Sulfobetaine zwitterion

Since DTC require alkaline conditions during chromatography to guarantee stability, silica materials cannot be used. Therefore, the polymeric ZIC-pHILIC column offered the great chance for an LC/MS approach, when a simple and salt-free gradient of acetonitrile and ammonium hydroxide solution is applied. The active sites of the ZIC-/ HILIC column consist of sulfobetaine (zwitterionic) groups (Figure 26.3), which also comprise... 

Initiated chemical vapor deposition (iCVD) is an all-dry free radical polymerization technique performed at low temperatures and low operating pressures [96]. Using this technique, an antifouling copolymer layer containing poly-(sulfobetaine) zwitterionic... 

Zwitterionic micelles of the sulfobetaine C16H33N+Me2(CH2)3SO 3 have effects very similar to those of cationic micelles (Table 7). This result is understandable if the substrate binds close to the quaternary ammonium center and the anionic sulfate moiety extends into the aqueous region. 

A slightly different mechanism of proteins separation results from the use of porous polymeric monoliths containing zwitterionic sulfobetaine groups [68]. 

The use of zwitterionic surfactants commercially has increased dramatically in recent years (U because of their unique properties, such as compatibility and synergism when used in conjunction with most other types of surfactants. This type of surfactant is used in textile processing aids, cosmetic products, cleaning agents, and as antistatic agents. The sulfobetaines have been found to be very good lime soap disperants ( ). 

In the present work, we have synthesized two betaines and three sulfobetaines in very pure form and have determined their surface and thermodynamic properties of micellization and adsorption. From these data on the two classes of zwitterionics, energetics of micellization and adsorption of the hydrophilic head groups have been estimated and compared to those of nonionic surfactants. 

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. 

Three-arm PB stars having arms of equal molecular weight but with different functional end-groups were prepared [58]. One or two functional dimethylamine groups were introduced using the functional initiator 3-dimethylaminopropyllith-ium (DMAPLi) [59-61]. Post polymerization reactions were carried out to transform the dimethylamine groups to zwitterions of the sulfobetaine type (Fig. 2). 

Snow, S.A., Fenton, W.N. and Owen, M.J. (1991) Zwitterionic organofunctional siloxanes as aqueous surfactants - synthesis and characterization of betaine functional siloxanes and their comparison to sulfobetaine functional siloxanes. Langmuir, 7(5), 868-71. 

The surface activity and solubihzation capacity of amphoteric polysoaps were studied [172,177,178]. The surface activity of zwitterionic polysoaps is diminished by added salt due to their antipolyelectrolyte character. The sequence to solubihze hydrophobic dyes is often mid-tail > head > tail-end geometry. An extended study on the solubilization abihty of hydrophobically modified polybetaines can be found in [232]. The surface activity of the cyclocopolymers containing the pH-responsive hydrophobic monomer WAf-diallyl-N-methylamine and the salt-sensitive sulfobetaine monomer 3-(WAf-diallyl-N-methylammonio) propanesulfonate was utilized to solubilize p-cresol within microdomains [233]. Other studies corroborate the general picture [182,183]. 

Zwitterionic Lauramidopropyl betaine Cocoamido-2-hydroxypropyl sulfobetaine CiiH23CONH(CH2)3N"(CH3)2CH2COO C H2 .iC0NH(CH2)3N-(CH3)2CH2CH(0H)CH2S03 ... 

Zwitterionic. Both positive and negative charges may be present in the surface-active portion, for example, RN H2CH2COO (long-chain amino acid), RN+(CH3)2CH2CH2S03 (sulfobetaine). 

For zwitterionics of the betaine and sulfobetaine types, Ci2H25N+(CH3)2(CH2)m COO- and C12H25N+(CH3)2(CH2)3S03-, respectively, the micellar aggregation number varies very little with change in surfactant concentration or electrolyte content (Kamenka, 1995a). 

The binding of the counterions Na+ and Cl to zwitterionics of the betaine and sulfobetaine types starts well above the CMC and hence does not affect its value. The degree of binding of the Cl is always larger than that of the Na+ (Kamenka, 1995b). 

Aqueous cationic micelles speed and anionic micelles inhibit bi-molecular reactions of anionic nucleophiles. Both cationic and anionic micelles speed reactions of nonionic nucleophiles. Second-order rate constants in the micelles can be calculated by estimating the concentration of each reactant in the micelles, which are treated as a distinct reaction medium, that is, as a pseudophase. These second-order rate constants are similar to those in water except for aromatic nucleophilic substitution by azide ion, which is much faster than predicted. Ionic micelles generally inhibit spontaneous hydrolyses. But a charge effect also occurs, and for hydrolyses of anhydrides, diaryl carbonates, chloroformates, and acyl and sulfonyl chlorides and SN hydrolyses, reactions are faster in cationic than in anionic micelles if bond making is dominant. This behavior is also observed in water addition to carbocations. If bond breaking is dominant, the reaction is faster in anionic micelles. Zwitterionic sulfobetaine and cationic micelles behave similarly. 

Thus far, only ionic micelles have been discussed, but some results were obtained for reactions in zwitterionic micelles of the betaine (Bl-12) and the sulfobetaine (SB3-16). These surfactants differ in that the carboxylate moiety of Bl-12 could react nucleophilically, and this behavior is observed in... 

The zwitterionic sulfonates (sulfobetaine monomers) also show a higher... 

Another diagnostic kinetic application with zwitterionic micelles was that of Rodriguez et al. [79], who investigated the reaction of DDT with hydroxide ions in micellar sulfobetaine solutions to determine the role cations play in the process. Micellar charge plays an important role in micellar catalysis [80]. The use of nonionic micelles affords a sensitive and refining means to measure the operative hydrophobic... 

Copolymerization of olefinic zwitterionic sulfobetaine siufactants with SO2 [87]. 

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