Solubility parameter calculation

The solubility parameters calculated at 25°C have been tabulated for numerous hydrocarbons in the API technical data book. They can also by calculated by the relationship ... 

Foster, A., Hempenstall, J., Tucker, I., andRades, T. Selection of excipients for melt extrusion with two poorly water-soluble drugs by solubility parameter calculation and thermal andlybid. Pharm.,... 

Solubility parameters calculated using the tables of Hoy, as given by Krause (1). 

One can then calculate the dispersive contribution from tabulated solubility parameters, or from solubility parameters calculated from group contributions. When the calculated dispersive contribution is subtracted from the observed heats of mixing the contribution of the specific interaction should remain. The results are shown in Fig, 21. There is considerable scatter which is not surprising considering the assump-... 

The plots suggested by Equation 3 for these systems are shewn in Figures 2, 3 and 4 and these show that the excellent correlation found with polymers is not obeyed with these compounds. The results arising from alkane probes show linearity, even with polar molecules such as NMP, but there are marked deviations with aromatic or polar probes. Table III shows the solubility parameters calculated using solely the linear portions of the graphs obtained with the alkane probes, and also using the results from all of the probes. The results do not show the consistency displayed by polymers, and the estimates of 62 differ greatly from literature values. There is no apparent pattern as to whether better results are found from the alkane solvents or from all of the results. 

Solubility parameter calculated by using ECOhi for the cohesive energy per mole. 

Just a few years ago, the limitations of solubility parameter calculations and measurements discussed above were serious impediments to modeling the phasic and interfacial behaviors of polymeric systems. The coming of age of atomistic simulation methods over the last few years has improved this situation dramatically. As discussed in Section 5.A.3, whenever accuracy is important in calculating the phasic or the interfacial behavior of a system, it is nowadays strongly preferable to use atomistic simulations employing modem force fields of the highest available quality instead of solubility parameters in order to estimate the Flory-Huggins interaction parameters (%) between the system components as input for further calculations. 

Solvent Surface tension, mN/m Molecular volume, V Solubility parameter, calculated, (J/cm ) Solubility parameter, actual, (J/cm ) ... 

Solubility parameters calculated from Klevelen and Hoftyzer s group contributions of solubility parameter components in reference (19). 

Such migration requires only partial miscibility in the polymer matrix, silicone in the particular case studied by Stein et al. Owen and co-workers [9] have suggested that solubility parameter calculations can be useful in designing suitable compositions with partial miscibility. These ideas appear superficially to be at odds with compatibility/penetration and interpenetrating network concepts. However, these contrary solubility requirements are a consequence of the initial placement of the adhesion promoter. When used as a primer, it is already placed at the interface so needs no partial solubility characteristic to drive it there, as is needed when it is initially dispersed throughout the polymer matrix. In both cases it is the development of a strengthening interfacial phase that accounts for the enhancement in adhesion that is sought by the user. 

Figure 1 Plotof density and Hildebrand solubility parameter for neat supercritical CO2 vs. pressure at various temperatures. Hildebrand solubility parameters calculated using equation 6 From top to bottom, the curves represent teinperatures of 32.2-C, 40 C, 50 C, 75 C, lOO C, 125X, and 150 C...

Table 7.2 Examples of solubility parameters calculated from those constants in Table 7.1... 

Fan CF, Olafson BD, Blanco M, Hsu SL (1992) Application of molecular simulation to derive phase-diagrams of binary-mixtures. Macromolecules 25(14) 3667-3676 Flory PJ (1953) Principles of polymer chemistry. Cornell University Press, Ithaca Forster A, Hempenstall J, Tucker I, Rades T (2001) Selection of excipients for melt extrusion with two poorly water-soluble drugs by solubility parameter calculation and thermal analysis. Int J Pharm 226(1-2) 147-161... 

Solubility parameter calculated by Molecular Modeling Pro Plus from ChemSW Inc. Polymeric excipients are categorized into two main categories (1) nonionic/non-pH dependent polymers and (2) ionic/pH dependent polymers... 

Table 1. Solubility Parameters calculated using the Hoftyzer and van Krevelen method [46].

The first two terms represent the combinational entropy of mixing. Since these entropy terms are usually small in polymer blends, AG, is dominated by the balance between the third and fourth terms. The third term represents physical forces that can be estimated using Hildebrand s approach from solubility parameters calculated using group contribution methods for a set of carefully chosen groups which are free from association (see also Section 2.1.6) [8,15]. The fourth term represents the favorable hydrogen-bonding contribution to AG - Its... 

The misdbilit) of PEA. PBA. PHA is roughly explained by solubility parameter calculated by the method of Small. The Tg of the PLA-rich phases decreases with decreasing differences in solubihty parameter values between PLA and PED. 

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