Polyelectrolyte complex structure

Many polymer-polymer complexes can be obtained by template polymerization. Applications of polyelectrolyte complexes are in membranes, battery separators, biomedical materials, etc. It can be predicted that the potential application of template polymerization products is in obtaining membranes with a better ordered structure than it is possible to obtain by mixing the components. The examples of such membranes from crosslinked polyCethylene glycol) and polyCacrylic acid) were described by Nishi and Kotaka. The membranes can be used as so-called chemical valves for medical applications. The membranes are permeable or impermeable for bioactive substances, depending on pH. 

Polyelectrolyte complexes are formed by the ionic association of two oppositely charged polyelectrolytes [60,117-119]. Due to the long-chain structure of the polymers, once one pair of repeating units has formed an ionic bond, many other units may associate without a significant loss of translational degree of freedom. Therefore the complexation process is cooperative, enhancing the stability of the polymeric complex. The formation of polyelectrolyte complexes... 

Polyelectrolyte complexes can be prepared in a desired range of mass, size and structure density. The behavior of the PECs can be controlled by external parameters such as the ionic strength, the pH of the medium or the temperature. Therefore, such complexes should be of great interest as potential carrier systems for drugs, enzymes, or DNA because charged species can easily be integrated into the complex particles. 

Fig. 4a, b. Effect of the structure of the polycation component on the yield of polyelectrolyte complexes, (a) Pendant-type polycation (QPVP)-NaSS (b) Integral-type polycation (3 X)-NaSS ... 

Fig. 9 a, b. Complex formation of polyelectrolytes with rigid polymer chains such as polysaccharides. (a) pH Dependence of the composition of the complex. (1) Theoretical values assuming stoichiometry (2) Experimental values (b) Schematic representation of a ladder-like complex structure of one part of SCS and two parts of GC SCS = Sulfated cellulose, GC = glycol chitosan... 

Fig. 50 a, b. Higher-order structure of aggregates of a polyelectrolyte complex of poly(methacry-lic acid) (PMAA) and integral-type polycation (2X), (a) Optical micrograph, (b) polarized light micrograph... 

Fig. 3.13. (Top) An electron micrograph of an artificial chromatin model composed of T4 DNA and cationic nanoparticles of diameter 15nm. (Bottom) Typical snapshots of a model DNA (semiflexible polyelectrolyte) complexed with cationic nanoparticles. At low salt concentration (Debye screening length m/a = 1), a beads-on-a-string nucleosome-like structure is observed (left), while locally segregated clusters are formed at higher salt concentrations (rn/a = 0.3) (right) (See [46] for more details)...

Dautzenberg H, Hartmann J.Grunewald S, Brand F (1996) Stoichiometry and structure of polyelectrolyte complex particles in diluted solutions. Ber Bunsenges Phys Chem 100 1024-1032... 

This chapter describes novel inkjet inks based on a variety of vehicles, and demonstrates several optical applications utilized by inkjet inks. It aims to provide a general description of inks which are based on unique components and structures, mainly micellar systems, polyelectrolyte complexes, microemulsions, miniemulsions, emulsions, liquid crystals, and interesting phase... 

The water-insoluble PMAA-poly(N-ethyl-4-vinylpyridinium bromide)polyelectro-lyte complex (5 l) formed at pH < 4 becomes soluble if the excess PMAA in the polyelectrolyte complex is ionized110. The solubility of the polyelectrolyte complex is apparently connected with the appearance of high negative charges of the complex particles and is accompanied by a conformational transition of PMAA in excess. It has been proposed that the water-soluble polyelectrolyte complex consists of the nucleus formed by bound base and acid units. This structure is retained in solution due to unbound parts (sequences) of ionized PMAA. 

Interactions between chemically and structurally complementary macromolecules have usually a cooperative character. Probably, the formation of cooperative systems involving two (or more) types of bonds at the same time (e.g. of ionic and hydrogen bonds)63 is possible. It should be mentioned here that hydrophobic interactions play an important role in the stabilization of synthetic and natural polyelectrolyte complexes and also of complexes with hydrogen bonds. The contribution of either interactions may be different, depending on the chemical structure of the components of the polycomplex and the nature of the medium. 

It has been attempted to perform template polymer syntheses without using biological sources. Concepts focus on the formation of a complex between monomer molecules and a present macromolecule [4,480], This way the monomer will get preorganized and the polymerization is supposed to follow a zip mechanism controlled by the length and the configuration of the template polymer, offering replication of the molecular weight and control of the stereo structure. Polymerization of acrylic acid in the presence of poly(ethyleneimine), N-vinylimidazole/ poly(methacrylic acid) or acrylonitrile with poly(vinylacetate) have been described [469,470,471,472,473]. Recently the preparation of solid polyelectrolyte complexes from chitosan and sodium-styrenesulfonate has been reported [481]. 

This pronounced change in the UCST indicates a strong interaction between the two polymers. The addition of the polycation PDMAPAA-Q until R = 0.17 (where R signifies the molar ratio of polyelectrolyte/polyDMAPS) decreases the UCST first from 65 to 15 °C. The mixtures with the cationic ionenes show a similar evolution of the UCST, but also exhibit a minimum at K = 0.1-0.17. Thus, when polycations are added to 23b, the UCST decreases first, then passes through a minimum and increases again. This was attributed to the different geometrical structure of polyelectrolyte complexes (Scheme 19). 

Fig. 3. Schematic refH-esentation of the structure of polyelectrolyte complexes...

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