Silicones with alkyl- or aromatic-substituted alkyl side chains can allow for many of the advantages of silicones to be formulated in organic based formulations. The alkyl-modified silicones offer greater organic compatibility with organic materials, improved lubricity, reduced tack, higher viscosity-temperature coefficients, lower compressibility, and decreased oxidation stability when compared to polydimethylsiloxanes. Both ethylene-dimethylsiloxane and alkylsiloxane-dimethylsiloxane copolymers are readily miscible in many hydrocarbons allowing for the introduction of silicone properties.
Modification of the alkyl chain length allows for varying the organic characteristics of the siloxanes. A longer alkyl chain translates to higher compatibility with hydrocarbon oils and increases in pour point. The series moves from liquid at room temperature (octyl) to pour points just above room temperature (tetradecyl) to creamy solids at room temperature (octadecyl and higher). Alkyl fluids improve plastic on plastic lubrication and have greater compatibility during processing and molding.
Alkyl Silicones
Alkylmethylsiloxane Homopolymers
| Product code | Name | Viscosity (cSt) | Pour point (°C) | Density | Refractive index | Surface tension | Flashpoint (°C) | CAS |
|---|---|---|---|---|---|---|---|---|
| ALT-143 | polyoctylmethylsiloxane | 600-1,000 | -44 | 0.91 | 1.445 | 30.4 | 250 | [68440-90-4] |
| ALT-173 | polytetradecylmethylsiloxane | 700-1,200 | 30 | 0.89 | 1.455 | 35 | -- | [76684-67-8] |
| ALT-192 | polyoctadecylmethylsiloxane (solid at room temperature) | 250-500 (50 °C) | 50 | 0.89 (50 °C) | 1.443 | 39.5 | -- | [68607-75-0] |
Alkylmethylsiloxane-Dimethylsiloxane Copolymers
| Product code | Name | Viscosity (cSt) | Pour point (°C) | Density | Refractive index | Surface tension | Flashpoint (°C) | CAS |
|---|---|---|---|---|---|---|---|---|
| ALT-281 | (45-55% hexadecylmethylsiloxane)-(dimethylsiloxane) copolymer | 40-70 | 19 | 0.86 | 1.448 | 28.3 | -- | [191044-49-2] |
| ALT-292 | (27-33% octadecylmethylsiloxane)-(dimethylsiloxane) copolymer (solid at room temperature) | 25-50 (40 °C) | 40 | 0.89 | 1.44 | -- | -- | [67762-83-8] |
| ALT-561 | (1-2% triacontylmethylsiloxane)-(dimethylsiloxane) copolymer | 2,000-4,000 (100 °C) | 75 | -- | -- | -- | -- | [17525-30-0] |
Alkyl-Terminated Polydimethylsiloxanes
| Product code | Name | Viscosity (cSt) | Pour point (°C) | Density | Refractive index | Surface tension | Flashpoint (°C) | CAS |
|---|---|---|---|---|---|---|---|---|
| DMA-021 | butyl-terminated polydimethylsiloxane | 10-15 | -40 | 0.92 | 1.413 | -- | >150 | R&D Only |
| DMA-091 | octadecyl-terminated polydimethylsiloxane | 20-30 (35 °C) | 14 | 0.88 | 1.434 | 25.1 | >150 | [128446-57-1] |
| DMA-131 | hexacosyl-terminated polydimethylsiloxane | 65 (55 °C) | 44-45 | 0.87 | 1.415 | -- | >150 | R&D Only |
| MMA-131 | monohexacosyl-terminated polydimethylsiloxane | 45 | 18-19 | 0.89 | 1.428 | -- | >150 | [1283601-17-1] |
Aryl-alkyl silicones exhibit an extended range of organic compatibility and lubricity when compared to dimethyl silicones. They behave as broad spectrum compatibilizing agents for silicone/hydrocarbon/fatty acid formulations in the lubricant and cosmetic industries. Fluids with methyl and 2-phenylpropyl groups maintain excellent release properties without interfering with paintability, making them preferred in mold release agent formulations for rubber and plastics and die casting. Other uses for organic compatible silicone fluids include surfactants or de-airing molded urethane and epoxy parts during fabrication and die-cast metal lubrication.
Aryl-Alkyl Silicones
Alkylmethylsiloxane-Arylalkylmethylsiloxane copolymers
| Product code | Name | Viscosity (cSt) | Pour point (°C) | Density | Refractive index | Surface tension | Flashpoint (°C) | CAS |
|---|---|---|---|---|---|---|---|---|
| APT-133 | poly(2-phenylpropyl)methylsiloxane | 1,000 | -- | 1.02 | 1.48 | 28.4 | 258 | [71329-48-1] |
| APT-213 | (75-85% ethylmethylsiloxane)-(15-25% 2-phenylpropylmethylsiloxane) copolymer | 1,200-1,600 | -- | 1.01 | 1.462 | 28.5 | 209 | [68037-77-4] |
| APT-233 | (45-55% hexylmethylsiloxane)-(45-55% 2-phenylpropylmethylsiloxane) copolymer | 1,500-2,000 | -- | 1.04 | 1.493 | 28.8 | 275 | [68952-01-2] |
| APT-263 | (60-70% dodecylmethylsiloxane)-(30-40% 2-phenylpropylmethylsiloxane) copolymer | 1,100-1,300 | -- | 0.91 | 1.464 | 32.3 | 277 | [68037-76-3] |