Oxyethylene unit detergency

In POE nonionics containing the same number of oxyethylene units, increase in the length of the hydrophobic group increases the efficiency of oily soil removal by decreasing the CMC and hence the concentration at which solubilization commences. Optimum detergency increases with increase in the chain length of the hydrophobe to a maximum that again is dependent on the temperature of the bath. 

On the other hand, the detergency of isotactic polypropylene at 90°C by these same surfactants in distilled water increases with increase in the number of oxyethylene units in the POE chain to a maximum at 12 and then decreases (Schwuger, 1971). The major factor involved here is probably the PIT of the surfactant, which increases with increase in the number of oxyethylene groups in the molecule. Detergency is optimum in the vicinity of the PIT, presumably because solubilization of oily soil by the surfactant increases markedly there. 

A similar detergency maximum at almost the same oxyethylene content has been observed in the removal of oily soil from metal surfaces using similar surfactants in an alkaline, built formulation (Komor, 1969). The maximum here is at 68% oxyethylene (about 11 oxyethylene units per nonylphenol) at bath temperatures from 40 to 80°C. For a series of polyoxyethylenated nonrandom linear alkylphenols with Cg-Cig alkyl chains, optimum removal of sebum soil from cotton at 49°C and 50 and 300 ppm water hardness was obtained at 63-68% oxyethylene content (Smithson, 1966). A study of the removal of oily soil from cotton and permanent press cloths, and of clay from permanent press cloths by commercial POE alcohols, showed that POE Ci2-Ci4 alcohols with 60% or greater ethylene oxide content achieved the best soil removal (Cox, 1989). 

Studies of the soil removal properties of polyoxyethylenated straight-chain primary alcohols on cotton and Dacron-cotton permapress fabric indicate that this detergency maximum with change in the number of oxyethylene units in the POE chain is also shown on these fabrics. In liquid no-phosphate formulations built only with diethanolamine to provide an alkaline pH, optimum removal of both sebum and clay soils from Dacron-cotton permapress at 49°C in 150 ppm hard water occurs with about 5, 9, and 10 oxyethylene units for POE C9-11, C12-15, and C16-18 alcohol mixtures, respectively. For removal of the same soils from cotton at the same temperature, the optimum POE chain lengths are about two oxyethylene units larger (Albin, 1973). 

It might be that this difference between Triton X-100 and polysorbate 80 may be the reason why the former is more toxic than polysorbate. Sulphate conjugation of non-ionic detergents yields anionic derivatives which are probably intrinsically more toxic. Different tissues produce different sulphate products [152] in the liver (in vitro) the products of Triton X-100 sulphation have 5 to 11 oxyethylene units while in the adrenal cortex the products have a shorter chain length, of 2 to 5 ethylene oxide units. 

E g-g- electrostatic (Donnan) exclusion of a component from a macromolecule oxyethylene unit in a detergent... 

Petroleum spillages can be removed from water surfaces more efficiently with the following detergent mixture [1692], which contains mainly oxyethyl-ate fatty Cio to C20 alcohols and additional oxyethylated fatty Cn to Cyj acids with an oxyethylene chain length of one to two units. It is used in the form of an aqueous 20% to 25% emulsion, which is sprayed onto a contaminated surface. 

Figure 1.4 Plots of the interfacial tension of corn oil/surfactant solutions and detergency as a function of the number of glycerol or oxyethylene (EO) units of polyglycerol laurate (filled symbols) and polyoxyethylene lauryl ether (open symbols).

The third class of novel heterochain block copolymers, inspired by interest in non-ionic detergents, was evolved in the early 1950s by Lundsted and co-workers " who found that substances composed of a central poly(oxypropylene) unit, itself having a sufficient MW (> 900) to be insoluble in water as a homopolymer and flanked by poly(oxyethylene) blocks, were water-soluble liquids or solids, according to the lengths of the end blocks, with valuable surfactant and detergent properties. 

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