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Adsorbed macromolecules, structure

The consideration made above allows us to predict good chromatographic properties of the bonded phases composed of the adsorbed macromolecules. On the one hand, steric repulsion of the macromolecular solute by the loops and tails of the modifying polymer ensures the suppressed nonspecific adsorptivity of a carrier. On the other hand, the extended structure of the bonded phase may improve the adaptivity of the grafted functions and facilitate thereby the complex formation between the adsorbent and solute. The examples listed below illustrate the applicability of the composite sorbents to the different modes of liquid chromatography of biopolymers. [Pg.142]

In filtration, the particle-collector interaction is taken as the sum of the London-van der Waals and double layer interactions, i.e. the Deijagin-Landau-Verwey-Overbeek (DLVO) theory. In most cases, the London-van der Waals force is attractive. The double layer interaction, on the other hand, may be repulsive or attractive depending on whether the surface of the particle and the collector bear like or opposite charges. The range and distance dependence is also different. The DLVO theory was later extended with contributions from the Born repulsion, hydration (structural) forces, hydrophobic interactions and steric hindrance originating from adsorbed macromolecules or polymers. Because no analytical solutions exist for the full convective diffusion equation, a number of approximations were devised (e.g., Smoluchowski-Levich approximation, and the surface force boundary layer approximation) to solve the equations in an approximate way, using analytical methods. [Pg.209]

Crystalline Hydroxylapatite is a structurally organised, highly polar material which, in aqueous solution (in buffers) strongly adsorbs macromolecules such as proteins and nucleic acids, permitting their separation by virtue of the interaction with charged phosphate groups and calcium ions, as well by physical adsorption. The... [Pg.22]

The results collected in this review are focused to demonstrate the advantages of electro-optics for investigation of the electrical properties of anisometric particles in dilute suspensions containing polyelectrolytes. Results on the structure of the adsorbed macromolecules and the stability of suspensions containing polyelectrolytes will also be discussed. [Pg.306]

In combination with adsorption measurements, electro-optics is proved to be a powerful technique for studying the structure of adsorbed polyelectrolyte layers. Our data show flat conformation of the adsorbed macromolecules, which slightly depends on the polyelectrolyte charge density in accordance with the theory for weak poly electrolytes. Counterion condensation is also suggested on the surface of weakly charged poly electrolytes, which has not been predicted from the theory. [Pg.338]

Pefferkorn E, Elaissari A. Adsorption—desorption processes in charged poly-mer/colloid systems structural relaxation of adsorbed macromolecules. J Colloid Interface Sci 1990 138 187-194. [Pg.564]

Elaissari A, Pefferkorn E. Polyelectrolyte induced aggregation of latex particles influence of the structural relaxation of adsorbed macromolecules on the colloid aggregation mode. J Colloid Interface Sci 1991 141 522-533. [Pg.564]

Often one relates this type of stabilization to the so-called steric factor [48-51], the notion of which was introduced much later than Rehbinder s concept of lyophilic structural-mechanical barrier. Steric factor primarily reflects configurational elasticity of tails and loops of adsorbed macromolecules as well as osmotic effects. Steric factor represents only an entropic ( generally speaking, small) contribution to the elastic resistance of film, and by itself can not account for the strong stabilization. [Pg.558]

The appearance of the Vroman effect and related phenomena can be inhibited by the roughness and the porosity of a surface or due to the formation of hybrid aggregates with macromolecules and oxide NP (Figure 6.41). All these structural features of the interfaces cause reduction of accessibility of pre-adsorbed macromolecules for co-adsorbate molecules as well as for solvent molecules. The confinement effects in restricted space of pores or surface roughness (valleys, Figure 6.34) diminish the mobility of the adsorbed molecules. Therefore, the possibility of the displacement of these molecules by other molecules (even of a larger size) decreases. [Pg.716]

The same interactions that determine intramolecular structure and aggregatirai also play a role in adsorption to surfaces. When a simple linear macromolecule interacts with a surface and becomes adsorbed, its structure changes from the 3D mushroom conformation to the (quasi)-2D pancake conformation [155]. In the... [Pg.162]

Adsorption of macromolecules has been widely investigated both theoretically [9—12] and experimentally [13 -17]. In this paper our purpose was to analyze the probable structures of polymeric stationary phases, so we shall not go into complicated mathematical models but instead consider the main features of the phenomenon. The current state of the art was comprehensively summarized by Fleer and Lyklema [18]. According to them, the reversible adsorption of macromolecules and the structure of adsorbed layers is governed by a subtle balance between energetic and entropic factors. For neutral polymers, the simplest situation, already four contributor factors must be distinguished ... [Pg.138]

In addition to theoretical considerations, some experimental studies were carried out to clarify the structures of adsorbed layers of hydrophilic macromolecules. [Pg.140]


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Adsorbate structure

Macromolecules structures

Structured Adsorbents

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