Ethoxylated alcohols cloud point

Genapol 26-L-60 C12C16 alcohol ethoxylate with cloud point of 60C Hoechs... 

When scouring synthetic fibres that are to be dyed with disperse dyes, nonionic scouring agents are best avoided unless they are formulated to have a high cloud point and are known not to adversely affect the dispersion properties of the dyes. Conversely, when scouring acrylic fibres, anionic surfactants should be avoided [156] because they are liable to interfere with the subsequent application of basic dyes. These fibres are usually scoured with an ethoxylated alcohol, either alone or with a mild alkali such as sodium carbonate or a phosphate. 

A significant increase in fp and similar elongated drops and emulsification were seen as the cloud point of 37 °C was approached for Dow s commercial secondary alcohol ethoxylate Tergitol 15-S-7 (Fig. 5). Its hydrophobe consists of various double-chain species with the sum of the chain lengths ranging between 11 and 15, and its average EO number is 7.3. In some cases a conical projection developed on the elongated drop, and a jet was emitted, which broke up into small droplets (Eig. 6). 

The physical chemical properties of the surfactants that contain an ester bond between the hydrophobic tail and the polar head group are very similar to those of alcohol ethoxylates of the same alkyl chain length and the same number of oxyethylene units. The CMC and the cloud point values of the linear ester surfactant 1 of Fig. 4 are approximately the same as those of the straight chained alcohol ethoxylate tetra(ethylene glycol)monooctyl ether (C8E4), i.e., around 10 mM and 40 °C, respectively. Thus it appears that the... 

As can be seen from Table 5.2, nonylphenol ethoxylates have a steeply increasing cloud point for very little addition of ethylene oxide. Most industrial products have a rounded up/down value of ethylene oxide in their nomenclature. Thus, NP9 from one company could be actually NP9.25 and from another could be NP8.75. The cloud point for these two products could be 15° C different and in some applications, such as in solubilisation of a fragrance or flavouring, this could be crucial. This is almost certainly due to the sharp (compared to alcohol-based products) Poisson isomer distribution and also variable polyethylene glycol levels in different manufacturers products. Therefore, it is suggested that product should always be purchased on a cloud point specification and not to an EO number. 

Correlation equations relating surfactant chemical structure to performance characteristics and physical properties have been established. One atmosphere foaming properties of alcohol ethoxyl-ates and alcohol ethoxylate derivatives have been related to surfactant hydrophobe carbon chain length, ethylene oxide content, aqueous phase salinity, and temperature. Similar correlations have been established for critical micelle concentration, surfactant cloud point, and surfactant adsorption. 

The cloud point (CP) of alcohol ethoxylates is the temperature at which solutions of these surfactants become cloudy. The turbidity is caused by the separation of the fluid into two phases a low surfactant concentration and a high surfactant... 

FIG. 8.10 Typical ethoxylate adduct distributions in narrow range and broad range C12-04 alcohol surfactants with similar cloud points. (Reproduced from Dillan, K.W.,. /. Am. Oil Chem. Soc., 62, 1144, 1985. With permission.)... 

Short-chain alkyl polyglycosides (C4-C10), because they have the large hydrophilic head group and short hydrophobic group needed to disrupt liquid-crystalline phases, are also effective hydrotropes. The Cs and C10 homologs are very effective in raising the cloud points (Section IIIB below) of some alcohol ethoxylates (Matero, 1998). 

Dimethicone copolyols exhibit an inverse cloud point phenomenon as an aqueous solution is heated. This same phenomenon is observed with ethoxylated fatty alcohol. The hydrogen bonding of the water with the polyoxyethylene portion of the molecule causes the cloud point. The inverse cloud point of the molecule is related to the length of the ethylene oxide chain and not the number of D units or molecular weight. The term inverse cloud point refers to the temperature at which a clear solution develops turbidity on heating. Cloud point is a phenomenon, relating to tnrbidity, which develops on cooling. 

The driving force for the inverse temperature dependence of ionic surfactants when compared to nonionic surfactants lies in the behaviour of the binary water/surfactant mixtures. In contrast to mixtures of ethoxylated alcohols and water, which become less miscible with water and de-mix and exhibit a cloud point upon heating (see Figure 4.4), ionic surfactants become more miscible with water (10). 

FIG. 6 Water solubility (inverse cloud point temperature) as a function of EO content (moles) for C12-16 alcohol and methyl ester ethoxylates made with Ca/Al-alkoxide catalyst. (Cloud point temperature = temperature at which 1 % aqueous solution turns cloudy upon slow heating C12-16 alcohol ethoxylate is described in Table 1 distribution of methyl ester = 9% Cj, 8% Cio, 46% C12, 18% C14, 9% Cig, and 10% C18.) (From Ref. 27.)... 

Ci2 16 methyl ester ethoxylate requires about two additional moles of ethylene oxide compared to a C12 16 linear alcohol ethoxylate. To obtain an inverse cloud point of 80 °C, approximately eight additional moles of ethylene oxide would be needed. 

In practice, inverse cloud point temperature is used more as a quality control measure rather than as a solubility requirement. Although methyl ester ethoxylates are less water soluble than their alcohol ethoxylate counterparts, they can achieve comparable formulatability characteristics at somewhat higher ethylene oxide levels. 

Alkyl Ether Sulfates These surfactants are also found in shampoo applications. They are prepared similarly to alkyl sulfates except that the fatty alcohol is first subjected to ethoxylation ethoxylation may range from 2 to 3 moles per mole of fatty alcohol. Lauryl alcohol is the typical fatty alcohol reacted. Because of high water solubility, alkyl ether sulfates have low cloud points, making them suited for clear shampoo formulations (5). Viscosities based on the ether sulfates can be easily controlled through addition of inorganic salts such as sodium chloride. 

Description. These surfactants are formed by the reaction of sodium chloracetate with ethoxylated alcohols. Due to the addition of ethoxylated groups, ether carboxylates are more soluble in water and less sensitive to water hardness compared to conventional soaps. Also, keeping the best properties of nonionic surfactants, they do not exhibit any cloud point and show good wetting and foam stability. 

The nonionic class of alkyl polyglycosides differs from fatty-alcohol ethoxy-lates by its characteristic structure which considerably affects the association of molecules in solution, the phase behavior, and the interfacial activity. The hydrophilic head of the glucose ring, associated with the surrounding water molecules by hydrogen bonds, is rather voluminous as compared to the alkyl chain. However, the hydration is low compared to fatty alcohol ethoxylates. Therefore, basic phenomena like cloud point, thermal phase inversion, or gel formation in medium concentrations of pure solutions cannot be observed in case of the alkyl polyglycosides. 

---