Influence of the Surfactant

The influence of the surfactant in the modified polymers of Figure 1 on n (aqueous solutions, Table I) is not overpowering. The surfactant s influence is diminished by the amphiphilic oxyethylene units which lie interfacially flat at the aqueous-air interface. The hydrophobes are structurally similar to the surfactants providing stability to commercial latices and should be capable of competing with the classical surfactants at the latex surface, but this ability is not reflected in 7T values. The oxyethylene units have been demonstrated(18) to provide osmotic stabilization to latex particles. 

A variety of nonpolar to moderately polar solvents has been evaluated for their ability to form stable CLAs (Table 15.2) [68]. As can be seen, as the solvent becomes more polar the aphron size increases and it becomes more unstable. Hence, the influence of the surfactant HLB number was evaluated using a moderately polar solvent, -pentanol [68]. This demonstrated that if the HLB number of the surfactant is high enough, then it is possible to formulate stable CLAs. 

In Section 3.2 it was shown that surfactants can influence the magnitude of Kp. To use equation (3) to simulate changes in Kp, the following information is required 1) the aqueous surfactant concentration in the CFSTR as a function of time 2) the sorbed phase surfactant concentration in each of the NK sites 3) the magnitudes of Kmn and Kmc for each surfactant and, 4) the magnitude of Ks. Unfortunately, the required information to incorporate equation (3) into the distributed-rate model was not determined for this study. As a result, the influence of the surfactants on the distribution coefficient was not considered. 

Martyanov, Igor N. is a Ph.D. researcher and recently worked in the laboratory of photocatalysis on semiconductors at the Boreskov Institute of Catalysis, SB RAS, Novosibirsk, Russia. The title of his PhD Thesis (1998) was Kinetics of photocatalytic redox reactions of organic molecules in semiconductor suspensions (CdS and TiC>2) . Areas of his interests kinetics of photocatalytic reactions in liquid phase at deep conversion the influence of the surfactants. 

To estimate the influence of the surfactant adsorption on the capillary forces, the wetting tension yiv cos was calculated from the values given in Fig. 10a. The results drawn in Fig. 10b show for both measurement series a minimum of the capillary forces exactly at the concentration ceff. The capillary forces are reduced by about 20% compared to water. This confirms the hypothesis that the reduction of the pattern collapse is caused by a hydropho-bizing of photoresist processed with the threshold dose by cationic surfactant adsorption. Unfortunately the inverse ADS A method could not be applied at relative surfactant concentrations >0.2 since the bubbles became unstable due to the lower surface tension. Thus it cannot be estimated how the wetting tension evolves at higher concentrations. 

Lemos-Senna, E., Wouessidjewe, D., Lesieur, S., and Duchene, D. (1998), Preparation of amphiphilic cyclodextrin nanospheres using the emulsion solvent evaporation method, influence of the surfactant on preparation and hydrophobic drug loading, Int. J. Pharm., 170,119-128. 

Fig. 9.13. Influence of the surfactant concentration on the defoaming ability of saturated alcohols ...

Araujo, L., Lobenberg, R., and Kreuter, J. (1999). Influence of the surfactant concentration on the body distribution of nanoparticles. J Drug Target 6, 373-385. 

Gradzielski, M., Langevin, D., Sottmann, T. and Strey, R. (1997) Droplet microemulsions at the emulsification boundary The influence of the surfactant structure on the elastic constants of the amphiphilic film. /. Chem. Phys., 106, 8232-8238. 

The influence of the surfactant on the formation of manganese (oxyhydr)oxide nanowires/rods was also investigated. As shown in Fig. 5, the product obtained after hydrothermal treatment of commercial y-Mn02 in a 8% solution of... 

Feitkenhauer, H. U. Meyer. Anaerobic digestion of alcohol sulfate (anionic surfactant) rich waste-water—Batch experiments. Part I Influence of the surfactant concentration. Bioresour. Technol. 2002a, 52, 115-121. 

Table 3 shows the influence of the surfactant, oil phase and reducing agent on... 

This result is not entirely unexpected as we mentionned that nematics have a smectic ordering at the solid surface and that for smectics influence of the surfactant itself... 

A latex used for coating applications and made from an acrylic phase and an alkyd phase contains surfactant particles that stabilize the phases after the film-forming process. Using STEM, the imaging of these surfactant molecules was carried out in order to understand the influence of the surfactant-polymer affinity on the surfactant location after film formation [59]. 

Some results of the numerical solution of Eqs. (22.60) are shown in Figs. 22.5 to 22.7. Dependences on parameters f and n that characterize the influence of the surfactant, and also on the parameter K that determines the influence of pressure, are of greatest interest. At small values of r, the effect of the surfactant causes a reduction of surface tension, and the bubble grows faster than it would grow in the absence of the surfactant. At n = 0, the surfactant layer on the surface does not impede the transition of dissolved substance into the bubble, and the influence of the surfactant is manifest only in the reduction of surface tension. With an increase of n, the rate of bubble growth slows down considerably. An increase of the parameter K (the fall of pressure poo) results in enhancement of the bubble growth rate. Fig. 22.6 shows the change of surface concentration of surfactant at K = 4.45 n = 0 xioo = 1, and = 1 for various values of fi. An in-... 

The second reason for the anomalous change of surface tension of a solid polymer containing surfactant lies in the structural and conformational conversions of the polymer itself under the influence of the surfactant. Such factors as the increase of the polymer surface tension when surfactant is added cannot be explained by the surfactant adsorption on the polymer surface only (see Fig. 2.13). Later we will consider this in detail. As was noted above, if the rate of aggregation of the surfactant molecules is higher than or equal to the rate of polymerization, the system surface tension alters during polymerization in the same way as in the coiu-se of the equilibrium process. At a high rate of polymerization, the formation of micelles of the maximum possible size can be hindered by the rapid increase of the system viscosity. In this case, when an IS substance is applied the split into two phases is not observed and the system appears to be more oversaturated by surfactant than in the first case. 

The data correlate well with turbidity data (Fig. 2.31, curves 2 ) and show that acceleration of the start of gel formation with 4-6 wt% OP-10 occurs because of accumulation of microgel formations under the influence of the surfactant at an earlier stage. Acceleration of the start of gel formation wih DC-10 is insignificant and remains directly dependent on DC-10 concentration, corresponding to the turbidity data that indicate that this surfactant does not influence the compatibility of the system components and speed of gel formation. 

Eqs. (54-55) show that the influence of the surfactant grows with time. 

In the same way from (56-57) we find that the capillary force influence is negligible and the influence of the surfactant is dominant if... 

Plucinski, P. The Influence of the Surfactants on the Permeation of Hydrocarbons Through Liquid Membranes. In Membranes and Membrane Processes, ed. E. Drioli and N. Nakagaki. New York Plenum Press, 1986. 

Non-ionic surfactants can be added to a fatty suppository base to enhance the release of poor water-soluble active substances [5b]. The results of studies on this subject, however, vary considerably. Often the in vitro release is improved, whereas the in vivo results are disappointing [8a]. This is partly caused by the formation of micelles in the rectal fluid and partly by the influence of the surfactant... 

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