Hydrogen bond statistical description

Various equations of state have been developed to treat association ia supercritical fluids. Two of the most often used are the statistical association fluid theory (SAET) (60,61) and the lattice fluid hydrogen bonding model (LEHB) (62). These models iaclude parameters that describe the enthalpy and entropy of association. The most detailed description of association ia supercritical water has been obtained usiag molecular dynamics and Monte Carlo computer simulations (63), but this requires much larger amounts of computer time (64—66). 

The probability p g of the third hydrogen bond decreases from methanol to ethanol, and it is always lower than pg this is very likely ascribable to steric effects (increasing with the molecular weight of the alcohol) which hinder formation of the third hydrogen bond. So in an alcohol with a long alkyl chain we can assume p g = 0, and for a statistical description of the network the binomial distribution... 

Deviations of real molecules from the reference system may occur, e.g., due to attractive interactions (dispersion), formation of hydrogen bonds (association), or the nonspherical shape of the molecules (which can be understood as the formation of chains from spherical segments). These contributions are usually assumed to be independent of each other and are accounted for by different perturbation terms. Depending on the kind of considered perturbation and on the expression used for its description, different models have been developed. One of the first models derived from that idea was the Statistical-Associating-Fluid Theory (SAFT) (Chapman et al. [12, 13] Huang and Radosz [14, 15]). 

This work deals with the statistical description of poly(dimethylsiloxane) chains adsorbed upon the surface of silica particles within silica-siloxane mixtures. In these systems, the incorporation of fumed silica into the PDMS polymer melt is obtained by mechanical mixing. Subsequently, the adsorption which occurs through the formation of hydrogen bonds between the oxygen atoms on the polymer chains and the silanol groups located on the silica s surface is a solvent free or melt adsorption process. Consequently, the law of adsorption observed from these systems is specific to such a process. 

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