Silicone surfactants polyurethane foam stabilization

The surface activity of silicones is often exploited by using them as additives. For this reason, aspects of the two most important additive forms, copolymers and surfactants, are also included in this discussion. These two classes come together in the relatively low molecular weight PDMS-poly(alkylene oxide) block and graft copolymers that are commonly used as polyurethane foam stabilizers. Other short-chain silicone surfactants designed for aqueous systems and other silicone-organic copolymers are also available. 

The real challenge in polyurethane foam formation is to control the chemical and physiochemical processes up to the point where the material finally sets. The sequence and the rate of the chemical reactions are predominately a function of the catalyst and the reactivity of the basic raw materials, polyol and isocyanate. The physiochemical contribution to the overall stability and processability of a system is provided by the silicone surfactants. Optimum foaming results will be achieved only if the correct relationship between chemistry and physics exists [4]. 

Uses Polyurethane foam stabilizers silicone defoamers and surfactants, air release agents additives for paints and coatings Regulatory Canada DSL Manuf/Distrib. Gelest... 

The high hydrophobicity of silicones can complicate their use in some applications. For example, proteins can undergo denaturation in contact with silicones [1]. In such cases, the siloxane can be modified to include a hydrophilic domain. This is typically accomplished by functionalizing the silicone with a hydrophilic polymer such as poly(ethylene oxide)(PEO). Silicone surfactants of this type have found widespread use as stabilizers for polyurethane foams, and have been investigated as a structurant to prepare siloxane elastomers for biomaterials... 

Tegostab . [Goldschmidt] Silicone surfactants stabilizer for polyurethane foams. 

The ability to spread and the intrinsic hydrophobidty of silicones make them among the lowest surface-energy compounds known [16]. Hence, siHcones are used as relejise agents to prevent adhesion in many applications. When silicones are chemically combined with hydrophilic species such as cationic species or poly(ethylene oxide), very interesting surfactant properties arise. For example, silicones are used as foam stabilizers in the making of polyurethane foams, while silicone copolymers are used as defoamers in the food, pulp and paper industries [13]. 

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