Cationic ammonium surfactants

A few commercial cationic latexes are offered, eg, by Du Pont Showa and Denki. These are stabilized with quaternary ammonium surfactants. 

Gravimetric and volumetric methods are practicable for the quantitative determination of the a-sulfo fatty acid esters. Using gravimetric methods the surfactant is precipitated with p-toluidine or barium chloride [105]. The volumetric determination method is two-phase titration. In this technique different titrants and indicators are used. For the analysis of a-sulfo fatty acid esters the quaternary ammonium surfactant hyamine 1622 (p,f-octylphenoxyethyldimethyl-ammonium chloride) is used as the titrant [106]. The indicator depends on the pH value of the titration solution. Titration with a phenol red indicator is carried out at a pH of 9, methylene blue is used in acid medium [106], and a mixed indicator of a cationic (dimidium bromide) and an anionic (disulfine blue VN150) dye can be used in an acid and basic medium [105]. 

Therefore, a C13-AE, a cationic (quaternary ammonium) surfactant (quat), an amphoteric Ci2-alkylamido betaine, and the non-ionic fatty acid diethanol amide (FADA) as presented with their FIA-MS spectra in Fig. 2.5.12(a)-(d) were analysed as pure blends and as mixtures always obtained from two blends in FIA-MS multiple ion detection mode (MID). Mixtures as well as pure blends contained identical concentrations of surfactant homologues. For AE quantitation the mass traces of all A m/z 44 equally spaced homologues (m/z 306-966) of the C13-AE were recorded. The cationic (quaternary ammonium) surfactant, the amphoteric Ci2-alkylamido betaine, and the non-ionic FADA were quantified recording the mass traces at m/z 214 and 228, or 184, 212, 240, 268, 285, 296, 313, 324 and 341, or 232,260, 288, 316 and 344, respectively. 

To recognise ion suppression reactions, the AE blend was mixed together either (Fig. 2.5.13(a) and (b)) with the cationic quaternary ammonium surfactant, (c, d) the alkylamido betaine compound, or (e, f) the non-ionic FADA, respectively. Then the homologues of the pure blends and the constituents of the mixtures were quantified as presented in Fig. 2.5.13. Ionisation of their methanolic solutions was performed by APCI(+) in FIA-MS mode. The concentrations of the surfactants in the mixtures were identical with the surfactant concentrations of the blends in the methanolic solutions. Repeated injections of the pure AE blend (A 0-4.0 min), the selected compounds in the form of pure blends (B 4.0—8.8 min) and their mixtures (C 8.8— 14.0 min) were ionised and compounds were recorded in MID mode. For recognition and documentation of interferences, the results obtained were plotted as selected mass traces of AE blend (A b, d, f) and as selected mass traces of surfactant blends (B a, c, e). The comparison of signal heights (B vs. C and A vs. C) provides the information if a suppression or promotion has taken place and the areas under the signals allow semi-quantitative estimations of these effects. In this way the ionisation efficiencies for the pure blends and for the mixture of blends that had been determined by selected ion mass trace analysis as reproduced in Fig. 2.5.13, could be compared and estimated quite easily. 

Fig. 2.12.1. Chemical structure of different classes of cationic surfactants (a) quaternary ammonium surfactants (quats) (b) dialkylcarboxyethyl hydroxyethyl methyl ammonium surfactants (esterquats) (c) alkyl polyglycol amine surfactants (d) quaternary perfluoro-alkyl ammonium surfactants (e) N, N, N1, JV -tetramethyl-iV, iV -didodecyle-l,3-propane-diyle-diammonium dibromide (cationic gemini surfactant). R = alkyl or benzyl group.

Fig. 2.12.4. FIA-APCI-MS-MS(+) CID product ion mass spectrum of selected [M]+ parent ion of cationic quat surfactant blend RR N (CH3)2X at mtz 304 characterised as alkyl di-methylbenzyl ammonium acetate fragmentation pattern presented in the... 

Fig. 2.12.8. FIA-APCI-MS-MS(—) (CID) product ion mass spectrum of a selected [M — H] parent ion (mlz 583) of cationic fluorinated quaternary alkyl ammonium surfactant blend (general formula CnF2n+i- S02-NH-CH2-CH2-CH2-N (CH3)3 x ...

In MEKC, mainly anionic surface-active compounds, in particular SDS, are used. SDS and all other anionic surfactants have a net negative charge over a wide range of pH values, and therefore the micelles have a corresponding electrophoretic mobility toward the anode (opposite the direction of electro-osmotic flow). Anionic species do not interact with the negatively charged surface of the capillary, which is favorable in common CZE but especially in ACE. Therefore, SDS is the best-studied tenside in MEKC. Long-chain cationic ammonium species have also been employed for mainly anionic and neutral solutes (16). Bile salts as representatives of anionic surfactants have been used for the analysis of ionic and nonionic compounds and also for the separation of optical isomers (17-19). 

An anionic surfactant is soluble only at a pH greater than tf pqf its ionizable group, whereas a cationic surfactant (e.g., primary, secondary, ortertiary amines) is soluble only at a pH less than its pKg. However, quaternary ammonium surfactants remain soluble at all pH values. Zwitterionic surfactants, for example, sulfobetaine surfactants, are neutral from pH 2 to 12, whereas some nonionic surfactants, for example, alkyldimethylamine oxides, are converted to cationic surfactants by protonation at acidic pH. 

Association of surfactant molecules onto humic substances is also termed sorption and has been given some attention. In the case of cationic alkyl trimethyl and dimeth-yldioctadecyl ammonium surfactants (Versteeg and Shorter, 1992), the presence of dissolved organic carbon in the water significantly reduced the toxicity of these compounds to fathead minnows. The effect of toxicity reduction increased with increasing hydrophobicity. For the anionic surfactant LAS, this mitigating effect was less pronounced (Traina et al., 1996). 

If the reaction takes place under basic conditions then the silica species are present as anions, that is, deprotonated silanol groups (Si-O-) in this case the surfactants have to be charged positively to ensure interactions between both components commonly cationic quaternary ammonium surfactants are used as the SDA this synthesis pathway is termed S+I (Fig. 3.6a). 

Zirconia. Mesoporous zirconia was first reported by Knowles and Hudson with cationic aUcyltrimethylam-monium siufactants. Starting from zirconium sulfate or propoxide, Schiith and Ciesla et al. synthesized hexagonal mesoporous zirconia using aUcyltrimethylammonium surfactants as templates. Reddy and Sayari obtained hexagonal or lamellar phases of mesostructured zirconia using quaternary ammonium surfactants and acidified primary aUcylamine,... 

In accordance with the observation that the anti-microbial effect of gases like nitrogen dioxide, carbon dioxide or xenon can be related to the effects of general anaesthetics, it seems natural to relate the well-knovm anti-microbial effect of cationic surfactants to local anaesthetic agents. The first type of perturbants shifts the actual transition in the direction La - whereas the second t)rpe of agent is expected to shift the transition in the opposite direction. It should be mentioned that quaternary ammonium surfactants such as cetyltrimethyl ammonium bromide in micellar solution in water were found to transform the cubic phase into the La phase [34]. 

The surfactant may be cationic, or anionic, even nonionic. The type most used for MCM-41 and MCM-48 is cationic quaternary ammonium surfactant. The inorganic resources are those monomers or oligomers that are polymerizable or condensable under certain conditions (concentration, temperature, pressure, pH, solvent, etc.) and form inorganic solid matter such as gel, ceramic, and glass. The depolymerization or hydrolysis is necessary sometimes, for example with TEOS, Ti(OC2H5)4, silicon sol, sodium silicate, and amorphous silica. 

There are many combinations of surfactants reported. For example, cationic CTA surfactant and cationic Gemini surfactant, CTA and long-chain pyridine quaternary ammonium surfactant,11] anionic and cationic surfactant,1126 CTA and amine (Q2H25NH2), neutral and cationic surfactant,11761 and neutral-neutral surfactants have been used to prepare silica with interesting mesostructures (e.g., Ia3d cubic) or morphologies (e.g., nanoparticles). 

Self-assembly using cationic quaternary ammonium surfactants... 

Benzethonium chloride (Hyamine 1622, [diisobutylphenoxyethoxyethyljdimethylbenzyl-ammonium chloride, (A,A-dimethyl-A-[2-[2-[4-(l,l,3,3-tetramethylbutyl)phenoxy]-ethoxy]-ethyl]-benzenemethanammonium chloride,) [121-54-0] M 448.1, m 164-166° (sinters at 120°, monohydrate). Crystallise it from boiling acetone after filtering or from CHCls/pet ether. The precipitate is filtered off, washed with diethyl ether and dried for 24hours in a vacuum desiccator. It is a cationic antiseptic surfactant which forms crystals also from a 1 9 MeOH/Et20 mixture. It foams in water. [Beilstein 12 IV 2187.]... 

Polymeric quaternary ammonium surfactants made from w-dodecyl bromide and poly(2-vinylpyridine) are better solubilizers for oil-soluble azo dyes and for n-decanol than monomeric quaternary cationics with similar (monomeric) structures (Tokiwa, 1963 Inoue, 1964). Solubilization of n-decanol in the polycationics increased as the alkyl chain content increased to a maximum at 24% alkyl content and resulted, at high decanol content, in intermolecular aggregation of the poly cationic molecules (Inoue, 1964). 

The organized mesoporous material MCM-41 [15] was obtained by combining at room temperature colloidal silica with a sodium aluminate solution in the presence of cetyltrimethyl-ammonium surfactant cations. After filtration, washing and drying, the solid was calcined in air at 200°C (4 h) followed by 10 h at 540°C. The Si/Al ratio was 23. 

The two-phase titration can be also successfully used for the determination of cationic surfactants using standardized solutions of anionic surfactants. In this case the mechanism of titration is the reverse, i.e. the chloroform layer undergoes color change from blue to pink. More often, and especially at higher concentrations, cationic surfactants are determined by two-phase titration using sodium tetraphenylborate titrant and bromophenol blue indicator [32], Tetraphenylborate ion is also used in the determination of potassium, rubidium and cesium, so the ions of these metals, if present, interfere with the determination of quaternary ammonium surfactants by this method. 

USE Cationic quaternary ammonium surfactant germicide and fungicide. Used in leather processing, textile dyeing. A mildew preventive in silicone-based water repellents. Compatible with many non-ionic detergents. Active in moderately alkaline solns. 

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