurethane foam, and as a moisture-proof treatment for building materials.

Researchers developed a completely degradable air-filter membrane that overcomes the traditional trade-off between efficiency and pressure drop and offers a high-performance, environmentally sustainable alternative for precision protection masks and environmental filtration applications. They used electrospinning to fabricate a bimodal network consisting of a 200 nm diameter scaffold fiber matrix, embedded with 32 ± 5 nm diameter polymethylhydrosiloxane-doped polylactic acid nanofiber. The engineered difference in size distribution increases interfiber spacing and enhances the air-slippage effect. The resulting mat, with its 0.62 µm pores, 93% porosity, and super-hydrophobic surface, can resist pressure of 68 Pa. It filters 99.99% of 0.3 µm diameter particles as electrospun and maintains 95.6% efficiency after 12 h of charge dissipation, while still exceeding 99% efficiency during continuous PM exposure.

Fig. 1 Electrospun Poly(methylhydrosiloxane)/PLA multiscale membrane for mask filters. (Shao W.; et al. 2024)

References

Shao W, et al. Electrospun Polymethylhydrosiloxane/Poly (lactic acid) Multiscale Nanofiber Membrane with Highly Hydrophobic Interface as Material for Protective Mask Filters. ACS Applied Nano Materials, 2024, 7(20): 24071-24081.

Molecular dynamics simulations found that Poly(methylhydrosiloxane) chains wrap around gypsum crystals and nano-cracks to create methyl-enriched silicone films. This enfolding layer is held in place by hydrogen bonds between Poly(methylhydrosiloxane) methyls/bridging oxygen and CaSO4, sealing off access to water and reducing surface energy. 1 wt% Poly(methylhydrosiloxane) increases the softening coefficient of the gypsum from 0.35 to 0.82 and enhances the wet compressive strength by 60%.

Fig. 2 Water resistance of Poly(methylhydrosiloxane)-modified gypsum. (Zhu Z.; et al. 2024)

References

Zhu Z, et al. Molecular dynamics simulation of water resistance enhancement of gypsum modified by polymethylhydrosiloxane (PMHS). Construction and Building Materials, 2024, 435: 136801.

What are the benefits of Poly(methylhydrosiloxane) as a reducing agent?

Poly(methylhydrosiloxane) is a low-cost, safe-to-handle reducing agent. It is a green alternative to more toxic reducing agents such as silanes and borohydrides.

Can Poly(methylhydrosiloxane) be used as a cross-linking agent?

Yes, it can be used as a cross-linking agent due to the presence of an active Si-H group.

What role does Poly(methylhydrosiloxane) play in the catalysis of organic synthesis?

It can increase the catalytic efficiency in various reactions such as organotin-mediated reactions.

Does Poly(methylhydrosiloxane) contribute to green chemistry?

Yes, its low toxicity and effectiveness make it compatible with the principles of sustainable and environmentally friendly synthesis.