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Macromolecules 1986,19, 1522-1525
(5) McCormick, C. L.; Blackmon, K. P.; Elliott, D. L., to be published in J . Polym. Sci., Polym. Chem. Ed. (6) McCormick, C. L.; Elliott, D. L. Macromolecules 1986,19,542. ( 7 ) Harwood, H. J.; Ritchey, S. Polym. Lett. 1964, 2, 601. (8) Igarashi, S. J. Polym. Sci., Polym. Lett. Ed. 1963, I, 359. (9) Carreau, P. J.; Dekee, D.; Daroux, M. Can. J.Chem. Eng. 1979, 57,135. (10) Billmeyer, F. W. Textbook ofpolymer Science, 2nd ed.; Wiley Interscience: New York, 1971; p 86. (11) Arai, F. Master's Thesis, University of Southern Mississippi, Hattiesburg, MS, 1984.
(12) Neidlinger, H. H.; Arai, F. DOE Contract No. DE-ASI980BC10321, Fifth Annual Report, 1982. (13) Tan, J. S.; Gasper, S. P. Macromolecules 1973, 6, 741. (14) Katchalsky, A.; Spitnik, P. J . Polym. Sci. 1947,2, 432. (15) Kulicke, W. M.; Kniewske, R. Makromol. Chem. 1980, 181, 823. (16) Kulicke, W. M.; Kniewske, R. Makromol. Chem. 1981, 182, 2277. (17) Manning, G. S. Acc. Chem. Res. 1979, 12, 443.
(18) McCormick, C. L.; Blackmon, K. P. Macromolecules,preceding paper in this issue.
Polymer Swelling. 5. Correlation of Relative Swelling of Poly(styrene-co-divinylbenzene)with the Hildebrand Solubility Parameter of the Swelling Liquid L. A. Errede 3M Science Research Laboratories of Central Research, 3M Center, Building 201 -2N-22, St. Paul, Minnesota 55144. Received October 17, 1985 ABSTRACT The swellability,S, of styrene-co-divinylbenzenepolymers in 20 aromatic and 24 aliphatic liquids was studied as a function of crow-link density, X-l, from A-' = 0.01 to A-' = 0.12. In every study the relationship was given by S = C(h1I3- ho1I3), where X is the average number of carbon atoms in the "backbone" of the polystyrene segments between cross-link junctions, C is the relative swelling power of the liquid, and A,,-' is the critical cross-link density, above which S = 0. The observed C was correlated with the corresponding known Hildebrand solubilityparameter, 6, for five liquid classifications. The solubilityparameter of the polymer, bSw, determined thereby was 9.5 for substituted benzenes, 9.2 for chlorocarbons, 9.1 for ketones, 8.4 for esters, and 7.3 for ethers. this set of observed astyspans the range reported by earlier investigators, i.e., bSty = 8.6-9.7. The plots of C as functions of the corresponding (asty - 6 ~ for~the) homologous ~ series of liquids Z(CH2),H, where n < 5, are almost parallel lines given approximately by C = A - 0.60(6~,,where A is 2.19 for Z = Ph, 1.48 for Z = RC02, 1.42 for Z = RCO, and 0.64 for Z = RO. Apparently, the major factor that determines swelling power is the relative affinity of Z for the polymer. The cumulative contribution to swelling power owing to the (CH2),H group is only a mitigating factor superimposed on the former.
Introduction
We reported1 that the magnitude of swelling of a polymer, S (in milliliters of liquid absorbed per gram of polymer in equilibrium with excess liquid), can be measured conveniently and reproducibly after the polymer is comminuted and then fabricated into a thin (250 psi), microporous (>0.5 porosity) composite membrane consisting of the particulate polymer (>BO% by weight) enmeshed in polyttetrafluoroethylene) microfibers ( COz > C=O > 0) and the phenyl group of polystyrene. This force of attraction is mitigated by the (CH2),H chain attached to the functional group, apparently in accord with the sum of the CHz para~hors'~ as explained by Scatchard15 and Small,lGwhich depends on additive enthalpy contributions in accordance with Hildebrands definition of cohesive energy d e n ~ i t y . ~ The contribution to relative swelling power owing to the affinity of a functional group Z in the solvent for the functional group Ph in the solute appears to be additive. Thus, a plot of C for the chlorocarbons of Table I1 as a function of the corresponding (asty - 61i)2 does not give a single line parallel to the lines shown in fii'igure 3. Instead, the data points lie in a broad band demarcated by two imaginary lines as defined by eq 2, where A = 2.4 and 1.2. The swelling power of the dicarbon molecules appears to increase monotonically with the number of chlorine atoms contained therein; i.e., the relative swelling powers C for
where 6, refers to the contribution by nonpolar London dispersion forces (as considered by Hildebrand), 6, refers to the contribution by dipole-dipole and dipole-induceddipole forces, and 8h refers to the contribution by hydrogen-bonding forces. These empirical relationships are complicated to use, and, at best, offer only a qualitative guess with respect to solubility of a given solute in a given solvent. It was inferred from the results observed in this correlation of swelling power with the corresponding reported solvent parameters that the major contributing factor to solubility of a polymer in a given liquid is the affinity of the functional group, Z, of the liquid for the functional group Ph in the polymer. It follows, therefore, that it may be advantageous to characterize this affinity of Z for Ph in terms of donor-acceptor relationships, as described by Gutmanl' and Drago18J9and to apply this to polymersolvent relationships, as suggested by Fowkes.20 The mitigating effect on solvent power caused by systematic modification of substituents attached to the functional groups of the solvent and polymeric solute should provide a better understanding of solubility in terms of the molecular structure of the solvent and solute. Such studies should identify solvent-solute systems where entropic considerations and/or mutually attractive sites outweigh the enthalpy contribution to free energy of solution, which presumably is a major reason why the principles of additive cohesive energy density do not explain adequately the solubility results observed for polymer-solvent systems. Accordingly, I have decided to undertake studies of the relative swelling powers exhibited by liquids in homologous series given by Z(CH2),H with respect to sets of crosslinked polymers of a given molecular type. It is hoped that
Macromolecules 1986,19, 1525-1528 this will lead to a better understanding of solubility in terms of the molecular structure of the polymeric solute and the liquid. The resulta of such studies will be reported in subsequent publications. Registry No. (Styrene).(divinylbenzene) (copolymer), 900370-7.
References and Notes (1) Errede, L. A.; Stoesz, J. D.; Sirvio, L. M. J. Appl. Polym. Sci., in press. ( 2 ) Errede, L. A. J. Appl. Polym. Sci., in press. Presented in part before the Society of Polymer Science, Japan, May 1985 (Polym. Prepr. Jpn. 1985,34(1), 9), and in part before the American Chemical Society, Sept 1985 (Polym. Prepr. (Am. Chem. SOC.,Diu. Polym. Chem.) 1985, 26(2),77). (3) Errede, L. A.; Newmark, R. A.; Hill, J. R. Macromolecules 1986, 19, 651. Errede, L. A. Macromolecules 1986, 19, 654. (4) Flory, P. J. Principles of Polymer Chemistry; Cornel1 University Press: Ithaca, NY, 1953. (5) Hildebrand, J. H.; Scott, R. L. The Solubility of Non-Electrolytes, 3rd ed.; Reinhold New York, 1950. (6) Gee, G. Trans. Faraday SOC.1946,42, 585.
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(7) Hoy, K. L. Paint Technol. 1970,42(541), 76. Hoy, K. L. Tables of Solubility Parameters, 1975, a bulletin published by Union Carbide Corp. (8) A Three Dimensional Approach to Solubility, a bulletin published by Eastman Co. (9) Hansen, C. M.; Skaarup, K. J. Paint Technol. Mol. 1976,39, 505. (10) Barton, A. F. F. Handbook of Solubility Parameters and Other Cohesion Parameters; CRC: Boca Raton, FL, 1983. (11) Boyer, R. F.; Spencer, R. S. J. Polym. Sci. 1948, 3, 97. (12) Magat, M. J. Chem. Phys. 1949,46, 344. (13) Scott, R. L.; Magat, M. J. Polym. Sci. 1949, 4, 555. (14) Van Krevelen, D. W.; Hoftyzer, P. J. Properties of Polymers; Elsevier: New York, 1976; 130. (15) Scatchard, G. Chem. Rev. 1945, 44, 7. (16) Small, P. A. J. Appl. Chem. 1949, 3, 71. (17) Gutman, V. The DonopAcceptor Approach to Molecular Interactions; Plenum: New York, 1978. (18) Drago, R. S.; Vogel, G. C.; Needham, T. E. J. Am. Chem. SOC. 1971,93,6014. (19) Drago, R. S.; Parr, L. B.; Chamberlain, C. S. J . Am. Chem. SOC. 1977,99, 3203. (20) Fowkes, F. W.; Tischler, P. 0.; Wolfe, J. A,; Lannigan, L. A.; Ademu-John, C. M.; Halliwell, M. J. J . Polym. Sci., Polym. Chem. Ed. 1984,22, 547.
Polymer Swelling. 6. A Study of Poly(styrene-co-divinylbenzene) Swelling in Liquids of the Homologous Series Ph(CH2),H L. A. Errede 3M Science Research Laboratories of Central Research, 3M Center, Building 201 -2N-22, St. Paul, Minnesota 55144. Received October 17, 1985 ABSTRACT It is shown that the relative swelling power, C, for styrene-co-divinylbenzenepolymers exhibited by liquids in the homologous series Ph(CH2),H decreases monotonically with n from n = 0 to n = 10; the relationship of C in terms of n for the first five members of the homologous series is given by C = 2.10 - 0.108n. Thereafter, C deviates negatively from this line by an amount A given approximately by A = 0.07m, where m = n - 6 for all n > 5 and also by A = 0.04Fcm,2 0.06Fm, 0.02, where F , = - 0.81 is the force of correlated molecular orientation measured by others for association of liquids in the homologous series H(CH2),H. A similar pattern is exhibited in the correlation of C with 6, the Hildebrand solubility parameter; i.e., C is a linear function of (9.5 - 6 1 ~for ~ )liquids ~ Ph(CH2),
