Weakly-charged polymers

The most important prediction of the theory is the fact that in the region of a poor solvent the extension of a weakly charged polymer network can induce jump-like decollapse of the gel. In contrast, the compression of the swollen gel must induce the collapse of the network. 

Lagueerr, A. and Stoll, S. (2005). Adsorption of a weakly charged polymer on an oppositely charged colloidal particle Monte Carlo simulations investigation. Polymer, 46, 1359-1372. 

Formation of ion pairs and multiplets. For weakly charged polymer chains, the effect of counterion condensation in its dassical form does not exist. Instead, the notion of ion pairs is usually introduced it is assumed that the pair charged monomer unit/counterion can, under given conditions, be in the bound form, where the counterion is no longer free and forms a dipole with the corresponding co-ion. 

BE1 Bergfeldt, K. and Piculell, L., Phase behavior of weakly charged polymer/surfactant/ water mixtures, J. Phys. Chem., 100, 5935, 1996. 

Liberelle, B., Giasson, S. 2008. Friction and normal interaction forces between irreversibly attached weakly charged polymer brushes, 24 1550-1559. 

The results of SAXS experiments may also be analyzed in terms of a model applied to weakly charged polymer gels. According to this model the intensity curve is presented as a linear combination of Omstein-Zemike model ... 

In 2002, O Brien extended the non-ionic polymer theory to allow for the effect of weakly-charged polymers on the dynamic mobility [15]. In this case the slip velocity is given by... 

In an ideal SEC separation, the mechanism is purely sieving, with no chemical interaction between the column matrix and the sample molecules. In practice, however, a small number of weakly charged groups on the surface of all TSK-GEL PW type packings can cause changes in elution order from that of an ideal system. Fortunately, the eluent composition can be varied greatly with TSK-GEL PW columns to be compatible with a wide range of neutral, polar, anionic, and cationic samples. Table 4.8 lists appropriate eluents for GFC of all polymer types on TSK-GEL PW type columns (11). 

The thermodynamics of weakly charged polyelectrolyte solutions have been the subjects of several recent investigations [110-112]. In these systems, the properties are intermediate between nonionic polymers and fully charged polyelectrolytes and both electrostatic and nonionic interactions can be important in determining the polymer characteristics. 

Biesheuvel, P.M., Cohen Stuart, M.A. (2004). Electrostatic free energy of weakly charged macromolecules in solution and intermolecular complexes consisting of oppositely charged polymers. Langmuir, 20, 2785-2791. 

When our work started, the phase transitions was observed only for weakly charged networks of PAA gels swollen in the mixtures of water (good solvent) with acetone (precipitant) of different compositions. The first stage of our work was the investigation of the nature and polarity of a precipitant on the position and the amplitude of the phase transition. According to the results of theoretical consideration of Refs. [7,18,20], the transition point and the value of the jump of the volume are primarily determined by the network structure and by the parameter of polymer-solvent interaction Xns- By smoothly changing the composition of the binary solvent, it is possible to vary effective value of the Xns parameter and to convert the network to a collapsed state. In this case, the amplitude of phase transition should not depend on the nature of precipitant. 

The pyroelectric current is expected from the depolarization of spontaneous polarization (i.e., motion of polarization charge) as well as from the motion of true charge. The polarity of the pyroelectric current is, however, inverted between the two, as is shown schematically in Fig. 22. It is difficult to assume a polarization charge in non-polar or weakly polar polymers such as polyethylene (PE), polypropylene (PP), and... 

The sorption of a weak electrolyte by a charged polymer membrane is another case where Nernst + Langmuir-like dual mode sorption, involving the undissociated and dissociated species respectively, may be expected. The concentration of each species in solution follows, of course, from the dissociation constant of the electrolyte. The sorption isotherms of acetic acid and its fluoroderivatives have been analysed in this manner, and the concentration dependence of the diffusion coefficient of acetic acid interpreted resonably successfully, using Nylon 6 as the polymer substrate 87). In this case the major contribution to the overall diffusion coefficient is that of the Nernst species consequently DT2 could not be determined with any precision. By contrast, in the case of HC1, which was also investigated 87 no Nernst sorption or diffusion component could be discerned down to pH = 2 and the overall diffusion coefficient obeyed the relation D = DT2/( 1 — >1D), which is the limiting form of Eq. (25) when p — 00. 

Answer Protein C has a net negative charge because there are more Glu and Asp residues than Lys, Arg, and His residues. Protein A has a net positive charge. Protein B has no net charge at neutral pH. A cation-exchange column has a negatively charged polymer, so protein C interacts most weakly with the column and is eluted first, foUowed by B, then A. 

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