Surface tension obtained from various smectic free-standing films: The molecular origin of surface tension

Langmuir

Volumn 14, Issue 15, 1998, Pages 4330-4341

  Mach, P ^a   Huang, C C ^a   Stoebe, T ^a,b   Wedell, E D ^a   Nguyen, T ^c   De Jeu, W H ^d   Guittard, F ^e   Naciri, J ^f   Shashidhar, R ^f   Clark, N ^g   Jiang, I M ^h   Kao, F J ^h   Liu, H ⁱ   Nohira, H ⁱ  

^a University of Minnesota   (United States)

^b EASTMAN KODAK COMPANY   (United States)

^c CENTRE DE RECHERCHE PAUL PASCAL   (France)

^d FOM INSTITUTE AMOLF   (Netherlands)

^e UNIVERSITÉ CÔTE D'AZUR   (France)

^f NAVAL RESEARCH LABORATORY   (United States)

^g UNIVERSITY OF COLORADO   (United States)

^h NATIONAL SUN YAT SEN UNIVERSITY   (Taiwan)

ⁱ SAITAMA UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

FILMS; MOLECULAR STRUCTURE; SMECTIC LIQUID CRYSTALS;

FREE STANDING FILMS;

SURFACE TENSION;

EID: 0032115649     PISSN: 07437463     EISSN: None     Source Type: Journal    
DOI: 10.1021/la980224j     Document Type: Article

References (62)

1. Adamson, A. W. Physical Chemistry of Surfaces, 5th ed.; Wiley: New York, 1990 and references therein.
2. Israelachvili, J. N. Intermolecular and Surface Forces, 2nd ed.; Academic Press: San Diego, 1992 and references therein.
3. Young, T. Miscellaneous Works; Peacock, G., Ed.; Murray: London, 1855; p 1.
4. Gibbs, J. W. Collected Works; Longmans, Green: New York, 1906; Dover: New York, 1961; Vol. 1.
5. Wu, X. Z.; Sirota, E. B.; Sinha, S. K.; Ocko, B. M.; Deutsch, M. Phys. Rev. Lett. 1993, 70, 958.
6. Frommer, J. Angew. Chem., Int. Ed. Engl. 1992, 31, 1298.
7. Naselli, C.; Swalen, J. D.; Rabolt, J. F. J. Chem. Phys. 1989, 90, 3855.
8. Barton, S. W.; Goudot, A.; Bouloussa, O.; Rondelez, F.; Lin, B.; Novak, F.; Acero, A.; Rice, S. A. J. Chem. Phys. 1992, 96, 1343.
9. Bain, C. D.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7155. Bain, C. D.; Evall, J.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7164.
10. Bain, C. D.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7155. Bain, C. D.; Evall, J.; Whitesides, G. M. J. Am. Chem. Soc. 1989, 111, 7164.
11. Schick, M. In Liquids at Interfaces; Charvolin, J., Joanny, J. F., Zinn-Justin, J., Ed.; Eisevier: Amsterdam, 1990.
12. Zisman, W. A. In Symposium on Adhesion and Cohesion; Weiss, P Ed.; Elsevier: New York, 1962; p 176.
13. Kissa, E. In Fluorinated Surfactants; Marcel Dekker: New York, 1994; Chapter 9.
14. Langmuir, I. J. Am. Chem. Soc. 1916, 38, 2221.
15. Mach, P.; Huang, C. C.; Nguyen, T. Phys. Rev. Lett. 1998, 80, 732.
16. de Gennes, P. G.; Prost, J. The Physics of Liquid Crystals, 2nd ed.; Clarendon Press: Oxford, 1993. Chandrasekhar, S. Liquid Crystals, 2nd ed.; Cambridge University Press: Cambridge, 1992.
17. de Gennes, P. G.; Prost, J. The Physics of Liquid Crystals, 2nd ed.; Clarendon Press: Oxford, 1993. Chandrasekhar, S. Liquid Crystals, 2nd ed.; Cambridge University Press: Cambridge, 1992.
18. Bahr Ch Int. J. Mod. Phys. B 1994, 8, 3051. Stoebe, T.; Huang, C. C. Int. J. Mod. Phys. B 1995, 9, 2285.
19. Bahr Ch Int. J. Mod. Phys. B 1994, 8, 3051. Stoebe, T.; Huang, C. C. Int. J. Mod. Phys. B 1995, 9, 2285.
20. Stoebe, T.; Huang, C. C.; Goodby, J. W. Phys. Rev. Lett. 1992, 68, 2944. Chao, C. Y.; Chou, Ho, J. T.; Hui, S. W.; Jin, A. J.; Huang, C. C. Phys. Rev. Lett. 1995, 74, 4863. Bahr, Ch.; Fliegner, D. Phys. Rev. Lett. 1993, 70, 1842. Veum, M.; Huang, C. C.; Chou, C. F.; Surendranath, V. Phys. Rev. E 1997, 56, 2298.
21. Stoebe, T.; Huang, C. C.; Goodby, J. W. Phys. Rev. Lett. 1992, 68, 2944. Chao, C. Y.; Chou, Ho, J. T.; Hui, S. W.; Jin, A. J.; Huang, C. C. Phys. Rev. Lett. 1995, 74, 4863. Bahr, Ch.; Fliegner, D. Phys. Rev. Lett. 1993, 70, 1842. Veum, M.; Huang, C. C.; Chou, C. F.; Surendranath, V. Phys. Rev. E 1997, 56, 2298.
22. Stoebe, T.; Huang, C. C.; Goodby, J. W. Phys. Rev. Lett. 1992, 68, 2944. Chao, C. Y.; Chou, Ho, J. T.; Hui, S. W.; Jin, A. J.; Huang, C. C. Phys. Rev. Lett. 1995, 74, 4863. Bahr, Ch.; Fliegner, D. Phys. Rev. Lett. 1993, 70, 1842. Veum, M.; Huang, C. C.; Chou, C. F.; Surendranath, V. Phys. Rev. E 1997, 56, 2298.
23. Stoebe, T.; Huang, C. C.; Goodby, J. W. Phys. Rev. Lett. 1992, 68, 2944. Chao, C. Y.; Chou, Ho, J. T.; Hui, S. W.; Jin, A. J.; Huang, C. C. Phys. Rev. Lett. 1995, 74, 4863. Bahr, Ch.; Fliegner, D. Phys. Rev. Lett. 1993, 70, 1842. Veum, M.; Huang, C. C.; Chou, C. F.; Surendranath, V. Phys. Rev. E 1997, 56, 2298.
24. Zisman, W. A. Adv. Chem. Ser. 1964, No. 43, 1.
25. While testing our system to ensure high-resolution reproducibility of surface tension values obtained from successive films of the same thickness, and at the same temperature, we found this secondary pumping step to be important in the case of some materials.
26. Rosenblatt, C.; Amer, N. M. Appl. Phys. Lett. 1980, 36, 432.
27. Sirota, E. B.; Pershan, P. S.; Sorensen, L. B.; Collet, J. Phys. Rev. A 1987, 36, 2890.
28. Mach, P.; Johnson, P. M.; Wedell, E. D.; Lintgen, F.; Huang, C. C. Europhys. Lett. 1997, 40, 399.
29. Stoebe, T.; Huang, C. C. Phys. Rev. E 1994, 49, 5238. Stoebe, T.; Mach, P.; Huang, C. C. Phys. Rev. Lett. 1994, 73, 1384.
30. Stoebe, T.; Huang, C. C. Phys. Rev. E 1994, 49, 5238. Stoebe, T.; Mach, P.; Huang, C. C. Phys. Rev. Lett. 1994, 73, 1384.
31. Miyano, K. Phys. Rev. A 1982, 26, 1820.
32. Pieranski, P.; Beliard, L.; Tournellec, J. Ph.; Leoncini, X.; Furtlehner, C.; Dumoulin, H.; Riou, E.; Jouvin, B.; Fenerol, J. P.; Palaric, Ph.; Heuving, J.; Cartier, B.; Kraus, I. Physica A 1993, 194, 364.
33. Eberhardt, M.; Meyer, R. B. Rev. Sci. Instrum. 1996, 67, 2846.
34. Mach, P.; Grantz, S.; Debe, D. A.; Stoebe, T.; Huang, C. C. J. Phys. II 1995, 5, 217.
35. For example, our γ = 26.8 dyn/cm value for the CBOOA compound in its Sm-A phase agrees well with measurements based on the bulk pendant drop method. (Krishnaswamy, S.; Shashidhar, R. Mol. Cryst. Liq. Cryst. 1977, 38, 353.) Light scattering studies on members of the nCB homologous series give values consistent with our γ = 27.1 dyn/cm for 12CB. (Böttger, A.; Joosten, J. G. H. Europhys. Lett. 1987, 4, 1297.) Our 12CB γ value is also in agreement with recent force balance studies on free-standing films of the analogous 8CB compound (ref 26). Additional data giving us confidence in our measurement technique come from X-ray studies and are cited above in the main text dealing with mixed fluoro- and hydroalkyl surfaces.
36. For example, our γ = 26.8 dyn/cm value for the CBOOA compound in its Sm-A phase agrees well with measurements based on the bulk pendant drop method. (Krishnaswamy, S.; Shashidhar, R. Mol. Cryst. Liq. Cryst. 1977, 38, 353.) Light scattering studies on members of the nCB homologous series give values consistent with our γ = 27.1 dyn/cm for 12CB. (Böttger, A.; Joosten, J. G. H. Europhys. Lett. 1987, 4, 1297.) Our 12CB γ value is also in agreement with recent force balance studies on free-standing films of the analogous 8CB compound (ref 26). Additional data giving us confidence in our measurement technique come from X-ray studies and are cited above in the main text dealing with mixed fluoro- and hydroalkyl surfaces.
37. To our knowledge, only a few experiments have been reported where independent measurements or estimates of all the parameters in Young's equations could be made. Where such data are available, they are in agreement with the relation given by Young. A thorough description of one such recent study, along with additional references, is given in ref 30.
38. Chaudhury, M. K.; Whitesides, G. M. Langmuir 1991, 7, 1013 and references found therein.
39. Good, R. J.; Girifalco, L. A. J. Phys. Chem. 1960, 64, 561.
40. Fowkes, F. M. Adv. Chem. Ser. 1964, No. 43, 99.
41. Gibbs, J. H.; Smyth, C. P. J. Am. Chem. Soc. 1951, 73, 5115.
42. Kissa, E. In Fluorinated Surfactants. Marcel Dekker: New York, 1994; Chapter 8.
43. Mach, P.; Huang, C. C.; Nguyen, H. T. Langmuir 1997, 13, 6357. This publication contains a brief discussion of our observed independence of surface tension on film thickness.
44. Mol, E. A. L.; Shindler, J. D.; Shalaginov, A. N.; de Jeu, W. H. Phys. Rev. E 1996, 54, 536.
45. Doi, T.; Takenaka, S.; Kusabayashi, S.; Nishihata, Y.; Terauchi, H. Mol. Cryst. Liq. Cryst. 1991, 204, 9. Liu, H.; Nohira, H. Liq. Cryst. 1996, 20, 581.
46. Doi, T.; Takenaka, S.; Kusabayashi, S.; Nishihata, Y.; Terauchi, H. Mol. Cryst. Liq. Cryst. 1991, 204, 9. Liu, H.; Nohira, H. Liq. Cryst. 1996, 20, 581.
47. Stoebe, T.;Mach, P.; Grantz, S.; Huang, C. C. Phys. Rev. E 1996, 53, 1662.
48. Clark, N. A.; Lagerwall, S. T. Appl. Phys. Lett. 1980, 36, 899. Epstein, K. A.; Keyes, M. P.; Radcliffe, M. D.; Snustad, D. C. US Patent No. 5417883, 1995.
49. Clark, N. A.; Lagerwall, S. T. Appl. Phys. Lett. 1980, 36, 899. Epstein, K. A.; Keyes, M. P.; Radcliffe, M. D.; Snustad, D. C. US Patent No. 5417883, 1995.
50. Lobko, T. A.; Ostrovskii, B. I.; Pavluchenko, A. I.; Sulianov, S. N. Liq. Cryst. 1993, 15, 361.
51. Kromm, P.; Cotrait, M.; Rouillon, J. C.; Barois, P.; Nguyen, H. T. Liq. Cryst. 1996, 21, 121. Kromm, P.; Cotrait, M.; Nguyen, H. T. Liq. Cryst. 1996, 21, 95.
52. Kromm, P.; Cotrait, M.; Rouillon, J. C.; Barois, P.; Nguyen, H. T. Liq. Cryst. 1996, 21, 121. Kromm, P.; Cotrait, M.; Nguyen, H. T. Liq. Cryst. 1996, 21, 95.
53. Diele, S.; Lose, D.; Kruth, H.; Pelzl, G.; Guittard, F.; Cambon, A. Liq. Cryst. 1996, 21, 603.
54. Liu, H.; Nohira, H. Liq. Cryst. 1997, 22, 217.
55. A direct experimental confirmation of this assumption would be extremely valuable, yet is not available to date.
56. Smart, B. In Organofluorine Chemistry: Principles and Commercial Applications; Banks, R. E., et al., Eds.; Plenum Press: New York, 1994; p 57 and references therein.
57. For completeness, there is one additional difference between the two tail types that should be mentioned. Namely, the fluoroalkyl tails have been shown to be more "stiff" than their hydroalkyl counterparts, assuming (in a thermal average sense) a helical as opposed to planar-trans chain conformation (ref 49), in which the energy for gauche bond orientations is larger (by over a factor of 2 (Bates, T. W. In Fluoropolymers; Wall, L. A., Ed.; John Wiley & Sons: New York, 1972; p 451.), indicated also in Table 2). It is possible that the greater conformational flexibility of the hydroalkyl tails at a given temperature may "dynamically" reduce the excluded volume difference between the hydrogen- and fluorine-containing tails, which are otherwise of roughly equal length. Countering this idea, however, we can consider (as a first approximation) the roughly 30% larger "static" excluded volume for fluoroalkyl versus hydroalkyl tails, compared with only a 15% larger specific volume for alkanes in liquid as opposed to crystalline state (ref 50). This suggests that dynamical effects do not wash out the steric differences discussed above. Molecular conformation simulations addressing these more subtle dynamical issues would be extremely valuable in confirming this reasoning. We plan to pursue such studies in the course of our continuing research on partially fluorinated materials.
58. The uncertainty reported here reflects the spread of γ values among the different liquid crystals in the group. The data shown in category A(i) exhibit a systematic variation with the length of the fluoroalkyl tail component.
59. The F4MOCPH11OB compound actually shows no Sm-A phase, but rather the Sm-C phase. Using our tensiometer, we have performed several studies on the temperature dependence of surface tension, for example, over a 10 K interval in the Sm-A phase of H(10)F(5)MOPP (ref 38). No systematic variation in surface tension was seen within our experimental resolution. We have found the same to be true for several compounds in temperature windows encompassing a Sm-A to Sm-C transition. Thus, although even higher resolution studies of temperature effects on the surface tension of liquid-crystal films remain an intriguing goal, the categorization of surface tension values as described in this report, with the reported uncertainties, is unaffected by temperature considerations or any subtle differences in the packing of molecular tails arising across the Sm-A to Sm-C transition.
60. Bunn, C. W.; Howells, E. R. Nature 1954, 174, 549.
61. Shafrin, E. G.; Zisman, W. A. J. Phys. Chem. 1962, 66, 740.
62. Guyot-Sionnest, P.; Hsiung, H.; Shen, Y. R. Phys. Rev. Lett. 1986, 57, 2963.