Macromolecules 1983, 16, 291-296
Finally, we discuss the influence of tacticity on ( y2)/ X and & / x . In Figure 4 we present calculations for the two sets of parameters indicated. The curves for ( y 2 ) / x agree with those presented by Cantera et al.19 and Boyd and Kessner.22 K , shows a remarkable sensitivity to tacticity, particularly for highly isotactic and syndiotactic PVC chains, which makes this quantity particularly important for characterizing the microstructure of vinyl polymers.
Conclusions The rotational isomeric state model of Williams, Pickles, and Flory as modified and presented here accounts fairly well for a large number of configurational-dependent properties of PVC and its oligomers. We have shown clearly the importance of second-order interactions, particularly between adjoining C1 atoms in determining the averages of various properties. C141 repulsive iateractions appear to be stronger27than previously assumed by Flory and c o - w o r k e r ~ . ~ Also, ~ , ~the ~ first-order interaction parameter E,,, which yields calculated K , and ( @ $ ) values in closest agreement with the observed values, is considerably less attractive than the value obtained from epimerization studies. K , appears to be remarkably sensitive to second-order interactions and the tacticity of PVC oligomers and polymers. Acknowledgment. We thank Dr. C. A. Daniels of BFGoodrich for his kind gift of the PVC sample. References and Notes (1) Flory, P. J. “Statistical Mechanics of Chain Molecules”; Interscience: New York, 1969; Chapters 111-VI and IX.
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Fujiwara, Y.; Flory, P. J. Macromolecules 1970, 3, 280. Tonelli, A. E,;Schilling, F. C. Acc. Chem. Res. 1981, 14, 233. Mark, J. E.Acc. Chem. Res. 1974, 7 , 218. Suter, U. W.; Flory, P. J. J . Chem. SOC., Faraday Trans. 2 1977, 73, 1521. (6) Saiz, E.;Suter, U. W.; Flory, P. J. J . Chem. SOC.,Faraday Trans. 2 1977, 73, 1538. (7) Tonelli, A. E.Macromolecules 1977, 10, 153. (8) Khanarian, G.;Tonelli, A. E. J. Chem. Phys. 1981, 75, 5031. (9) Khanarian. G.:Tonelli. A. E. Macromolecules 1982, 15, 145. (10) Schilling, F. C.,in preparation. (11) Cragnola, A,: Danusso, F. J. J . Polym. Sci., Polyrn. Lett. Ed. 1968, 6,535. (12) Reference 1, p 211. (13) Chen, C. Y.;Le FBvre, R. J. W. J . Chem. Soc. B 1966, 40. Faraday Trans. (14) Patterson, G.D.;Flory, P. J. J. Chem. SOC., 2 1972, 68,1098. Faraday Trans. 2 (15) Carlson, C.W.; Flory, P. J. J . Chem. SOC., 1977, 73, 1505. (16) Williams, A. D.; Flory, P. J. J. Am. Chem. SOC. 1969,91, 3118. (17) Pickles, C. cJ.; Flory, P. J. J . Chem. SOC., Faraday Trans. 2 1973, 69, 632. (18) Mark, J. E. J . Chem. Phys. 1972, 56, 451. (19) Cantera, F. B.; Riande, E.; Almendro, J. P.; Saiz, E., Macromolecules 1981, 14, 138. (20) Le FBvre, R. J. W.; Sundaram, K. M. S. J . Chern. SOC.1962, 1494. (21) Khanarian, G.;Tonelli, A. E., in preparation. (22) Boyd, R. D.; Kessner, L. J. Polym. Sci., Polyrn. Phys. Ed. 1981, 19, 375. (23) Sato, M.; Koshiishi, Y.; Asahina, M. J . Polym. Sci, Part B 1963, I , 233. (24) Flory, P. J. “Principles of Polymer Chemistry”; Cornel1 University Press:Ithaca, NY, 1953. (25) Kurata, M. ”Polymer Handbook”, 2nd ed.; Brandrup, J., Immergut, E. H., Eds.; Wiley: New York, 1975; Chapter IV. (26) Bohdanecky, M.; Petrus, V.; Kratochvil, P. Collect. Czech. Chem. Commun. 1968, 34, 1168. (27) Matsuo, K.; Stockmayer, W. H. Macromolecules 1975, 8, 660. (2) (3) (4) (5)
Synthesis and Hydrolysis of Poly(viny1 acetals) Derived from Poly(viny1 alcohol) and 2,6-Dichlorobenzaldehydel Etienne Schacht, Guido Desmarets, Eric Goethals, and Thomas St. Pierre* Laboratory f o r Organic Chemistry, Rijksuniversiteit-Gent, B-9000 Gent, Belgium, a n d Department of Chemistry, University of Alabama in Birmingham, Birmingham, Alabama 35294. Receiwd January 4, 1982
ABSTRACT: We describe the synthesis and hydrolysis of poly(viny1 acetals) derived from poly(viny1 alcohol) and the pesticide 2,6-dichlorobenzaldehyde.The acetalization reaction under a variety of conditions gave a t best a polymer with 68% acetalization. The structure of the polymer, Le., the ratio of acetal units derived from meso and racemic dyads of poly(viny1alcohol), was determined by ‘H NMR. The acid-catalyzed hydrolysis of this poly(viny1acetal) in aqueous dioxane at 60 OC was studied in detail. The rate constant for the hydrolysis of the meso and racemic acetal units and the equilibrium constant for meso-racemic intramolecular acetal exchange were determined from these measurements.
Introduction As part of a geteral program dealing with controlledrelease pesticides, we have prepared a poly(viny1 acetal) from poly(viny1 alcohol) and 2,6-dichlorobenzaldehyde. This aldehyde has been reported* to have strong herbicidd and moderate fungicidal activity. In this paper we report the preparation and characterization of the polymer and a detailed study of the kinetics of hydrolysis. *To whom correspondence should be addressed at the University of Alabama in Birmingham.
Results and Discussion Synthesis and Characterization. The acetalization of poly(viny1 alcohol) (PVA) has been studied for a variety of aldehyde^.^ The reaction leads t o (1) intramolecular acetdization of primarily 1,3-diolgroups, (2) intramolecular acetalization of the occasional 1,2-diol groups, and (3) intermolecular acetalization. Intermolecular acetalization is more a function of reaction conditions and can lead to branched and eventually cross-linked polymer. The latter is easily removed in the purification process. The number of 1,2-diol units in commercial PVA is generally 1-2% and
0024-9297/83/2216-0291$01,50/0 0 1983 American Chemical Society
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Macromolecules, Vol. 16, No. 2, 1983
Table I Acetalization of Poly(viny1 alcohol) with 2,6-Dichlorobenzaldehydea reaction 573 DCBA, time, acetali zapolymer solvent M h % C1 tion I I1 I11 IV V VI VI1 VI11 IX
CHCl,
CHC1, CHCl, CHCl, CHCI,
CHCI, dioxane dioxane Me,SO
0.55 0.55 0.65 0.55 0.55 1.60 1.60 1.60 0.50
10 23 45 64 64 72 72 72 58
11.2 18.9 22.4 23.3 23.5 24.7 7.9
