Dye-polymer complexes

Reorientation dynamics of molecular tracers in polymers is not only important for the understanding of slow relaxation phenomena in glassy polymers but plays also a critical role in practical problems such as molecular design of nonlinear optical materials with long-term stability based on dyes/polymers complexes. We show here the reorientation dynamics of molecular tracers in glassy polymers obtained by the armealing-after-irradiation method described below. These experimental results are compared to the local relaxation processes of glassy polymers obtained by the already established measurement techniques such as dielectric relaxation and solid state NMR. Finally, the molecular interpretation of the relaxation of free-volume distribution in polymers will be discussed. 

In a related phenomenon, the spectral shifts which accompany aggregation-deaggregation have been reported as a basis of yet another erasable medium.24 The active layer consists of discrete particles of a cocrystalline complex of a pyrylium dye with a polymer such as polycarbonate. Pulsed irradiation of this aggregated film resulted in an instantaneous deaggregation process which was accompanied by a hypsochromic shift of about 100 nm. The recording mechanism is believed to be thermal and a thermal erasure (reaggregation of the dye-polymer complex) was also demonstrated. 

Because the matrix has permeable characteristics, the ability of the molecules to diffuse will depend on the pore size of the permeable polymer and the available free space in the pores. Obviously, larger molecules would not be able to penetrate the matrix and complex with the NIR dye. As the amount of the dye-analyte complexes increase, the amount of free space into which other analytes can diffuse decreases. Therefore, a relation of the mobility with free space is defined as... 

Photoeffect sensitization in polymers is realized by means of charge-transfer complexes, dyes, polymers, heterogenous and multilayer structures. Every method permits us to obtain some information about photogeneration, charge transfer processes and can be used for concrete practical applications. 

Besides the PVK band (in the UV range) and the dye band a new peak appeared in the photoconductivity spectrum. In the case of Methylene Blue it appears at 490 nm, i.e. between the polymer and the dye bands. This new peak is not a PVK/TCNE band since that appears near 600 nm and it is not a peak of the dye/TCNE complex since it does not vary with the nature of the dye. Although not supported by any other example in the literature, this can be an interesting concept of practical consequences. 

Molecular donor-acceptor complexes, such as the complex formed between poly(N-vinylcarbazole) (PVK) and 2,4,7-trinitro-9-fluorenone (TNF), and dye-polymer aggregates were widely used as generation materials in early applications. Since these materials are not infrared sensitive, there has been increasing emphasis on pigments during the past two decades. Because of the long... 

Polymer-polymer complexation is generally detected via conductometric or potentiometric titrations. Colloid titration represents an inverse-system where a polymer with known characteristics, such as potassium poly (vinylalcohol-sulfate) or poly(diallyldimethylam-moniumchloride), are used to quantify the concentration of polycation or polyanion, hence relying on a 1 1 stoichiometry. Using the cationic dye, tol-uidine blue, as an indicator, a metachromatic end point is detected. Both methods are volumetric. 

Most of the azo dyes destruct because of the low resistance of azo-groups to reducing medium of polymer melt. Azo-dyes metallo-complexes with the composition (1 2), not having free sulfo - and carboxyl groups in the molecule composition are the exception. 

As will be discussed in more detail in Chapter 16, a useful characteristic of many micellar systems is their ability to solubilize otherwise water-insoluble materials such as hydrocarbons, dyes, flavors, or fragrances. Some surfactant-polymer complexes have been shown to solubilize materials at surfactant concentrations well below the cmc of the surfactant in the absence of polymer. The effectiveness of such complexes differs quantitatively from that of conventional micelles. 

The mechanism of dye incorporation into triple complexes was also intensively studied by Zemaitaitiene et al. It was shown that cationic polymer tends to react with anionic textile finishing chemicals and auxiliaries such as anionic detergents, forming intermolecular complexes of different stoichiometry. Under controlled conditions, these complexes can incorporate the dye and precipitate. Surprisingly, the disperse dye (which was uncharged) also seemed to be bound by polymer-polymer complexes [98,99]. 

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