Adsorbing water-soluble polymers

Cabane B and Dupplessix R 1985 Neutron soattering study of water-soluble polymers adsorbed on surfaotant mioelles Colloids Surf. 13 19-33... 

It has been outlined by several authors that the single macromolecule may be irreversibly bound because of the large number of weakly interacting segments. The first papers on the construction of polymer-coated silica adsorbents involved the physical adsorption of water-soluble polymers. Polyethylene oxides [28, 29] and poly-/V-vinylpyrrolidone [30] are examples of the stationary phases of this type. 

Figure 9.4 Core-shell polyplex structures (A) cationic particles with a core from neutralized DNA and polycation and a corona from polycation chains adsorbed on the core (B) electroneutral particles ( polyion complex micelles or block ionomer complex ) with a core from neutralized DNA and poly cation and a corona from nonionic water soluble polymer.

Water-soluble polymers coat hydrophobic solid surfaces with multilayers and thus render the solid hydrophilic (i.e., wetting). The number of adsorbed chains (or the amount of polymer adsorbed) per surface site (or unit weight of adsorbent) is related to the volume fraction of segments in each layer. As the length of the chains increases,... 

A new process from the paint industry may have application for the suspension coating of pesticide crystals [25]. Low molecular weight water-soluble vinyl polymer chains are synthesized and the process stopped with a terminal vinyl group on each polymer chain. Hydrophobic acrylic monomers are then idded to create the hydrophobic strongly adsorbing backbone polymer. As each water-soluble polymer terminal vinyl group reacts with the growing hydrophobic backbone polymer it becomes inserted like a tooth on a comb. Indeed, these polymer structures are referred to as comb polymers. 

For example, cellulose ethers and other water-soluble polymers may adsorb at the cornea-aqueous tear layer interface, thereby stabilizing a thicker layer of fluid adjacent to the adsorbing surfece.The observation that these compoimds can prolong TBUT snpports such assumptions.The cellnlose ethers are generally nonirritating and nontoxic to the ocular tissues. 

When an emulsifier is used, its type and concentration primarily affects the number of latex particles formed, which in turn determines the rate of polymerization and, depending also on the rate of initiation, the molecular weight of the polymer formed. Although the physical properties of the polymer are primarily dependent on its molecular waght and molecular weight distribution, the properties of the latex depend on its concentration, average particle size, particle size distribution, and the viscosity of the aqueous phase, which may be enhanced by addition of a thickener—a water-soluble polymer not adsorbed by the polymer phase which does not affect the course of the reaction,... 

Water-soluble polymers have an ability to increase the viscosity of solvents at low concentrations, to swell or change shape in solution, and to adsorb at surfaces. These are significant features of their behaviour, which we will deal with briefly. 

Li (2007) observed that the adsorption of a hydrophobically associating water-soluble polymer, AP-2, did not follow the Langmuir-type isotherm. Figure 5.37 shows that the adsorption increased to a maximum and then decreased as the polymer concentration was increased. The reason is probably that the hydrophobic polymer has an adsorption layer of multiple molecules on rock surfaces. When the polymer concentration is increased, the adsorption layer becomes thicker because of more adsorption. When the polymer concentration is further increased, the molecular interaction in the liquid is stronger than that between the adsorbed molecules and rock surfaces. Then the adsorbed molecules may leave the rock surfaces and redissolve into the liquid. Thus, the adsorption decreases. 

In this section, we will consider only water-soluble polymers adsorbing at homogeneous surfaces, A-W, O W, or S W. The conformation in which polymers adsorb will be considered first. 

The increase in size of water consumption and decrease of water quality due to man s impact make the problem of water purification and treatment from different contaminants, such as suspended and colloidal disperse particles, more acute. The efficiency of dispersion precipitation can be greatly improved with the use of flocculants - high-molecular compounds that have the ability to adsorb themselves on disperse particles and form fast precipitating aggregates [1], Both natural and synthetical water soluble polymers can be used as flocculants. The most commonly used and the most active of these polymers are polyacrylamide (PAA) and some of its derivatives. 

This anomalous wetting behavior of the low surface tension liquids on additive-free PAM may indicate that the polymer surface is contaminated. The most probable contaminant on the surface of this water-soluble polymer would be a layer of strongly adsorbed water, which is... 

A combination of two surfactants was studied in [279] ethoxylated nonylphenol of 150 moles EO (DNP 150) and adsorbing on the coal particle surface, and a water-soluble polymer polyethylene oxide (POE) the adsorption of which on the particles was not fixed. At a closely packed adsorption layers of DNP 150 on the surface of the coal particles and a minimum POE addition, a suspension was obtained which did not settle for 2 weeks. After this time, the suspension exhibited minimum settling without large increases in suspension viscosity. 

Twiss and Carpenter (1938) had also proposed that the water soluble polymers induced creaming by a type of cross-linking mechanism. They pointed out that water soluble polymers of the type studied formed a loose network in solution, as witnessed by their exhibition of a high structural viscosity. Twiss and Carpenter argued that if the chains of the water soluble polymer were adsorbed onto the latex particles, then the particles might be interlinked by network formation between polymer chains adsorbed on different particles. 

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