Cationic-nonionic interactions, amine

Another important class of nonionics are amine oxides, such as DMDAO (dimethyldodecyl amine oxide) and CAPAO (cocoamidopropyldimethyl amine oxide). This type of surfactant is nonionic at pH values above its pKa and cationic below that point. When functioning as a nonionic, amine oxides have many useful properties. They interact strongly with anionics which can result in performance benefits [17]. Amine oxides help to mitigate anionic surfactant irritation, act as foam stabilizers, and can also function to improve grease removal. 

Examination of the second Hn system which contains the cationic surfactant oleyl amine shows very moderate changes upon incorporation of DNA in all the bands considered when compared to the nonionic mesophase. These data clearly suggested that in the presence of a cationic surfactant decorating the interface of the water channels, the interactions between the lipid polar heads and DNA change in nature, as the hydrogen bonding of D2O and the GMO polar heads is mostly unaffected by the presence of DNA. It was inferred that the DNA is confined in the water channels also in the cationic Hn mesophases, and electrostatically bound to their surfaces [58]. 

In acid solutions, the amino group is protonated and acts as a cationic surfactant, whereas in neutral or alkaline solution the amine oxides are essentially nonionic in character. Alkyl dimethyl amine oxides are water-soluble up to Cj, alkyl chain. Above pH 9, amine oxides are compatible with most anionics, but at pH 6.5 and below some anionics tend to interact and form precipitates. In combination with anionics, amine oxides can be used as foam boosters (e.g., in shampoos). 

The self-assembling process involves noncovalent or weak interactions (van der Waals, electrostatic, and hydrophobic interactions, hydrogen and coordination bonds, and r-7T stacking). This process corresponds to a variation of reversed pore structures. Most ordered mesoporous materials are derived from the thermodynamically stable and ordered a regates spontaneously driven by the noncovalent interactions between molecules. These aggregates come from the cationic, anionic and nonionic surfactants, neutral amines, block copolymers, or their mixtures (Figure 13.1). They are disordered on the atomic or... 

Surfactants are usually determined as a group of compovmds, so that sophisticated chromatographic procedures are not needed. Ion-pair formation between both anionic and cationic surfactants with polar dyes, such as methylene blue and brom-ocresol purple, respectively, with or without subsequent inline solvent extraction has been assessed using spectrophotometric or spectrofluorimetric detection as shown in Table 1. Polyoxyethylene and amine ethoxylate-based nonionic surfactants in environmental waters have been determined by spectrophotometry following polar interactions with chromogenic agents, and by CL detection in the presence of sensitizers, respectively. 

Cationic and anioiuc antistatic agents perform best in polar polymers, but their interaction with PVC heat stabilizers must be considered. Fatty acid based amines can react with the chlorine in PVC. Nonionic antistats are deployed in polyolefins, ABS and styrene polymers. 

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