Hydrophilic cationic polymers

Cationic polymers are strongly adsorbed on the support by ionic interaction in distilled water. Although salt solutions are useful in preventing ionic adsorption, a rather high salt concentration is required. For example, salt concentrations below 0.4 M were not sufficient to prevent adsorption when some hydrophilic cationic polymers, glycol chitosan, DEAE-dextran and poly(trimethylaminoethyl methacrylate) iodide salt were separated on TSKgel... 

GMPW columns, as shown in Figure 7.9. However, these hydrophilic cationic polymers were successfully separated with no evidence of adsorption when the salt concentration was increased to 0.8 M, as in Figure 7.10. Consequently, salt solutions of concentrations of around 1M seem to be suitable for hydrophilic cationic polymers. 

Anionic and neutral polymers are usually analyzed successfully on Syn-Chropak GPC columns because they have minimal interaction with the appropriate mobile-phase selection however, cationic polymers adsorb to these columns, often irreversibly. Mobile-phase selection for hydrophilic polymers is similar to that for proteins but the solubilities are of primary importance. Organic solvents can be added to the mobile phase to increase solubility. In polymer analysis, ionic strength and pH can change the shape of the solute from mostly linear to globular therefore, it is very important to use the same conditions during calibration and analysis of unknowns (8). Many mobile phases have been used, but 0.05-0.2 M sodium sulfate or sodium nitrate is common. 

Synchropak columns are very useful for characterizing hydrophilic, anionic, and nonionic, water-soluble polymers, CATSEC columns work best for characterizing cationic polymers utilizing both light scattering and/or differential viscometry detection over a wide range of molecular weights. 

Howard, K.A., Dash, P.R., Read, M.L., Ward, K., Tomkins, L.M., Nazarova, O., Ulbrich, K. and Seymour, L.W. (2000) Influence of hydrophilicity of cationic polymers on the biophysical properties of polyelectrolyte complexes formed by self-assembly with DNA. Biochim. Biophys. Acta., 1475, 245-255. 

Optional hydrophilic polymer block Cationic polymer... 

Sherrington and coworkers161 have examined the chlorination of phenol by J-butyl hypochlorite in the presence of cross-linked polystyrenes substituted by pendant polymethylene chains terminated with anionic or cationic head groups, as well as some hydrophilic acrylic polymers, in four solvents water, methanol, 1,2-dichloroethane and xylene. The polymers exerted a significant influence on the chlorination, particularly in polar solvents. However, no changes in the regioselectivity of the chlorination, in comparison to homogeneous systems, was observed. 

The choice of eluent system depends on the polymer type. For most non-ionic hydrophilic polymers, water can be used. However much more complex eluent systems are needed, for anionic and cationic polymers where interactions with the column based on ion exclusion, inclusion and exchange, adsorption by hydrogen bonding or hydrophobic interactions and intramolecular electrostatic effects, are possible. This can often make method development in aqueous SEC extremely difficult and time-consuming. 

Another approach to reducing the EOF as well as wall adsorption is to add a compound to the running buffer that will compete with the solute for the silanol sites on the surface. These materials must have some affinity for the charged or polar sites on the inner wall and so they must, themselves, be hydrophilic or charged. Nonionic surfactants are hydrophilic to prevent solute adsorption on the wall and block the silanols in order to reduce the EOF. The use of cationic polymers in the buffer results in a reversal of EOF to the anodic direc-... 

Howard K A, et al. (2000). Influence of hydrophilicity of cationic polymers on the biophysical properties of polyelectrolyte complexes formed by self-assembly with DNA. Biochim. Biophys. Acta. 1475 245-255. 

Particulate soils arise from dust, dirt, soot, hydrocarbons, metal oxides and even from hair products based on materials such as silicas or aluminas from about 1pm to less than 0.1-pm particle size see Figure 5-3. The removal of particulate soil is not controlled by the hydrophilicity of the fiber surface. Particulate soil removal depends on the bonding of the particle to the surface, the location of the particle [14], and the size of the particle. Particle size is perhaps the most critical variable for the removal of particulates. As the particle size decreases, the area of contact with the fiber increases, making it more difficult to remove from the hair. At particle sizes of less than 0.1 pm, it is very difficult to remove material from hair surfaces by ordinary shampooing [15]. When the soil particle consists of nonpolar components, its adhesion depends mainly on Van der Waals forces (e.g., waxes or polymeric resins and dimethicone polymers and the molecular size and shape are critical to their removal). Unless very high molecular weights are involved, the removal of such soils is oftentimes easier than for cationic polymers where adhesive binding includes a combination of ionic and Van der Waals forces. 

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