DDAB surfactant

What approximate composition of DDAB surfactant in water would you recommend to pump down an oil well to improve oil recovery if the main cost of the process was the cost of the surfactant ... 

Bettelheim et al. investigated nitrosyl adducts of cobalt tetrasulfonated ph-thalocyanine, Co(TSPc) , dissolved in aqueous solution or incorporated into a DDAB surfactant film where Co(TSPc)" acts as the counterion for four DDA+ forming Co(TSPc)(DDA)4 (this was also done with dodecyltrimethylam-monium) " . Using FTIK and electrochemical experiments the conformational orientation of the NO adduct was determined to be bent, Eq. (4.33). When exposing the phthalocyanin to NO in solution, a sharp band at 1,646 cm appears but is quickly replaced by a broader band at about 1,700 cm implicit of the N-Co bond shortening, this also occurs for the solid form of Co(TSPc) and Co(TSPc)(DDA)4, Eq. (4.34). A plot of E v. l/[NO], using CV, yielded a slope of 65 mV, ruling out the possibility of a Co(TSPc)(NO)2, complex. 

Mimica et al. and Lin et al. employed haemin , myoglobin - and hemoglobin to electrocatalytically reduce of nitrite. These iron porphrin complexes were embedded in DDAB surfactant fllms and were found to be active catalysts. The catalytic currents were observed at potentials close to the Fe /Fe couple . ... 

Finally, Yamada and Suzuki made a comparative study of the use of DDAB, HTAB, STAC, and CEDAB to improve the sensitivity and selectivity of the determination of ultratraces of Cu(II) by means of the CL reaction of 1,10-phenanthroline with hydrogen peroxide and sodium hydroxide, used as detection in a flow injection system [46]. Of the four cited surfactants it was found that CEDAB causes the greatest enhancement of the chemiluminescent signal (Fig. 12) (an enhancement factor of 140 with respect to the absence of surfactant). 

In this case the liposomes are generally dubbed with positively charged co-surfactants, such as DDAB (dimethyl-didodecylammonium bromide) or CTAB... 

As DDAB contains a quaternary N in the head group, the cationic charge is independent of pH. The stoichiometry in Eq. (3) for the [MCI, ]2- (/i = 4, M = Pt, Pd n = 6, M = Pt) complex ions has been established by XPS and optical absorbance measurements. The (PtClb)2 anion has also been incorporated into LB films using a tertiary amine surfactant (38). In this case the charge of the head group, and therefore the complexation to the anion, is pH dependent. 

FTIR has also been used to confirm hydration of (PdCI4)2- ions incorporated into LB films made from the cationic surfactant DDAB (10) and the coordination modes of amine ligands of complex metal ions of M(II) (M = Pt, Pd) in LB films... 

AFM images were obtained for films constructed, on freshly cleaved mica, from compressed monolayers of DDAB on a subphase of HMP-stabilized CdS (81). Particles, with dimensions of 8 3 nm, were seen to be evenly distributed. The determined area of 58 nm2/particle coincided well with the area per molecule determined for DDAB from its spreading isotherm, implying 1 1 particle/surfactant stoichiometry. This result is puzzling given that freshly cleaved mica is hydrophilic and therefore any particles would be buried under a layer of the hydrophobic tails of the DDAB and unaccessable to the AFM tip. 

Figure 12 CL enhancement versus surfactant concentration. (A) DDAB ( ) HTAB, ( )STAC (O) CEDAB. CCu(II) = 2.0 X 10 8 M CH202 = 5% Q i0-Phenantroiine = 6-0 X 10 5 M CNa0H = 0.1 M. (From Ref. 46 with permission.)...

Materials. Sodium dodecylsulfate (SDS) and fully deuterated sodium dodecylsulfate (SDS-d ) were obtained from Sigma and Cambridge Isotope Laboratories respectively, and used as received. The cationic surfactants, dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB), and didodecyldimethylammonium bromide (DDAB) were purchased from Eastman Kodak, and purified by repeated recrystallization from an ethanol/acetone solvent pair. Even so, a small amount of surface active impurity was observed in surface tension plots for DTAC. The tetradecyldimethylamine oxide (C14AO) was a commercial sample (Ammonyx MO) obtained from Stepan (Control No. 533-30027). This sample is primarily C14AO, but also contains other chain length components. Sodium chloride (NaCl) was obtained from EM Science and used as received. Water was purified by a three stage Bamstead water purification system. 

Variation of v. The last mixed micelle case studied were mixtures in which the volume of the hydrophobic tails was varied by mixing monoalkyl and dialkyl cationic surfactants (DTAB/DDAB). The aggregate structures found as a function of composition are detailed in Table IV. TTiey range from lamellar packed liquid... 

Why is it that the preadsorbed surfactant layer on the electrode (e.g., the DDAB), has such a helpful effect in facilitating the reactions of enzymes on electrodes For one thing, the surfactant is a good adsorber on the metal or graphitic electrode. Correspondingly, if, upon adsorption, there is some partial dissociation of the complex enzyme, the preadsorbed surfactant makes it difficult for such fragments to build up passive layers on the electrode, layers that could diminish electron transfer. 

Reversal of the direction of the EOF using the cationic surfactant didodecyldimethylammonium hydroxide (DDAOH) in reversed polarity mode has also been reported (16). The bromide form of this surfactant (DDAB (didodecyldimethylammonium bromide)) was converted to the hydroxide form to eliminate an undesirable system peak caused by bromide. Using 10 mM phenylphosphonic acid as the probe and a buffer consisting of 200 mM borate, 0.35 mM DDAOH, and 0.03% Trition X-100 at pH 4.0, the separation of 8 alkylphosphonates was achieved in less than 3 min. Eimits of detection were in the 100 xg/L range. 

McGillivray et al. [71] have also observed stable layered structures adsorbed at the silicon-solution (and air-solution) interface for didodecyl dimethylammo-nium bromide (DDAB) and the corresponding diundecyl (DUDAB) cationic surfactants, in the concentration range 0.2-2 wt.%. Similar to AOT, the surface structures that are found are highly sensitive to temperature, with the repeat distance decreasing with increasing temperature. A notable difference between these systems and AOT [69] is that for the DDAB and DUDAB, the repeat distances are much larger, 600-1500 A. Furthermore, the observed structures... 

Very few rheological data have been reported for ordered cubic phases of surfactant solutions. However, Radiman et al. (1994) have reported dynamic oscillatory data for solutions of didodecyldimethylammonium bromide (DDAB) in deuterated water and octane. Their data for type II cubic P and D phases are shown in Fig. 12-29. They report that the samples... 

Furfiier evidence fiiat supports these calculations derives from studies of the ternary mixtures of the cationic double-chain surfactant DDAB (didodecyl dimethyl ammonium bromide), cyclohexane and water. Within the cubic mesophase region of fiiis surfactant-water-oil mixtiure, all the cyclohexane is adsorbed between the surfactant chains, so that the system is a pseudo-binary one, for which our theoretical analysis ought to hold. (The effective surfactant parameter for fliis surfactant in the presence of cyclohexane is slightly larger tiian unity.) Close scrutiny of the cubic phase region within this ternary phase diagram has revealed the presence of at least one - and... 

The geometrical constraints for a ternary mixture of surfactant, nonpolar solvent and water are less easily calculated for more general systems, which contain more than two components. Nevertheless, geometric considerations lead to similar behaviour as has been detailed in the previous sections. To illustrate this point, we analyse the microstructure of simple ternary microemulsions, consisting of a mixture of the cationic surfactant, didodecyl dimethyl ammonium bromide (DDAB), a range of alkanes and water. 

But some double-chain cationic surfactants form microemulsions when mixed with only water and oil over a large region of the ternary phase triangle [38, 39]. These surfactants are virtually insoluble in both water and oil and therefore are located exclusively at the oil-water interface. This aids structural analyses significantly. We shall focus on mixtures containing DDAB. Some typical phase diagrams for these mixtures are reproduced in Fig. 4.19. 

---