Preparation of smectic layered polymer networks using dide chain liquid crystalline polymers having latent reactive monomeric units
- 199 Downloads
We prepared side-chain liquid crystalline polymers comprising two monomeric units, one having a mesogenic side group that could form a smectic mesophase and the other having a phenolic group attached to the polymer backbone via a thermally reversible urethane bond. The urethane linkage between the isocyanate and phenol groups was stable at room temperature, but it cleaved to generate an isocyanate group when the temperature was increased. When annealed, the copolymers in their smectic mesophases became insoluble in common organic solvents, suggesting the formation of network structures. XRD analysis showed that the annealed polymers maintained their smectic LC structures. The crosslinking process probably proceeded via the reaction of the dissociated isocyanate groups. Some of the isocyanate groups would have first reacted with moisture in the atmosphere to yield amino groups, which underwent further reaction with other isocyanate groups, resulting in the formation of urea bonds. We presume that only polymer chains in the same layer were crosslinked by the reaction of the isocyanate groups, resulting in the formation of a layered polymer network structure. Reactions between the layers did not occur because of the wide layer spacing.
Keywordslayered polymer network side chain liquid crystalline polymer thermally reversible bond crosslinking reaction pyrolysis
Unable to display preview. Download preview PDF.
- (1).(a) D. T. McCormick, K. D. Stovall, and C. A. Guymon,Macromolecules,36, 6549 (2003). (b) D. J. Broer, J. Lub, and G. N. Mol,Macromolecules,26, 1244 (1993). (c) C.-S. Hsu and H.-L. Chen,J. Polym. Sci. Part A: Polym. Chem.,37, 3929 (1999). (d) B. C. Baxter and D. L. Gin,Macromolecules,31, 4419 (1998). (e) D. L. Gin, W. Q. Gu, B. A. Pindzola, and W. J. Zhou,Acc. Chem. Res.,34, 973 (2001). (f) R. A. M. Hikmet, J. Lub, and A. J. W. Tol,Macromolecules,28, 3313 (1995). (g) C. D. Favre-Nicolin and J. Lub,Macromolecules,29, 6143 (1996). (h) R. A. M. Hikmet and J. Lub,Prog. Polym. Sci.,21, 1165 (1996). (i) J. Y. Chang, J. R. Yeon, Y. S. Shin, M. J. Han, and S.-K. Hong,Chem. Mat.,12, 1076 (2000). (j) J. Y. Chang, J. H. Baik, C. B. Lee, M. J. Han, and S.-K. Hong,J. Am. Chem. Soc.,119, 3197 (1997). (k) S. W. Nam, S. H. Kang, and J. Y. Chang,Macromol. Res.,15, 74 (2007).CrossRefGoogle Scholar
- (2).(a) J. C. Peter and H. Michael, Introduction to Liquid Crystals Chemistry and Physics, Taylor & Francis Ltd., 1997. (b) B. G. Kim, J. K. Moon, E. H. Sohn, J. C. Lee, and J. K. Yeo,Macromol. Res.,16, 36 (2008).Google Scholar
- (4).(a) D. O’Hare, inInorganic Materials, D. W. Bruce and D. O’Hare, Eds., Wiley & Sons, Chichester, 1996, p 171. (b) G. Wegner, M. M. Demir, M. Faatz, K. Gorna, R. Munoz-Espi, B. Guillemet, and F. Grohn,Macromol. Res.,15, 95 (2007).Google Scholar
- (7).(a) V. P. Shibaev and N. A. Platé,Adv. Polym. Sci.,60, 173 (1984). (b) I. I. Konstantinov, A. A. Sitnov, V. S. Grebneva, and Y. B. Amerik,Eur. Polym. J.,19, 327 (1983).Google Scholar
- (8).G. Oertel,Polyurethane Handbook, 2nd ed., Hanser Publisher, Munich, 1994.Google Scholar
- (9).(a) T. Kowalewski, N. V. Tsarevsky, and K. Matyjaszewski,J. Am. Chem. Soc.,124, 10632 (2002). (b) T. Kowalewski, R. D. McCullough, and K. Matyjaszewski,Eur. Phys. J. E.,10, 5 (2003). (c) C. Tang, A. Tracz, M. Kruk, R. Zhang, D. Smilgies, K. Matyjaszewski, and T. Kowalewski,J. Am. Chem. Soc.,127, 6918 (2005).CrossRefGoogle Scholar