Chain length soluble polymer adsorption

Molecular-based theories are useful for developing rational stabilizer design criteria and investigating the correlation with bulk phase behavior for stabilizers in supercritical fluids. Molecular theories of polymer adsorption, such as the lattice self-consistent field (SCF) theory of Scheutjens and Fleer[69], allow chain structure, adsorption energy, solubility, length, and concentration to be varied independently. Simulation, while more computationally intensive, offers the additional advantages of... 

Fig. 13 Left Density profiles of carlxMi dioxide and hexadeeane across the two interfaces in a box of linear dimension L = 98.88(Tpp. Densities are quoted in LI units (p = pffpp). The dotted ellipses highlight the interfacial adsorption of CO2 at the polymer-C02 vapor interface. Right The snapshots show Lx Lx. 5a slices where the positions of the CO2 molecules (lower image) and the polymer (upper image) are shown separately. Note that a few hexadeeane molecules are dissolved in the vapor phase as well (this finite solubility in the gas decreases rapidly with increasing polymer chain length)...

Since from an ideal point of view polymer solubility and adsorption are not occurring in this chromatographic process, the volume of eluent required for the elution of any macromolecules species must essentially be dependent on chain length and appears to be insensitive to structure (universal calibration). However, this seems to be not always the case (non-exclusion effects). 

Polymers can adsorb spontaneously from solution on to surfaces if the interaction between the polymer and the surface is more favorable than that of the solvent with the surface. For example, a polymer like poly(ethylene oxide) (PEO) is soluble in water but will adsorb on various hydrophobic surfaces and on the water/air interface. This is the case of equilibrium adsorption where the concentration of the polymer monomers increases close to the surface with respect to their concentration in the bulk solution. We discuss this phenomenon at length both on the level of a single polymer chain (valid only for extremely dilute polymer solutions), see Section II, and for polymers adsorbing from (semidilute) solutions, see Section III. In Fig. 2a we schematically show the volume fraction profile (p(z) of monomers as a function of the distance z from the adsorbing substrate. In the bulk, i.e., far away from the substrate surface, the volume fraction of the monomers is (p], whereas, at the surface, the corresponding value is (p > (p]. The theoretical models address questions in relation to the polymer conformations at the interface, the local concentration of polymer in the vicinity of the surface, and the total amount of adsorbing polymer chains. In turn, the knowledge of the polymer interfacial behavior is used to calcu-... 

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