Fluorinated cationic surfactants

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 ...

Figure 11.15 Electron microscopy images, (a) SEM and (b) TEM, of hollow particles with mesopores in the shell. The particles were prepared using a cationic fluorinated surfactant (Reproduced from Ref [69], with permission).

It should be pointed out that although most of the research works used silica as a model material, fluorinated surfactants can be used for the preparation of a very wide variety of different mesoporous materials, including TiOj [70], aluminophos-phates and Fe- aluminophosphates [71], and Fe-Si oxides [72]. Organic functionalizations can also be obtained in direct synthesis processes. An example is the preparation in a one-step precipitation process, by Rankin et al., of vinyl-functionalized porous silica materials using mixtures ofTEOS and vinyltriethox-ysilane in aqueous solutions of cationic fluorinated surfactants [73]. 

The cationic fluorinated surfactant, FC-4, unlike other surfactants, forms micelles in the room temperature ionic liquid, l-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N). Surface tension, freeze-fracture TEM, F NMR, H NMR, and FTIR measurements revealed that the FC-4 cation forms an ion pair with the Tf2N anion, the ion pairs undergo association to form premicellar aggregates, and the premicellar aggregates transform into micelles at the CMC. Reverse micelles are... 

Some cationic fluorinated surfactants contain both quaternary and secondary amino groups and carbonamido or sulfonamido linkages. Examples of cationic fluorinated surfactants are given in Table 1.5. 

Cationic fluorinated surfactants can be prepared by reacting the pentamer with phenol and, subsequently, with chlorosulfonic acid. The sulfonyl chloride reacts with A,A-dimethylpropanediamine to form a tertiary amine sulfonamide, which can be quaternized to form a cationic surfactant ... 

Carbonyl or sulfonyl fluorides obtained by electrochemical fluorination yield cationic fluorinated surfactants by a reaction with MA -dimethyl-1,3-diamino-propane and quaternization with methyl iodide or dimethyl sulfate [5,160] ... 

In a similar fashion, cationic fluorinated surfactants are prepared from telomer iodides by converting perfluoroalkylethyl iodides to sulfonyl chlorides and reacting these with A, A -dimethyl-l,3-diaminopropane [161]. 

In some cationic fluorinated surfactants, the positively charged nitrogen atom is part of a heterocyclic ring [163]. Katritzky et al. [164] prepared cationic fluorinated surfactants derived from N-(perfluorooctanesulfonyl)piperazine ... 

Cationic fluorinated surfactants have been prepared from perfluoroalkyl esters, obtained by converting an acid fluoride into an ester. Reaction of the ester with a diamine and alkylation with a halide or sulfonate gives a cationic surfactant, for example [166] ... 

Using 3-(perfluoro-1,1-dimethyl-butyl)-1-propene as the starting material, cationic fluorinated surfactants have been prepared via the corresponding epoxypropane reacted with a secondary amine [168-170] ... 

A mixture of an anionic (Fluorad F-95) and a cationic fluorinated surfactant (Fluorad FC-134) has been recommended for foam suppression in organic liquids [140]. 

When the chain length of the fluorinated counterion is increased further, the counterion assumes surfactant characteristics in its own right. The cationic surfactant then becomes a mixed surfactant consisting of a fluorinated surfactant anion and a hydrocarbon surfactant cation (see Section 7.2). 

Cryogenic transmission electron microscopy was used also by Wang et al. [61] to study the aggregation behavior of cationic fluorinated surfactants 1,1,2,2-... 

Research on the micelle structure and interactions of fluorinated surfactants is ongoing with the main focus on mixed-surfactant systems. Mixtures of fluorinated and nonfluorinated surfactants may consist of anionic, nonionic, or cationic components. Most of the systems investigated so far have contained a fluorinated anionic surfactant and an anionic hydrocarbon surfactant. Anionic fluorinated surfactant mixtures with nonionic or cationic hydrocarbon-type surfactants have been investigated as well. The nonionic fluorinated hydrocarbon surfactant mixtures and cationic fluorinated hydrocarbon surfactant mixtures have been the subject of only a few studies. 

Fluorinated surfactants usually differ widely in their foaming power (see Section 4.9). Cationic fluorinated surfactants and amphoteric fluorinated surfactants (e.g., Zonyl FSK) are foaming agents in aqueous media. On the other hand, nonionics (e.g., Zonyl FSN and Zonyl FSO) are low-foaming surfactants [1]. Endcapping reduces foaming. 

Anionic fluorinated surfactants form liquid crystals with cationic fluorinated surfactants (see Chapter 7). Liquid crystals of fluorinated surfactants are used in various industrial applications and as biological membrane models. 

Perlite or vermiculite, treated with a cationic fluorinated surfactant, is claimed to be hydrophobic and effective in cleaning oil spills [231]. 

The water permeability of dialysis membranes containing fluorocarbon polymers can be increased by a surface treatment with a cationic fluorinated surfactant [281]. 

Fluorinated surfactants facilitate coplating of polytetrafluoroethylene and metals onto a metal substrate [43]. A cationic fluorinated surfactant adsorbed onto the polymer particles imparts a positive charge and thus allows the polymer and metal to be electrolytically coplated. 

Batts and Paul [101b] used time-of-flight secondary-ion mass spectrometry (ToF-SIMS) to investigate the competitive adsorption of a cationic fluorinated surfactant (FC-134) at the gelatin-air interface. ToF-SIMS is a very sensitive surface analysis technique. In the static mode, the sampling depth of ToF-SIMS is only one to two monolayers. However, the ToF-SIMS data are difficult to interpret in quantitative terms and experimental conditions must be carefully controlled. Batts and Paul used positive secondary-ion spectra only, although negative-ion spectra may have been used as well. 

Surfactants used as lubricants are added to polymer resins to improve the flow characteristics of the plastic during processing they also stabilise the cells of polyurethane foams during the foaming process. Surfactants are either nonionic (e.g. fatty amides and alcohols), cationic, anionic (dominating class e.g. alkylbenzene sulfonates), zwitterionic, hetero-element or polymeric (e.g. EO-PO block copolymers). Fluorinated anionic surfactants or super surfactants enable a variety of surfaces normally regarded as difficult to wet. These include PE and PP any product required to wet the surface of these polymers will benefit from inclusion of fluorosurfactants. Surfactants are frequently multicomponent formulations, based on petro- or oleochemicals. 

The determination of bismuth activity as an indicator of non-ionic surfactants also suffers from interference in environmental samples. Substance group specific methods also failed to detect different types of fluorine-containing anionic, cationic and non-ionic surfactants. Already marginal modifications in the precursor surfactant due to primary degradation or advanced metabolisation implicated their lack of detection [45]. 

The trend of discovering the analytical field of environmental analysis of surfactants by LC-MS is described in detail in Chapters 2.6-2.13 and also reflected by the method collection in Chapter 3.1 (Table 3.1.1), which gives an overview on analytical determinations of surfactants in aqueous matrices. Most methods have focused on high volume surfactants and their metabolites, such as the alkylphenol ethoxylates (APEO, Chapter 2.6), linear alkylbenzene sulfonates (LAS, Chapter 2.10) and alcohol ethoxylates (AE, Chapter 2.9). Surfactants with lower consumption rates such as the cationics (Chapter 2.12) and esterquats (Chapter 2.13) or the fluorinated surfactants perfluoro alkane sulfonates (PFAS) and perfluoro alkane carboxylates (PFAC) used in fire fighting foams (Chapter 2.11) are also covered in this book, but have received less attention. 

Quaternary fluorinated alkyl ammonium compounds The fluorine-containing cationic surfactants of quat type with the general formula C F2 , 1-S02-NH-CH2-CH2-CH2-N (CH3)3 X (n = 8) (Fig. 2.12.1(d)) were examined by FIA—MS using APCI and ESI in the positive and negative modes. The APCI(- -/—) ionisation resulted in a dealkylation at the nitrogen with ions at m/z 585 or 583, respectively. The alkyl chain of this compound contained the moiety C8Fi7. The ions generated under APCI conditions were characterised as dealkylation products—m/z 585 [M — CH2]+ or m/z 583 [M — H— CH3] —as reported in the literature [35,37]. 

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