wannafbody
wannafbody
Interface Science
What Makes Silicones Special?
Silicones are the only organic/inorganic hybrid polymers that have been extensively commercialized. This is true for several important reasons.
The organic portion in poly(dimethylsiloxane) or PDMS – by far the most common silicone polymer – is the methyl group. The surface energy of any substance is a direct manifestation of the intermolecular forces between molecules. In the case of the methyl group, these forces are almost the weakest possible (only aliphatic fluorocarbon groups are lower).
The inorganic siloxane backbone is the most flexible polymer backbone available. This allows the methyl groups to be arranged and presented to their best effect. Consequently, PDMS provides one of the lowest-energy surfaces known. This results in a low-surface-energy polymer that can be bettered only by more expensive fluorocarbon polymers. It is this unique surface behavior that accounts for many silicone applications.
Adhesives, Emulsions, Antifoams, and Surfactants
In many applications it is critical for the silicone product to stick (adhere) to another material. Whether the silicone is used as a coating, sealant, or an adhesive, a low-surface-energy polymer is being “stuck” to another material, which is not an easy challenge. It is achieved by carefully designing and formulating silicone products that bond directly with the substrate.
Silicone coatings can be designed to have unique release behavior, with no adhesion between the silicone coating and an adhesive layer required. Adhesives can then be peeled off a silicone backing film, while retaining their adhesive performance.
Silicone polymers are widely used in water-based processes and applications. Most silicone polymers are not water-soluble. For aqueous delivery, they are usually formulated as an emulsion – a dispersion of small droplets of silicone oil within an aqueous surfactant solution. Mechanical emulsification and emulsion polymerization also allow silicones that are difficult to handle or manufacture to be used with ease in an aqueous formulation or end application – eliminating the need for solvents to disperse the polymers.
Silicone polymers formulated in this way are often used in cosmetics, industrial release, or fabric care applications. The silicone usually brings a functionality such as hair conditioning or mold release.
Silicones may be formulated as opaque emulsions or as clear microemulsions.
The reduction or elimination of foam is critical for many industrial processes and some domestic ones, such as laundering clothes. Silicone is an ideal antifoam. It is liquid within a wide range of viscosities, has a low surface energy, and is clean. This means it is easily formulated, will penetrate aqueous films, and is suited to domestic use.
Although most silicone polymers are not water-soluble, an important class of water-soluble silicone surfactants does exist. Surfactants are typically polymer molecules with two distinctive regions or “ends” – a hydrophobic (water-fearing) oil-soluble end and a hydrophilic (water-loving) water-soluble end. Such a molecule is very effective at stabilizing an oil-water interface. In the case of silicone surfactants, the silicone is the hydrophobic end, with the hydrophilic end often poly(ethylene) oxide.
Silicone surfactants have unique properties, including wetting and emulsification behavior. Unlike many alkyl-based surfactants, they are active in organic media and can be used in either water or solvents. A major application for silicone surfactants is in the production of poly(urethane) foams, an organic-based process where normal alkyl surfactants would be ineffective.
Find out what an interface is and why it is important.
(Doesn't this article say that the methyl bonding of PDMS is weak? Wouldn't this indicate that in a wax they'd wash away? Also compare silicone caulk(silicone resin I believe) with silicone dielectric compound-the dielectric grease doesn't harden and doesn't bond to the surface(it can be wiped off). Isn't the PDMS used in dielectric grease the same PDMS used in car waxes?) -wannafbody
What Makes Silicones Special?
Silicones are the only organic/inorganic hybrid polymers that have been extensively commercialized. This is true for several important reasons.
The organic portion in poly(dimethylsiloxane) or PDMS – by far the most common silicone polymer – is the methyl group. The surface energy of any substance is a direct manifestation of the intermolecular forces between molecules. In the case of the methyl group, these forces are almost the weakest possible (only aliphatic fluorocarbon groups are lower).
The inorganic siloxane backbone is the most flexible polymer backbone available. This allows the methyl groups to be arranged and presented to their best effect. Consequently, PDMS provides one of the lowest-energy surfaces known. This results in a low-surface-energy polymer that can be bettered only by more expensive fluorocarbon polymers. It is this unique surface behavior that accounts for many silicone applications.
Adhesives, Emulsions, Antifoams, and Surfactants
In many applications it is critical for the silicone product to stick (adhere) to another material. Whether the silicone is used as a coating, sealant, or an adhesive, a low-surface-energy polymer is being “stuck” to another material, which is not an easy challenge. It is achieved by carefully designing and formulating silicone products that bond directly with the substrate.
Silicone coatings can be designed to have unique release behavior, with no adhesion between the silicone coating and an adhesive layer required. Adhesives can then be peeled off a silicone backing film, while retaining their adhesive performance.
Silicone polymers are widely used in water-based processes and applications. Most silicone polymers are not water-soluble. For aqueous delivery, they are usually formulated as an emulsion – a dispersion of small droplets of silicone oil within an aqueous surfactant solution. Mechanical emulsification and emulsion polymerization also allow silicones that are difficult to handle or manufacture to be used with ease in an aqueous formulation or end application – eliminating the need for solvents to disperse the polymers.
Silicone polymers formulated in this way are often used in cosmetics, industrial release, or fabric care applications. The silicone usually brings a functionality such as hair conditioning or mold release.
Silicones may be formulated as opaque emulsions or as clear microemulsions.
The reduction or elimination of foam is critical for many industrial processes and some domestic ones, such as laundering clothes. Silicone is an ideal antifoam. It is liquid within a wide range of viscosities, has a low surface energy, and is clean. This means it is easily formulated, will penetrate aqueous films, and is suited to domestic use.
Although most silicone polymers are not water-soluble, an important class of water-soluble silicone surfactants does exist. Surfactants are typically polymer molecules with two distinctive regions or “ends” – a hydrophobic (water-fearing) oil-soluble end and a hydrophilic (water-loving) water-soluble end. Such a molecule is very effective at stabilizing an oil-water interface. In the case of silicone surfactants, the silicone is the hydrophobic end, with the hydrophilic end often poly(ethylene) oxide.
Silicone surfactants have unique properties, including wetting and emulsification behavior. Unlike many alkyl-based surfactants, they are active in organic media and can be used in either water or solvents. A major application for silicone surfactants is in the production of poly(urethane) foams, an organic-based process where normal alkyl surfactants would be ineffective.
Find out what an interface is and why it is important.
(Doesn't this article say that the methyl bonding of PDMS is weak? Wouldn't this indicate that in a wax they'd wash away? Also compare silicone caulk(silicone resin I believe) with silicone dielectric compound-the dielectric grease doesn't harden and doesn't bond to the surface(it can be wiped off). Isn't the PDMS used in dielectric grease the same PDMS used in car waxes?) -wannafbody
