Polymer solubility predicting

The solubihty coefficients are more difficult to predict. Although advances are being made, the best method is probably to use a few known solubility coefficients in the polymer to predict others with a simple plot of S vs ( poiy perm Y where and are the solubility parameters of the polymer and permeant respectively. When insufficient data are available, S at 25°C can be estimated with equation 19 where k = 1 and the resulting units of cal/cm are converted to kj /mol by dividing by the polymer density and multiplying by the molecular mass of the permeant and by 4.184 (16). 

The solubility parameter is in the range 18.4-19 MPa and the polymer is predictably dissolved by halogenated and aromatic hydrocarbons of similar solubility parameter. Stress cracking can occur with some liquids. 

Block copolymers of polystyrene (PSt, hydrophobe) and polyoxyethylene (PEO, hydrophile) form spherical micelles in water when the length of water soluble PEO is significantly larger than that of the insoluble PSt portion of the molecule [62]. In analogy with low molecular weight surfactants, one defines the onset of intermolecular association as the critical micelle concentration (CMC). Theories of polymer micellization predict that the concentration of free, unassociated block copolymers is close to that of the CMC. 

The molecular weights of most of the soluble polymers were predicted by gel permeation chromatography (GPC) analyses against polystyrene calibration. While GPC does not give absolute values of molecular weights but provides a measure of hydrodynamic volume, there is probably some differences in... 

Table 1.1 contains typical solubility prediction data for an ultrahigh free-volume polymer (PTMSP) and a polymer with more conventional transport properties (PTMSS). 

Solubility Polymer solubility can be predicted by the Hildebrand solubility parameter. The Hildebrand solubility parameter, 8, is defined as the square root of the molar energy of vaporization, LE = AH - R, ... 

Calculation of octanol/water partition coefficients. SciLogW for aqueous solubility prediction. SciPredictor for protein secondary structure and homology modeling. SciPolymer for polymer property estimation. PCs under Windows. CAD Gene for gene constructs. Macintosh. 

A new set of solubility parameter data has been provided by Hoy (11). He gives tables arranged alphabetically, numerically, and by boiling point in which the solubility parameters were calculated by computer from the Antoine equation extrapolated to 25 °C. While these values are quite precise, they are sometimes quite different from previously reported values. They should therefore be used with caution in predicting polymer solubility when using published solubility parameter ranges for polymers (6). For the experimenter who wishes to set up his own solubility parameter range data, these tables can be quite useful. 

In spite of the many potential reasons why solubility parameters would fail, the fact remains that Burrell s original paper in 1955 was a great success. It showed that order could be brought out of the chaos of industrial experience. Not only could data be systematized post facto, but some progress toward prediction of polymer solubility was made, although many problems still remained. Specifically, the predictions of polymer compatibility with nonsolvent mixtures were successful in only 20% of the examples tried. 

If Rab lies below a certain threshold Ro, the substances are predicted to be miscible, i. e.the polymer is predicted to be soluble in the solvent. On the other hand, the solvent will neither dissolve nor swell the solute in case of Rab Ro- Furthermore, the Hansen solubility parameters can be used for estimating the Flory-Huggins interaction parameter of two polymers... 

With one exception, the solubility predictions based on the Hansen solubility parameters were fairly consistent with the experimental findings of this study. The results together with the calculated Rab values for several solvents are listed in Table 7.2. Note that the Hansen sphere radius Ro = 12.7 of poly(styrene) is expected to be considerably larger than that of conjugated polymers. 

Thus, Fig. 2.3 a gives an example of the ability of PC-SAFT to predict the molecular-weight dependence of polymer-solubility data. Although the binary parameter... 

Although eqn (6.43) is usually valid only over relatively small ranges of temperature, the values for 8 obtained at 25°C are in. good agreement with the literature data (Table 5.3), suggesting that the resulting parameters may be further used in predicting polymer solubility even at finite concentrations. 

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