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a b s t r a c tThe vapor pressure of four liquid 1H,1H-perfluoroalcohols (CF 3 (CF 2 ) n (CH 2 )OH, n ¼ 1, 2, 3, 4), often called odd-fluorotelomer alcohols, was measured as a function of temperature between 278 K and 328 K. Liquid densities were also measured for a temperature range between 278 K and 353 K. Molar enthalpies of vaporization were calculated from the experimental data. The results are compared with data from the literature for other perfluoroalcohols as well as with the equivalent hydrogenated alcohols. The results were modeled and interpreted using molecular dynamics simulations and the GC-SAFT-VR equation of state.

Biodiesel fuels, which consist of a blend of long chain fatty acid methyl esters, have attracted increased interest in recent years as possible alternates to fuels derived from petroleum. An understanding of the thermophysical properties and phase behavior of these molecules are therefore important to the investigation and design of biodiesel processes; however, such data is limited making the development of molecular based modeling approaches that can accurately and reliably determine the thermophysical properties of fatty acid methyl esters an important research area. Here we apply the group contribution based statistical associating fluid theory for potential of variable range (GC-SAFT-VR) equation of state to the study of long chain fatty acid methyl esters that comprise biodiesel fuels. With minimal reliance on experimental data, the GC-SAFT-VR equation of state offers a predictive approach that allows for the description of heterosegmented chains to correlate and predict the phase behavior of pure associating and nonassociating fluids and their mixtures. Model parameters for the C=O, CH 3 , CH 2 , CH=CH2, OCH 2 , and OCH 3 functional groups and their cross interactions were taken from earlier work and used here in a transferable fashion to predict the thermophysical properties and phase behavior of pure fatty acid methyl esters and their mixtures with other fatty acid methyl esters, alcohols, and carbon dioxide. It is shown that the GC-SAFT-VR approach can be used as a purely predictive tool, without fitting any new model parameters, to accurately predict the phase behavior of the fatty acid methyl ester fluids and their mixtures studied.

Fluorinated molecules such as perfluoroalkanes (PFA), perfluoroalkylalkanes (PFAA), fluoroalkanes, and hydrofluoroethers (HFE) possess attractive physical properties that have resulted in their use in a wide range of applications. However, while there is an abundance of thermophysical data for alkanes in the literature, only limited studies have been performed that report the properties of the corresponding fluorinated species. Predictive approaches are therefore needed to accurately and reliably determine the physical properties of these molecules. The statistical associating fluid theory (SAFT) is a commonly used molecular-based equation of state that in its various forms has been applied to study a wide range of fluid systems. In recent work, several group contribution (GC) SAFT equations of state have been proposed, such as the GC-SAFT-VR equation that combines the SAFT equation for potentials of variable range (VR) with a group contribution approach that uniquely allows for the description of hetero-segmented chains. The GC-SAFT-VR equation has been shown to provide an excellent description of the phase behavior of pure associating and non-associating fluids and their mixtures, with a minimal reliance on fitting the model parameters to experimental data. Specifically, parameters for key functional groups (such as CH 3 , CH 2 , CH, CH 2 =CH, C=O, C 6 H 5 , ether and ester, OH, NH 2 , CH=O, COOH) have been obtained by fitting to experimental vapor pressure and saturated liquid density data for selected low molecular weight fluids and then used to predict the phase behavior of pure fluids and their mixtures without further adjusting the group parameters. To expand upon this effort, here we report parameters for the CF 3 , CF 2 , CF, CH 2 F, CHF 2 , and CHF functional groups and their cross interactions. The theoretical predictions are compared with experimental data for pure PFAs, PFAAs, and HFEs, as well as binary mixtures of alkanes, alkenes, PFAs, PFAAs, and CO 2 in order to test the transferability of the new group parameters. The GC-SAFT-VR approach is found to accurately predict the phase behavior of the systems studied.

Grafting polymers to nanoparticles is one approach used to control and enhance the structure and properties of nanomaterials. However, predicting the aggregation behavior of tethered nanoparticles (TNPs) is a somewhat trial and error process as a result of the large number of possible polymer tethers, nanoparticles, and solvent species that can be studied. With the main goal of understanding how to control the dispersion and aggregation of TNP systems, molecular simulations and the hetero-statistical associating fluid theory for potentials of variable range have been used to calculate the fluid phase equilibrium of TNPs in both vacuum and in simple solvents under a wide range of conditions. The role of graft length, graft density, and solvent interactions is examined and trends established. Additionally, the fluid distribution ratio (k value) is used to study the solubility of TNPs in industrially relevant solvents including carbon dioxide, nitrogen, propane, and ethylene.