Silicone surfactants Applications

The unique surface characteristics of polysiloxanes mean that they are extensively used as surfactants. Silicone surfactants have been thoroughly studied and described in numerous articles. For an extensive, in-depth discussion of this subject, a recent chapter by Hill,476 and his introductory chapter in the monograph he later edited,477 are excellent references. In the latter monograph, many aspects of silicone surfactants are described in 12 chapters. In the introduction, Hill discusses the chemistry of silicone surfactants, surface activity, aggregation behavior of silicone surfactants in various media, and their key applications in polyurethane foam manufacture, in textile and fiber industry, in personal care, and in paint and coating industries. All this information (with 200 cited references) provides a broad background for the discussion of more specific issues covered in other chapters. Thus, surfactants based on silicone polyether co-polymers are surveyed.478 Novel siloxane surfactant structures,479 surface activity and aggregation phenomena,480 silicone surfactants application in the formation of polyurethane foam,481 foam control and... 

Snow, S. A. Stevens, R. E. The Science of Silicone Surfactant Application in the Formation of Polyurethane Foam. In Silicone Surfactants-, Hill, R. M., Ed. Surfactant Science Series Dekker New York, 1999 Vol. 86, Chapter 5, pp 137-158. 

Floyd, D.T. (1999) Silicone surfactants applications in the personal care industry. Surfactant Sci. Ser., 86, 181-207. 

Hill RM (Ed.), Silicone Surfactants Applications in Personal Care Industry, Surfactant Science Series, Vol. 89, Marcel Dekker, New York, 1999. 

Industrially, silicone surfactants are used in a variety of processes including foam, textile, concrete and thermoplastic production, and applications include use as foam stabilisers, defoamers, emulsifiers, dispersants, wetters, adhesives, lubricants and release agents [1]. The ability of silicone surfactants to also function in organic media creates a unique niche for their use, such as in polyurethane foam manufacture and as additives to paints and oil-based formulations, whilst the ability to lower surface tension in aqueous solutions provides useful superwetting properties. The low biological risk associated with these compounds has also led to their use in cosmetics and personal care products [2]. 

As shown in Table 5.5.1,15% of the silicone surfactants annually used were disposed of via wastewater treatment plants [6], but no studies have addressed their fate or persistence in this environmental compartment. Due to the hydrolytic instability and tendency for sorption to surfaces, it is generally thought that limited persistence of the parent molecule in aqueous systems should occur. Consequently more attention has been focused on interactions with solid media such as that resulting from direct application as agricultural adjuvants, and in re-use of sludge. Increased water solubility for the degradation products of trisiloxane surfactants has, however, been observed [10,12,15], demonstrating the need to also monitor the... 

A significant amount of information regarding the uses of silicone surfactants is still found primarily in the patent art, but the major applications have recently been reviewed in journals. Silicone (or siloxane) surfactants are also called silicone polyethers (SPEs), polyalkylene oxide silicone copolymers, silicone poly(oxyalkylene) copolymers and silicone glycols. The International Cosmetic Ingredient Nomenclature and the Cosmetic, Toiletry and Fragrance Association (CTFA) adopted name is dimethicone copolyol. 

Silicone surfactants are specialty surfactants that are primarily used in applications that demand their unique properties. Most applications are based on some combination of their (a) low surface tension, (b) surface activity in nonaqueous media, (c) wetting or spreading, (d) low friction or tactile properties, (e) ability to deliver silicone in a water-soluble (or dispersible) form, (f) polymeric nature or (g) low toxicity. The major applications will be discussed briefly in following sections. 

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... 

The combination of both the biodegradability and the stability towards hydrolysis is unique in the field of well known silicone surfactants and will ensure the widespread application of trimethylsilane based surfactants. Considering all these facts all applications for which trisiloxane surfactants are already used or at least recommended are opened up in general for the new silane surfactants. Furthermore, applications now can be taken into consideration for which the hydrolytically unstable trisiloxane derivatives failed in the past. 

G.L. F. Schmidt, Specific properties of silicone surfactants, in Industrial Applications of... 

Although most of the silicone surfactants on the market are of the nonionic or amphoteric type, there are also some anionic materials. For instance, by the reaction of an epoxysiloxane intermediate with sodium sulfite, a silicone sulfonate can be obtained. Silicone surfactants, including the anionic forms continue to find new fields of application. 

Originally, this model was proposed for classic surfactants with alkyl chains as the hydrophobe. However, this model also appears to be applicable to silicone surfactants. The four trisiloxane... 

Silicone surfactants were limited primarily to dimethicone copolyol compounds before 1989. These materials are analogons to fatty alcohol alkoxylates. Althongh nseful in some applications, there were many applications where they were simply ineffective. 

Since the word silicone has been used synonymously with silicone flnid, several misconceptions have arisen about using silicone surfactants in many detergent applications. The following properties of silicone fluids have been attribnted to aU silicone compounds and conseqnently are misconceptions. 

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