Fluorinated cationic

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 ...

IL with alkylimidazolium cation-fluorinated anion combination IL with non-imidazolium cation-fluorinated anion combination... 

IL with Alkylimidazolium Cation-Fluorinated Anion Combination... 

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]. 

Even electrophilic fluorination of alkanes has been reported. F2 and fluoroxytrifluoro-methane have been used to fluorinate tertiary centers in steroids and adamantanes by Barton and coworkers ". The electrophilic nature of a reaction involving polarized but not cationic fluorine species has been invoked. Gal and Rozen have carried out direct electrophilic fluorination of hydrocarbons in the presence of chloroform. F2 appears to be strongly polarized in chloroform (hydrogen bonding with the acidic proton of CHCI3). However, so far no positively charged fluorine species (fluoronium ion) is known in solution chemistry. 

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]. 

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]. 

---