Poly preferential adsorption behavior

In order to investigate the effect of the ring substitution on preferential adsorption of water in poly(phenyl methacrylate) derivatives, it has been studied the preferential adsorption behavior of poly(2,4 - dimethylphenyl methacrylate) (2,4 - DMP), poly(2,5 - dimethylphenyl methacrylate) (2,5 - DMP) and poly(3,5 -dimethylphenyl methacrylate) (3,5 - DMP) in THF/water mixtures [109],... 

The preferential adsorption behavior of poly(vinylpyrrolidone) (PVP) in binary solvent containing aromatic components has been also studied [110]. In this case, it was concerned with the influence of the chemical structure of different binary solvents in the preferential adsorption of this polymer. 2 - propanol - cumene, 2 -propanol - mesitylene, 2 - propanol - p-xylene, 2 - propanol - ethylbenzene and 2 - propanol - toluene. Figure 1.15 shows the variation of X with the solvent composition. In both cases aromatic components are adsorbed in the range 0 to 40%, but the amount of adsorbed molecules is rather different for the two isomers. This result could be explained in terms of steric hindrance due to the isopropyl groups of cumene, which would be reflected in the lower X value. 

In the case of poly(methacrylates) mentioned above there is a decreasing in the X values when the aromatic ring has alkyl groups as substituents. This behavior was explained taken into account at least two factors. If the model accepted to explain the preferential adsorption is that which consider that this phenomenon occurs along the polymer chain, the rigidity of the macromolecule must influence the amount of the adsorbed solvent. 

There are some important structural aspects of the polymer which are necessary to take into account in the analysis of the polymer behavior in mixture solvents, such as its polarity, chemical structure, microtacticity, molecular weight. The analysis of these properties shows that they are determinant factors in preferential adsorption phenomena involved. It has been pointed out that the effect of tacticity, and particularly the molecular weight, is a complex problem. In the case of poly(2-vinylpyridine), when the polar solvent is preferentially adsorbed, preferential solvation is independent of molecular weight but when the non-polar solvent is adsorbed, there is a dependence on the molecular weight. ... 

Apparently, there will not be exhaustive results either with the chemical structure of the polymer on the preferential adsorption," or the influence of the tacticity on the preferential adsorption. In the last years, investigations regarding the effect of ortho-substituents in polymers with aromatic bulky side groups on the preferential adsorption and viscometric behavior have been reported for poly(phenyl methacrylate) and its dimethyl and diisopropyl ortho derivatives in tetrahydrofiiran/water. " Figure 5.4.5 from ref " shows the Xvalues for three polymers in THF/water. 

Ferrocene units were tethered to electrodes by telechelic poly(ethylene oxide) [579] and showed preferential adsorption of pyrene end groups to highly oriented pyrolytic graphite [580]. Ferrocene-based polymer brushes were grafted from conducting surfaces, which imparted special electrochemical behavior [581-584] e.g., the interaction of these surfaces with cyclodextrin could be modulated by electrochemical means (Fig. 51) [583, 585]. 

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