Polyanion/polycation

The evaluation of each individual polyelectrolyte and binary polyanion-polycation pairs has followed the protocol described in Fig. 1. 

Each polyion pair which yielded a stable membrane was removed from the receiving bath and treated. In general, quintuple washings with an excess (50 ml) of PBS were required to remove all traces of the polymeric reagents. The PBS also simulated the osmotic pressure which the capsule, and mammalian cells, would encounter in vivo. For several polyanion-polycation systems the membranes which were produced were not sufficiently strong to survive the rinsings. Leaky membranes and the complete collapse of the capsule were two common failures. 

A limited number of polyanion-polycation systems were tested using a droplet/falling annulus method (Fig. 4). This technique, which has been described elsewhere [64] reduces the net impact velocity between the droplet with the oppositely charged counterion fluid. A stream of droplets was directed into a collapsing annular liquid sheet. By matching the velocities of the droplet and sheets, the impact conditions can be moderated. It has been shown to produce monodisperse spherical capsules, though it requires several days of calibration for each new system and is obviously not practical for a massive screening such as was carried out herein. 

Table 5 summarizes the type of complex produced for each polyanion-polycation pair investigated. There are relatively few systems which yielded soluble complexes (13.6%) with the majority of polyanion-polycation reactions yielding either precipitates (43.7%) or weak membranes (30.7%). Indeed, as one scans across rows of polycations or down columns of polyanions, many of the naturally occurring or synthetic species predominantly form precipitates. This is, perhaps, due to the high content of ionic groups (one per repeat unit) charac-... 

For a review, see Kotz, J. and Beitz, T. The phase behaviour of polyanion-polycation systems. Trends in Polymer Science 1997, 5(3), 86-90. 

The behaviour of ternary systems consisting of two polymers and a solvent depends largely on the nature of interactions between components (1-4). Two types of limiting behaviour can be observed. The first one occurs in non-polar systems, where polymer-polymer interactions are very low. In such systems a liquid-liquid phase separation is usually observed each liquid phase contains almost the total quantity of one polymer species. The second type of behaviour often occurs in aqueous polymer solutions. The polar or ionic water-soluble polymers can interact to form macromolecular aggregates, occasionally insoluble, called "polymer complexes". Examples are polyanion-polycation couples stabilized through electrostatic interactions, or polyacid-polybase couples stabilized through hydrogen bonds. 

The polyanion-polycation complex (symplex) formation process is a phenomenon that had long been known on an empirical base from the mutual precipitation of proteins [150]. The internal structure and the properties of the resulting complexes are strongly influenced by the nature of the polymeric components and the system conditions. The polymer parameters include the molar mass, the... 

Laugel N, Betscha C, Winterhalter M et al (2006) Relationship between the growth regime of polyelectrolyte multilayers and the polyanion/polycation complexation enthalpy. J Phys ChemB 110 19443-19449... 

Ruths, J., Essler, F., Decher, G., Riegler, H. (2000). Polyelectrolytes I polyanion/polycation multilayers at the air/ monolayer/water interface as elements for quantitative polymer adsorption studies and preparation of hetero-superlattices on solid surfaces. Langmuir 16 8871-8. 

D.M. Kaschak, J.T. Lean, C.C. Waraksa, G.B. Saupe, H. Usami, T.E. Mallouk, Photoin-duced Energy and Electron Transfer Reactions in Lamellar Polyanion/Polycation Thin Pilms Toward an Inorganic Leaf , J. Am. Chem. Soc., 121, 3435 (1999)... 

Electric charge has crucial importance to the bioeffects of polynucleotide analogs and can be used to subdivide these compounds into three subgroups (i.e., electroneutral, polyanions, polycations) that have distinctly different biochemical effects. 

Energy dependent amphipatic cation inhibitor. pH dependent polyanion-polycation CD change. Energy dependent change in gate. 

The polyanion-polycation combination generally involves one permanently charged polymer with a... 

K5tz, J. Koepke, H. Schmidt-Naake, G. Zarras, P. Vogl, O. Polyanion-polycation complex formation as a function of the functional-groups. Polymer 1996, 57 (13), 2775-2781. 

In former investigations by using a combined titration technique [25] we could already show that the turbidimetric endpoint of the polyanion-polycation complex formation in the absence of kaolin correlates quite well with the one in the presence of kaolin. This agreement means that polyanion-polycation interactions are dominant in this system and the complexes with kaolin were formed due to an interparticle bridging through the polyelectrolyte complexes formed on kaolin. 

J Kotz, S Kosmella. Interactions between polyanion-polycation systems and kaolin. J Coll Interf Sci 168 505-513, 1994. 

Synthesis and characterization of some insoluble polyanion—polycation complexes. J Polym Sci Part A Polym Chem 1996 34(17) 3485-3494. 

Previous synthesis of this complex at twice the present scale gave a yield of 70% (see refs. 1 and 2a), the present synthesis gives a 52% yield, and syntheses done at one-third of the present scale are less satisfactory, giving overall yields of approximately 30°/. Clearly, the observed yields are significantly concentration-dependent (as perhaps would be expected given the polyanion-polycation nature of the complex), and it appears that yields > 70% are possible from syntheses done at larger scale. 

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