Alcohol ethoxylates characterization

Di Corcia A, C Crescenzi, A Marcomini, R Samperi (1998) Liquid-chromatography-electrospray-mass spectrometry as a valuable tool for characterizing biodegradation intermediates of branched alcohol ethoxyl-ate surfactants. Environ Sci Technol 32 711-718. 

Feijtel, T.C.J. and Belanger, S.E. (1999) Predicted no-effect concentrations and risk characterization of four surfactants linear alkyl benzene sulfonate, alcohol ethoxylates, alcohol ethoxylated sulfates, and soap. Environ Toxicol Chem, 18, 2653-2663. 

Fatty alcohol ethoxylates were spotted and characterized by Spriestersbach, Rode, and Pasch [128]. Other applications of semi-on-line LC—MALDl coupling via a spraying interface for synthetic polymers involve copolyesters [129], silsesquioxanes [130], and hydroxyl-terminated polydimethylsiloxane [131,132]. Reference [103] summarizes different applications, comparing their advantages and drawbacks. 

The focus of this report concerns nanocomposites from poly(propylene carbonate) (PPG) and multiwall carbon nanotubes (MWNTs). A solvent route using THF, ethoxylated non- ionic surfactants combined with sonication was found to be successful in deagglomerating and dispersing the nanotubes. The morphology and molecular mobility of the prepared nanocomposites (0.5, 3.0 and 5.0 wt% of nanotubes) were characterized by rheology, microscopy, low-field SS NMR, and electrical conductivity. The networking of nanotubes was highest with a steatyl alcohol ethoxylate surfactant, and was found to improve with the sonication... 

Surface tension methods measure either static or dynamic surface tension. Static methods measure surface tension at equilibrium, if sufficient time is allowed for the measurement, and characterize the system. Dynamic surface tension methods provide information on adsorption kinetics of surfactants at the air-liquid interface or at a liquid-liquid interface. Dynamic surface tension can be measured in a timescale ranging from a few milliseconds to several minutes [315]. However, a demarkation line between static and dynamic methods is not very sharp because surfactant adsorption kinetics can also affect the results obtained by static methods. It has been argued [316] that in many industrial processes, sufficient time is not available for the surfactant molecules to attain equilibrium. In such situations, dynamic surface tension, dependent on the rate of interface formation, is more meaningful than the equilibrium surface tension. For example, peaked alcohol ethoxylates, because they are more water soluble, do not lower surface tension under static conditions as much as the conventional alcohol ethoxylates. Under dynamic conditions, however, peaked ethoxylates are equally or more effective than conventional ethoxylates in lowering surface tension [317]. 

These products are characterized by using the procedures (appropriately modified) for characterization of the parent compound. For example, phosphate esters of ethoxylated alcohols can be analyzed for EO content, alkyl chain length, and free alcohol by the methods described in Chapter 2 for analysis of alcohol ethoxylates. 

GC methods are summarized in Tables 2 and 3. Sulfates of alcohols and ethoxylated alcohols are readily decomposed by acid hydrolysis to yield the free alcohols or ethoxylated alcohols. The trimethylsilyl derivatives of these are easily analyzed by gas chromatography (24). Derivatization of the alcohols may be omitted if they have reasonable volatility (25). Alternatively, the surfactant may be decomposed by hydriodic acid, giving alkyl iodide derivatives of the starting alcohols for characterization by gas chromatography (26). Hydrolysis can be combined in the same step with derivatization. Reaction of alkyl sulfates with silylating agents such as BSTFA/1% TMCS results in cleavage of the sulfate and formation of the trimethylsilyl ethers of the alcohols (27). GC or GC-MS analysis will... 

In addition to their poor solubility in water, alkyl phosphate esters and dialkyl phosphate esters are further characterized by sensitivity to water hardness [37]. A review of the preparation, properties, and uses of surface-active anionic phosphate esters prepared by the reactions of alcohols or ethoxylates with tetra-phosphoric acid or P4O10 is given in Ref. 3. The surfactant properties of alkyl phosphates have been investigated [18,186-188]. The critical micelle concentration (CMC) of the monoalkyl ester salts is only moderate see Table 6 ... 

It is only a small step from the alkyl sulfates to the so-called alkyl ether sulfates. These surface-active agents are made from alcohols which are ethoxylated. The formed fatty alcohol polyglycol ethers possess a final OH-group which then reacts with sulfuric acid. Fatty alcohol polyglycol sulfates are characterized by an insensitivity to water hardness and low irritation of the skin. Their aqueous solutions can be easily thickened by the addition of sodium chloride. These properties thus attract attention for the use of fatty alcohol polyglycol sulfates in cosmetic products. 

Jandera et al. [644] separated ethoxylated alkylphenols (the alkyl was methyl to pentadecyl) using either a 25/75- 85/15 ethanol/heptane gradient on a silica column (/ = 254 nm or 230 nm) or a 60/40->90/10 -propyl alcohol/heptane gradient on a cyanopropyl column. These methods were used to characterize a number of commercial formulations. Most analyses were complete in less than 40 min. In general, excellent peak shapes and elution profiles were generated with these systems. Analyses were complete in 30-40 min. 

Elhoxylated alcohol distributions from 2 to 40 ethylene oxide units (e.g., Brij 76) were characterized on a diol phase (ELSD) using a 25-min 90/10->20/80 hexane/(98/2 chloroform/IPA) gradient [645]. Good separation throughout the homologous series resulted. Peak shapes were acceptable as well. Tables of retention times for hexadecylalcohol-ethoxylated compounds (1-6 ethoxy groups) and for Cio-Cig hexaethoxylated alcohols were presented. 

Characterization of ethoxylated Trathnigg B, Thamer D, Yan X, fatty alcohols. Two-dimensional Maier B, Holzbauer HR, Much H separation. [118]... 

Characterization of ethoxylated Trathnigg B, Kollroser M, Parth fatty alcohols. Two-dimensional M, Roblreiter S [119], Trathnigg separation. B, Kollroser M, Rappel C [120]... 

Henrich developed a comprehensive TLC method for identification of surfactants in formulations (4). She specified two reversed-phase and four normal phase systems, with detection by fluorescence quenching, pinacryptol yellow and rhodamine B, and iodine. Prior to visualization, one plate was scanned with a densitometer at 254 nm, and UV reflectance spectra were recorded for each spot detected. Tables were prepared showing the Rf values of 150 standard surfactants in each of the six systems, along with the reflectance spectra and response to the visualizers. This system allows for systematic identification of compounds of a number of surfactant types (LAS, alcohol sulfates and ether sulfates, alkane sulfonates, sufosuccinate esters, phosphate compounds, AE, APE, ethoxylated sorbi-tan esters, mono- and dialkanolamides, EO/PO copolymers, amine oxides, quaternary amines, amphoterics and miscellaneous compounds). Supplementary analysis by normal phase HPLC aided in exactly characterizing ethoxylated compounds. For confirmation, the separated spots may be scraped from one of the silica gel plates and the surfactant extracted from the silica with methanol and identified by IR spectroscopy. 

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