Free-Volume Activity Coefficient Models for Dendrimer Solutions

Abstract

The ability of the Unifac-FV and Entropic-FV models to predict phase equilibria for dendrimer systems is investigated in this work. Different approaches are considered for the estimation of the density of the dendrimers, which is required as input parameter in the free-volume models. The density is not always available for such polymers.The predictions obtained by the two models are compared with recent vapor-liquid equilibrium experimental data for dendrimer systems. It is shown in this study that both methods represent satisfactorily the experimental data in many cases, whereas Unifac-FV performs better for PAMAM dendrimers (where some of the interaction parameters are missing). However, Unifac-FV is the model that is most influenced by the dendrimer's density. Both models yield better results when experimental densities are employed (for AR dendrimers), but in those cases where such data are not available, predicted densities can be reliably obtained via the van Krevelen method (for C12 and A4 dendrimers).

Interactions between DNA and Poly(amido amine) Dendrimers on Silica Surfaces

“…The formed adsorbed layers had thicknesses that were 51%, 37% and 43% of the corresponding diameters predicted using the hydrodynamic radii in Table , respectively. The neutron reflectivity data were further evaluated using the molecular volumes of 5149 Å 3 for G2, 22481 Å 3 for G4 and 91803 Å 3 for G6 (obtained using the dendrimer density of 1.2 g cm −3 Table ), which showed that the number of adsorbed particles ( N ) decreased for higher generations as the average dendrimer molecular area (including solvent, A m ) increased. With an accurate determination of N , the dendrimer surface excess (Γ) could then be calculated.…”

Measurements of mass-fraction activity coefficient at infinite dilution of aliphatic and aromatic hydrocarbons, thiophene, alcohols, water, ethers, and ketones in hyperbranched polymer, Boltorn H2004, using inverse gas chromatography

“…The group contribution method UNIFAC-FV model [34,[44][45][46] allows for the prediction of the solubility behaviour and the mass-fraction activity coefficient at infinite dilution, X 1 13;pred . According to UNIFAC-FV, the prediction in the systems with hyperbranched or dendritic polymers assumes the structure of the poly-FIGURE 2.…”

Hyperbranched Polymers in a Supercritical Fluid: Recent Progress on Phase Behavior and Modeling

“…Experimental results on the phase behavior and density data offer a database for the theoretical researchers to develop and test suitable thermodynamic models to predict the solution behavior of hyperbranched polymer systems. Earlier modeling work includes Monte Carlo simulation by Lue [64] and Timoshenko and Kuznetsov [65], molecular dynamics method by Steinhauser [66], lattice cluster theory (LCT) modeling by Jang, et al [45,[67][68][69][70][71], universal functional activity coefficients-free-volume (UNIFAC-FV) method by Kouskoumvekaki, et al [72] and Seiler, et al [47], etc., which have been reviewed by Seiler [7]. In the past eight years after the review, more models have been developed for hyperbranched polymer systems accompanied with a deeper understanding of the hyperbranched polymer architecture and an increasing number of low-pressure and high-pressure experimental data.…”