Sodium lauryl sulfate emulsifier

A first set of experiments was carried out in batch, varying either the amount of emulsifier, sodium lauryl sulfate (SDS) from 2 to 8 g, or the amount of monomers from 1 to 2.7 moles (X AN/S being kept constant at 4). 

Rao and co-workers [82] used an inverted emulsion process for the synthesis of the emeraldine salt of PAM using a novel oxidising agent, benzoyl peroxide. The polymerisation was carried out in a non-polar solvent in the presence of four different protonic acids as dopants and an emulsifier (sodium lauryl sulfate). The polymer salts were characterised spectroscopically by ultraviolet-visible, Fourier-transform infrared, Fourier-transform Raman and electron paramagnetic resonance spectroscopy. Thermogravimetric analysis, was used to determine the stability of the salts and the activation energy for the degradation. The conductivity of the salts was found to be in the order of 10 S/cm. 

Propagation. The rate of emulsion polymerization has been found to depend on initiator, monomer, and emulsifier concentrations. In a system of vinyl acetate, sodium lauryl sulfate, and potassium persulfate, the following relationship for the rate of polymerization has been suggested (85) ... 

The active ingredients in a shampoo play three fundamental roles. Some allow water to wash away the substances that make hair dirty. Others adhere to hair to impart a desirable feel and texture. The rest are emulsifiers that keep the mixture from separating into its components. To accomplish these effects, ingredients combine two types of interactions a strong attraction to water (hydrophilic) and an aversion to water (hydrophobic). It may seem that these properties are incompatible, but shampoos contain molecules that are designed to be simultaneously hydrophilic and hydrophobic. One example is sodium lauryl sulfate, our inset molecule. The ionic head of the molecule is hydrophilic, so it interacts attractively with water. The hydrocarbon tail is hydrophobic, so it interacts attractively with grease and dirt. Molecules of the shampoo associate with hydrophobic dirt particles to form hydrophilic clumps that dissolve in water and wash away. 

Composition of Emulsion, The prototype oil/water emulsion described in Table I contained ingredients typical of a large number of cosmetic products, although simplified somewhat to avoid analytical problems. The aqueous phase contained sodium lauryl sulfate (SLS) as emulsifier, 0,2% (19 n ) DEA as precursor to NDEIA and 0,1% benzoic acid as preservative. 

Surfactants can act like lipids or emulsifiers in solubilizing flavor materials in surfactant micelles. Headspace analysis techniques were used to follow the release of several common dentifrice flavorants from a solution containing the surfactant sodium lauryl sulfate. Water/micelle partition coefficients were derived to describe the solubilization of the flavorants in tiie surfactant micelle (76). Initially, the flavor is solubilized in the surfactant micelle. As both the micelle and flavor concentration decrease on dilution, flavor compounds, which are highly soluble in the micelle, preferentially increase in the headspace [HGURE11]. 

Deionized water (720 g), sodium lauryl sulfate (4.3 g), dioctanoyl peroxide (40 g), and acetone (133 g) were emulsified using an ultrasonic probe for 10 minutes. The step 1 polystyrene seed (48.0 g seed, 578 g latex) was added to the emulsion together with lauryl sulfate (0.8 g) and acetone (29.6 g). The mixture was transferred to a flask and left to agitate at approximately 25°C for 48 hours. Acetone was then removed and the solution added to a 5-liter double-walled glass reactor. The temperature was increased to 40°C while styrene (336 g) and divinyl benzene (0.88 g) were added drop-wise over approximately 60 minutes. After 4 hours the mixture was treated with deionized water (1200 g), potassium iodide (1.28 g), and polyvinyl pyrrolidone (18.48 g) with the temperature increased to 70°C. The polymerization continued for 6 hours at 70°C and 1 hour at 90°C. Styrene-based oligomer particles with a diameter of 1.7 pm and with a narrow size distribution were obtained. 

Table IV shows that dialysis is ineffective in cleaning the latexes for characterization. Earlier work (3,5) also showed that dialysis is ineffective in removing the adsorbed emulsifier and replacing the Na+ and K counterions with H ions. Others have also found that dialysis does not remove emulsifier completely. Brodnyan and Kelley (10) found that aqueous solutions of C14-tagged sodium lauryl sulfate equilibrated upon dialysis, but only 9.5% and 22% of the emulsifier was removed from latexes dialyzed under the same conditions. Matijevic et al. (11) dialyzed a butadiene-styrene copolymer latex prepared using rosin acid soap for 160 days and removed only about 50% of the emulsifier.

Vinyl acetate-butyl acrylate copolymers (0-100% butyl acrylate) were prepared by both batch and starved semi-continuous polymerization using sodium lauryl sulfate emulsifier, potassium persulfate initiator, and sodium bicarbonate buffer. This copolymer system was selected, not only because of its industrial importance, but also because of its copolymerization reactivity ratios, which predict a critical dependence of copolymer compositional distribution on the technique of polymerization. The butyl acrylate is so much more reactive than the vinyl acetate that batch polymerization of any monomer ratio would be expected to give a butyl acrylate-rich copolymer until the butyl acrylate is exhausted and polyvinyl acetate thereafter. 

Materials. Emulsifier A very pure grade of sodium lauryl sulfate (Stepanol WA-100) was obtained from Stepan Chemical Company and was used directly from the bottle. 

Water-removable ointments and creams are basically hydrophilic-type emulsions. They are prepared by fusion followed by mechanical addition approach. Hydrocarbon components are melted together and added to the aqueous phase that contains water-soluble components with constant stirring until the mixture congeals. A hydrophilic emulsifying agent is included in the aqueous phase in order to obtain stable oil-in-water dispersion. Sodium lauryl sulfate is used in the preparation of hydrophilic ointment USP. 

Surfactant Substance that adsorbs to surfaces or interfaces to reduce surface or interfacial tension may be used as wetting agent, detergent, or emulsifying agents Benzalkonium chloride, nonoxynol 10, oxtoxynol 9, polysorbate 80, sodium lauryl sulfate, sorbitan monopalmitate... 

In order to delve deeper into the similarities and differences between the kinetic behaviors of emulsion polymerization initiated by oil-soluble initiators or water-soluble initiators, Nomura et al. [199-202] carried out extensive investigations into the kinetics and mechanisms of the unseeded and seeded emulsion polymerizations of St at 50 °C using sodium lauryl sulfate (NaLS) as the emulsifier and AIBN as the initiator, and obtained the following conclusions ... 

The influence of the monomer to water ratio on the polymerization rate was studied with sodium lauryl sulfate as the emulsifier. The conversion curves for the case of 3% emulsifier are shown in Figure 5. In Figure 6 the linear conversions for ten minutes of irradiation at 0.175 Mrads per hour are plotted against the water-monomer ratio for 1, 3, and 5% emulsifier. All three sets of data show a linear dependence of the rate on the ratio, in other words, the rate per cubic centimeter of water phase is independent of the monomer-water ratio. 

Materials and Polymerization. Styrene and methyl methacrylate were obtained from commercial sources and were distilled to remove inhibitor. After distillation, the monomers were stored, under nitrogen, in a refrigerator. For the mixed emulsifier system, Emulphogene BC840(GAF), tridecyloxy-polyethylene-oxyethanol, was used as the nonionic constituent, and sodium lauryl sulfate (K and K Labs) was used as the ionic constituent. The sodium lauryl sulfate was at a concentration below its cms whereas the BD-840 was at a concentration above its cmc. This emulsifier system has been shown to yield mixed micelles (2)/ having a low ionic change (2)/ which produce latlces with rather narrow particle size distributions (2 ) ... 

Lipopeptldes emulsify with difficulty aromatic oils such as styrene or toluene. Furthermore they are not able to emulsify some oils such as vaseline, ricin, wheat germ and silicon oils. To emulsify such oils we have used a binary emulsifying system consisting of a mixture of a fatty alcohol (cetyl alcohol) and a ionic lipopeptide (liposarcosine chlorhydrate, lipolysine bromhydrate or llpoglutamic acid sodium salt). With concentrations of lipopeptide and cetyl alcohol of 1 to 3 % we have obtained miniemulsions similar to those obtained by El Aasser and al. with sodium lauryl sulfate and cetyl alcohol (10). 

Influence of the Molar Ratio Lipopeptide/Cetyl Alcohol. As already shown by different authors in the case of classical emulsifiers such as sodium lauryl sulfate (10,14,15), the mixed emulsifier system lipopeptide/cetyl alcohol gives stable miniemulsions for molar ratios LP/C15OH between 2/1 and 1/3. 

Hoigne and O Neil (1972) studied several features of the y radiation-initialed polymerization in emulsion. Sodium lauryl sulfate, dioctyl and dibutyl sodium sulfosuccinates, and two nonionic, polyoxyethylene-type emulsifiers were used. Sodium lauryl sulfate gave, by far, the hipest rates and most stable lattices and was used for all of the results reported. The rates were found to be 0.43 order on the dose rate and 0.53 on the... 

Araki et at. (1967, 1969) carried out a more systematic study of the kinetics and other features of the y-iniliated emulsion polymerization of vinyl acetate using sodium lauryl sulfate as the emulsifier. This system had been thoroughly investigated with potassium persulfate as the initiator (Litt et cL. 1960,1970). Some post ei cts have been observed with vinyl acetate, particularly above 50% conversion (Friis, 1973 Sunardi, 1979). These effects had been used by Allen cr at. (1960,1962) for the possible synthesis of block and graft polymers and will be described later in this chapter. The half-life of the radicals in a vinyl acetate latex polymerization was determinad by Hummel et at. (1969) as 0.8 min at 53.8% conversion. Araki et fll. (1967, 1969) determined all the normal rate dependencies and included some seeded latex studies. Their results and those of other investigators are summarized in Table II together with those found with potassium persulfate initiation and those predicted by the Smith-Ewart Case 2 theory. The... 

Panajkar and Rao (1979) have reported a ratber extensive study of the y radiation-initiated polymerization of vinylidene chloride in emulsion. With sodium lauryl sulfate as the emulsifier smooth polymerization-time curves at high rates were obtained, up to more than 9 conversion. Between 45 and 60% conversion, the linear region, the rate was 0.3 order with respect to tbe emulsifier concentration. The molecular weights were found to increase with conversion and values up to 79,000 were obtained. Some reasons for the departure from Smith Ewart behavior were suggested. Earlier. Hummel el al. (1967) had presented some interesting data on a closely related system, a similar rate-time behavior was observed and a tentative explanation proposed. Both discussions were based on tbe insolubility of the polymer in its own monomer. 

The active portion of this class of emulsifiers is the anion. In general, these emulsifiers are more acid-stable and permit adjustment of the emulsion pH level to the desirable range of 4.5 and 6.5. Common examples include sodium lauryl sulfate and soaps such as triethanolamine stearate. Triethanolamine stearate is one of the most popular emulsifiers for creams and lotions in use today. It is usually prepared in situ during manufacture from stearic acid in the hot oil phase and from triethanolamine in the hot aqueous phase. The amount of triethanolamine controls the pH level of the resulting product. 

---