Silicone surfactants propylene oxide

The surfactant properties of polymeric silicone surfactants are markedly different from those of hydrocarbon polymeric surfactants such as the ethylene oxide/propylene oxide (EO/PO) block copolymers. Comparable silicone surfactants often give lower surface tension and silicone surfactants often self-assemble in aqueous solution to form bilayer phases and vesicles rather than micelles and gel phases. The skin feel and lubricity properties of silicone surfactants do not appear to have any parallel amongst hydrocarbon polymeric surfactants. 

To this liquid mixture was added a mixture of 50 parts by weight (0.473 equivalent) of a polyol of equivalent weight 105.6 (the adduct of propylene oxide and a mixture of polyamines containing 50% by weight of methylenedianiline obtained by the acid condensation of aniline and formaldehyde) 50 parts by weight of dimethyl sulfoxide and 10 parts by weight of a silicone surfactant. 

The most widely used surfactants are copolymers based on dimethyl polysiloxane and polysiloxanes. Some of these silicones are prepared with ethylene and propylene oxides. Some silicones contain Si-... 

The silicone surfactants can be viewed as PDMS-polyether-copolymers which are mainly based on a combination of just three structural units the methyl substituted siloxane backbone as well as a sophisticated ratio and arrangement of ethylene oxide and/or propylene oxide forming the attached polyethers and, in some cases, additional modifications. 

Not taking cyclic molecules into account, the general structures of industrial silicone surfactants for flexible slabstock foam production can be seen in Figure 2.13. The main building blocks of these materials are a PDMS backbone and attached polyethers based on ethylene oxide and propylene oxide addition products. The siloxane backbones can either be linear or branched and can have their polyether substituents attached in an either pendant or terminal location. These four general structures are outlined in Figure 2.13). 

All types of conventional non-ionic surfactants have at one time or another been recommended for use in polyester and, in certain instances, in polyether polyurethanes. However, the predominant surfactants used today are the silicones. These materials are block or graft copolymers or polydimethyl siloxanes and polyalkylene oxides. The polyether part is usually a copolymer of propylene and ethylene oxides. Variations in the commercially available surfactants are in the molecular weight and the weight ratio of the two blocks, the ratio of ethylene oxide to propylene oxide in the polyether portion, and the type of link between the silicone and... 

As an alternative to pressed powders, liquid foundations have attracted special attention in recent years. Most foundation make-ups are made of O/W or W/0 emulsions in which the pigments are dispersed either in the aqueous or the oil phase. These are complex systems consisting of a suspension/emulsion (suspoe-mulsion) formulation. Special attention should be paid to the stability of the emulsion (absence of flocculation or coalescence) and suspension (absence of flocculation). This is achieved by using specialised surfactant systems such silicone polyols or block copolymers of poly(ethylene oxide) and poly(propylene oxide). Some thickeners may be also added to control the consistency (rheology) of the formulation. 

For polyethers in polysiloxanes, allyl or butyl alcohol (R ) is commonly used as a starting molecule. The most popular monomers for polyethers are ethylene oxide (EO), propylene oxide (PO), and mixtures thereof. The effect of their ratio can be described with the hydrophilic-lipophilic balance (FILB) concept, which will be discussed later [11]. The higher the PO content, the more hydrophobic is the corresponding polyether. Thus, by varying the composition of the polyethers, sometimes denoted as polyoxyalkylene, it is possible to adjust the polarity of the polydimethylsiloxane polyether copolymer. A macroscopic measure for the polarity of both polyethers and polyethersi-loxanes is the cloud point of a 1% aq. solution. The higher it is, the more hydrophilic is the molecule. In this chapter we will denote these compounds as polyethersiloxanes. It is possible to design silicone surfactants that are suitable for aqueous and nonaqueous systems. 

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