Chain length dispersions

A large variety of peptoid side chains have been introduced (Fig. 3) [24—27]. Moreover, commercially available automated peptide synthesizers can be used for SPSS. Typically, SPSS is used to prepare sequence-specific peptoids, but Rosales et al. have also demonstrated the successful preparation of highly repetitive sequences that resemble homopolymers, without chain length dispersity [28]. The SPSS is also ideally suited for automation to create large combinatorial libraries via the mix-and-split method [15]. 

The composites with the conducting fibers may also be considered as the structurized systems in their way. The fiber with diameter d and length 1 may be imagined as a chain of contacting spheres with diameter d and chain length 1. Thus, comparing the composites with dispersed and fiber fillers, we may say that N = 1/d particles of the dispersed filler are as if combined in a chain. From this qualitative analysis it follows that the lower the percolation threshold for the fiber composites the larger must be the value of 1/d. This conclusion is confirmed both by the calculations for model systems [27] and by the experimental data [8, 15]. So, for 1/d 103 the value of the threshold concentration can be reduced to between 0.1 and 0.3 per cent of the volume. 

The ability to disperse the calcium soap formed from a given amount of sodium oleate has been studied for a number of a-sulfo fatty acid esters with 14-22 carbon atoms [28,30]. In principle, the lime soap dispersion property increases with the number of C atoms and the dissymmetry of the molecule. Esters with 14 C atoms have no dispersion power and in the case of esters with 15-17 carbon atoms the least symmetrical are the better lime soap-dispersing agents. However this property does not only depend on the symmetry but on the chain length of the fatty acid group. For example, methyl and ethyl a-sulfomyristate have better dispersing power than dodecyl propionate and butyrate. The esters with 18 and more carbon atoms are about equal in lime soap dispersion power. Isobutyl a-sulfopalmitate is the most effective agent under the test conditions. 

This initiator is aggregated but heterogeneous initiation is not harmful, provided the growing chains are dispersed as soon as they have reached a certain length. 

It follows that in spite of the apolar coat surrounding water-containing AOT-reversed micelles and their dispersion in an apolar medium, some microscopic processes are able to establish intermicellar attractive interactions. These intermicellar interactions between AOT-reversed micelles increase with increasing temperature or the chain length of the hydrocarbon solvent molecule, thus leading to the enhancement of the clustering process [244-246], whereas they are reduced in the presence of inorganic salts [131]. 

The x-ray diffraction patterns for MTF, PTF, and BTF are given in Figure 2. The unsymmetrical BTF shows broad dispersed peaks indicating an increase in amorphousness compared to MTF, its symmetrical analogue. The peaks in the pattern for PTF, on the other hand, are broader and less sharp than those for MTF, which may be the result of an increase in the alkyl chain length by two carbon atoms. 

The next problem is to find an expression for Asg. This entropy difference is a function of the particle volume fractions in the dispersion ( ) and in the floe (<(> ). As a first approximation, we assume that Ass is independent of the concentration and chain length of free polymer. This assumption is not necessarily true the floe structure, and thus < >f, may depend on the latter parameters because also the solvent chemical potential in the solution (affected by the presence of polymer) should be the same as that in the floe phase (determined by the high particle concentration). However, we assume that these effects will be small, and we take as a constant. 

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