Polyelectrolyte, anionic, binding

To date, the vast majority of work deals with hydrophilic GNRs functionalized by electrostatic attraction of CTAB molecules, anionic polyelectrolytes, or covalent binding of hydrophilic thiols. Hydrophobic GNRs are mainly produced by depositing octadecyl-trimethoxysilane as a coating agent onto the nanorod surface either in the presence [178, 179] or absence of a silica shell [180]. 

Employing a polyelectrolyte to bind to and preferentially align the aniline monomers before polymerization (e.g., by S2082-) has shown promise in facilitating the desired head-to-tail coupling of the aniline substrates. During polymerization, the anionic polyelectrolytes such as poly(styrenesulfonate) and poly(acrylate)86-88 also provide the required counterions for charge compensation in the doped PAn products. This can lead to water-soluble or water-dispersed ES products. 

A different effect occurs with the use of polycarboxy-lates in combination with zeolites. Small amounts of polycarboxylates or phosphonates can retard the precipitation of sparingly soluble calcium salts such as CaCOs (the threshold effect ). As they behave as anionic polyelectrolytes, they bind cations (counterion condensation), and multivalent cations are strongly preferred. Whereas the pure calcium salt of the polymer is almost insoluble in water, mixed Ca/Na salts are soluble, i.e. only overstoichiometric amounts of calcium ions can cause precipitation. Polycarboxylates are also able to disperse many solids in aqueous solutions. Both dispersion and the threshold effect result from the adsorption of the polymer on to the surfaces of soil and CaCOs particles, respectively. 

The cationic charge on a polymer affects its behavior considerably when surfactants are included in formulations. Cationic polymers (a member of the broader class of polymers termed polyelectrolytes) usually interact strongly with anionic surfactants, weakly with cationic surfactants, and unpredictably with nonionic and amphoteric surfactants (14,167-169). Anionic surfactant binds to cationic polymers at concentrations well below the critical micelle concentration (cmc). The low surfactant concentration where polymer and surfactant begin to interact is known as the critical aggregation concentration (cag). 

The interaction between three thiazine dyes, namely Azure B, Methylene blue, and Toluidine blue with an anionic polyelectrolyte, and Sodium Carrageenate has been investigated by spectrophotometric method. The polymers induced metachromasy in the dye resulting in the shift of the absorption maximum towards shorter wavelengths. The stoichiometiy and stability of the complexes formed between Thiazine dyes and the polymers are found to be dependent on the stracture of the polymers. The stability of the complexes followed the order AB-NaCar>MB-NaCar>TB-Na-Car. This iirference was further confirmed by reversal of metachromasy by alcohols, urea, surfactants, and electrolytes. The thermodynamic parameters of interaction revealed that binding between Thiazine dyes and the polymers was found to involve both electrostatic and hydrophobic forces. 

In this study, we report the release properties of two new polyelectrolyte materials poly(acrylamido-methyl-propanesulfonate) (PAMPS) and poly (diallydimethyl ammonium chloride) (PDADMAC), which were used as anionic and cationic carriers, respectively, for oppositely charged drugs. These polymers proved to be very promising and practical as erodible carriers for controlled drug delivery as they are available commerically. Binding ionic moieties to the linear polymer backbone can be done by a simple mixing process. 

One other design developed by Wang s group uses the same base sensor (GCE), which is coated with a layer of poly(4-vinylpyridine) (PVP). This cationic polyelectrolyte was one of the first polymers used to modify electrode surfaces [27]. Much research effort in this context has been directed to the characterization of the transport and electrostatic binding of multi-charged anions at PVP-coated electrodes. The ability of this polymer... 

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