Concentration hydrophobic monomers, effect

In addition to monomers and the initiator, an inert liquid (diluent) must be added to the monomer phase to influence the pore structure and swelling behavior of the beaded resin. The monomer diluent is usually a hydrophobic liquid such as toluene, heptane, or pentanol. It is noteworthy that the namre and the percentage of the monomer diluent also influence the rate of polymerization. This may be mainly a concentration or precipitation effect, depending on whether the diluent is a solvent or precipitant for the polymer. For example, when the diluent is a good solvent such as toluene to polystyrene, the polymerizations proceed at a correspondingly slow rate, whereas with a nonsolvent such as pentanol to polystyrene the opposite is true. 

Table 2. Effect of mixtures of ionic surfactant and long-chain alcohols on the stability of the o/w concentrated emulsions. The concentrated emulsion contains a hydrophobic monomer and water as the two phases. The volume fraction of the dispersed phase is 0.9. The concentrated emulsions were prepared at room temperature and their stability tests were conducted by heating the emulsions at 50 °C for 3 and 24 h, respectively...

The authors found that the hydrophilic monomer did not affect the evolution of oxygen as much as the hydrophobic monomer. In addition, it was reported that concentration of starting material and time after monomer addition decreased the effectiveness of the chloroplast in evolving 02 ... 

Vigon B.W. and Rubin AJ. (1989) evaluated surfactant selection and dose optimization through evaluation of parameters such as surface tension, cmc. extent of hydrophilic-hydrophobic balance, solubilizaton efficiency, and partition coefficient. Chu W. and So W.S. (2000) has studied the surfactant aided soil washing of some contaminated non-chlorinated aromatic dyes. They concluded that dye concentration increased slightly until the surfactant monomers in the bulk solution was saturated the washing performance was 1 1 proportional to the monomer concentration. Above the effective critical micelle concentration (as the result of the sorption of surfactant monomer onto soil), the soilwashing performance increased linearly with increasing available surfactant micelles in the aqueous phase. 

Effect of Hydrophobic Monomer Concentration. Results of the effect of LMA concentration in the prepolymerization solution are given in... 

Nonylphenyl methacrylate was synthesized as a UV-absorbing monomer to confirm the effect of this type of hydrophobic monomer on the surfactant solution. Results are shown in Figure 5 (the monomer concentration has been adjusted on the basis of the number of double bonds obtained from the NMR results see the Experimental Details section). Although the points are in an almost straight line, the intercept of a least-squares line through all of the points would be about 5000 however, the intercept must be zero. Therefore, there must be an initial linear relationship that includes the origin. At higher nonylphenyl methacrylate concentrations, the MW is lower than extrapolated from the initial line. Thus, this hydrophobic monomer also acts as a cosurfactant. 

Figure 4. Effect of molecular weight on the concentration dependence of vis-cosity at 1.3 s K Solvent is 2.0 wt % NaCl. Hydrophobe monomer is 1.0 mol % N-n-octylacrylamide. Hydrolysis level is 18 mol %. Intrinsic viscosity (dL/g) , 2.0 u, 7.6 x, 8.4.

In the random copolymers shown in Scheme 1, hydrophobic associations occur completely in an intrapolymer mode [20-22] hence, the polymers form unimer micelles independent of the polymer concentration in water. The sequence distribution of electrolyte and hydrophobic monomer units in the polymer chain is a critical structural factor to determine whether the hydrophobic self-associations are an intra- or interpolymer mode. Block sequences of hydrophobic units have a strong tendency for interpolymer association, whereas random and alternating sequences tend to associate in an intrapolymer mode [20-22]. Even a subtle difference in the sequence distribution in random copolymers has a significant effect on the self-association mode [23]. If the sequence distribution is blocky in nature, there is a propensity for interpolymer association. Other important structural factors that induce polymers to form unimer micelles are that the hydrophobic groups should be bulky and have cyclic structures, such as cyclododecyl, adamantyl, and naphthyl groups, and their contents in the copolymers should be higher than about 30 mol%, as shown in Scheme 1 [20-22]. In addition. 

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