Name: Methyltrichlorosilane (MTCS, CH₃SiCl₃)
Brand: Coatingsink
SKU: mtcs
Availability: InStock

Question 1

How does MTCS function as a building block for methyl silicone resins?

Accepted Answer

MTCS (CH₃SiCl₃) is a T-functional silane monomer: upon hydrolysis, each molecule yields a methylsilanetriol unit (CH₃Si(OH)₃) that condenses to form T-branching points in silicone network resins. Co-hydrolysis of MTCS with D-functional dichlorosilanes (dimethyldichlorosilane, Me₂SiCl₂) and M-functional monochlorosilanes (Me₃SiCl) allows precise control of resin branching density, crosslink density, and MW. High T-content resins (>50 mol% T units) yield hard, thermally stable silicone binders for 200–250°C heat-resistant coatings used on exhaust systems and industrial ovens. Lower T-content with D units gives more flexible, weatherable silicone resins for architectural coatings.

Question 2

What conditions are needed for hydrophobic surface treatment with MTCS?

Accepted Answer

For vapor-phase hydrophobic treatment of mineral fillers (silica, calcium carbonate, talc), MTCS is introduced as vapor at 80–120°C under dry conditions. Surface silanol groups (Si–OH) on the filler react with MTCS to form covalent Si–O–Si bonds, grafting monomethylsilyl groups onto the surface: filler–OH + CH₃SiCl₃ → filler–O–Si(CH₃)Cl₂ + HCl → further hydrolysis/condensation. The resulting hydrophobic filler shows contact angle >100°, dramatically improved dispersibility in nonpolar resins, and reduced water uptake. Residual HCl must be removed by purging with N₂ at 100–120°C. For liquid-phase treatment, dilute MTCS in dry toluene or hexane (5–10 wt%) and treat filler slurry under anhydrous conditions.

Purity	≥99.0%
Appearance	colorless fuming liquid
HCl (free)	≤100 ppm
Flash Point	-9°C (closed cup)
Boiling Point	65.7°C
Water Content	≤20 ppm
Density (20°C)	1.273 g/cm³
SiCl₄ Content	≤0.3%
Silicon Content	≥18.7%
Molecular Weight	149.48 g/mol

Methyltrichlorosilane (MTCS, CH₃SiCl₃)

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