Polyampholyte behavior

The third polyampholyte, poly(METMA/MES), followed the usual Huggins equation and showed typical polyampholyte behavior. This polymer should be a random copolymer of the two methacryl monomers and therefore should have a lower degree of disparity of the charges between different chains compared to poly(MPTMA/AMPS). 

The free radical polymerizations of 3-[(2-Acrylamido-2-mefliyl propyl)dimethylammonio]-l-propanesulfonate with acrylamide and/or acrylic acid, and 3-(i Tj -diallyl-i /-methylammonio)-l-propanesulfonate with A, iV diailyl-i, iV-dimethyl ammonium chloride or AT,A/-diallyl-iV,-methyl amine have been studied. Reactivity ratios indicate random incorporation of comonomers. Molecular weights range from 3.0 x 10 to 15.1 x 10 g mol for the acrylamido-based copolymers and from 2.2 x 10 to 6.0 x 10 g mol for the cyclocopolymers. Second virial coefficients and viscosities decrease as sulfobetaine content increa s for each of the copolymers. A transition from polyelectrolyte to polyampholyte behavior is observed with added NaCl for those copolymers with sulfobetaine monomer incorporation greater than 40 mol%... 

In this chapto, we have illustrated the effects of molecular architecture of polysulfobetaines on solution behavior under specilBc environmental conditions of pH, added electrolytes, and polymer concentration. The nature of the comonomer and amount of incorporation of the sulfobetaine within the polymer chain dictate the polymer solubility and solution behavior. Polyampholyte behavior is realized for acrylamide-based systems containing the sulfobetaine moiety. Polyelectrolyte behavior is coupled with polyampholyte behavior for cyclopolymers containing >40mol% sulfobetaine. Incorporation of the sulfobetaine monomer hinders hydrophobic association for the pH responsive copolymers of series TV at low degrees of ionization. 

All these polymers display a poly-a-amino acid structure. Their polyampholytic behavior has been examined from the point of view of their two step dissociation constants, and their complexing properties towards bivalent metal ions. 

Cationic, anionic, and nonionic polyferrocenylsilane-based hydrogels were recently introduced [356-358]. In the case of anionic, permanently charged hydrogels, the electrochemical oxidation to ferrocenium imparts a polyampholytic behavior together with a color change. In addition, oxidation leads to shrinkage of the gel and to a loss of elasticity upon reduction, the former properties could be reached reversibly. 

Investigation of Solution Behavior of Polyampholytes using Gradients. . 95... 

While the bulk behavior of polyampholytes has been investigated for some time now, studies of interfacial performance of polyampholytes are still in their infancy. There are several reasons for the limited amount of experimental work the major one being the rather complex behavior of polyampholytes at interfaces. This complexity stems from a large array of system parameters governing the interaction between the polymer and the substrate. Nearly all interfacial studies on polyampholytes reported to-date involved their adsorption on solid interfaces. For example, Jerome and Stamm and coworkers studied the adsorption of poly(methacryhc acid)-block-poly(dimethyl aminoethyl methacrylate) (PMAA-fc-PDMAEMA) from aqueous solution on sihcon substrates [102,103]. The researchers found that the amount of PMAA-fo-PDMAEMA adsorbed at the solution/substrate interface depended on the solution pH. Specifically, the adsorption increased... 

Amphiphilic polymers have been applied in numerous surface technologies and reviewed in various aspects. These polymers are polyampholytes, which contain, as it was remarked, both hydrophilic and hydrophobic components in their macromolecules. Their peculiar adsorption behavior is another interesting and fundamental issue [112],... 

Corpart and Candau [68, 69] described the formulation of polyampholytes containing both positive and negative charges in inverse microemulsions. The copolymers can show very different behaviors in the aqueous solution, ranging from insoluble, water-swollen hydrogels to water-soluble compounds, depending on the monomer composition. For polyampholytes with balanced stoichiometry, the polymer behavior is controlled by attractive electrostatic forces. The compound is usually insoluble in water, but becomes soluble upon the addition of salt. 

Interpolymer, polymer-surfactant, and coordination complexes of polybetaines are less developed. The cascade -type complexation observed for the polybetaine-polyelectrolyte system is similar to the layer-by-layer deposition found for oppositely charged polyelectrolytes. The behavior of the polybetaine-surfactant system differs from that of polyelectrolyte-surfactant and polyampholyte-surfactant complexes, leading to inter- or intramolecular comicellization or converting the whole macromolecule to either a polycation or polyanion. 

The adsorption behavior of weak polyampholytes from aqueous solutions on to a solid wall is strongly determined by the pH of the polymer solution. So it is absolutely necessary to investigate the adsorption as function of pH. As an example the adsorbed amount of two polyampholytes with medium molecular weight of around 60,000 g mol-1 and different block sizes is shown in Fig. 14 [13]. In every case the isoelectric point IEP of the polymer, which is determined by the block ratio, is the prominent feature of adsorp-... 

Dependence of the adsorption behavior on the molecular weight has been observed only in the case of polyampholytes of small molecular weight [13]. These polymers show an increase in the adsorbed amount compared to larger polyampholytes, as shown in Fig. 17. This tendency is expected to result from the adsorption of whole micelles of high density. One generally has to consider micelle formation in solution and at the interface to obtain a better understanding of the complex adsorption behavior of polyampholytes. 

Blends of homopolyelectrolytes were compared with corresponding diblock polyampholytes with respect to their adsorption behavior [61]. All those investigations show that the use of diblock polyampholytes offers a unique way to control adsorption behavior by pH and to generate structured monolayers with partial highly regular order which can be used to modify the surface properties of solid substrates. 

Synthesis and Aqueous Solution Viscosity Behavior of Polyampholytes from Cationic-Anionic Monomer Pairs... 

This chapter reports the syntheses and viscosity behavior in aqueous salt solution of two recently prepared polyampholytes. These polymers, derived from cationic-anionic vinyl monomer pairs, exhibit viscosity behavior in salt solution that is contrary to that of normal polyelectrolytes. The intrinsic viscosity is found to increase with increasing salt concentration for one of the samples and remain virtually unchanged for the other. Also, a modified form of the EinsteinSimha equation is observed to correlate especially well with the experimental data, where, in some cases, the Huggins equation apparently is not appropriate. In the context of these findings, some previous results with regard to the behavior of a polyvinylimidazolium sulfobetaine are discussed. 

We investigated the syntheses and viscosity behavior of polyampholytes derived from cationic-anionic monomer pairs of the type shown in Figure 2. It should be noted that the cationic-anionic monomer pairs that are under consideration contain no nonpolymerizable ions. 

Large polyelectrolytes, such as nucleic acids, and polyampholytes, such as proteins, are classified together as macroions. The electrostatic forces of attraction or repulsion between such charged particles play a major role in determining their behavior in solution. 

Polyampholytes. Ampholytic copolymers (i, 30-35) exhibit interesting viscosity behavior in electrolyte solutions that is quite opposite to the behavior of conventional polyelectrolytes. Recently we prepared high charge density copolymers from the matched, nonhydrolyzable comonomer pairs sodium 2-acrylamide-2-methylpropanesulfonate (NaAMPS) and 2-acrylam-ide-2-methylpropanedimethylammonium chloride (AMPDAC) (1, 33) see structures). 

Effects of Shear Rate and Temperature. In nearly all instances, the polyampholytes showed only slight pseudoplastic or Newtonian behavior in deionized water and salt solutions in the dilute regime. In semidilute solutions near C, some shear thinning was observed by using Contraves rheometry however, the behavior was not pronounced. Only the imbalanced terpolymer systems, which are in essence polyelectrolytes, exhibited pseu-... 

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