Charge oligomers

It is reported that ammonium sulfate can produce the negatively charged oligomers through sulfate bridges, which induced the electrostatic interaction with the surfactant and therefore facilitate the formation of zirconia/CTAB mesophase [9]. Since Ti(S04)2 was used as Ti precursor in the present study, a various amounts of (NH4)2S04 was added into the CTAB solution in order to investigate the sulfate effect... 

If one has an electrostatic repulsion between charged oligomers and equally charged partit s the diffusion rate is given by (Hansen and Ugelstad, 1978)... 

Da. Close examination of the region from 600 to 1200 Da shows a 22-Da repeat unit due to the doubly charged oligomers. 

The counterion may be catalytic,51 in which case it will have a dramatic effect on the polymerization process. For example, Tiron 4 (shown earlier) has a catalytic effect on the electropolymerization of pyrrole, thereby enabling the process to be carried out at a more rapid rate at lower applied potentials. The ability of the counterion to ion pair with charged oligomers produced as part of the polymerization process will also have an effect. 

Fig. 1. AMI total energy for the isolated neutral, single and doubly charged wPDAs (n = 3,15) as computed at the optimized geometry of the neutral or doubly charged oligomer. The charge of the oligomer is shown in brackets.

Fig. 3. Sketch of the electrostatic interaction between three oligodiacetylene chains. Unit II is the doubly charged one at the optimized geometry of the isolated doubly charged oligomer, and units I and III the neutral ones at the optimized geometry of the neutral.

The Raman spectra of doped states of polyaniline [99], poly(/ -phenylenevinylene) [75, 100-102], and polythiophene [72, 73] have been also analyzed on the basis of the data of charged oligomers (charged oligomer approach). The detected self-localized excitations are summarized in Table 4-5. Some important conclusions can be drawn from these Raman studies. 

Bizjak A, Rescic J, Kalyuzhnyi YV, Vlachy V (2006) Xheoretical aspects and computer simulations of flexible charged oligomers in salt-free solutions. J Chem Phys 125 214907. doi 10.1063/1.2401606... 

There is still another closely related supramolecular concept, whereby a polyelectrolyte is nominally stoichiometrically complexed with oppositely charged oligomers containing a mesogenic (rigid) unit [78, 106, 107], such as shown in Figure 4f. In general. 

To produce monodisperse nanoparticles vsdth very small sizes, high surfactant concentrations (up to 10-15 wt%) are usually required. However, colloidal crystal assemblies require a surfactant-free polymer surface. Surfactant-free emulsion polymerization processes have been developed for PS and a number of acrylate-based polymers [15-21]. In this process a poorly water-soluble monomer and water-soluble initiator, usually peroxodisulfate, are dispersed in water. Polymerization is initiated by the sulfate radical and charged oligomers are formed, which, when above the critical micelle concentration, aggregate into micelles. Polymerization further takes place in these micelles, resulting in monodisperse polymer nanopartides on the scale of the original micelles. 

We now consider the theoretical results obtained on the sexithiophene molecule. The AMI-optimized geometries of the doubly charged oligomers show that the... 

Although the absorption spectrum of chemically polymerized PEDOT may result from various chemical species present, it is a common understanding that predominantly the main contribution stems from oxidatively charged oligomers consisting of 5 to 15 monomeric units. 

Asymmetrical flow field-flow fractionation (flow FFF) and specifically hoUow-fibre flow FFF (HFs) have the potential of combining latex clean-up and characterization. Capillary electrophoresis has seen significant advances in the last decade. It may potentiaUy be used to separate and characterize charged latex beads and low-Mr charged components (stabilizers, surfactants and charged oligomers) without prior sample clean-up. 

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