Concentration without surfactant

Self-emulsification The polymer molecules are modified chemically by the introduction of basic (e.g., amino) or acidic (e.g., carboxyl) groups in such concentration and location that the polymer undergoes self-emulsification without surfactant after dispersion in an acidic or basic solution. 

The addition of a surfactant counter-ion reduced the retention factor at low pH due to the surface modification of the stationary phase material. Covering the surface of the stationary phase with the surfactant reduces the hydro-phobicity of the stationary phase material. The addition of the tetrabutyl-ammonium counter-ion increased the retention factor at high pH. The pKa of the indole acetate was 5.15 without surfactant, 4.85 with octyl sulfate ion, and 5.60 with tetrabutylammonium ion. That is, the addition of a same-charged hydrophobic ion reduced the pKa value, and the addition of the counter-ion increased the pKa value. The difference in the pKa value on the addition of surfactant is not constant it is affected by the kind of ion and the concentration. It is difficult to estimate the pKa change. 

Menne T, Calvin G. 1993. Concentration threshold of non-occluded nickel exposure in nickel-sensitive individuals and controls with and without surfactant. Contact Dermatitis 29 180-184. 

Here km and kw are the second-order rate constants in the micellar pseudo-phase and the aqueous phase, respectively, Phrp and Prfc are the partition coefficients for HRP and RFc, respectively, between the micellar and aqueous phases (PA= [AJm/fA],, A = HRP or RFc), C is the total surfactant concentration without cmc (C = [surfactant] t-cmc), and V is the molar volume of micelles. Equation (39) simplifies assuming Phrp <3C 1 and PRFc 1. In fact, the hydrophilic enzyme molecule is expected to be in the aqueous phase, while hydrophobic, water-insoluble ferrocenes have a higher affinity to the micellar pseudo-phase. Taking also into account that relatively low surfactant concentrations are used, i.e., CV <5iC 1, Eq. (39) transforms into Eq. (40). 

Recall that kexp and k0 are rate constants with and without surfactant, respectively, for the reaction in question, and that c and cCMC are surfactant concentrations in the reaction mixture and at the CMC, respectively. Therefore kexp> k0, c, and cCMC are experimentally accessible. Equation (28) predicts that a plot of (kexp — k0) -l versus (c — cCMC) -l is a straight line with a slope and intercept that have the following significance ... 

The phase separation behavior of a sample of poly(N-vinyl-2.pyrrolidone) (PVP) in aqueous Na2S04 (0.55 M) containing a surfactant, sodium dodecyl sulfate (SDS), was reported [83], This phenomenon was studied in function of temperature and surfactant concentration as independent variables. Without surfactant, the polymer exhibits a lower solution temperature (LCST) of 28°C, above which it precipitates. At SDS concentrations of only 300 mg L-1, aggregation was prevented and the behavior of isolated polymer molecules could be studied. 

To investigate whether the rinse with cationic surfactants does affect the pattern collapse, the photolithographic process as described in Experimental was performed without surfactant rinse and with an additional rinse step with four different concentrations of the surfactant. The results of these experiments have been discussed in detail by Wun-nicke et al. [21], Here only a short summary is given. 

Oh et al. [16] have demonstrated that a microemulsion based on a nonionic surfactant is an efficient reaction system for the synthesis of decyl sulfonate from decyl bromide and sodium sulfite (Scheme 1 of Fig. 2). Whereas at room temperature almost no reaction occurred in a two-phase system without surfactant added, the reaction proceeded smoothly in a micro emulsion. A range of microemulsions was tested with the oil-to-water ratio varying between 9 1 and 1 1 and with approximately constant surfactant concentration. NMR self-diffusion measurements showed that the 9 1 ratio gave a water-in-oil microemulsion and the 1 1 ratio a bicontinuous structure. No substantial difference in reaction rate could be seen between the different types of micro emulsions, indicating that the curvature of the oil-water interface was not decisive for the reaction kinetics. More recent studies on the kinetics of hydrolysis reactions in different types of microemulsions showed a considerable dependence of the reaction rate on the oil-water curvature of the micro emulsion, however [17]. This was interpreted as being due to differences in hydrolysis mechanisms for different types of microemulsions. 

Nanospheres of P-CDC6 prepared without surfactant and with Pluronic F68 of varying concentrations between 0.1 and 1% were found to be slightly less cytotoxic than nanocapsules to both L929 and human PMNC cells. It was concluded that cytotoxicity increased with increasing concentration of surfactant and the most suitable percentage for surfactant if required was found to be 0.1% [80],... 

Nonionic detergents formulated for use in high turbulence equipment such as jets. Offering efficient oil removal and emulsification properties, KLENZOL 201 is especially useful in processing goods where excessive amounts of oil warrant higher than normal surfactant concentrations without foaming difficulties. 

The foregoing mechanism is amenable to mathematical analysis, with the salient results that during ideal interval II polymerization, the rate of reaction is proportional to and while DP depends on and [1] . (Here [I] is the initiator molar concentration and S is the weight concentration of surfactant.) In conventional solution, suspension, or low-conversion bulk free-radical reactions, the rate of polymerization depends on [1] / while DP is proportional to [I]". In these cases DPp cannot be increased at given [M] without decreasing Rp. In emulsion polymerization, however, both Rp and DP can be changed in parallel by controlling the soap concentration. 

FIGURE 8.27. The maximum pore depth that can be achieved without a degeneration at the pore tips as a function of electrolyte concentration (with surfactant) for cylindrical pores. (Reprinted from Lehmann and Griining. 1997, with permission from Elsevier Science.)... 

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