Adsorbed flexible polymer chains

Flow-Enhanced Desorption of Adsorbed Flexible Polymer Chains... 

It is well known that a free flexible polymer chain in bulk solution behaves as a random coil. When such a polymer chain is adsorbed on a surface, there occurs a change in its conformation. Some portions of the polymer chain get in direct contact with the surface... 

Studies of polymer adsorption have shown that an adsorbed flexible polymer molecule may be divided into three parts (1) the trains, which are segments adsorbed at the interface (2) the loops, which are segments of the chain that extend into the adjacent bulk phase(s) (3) the tails, the two segments at the two ends of each polymer chain these generally have lower free energies of adsorption than other segments and thus also tend to extend into the bulk phase. 

Silberberg47) used a quasi-crystalline lattice model for the adsorption of flexible macromolecules. If it is assumed that an adsorbed polymer chain with P segments consists of ma trains of length i and mBi loops of length i, the total number of configurations of the chains is given by... 

Several papers compare the properties of sulfobetaine (meth)acrylic polymers. NMR spectra and solution properties of 23a and 23b [59,60] are correlated with data from the corresponding polycarbobetaines [26]. The photophysical and solution properties of pyrene-labeled 23c were studied in terms of fluorescence emission. Addition of surfactants induces the formation of mixed micelles in aqueous solution [61]. Excluded volume effects of the unlabeled polymer were measured by light scattering [62], its adsorption on silica was studied by adsorbance measurement and ellipsometry [62,63], and the electrostimulated shift of the precipitation temperature was followed at various electric held intensities [64]. Polysulfobetaines may accelerate interionic reactions, e.g., oxidation of ferrocyanide by persulfate [65]. The thermal and dielectric properties of polysulfobetaines 23d were investigated. The flexible lateral chain of the polymers decreased Tg, for which a linear relationship with the number of C atoms was shown [66,67]. 

It is well known that a long flexible polymer in a good solvent can form a self-similar adsorbed layer near an attractive wall at the critical temperature T . Using the correspondence between an cidsorbed polymer chain and the model of ferromagnets with n-vector spins in the limit n — 0 with a free surface, it hcis been shown that the adsorption point Ta corresponds to a tricritical point and in its proximity a crossover regime is observed. In particular, the mean number of monomers, M, at the surface is shown to behave as [47]... 

In another work, shear-induced stretching of relatively flexible positively charged poly[methacryloylojqrethyl-dimethyl-(3-pyirol-l-yl-propyl) ammonium bromide] (PME-D-AB) chains adsorbed on a planar substrate (mica) was explored by AFM and Brownian dynamics computer simulations by Stamm s and Lowen s groups. Considerably sttetched polymer chains along the shear flow with a wealth of different individual shapes were found (Figure 12). 

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