Polymer solubility parameters

Liquid solvent/polymer Solubility parameter, <5, (J/cm ) / Molar volume, V (cm /mol)... 

Keywords. Porous polymer, Solubility parameter, Phase separation. Epoxy, Cyanurate,... 

Figure 2.25 The dissolution temperature method for determining polymer solubility parameters. Reprinted with permission from J. E. Mark, Physical Chemistry of Polymers, ACS Audio Course C-89, American Chemical Society, Washington, DC, 1986. Copyright 1986, American Chemical Society.

DiPaola-Baranyi, G., "Estimation of Polymer Solubility Parameters by Inverse Gas Chromatography," Macromolecules, 15, 622 (1982). 

Eguiazabal, J. I. Fernandez-Berridi, M. J. Iruin, J. J. Elorza, J. M., "Chromatographic Determination of Polymer Solubility Parameters," Polym. Bull., 13, 463 (1985). 

Galin, M., "Gas-Liquid Chromatography Study of Polyethylene oxide)- Solvent Interactions Estimation of Polymer Solubility Parameter," Polymer, 24, 865 (1983). 

Merk, W. Lichtenthaler, R. N. Prausnitz, J. M., "Solubilities of Fifteen Solvents in Copolymers of Poly(Vinyl- Acetate) and Poly(Vinyl Chloride) from Gas-Liquid Chromatography. Estimation of Polymer Solubility Parameters," J. Phys. Chem., 84, 1694 (1980). 

Interaction characteristics in polymer-related areas frequently make use of solubility parameters (16). While the usefulness of solubility parameters is undeniable, there exists the limitation that they need to be estimated either by calculation or from indirect experimental measurements. The thermodynamic basis of IGC serves a most useful purpose in this respect by making possible a direct experimental determination of the solubility parameter and its dependence on temperature and composition variables. Price (17) uses IGC for the measurement of accurate % values for macromolecule/vapor pairs, which are then used for the evaluation of solubility parameters for a series of non-volatile hydrocarbons, alkyl phthalates, and pyrrolidones. It may be argued that IGC is the only unequivocal, experimental route to polymer solubility parameters, and that its application in this regard may further enhance the practical value of that parameter. Guillet (9) also notes the value of IGC in this regard. 

Figure 1. Calculation of polymer solubility parameters at 25°C for poly(dimethyl siloxane), PDMS, ethylenepropylene rubber, EPR, and polyisobutylene, PIB.

The solubility parameters of the homopolymers and those of the blends have been determined using the method of Guillet and coworkers (8-10) as modified in Equation 6 above. The values of 53 and 0 (23) are presented in Tables IV and V. (A more detailed discussion of the Guillet method is presented in the next section). Using these values of the polymer solubility parameters, the polymer-polymer interaction parameter B23 has been determined. 

Determination of the polymer solubility parameter using the Guillet approach yields deceptively linear dependences compared to the scatter inherent in the experimental data. While the technique is more than adequate, compared with values obtained from more time consenting classical methods, one should be aware of the limitations of generating the linear dependence. 

Polymer Solubility parameter Polymer Solubility parameter... 

Equation 16.44 can be used in the following way If experimental data for the FH parameter are available, e.g., via chromatographic measurements for a series of systems with the same polymer in different solvents, then from the linear plot depicted by Equation 16.44, the solubility parameter of the polymer can be estimated. Solubility parameters of the solvents are known from direct experimental measurements. Thus, Equation 16.44 represents one of the various indirect methods for estimating polymer solubility parameters. 

Often, the Flory-Huggins solvent-polymer interaction parameter is applied instead of 1 P or G. There are some books (Refs. 1-3) giving details for such procedures as well as extensive tables of polymer solubility parameters from which the table below is extracted. Methods for calculating solubility parameters can be found in Refs. 4-7. 

The energy of vaporization is not accessible for polymers, but cohesive energy density of polymers can be determined from PVT-data. However, common ways for determining polymer solubility parameters use thermodynamic properties of polymer solutions and their relations to excess enthalpy or excess Gibbs energy per unit volume. These excess quantities are related to the (square) difference between the solubility parameters of solvents and polymers, i.e. (d -... 

When a polymer absorbs a liquid or gas, that results in plasticization or swelling of the thermoset network, physical corrosion has taken place. For a cross-linked thermoset, swelling caused by solvent absorption will be at a maximum when the solvent and polymer solubility parameters are exactly matched. 

The viscosity method for soluble polymers and the swelling method for cross-linked network polymers yield quite unambiguous values for polymer solubility parameters, so long as one is confined to a series of structurally similar solvents. For example, the data in Figure 6-1 apply to aliphatic hydrocarbons as well as to long-chain esters and ketones. Cycloaliphatic hydrocarbons and short-chain esters such as ethyl acetate deviate significantly from the curves shown. 

The authors [91] proposed description of organic phase influence on limiting characteristics of polyurethanearylates (PUAr) interfacial polycondensation. As it is known [55], one from the methods of polymer solubility parameter 5 experimental determination is plotting of the dependence of intrinsic viscosity [t ], measured in several solvents, on this solvents solubility parameter 5 value. The smaller difference 6p-5J or the better solvent thermodynamical quality in respect of polymer is, the larger [q] is. The dependences [q](5 ) have usually belllike shape and such dependence maximum corresponds to 5 [55]. In Fig. 23 the dependence of on 5 of solvents, used as organic phase at PUAr interfacial polycondensation is adduced. The dependence q /S ) bell-like shape is obtained again and its maximum corresponds to 5 10 (cal/cm ), that is a reasonable estimation for PUAr [36, 55]. Let us note that all q values were determined in one solvent, which was not used at synthesis, namely, in mixture phenol-simm-tetrachloroethane. The dependence qj 4(5 ), adduced in Fig. 23, allows to make two conclusions. Firstly, the value q, reached in PUAr interfacial polycondensation process, is controlled by solvent thermodynamical qnality and the greatest... 

The thermodynamic affinity between components of a solution is important for quantitative estimation of mutual solubility. The concept of solubility parameters is based on enthalpy of the interaction between solvent and polymer. Solubility parameter is the square root of the cohesive energy density, CED ... 

Evaluation of solubility parameters of polymers by direct methods is not possible. All the methods of evaluation of polymers solubility parameters are indirect. The assumption of the solutions theory in which the best mutual dissolution of substances is observed when solubility parameters are equal serves as the basis for indirect methods (see 6.2.1). 

An attempt was made to relate intriitsic viscosity [t]] to the solubility parameters of components. Also, 82 was calculated from the relationship [t]] = f(8i). The authors assumed that the maximitm value of [11] shoitld be obtained in a liquid in which its solubility parameter, 81, is eqital to the polymer solubility parameter, 82. Intrirtsic viscosity should be thus smaller for both smaller and larger values of 8[. From strrdies of [11] for polymethylmetacrylate in foirrteen different liqitids, a wide scattering of experimental points was obtained. The 82 value lies within 10% scatter. 

Hansen developed a visual interpretation of his method. This is a three-dimensional sphere of solubility in which the centre of the sphere has coordinates corresponding to the values of the components of the polymer solubility parameter. A sphere radius can be used to characterize dissolving characteristics of polymers by different solvents. Each solvent is represented by a point on a three-dimensional space with 8, 8p, 8 as axes. The point should be inside the sphere (the solubility volume) for polymer and all non-solvents should be outside the solubility volume. 

The larger the difference between polymer and solvent interaction parameters, the smaller the chanceof polymer pseudo-solution foimation. A collection of solvents, solubility parameters, and polymer solubility parameters for polymers covered by this book are given in Table 8. 

Another method of determining polymer solubility parameters is to prepare a lightly crosslinked form of the polymer and to place this in a similar series of solvents. The amount of swelling should be greatest for the liquid having the same solubility parameter as the polymer. A further possibility involves the calculation of the polymer solubility parameter from group contributions as proposed by various authors. 

---