Wetting and fourier transform infrared spectroscopy studies of mixed self-assembled monolayers of 4′-methyl-4-mercaptobiphenyl and 4′-hydroxy-4-mercaptobiphenyl

Langmuir

Volumn 14, Issue 15, 1998, Pages 3983-3985

  Kang, Jung F ^a   Jordan, Rainer ^a   Ulman, Abraham ^a  

^a NONE

Author keywords

[No Author keywords available]

Indexed keywords

CONTACT ANGLE; FOURIER TRANSFORM INFRARED SPECTROSCOPY; GLYCEROL; GOLD; MONOLAYERS; PHENOLS; WATER; WETTING;

SELF ASSEMBLED MONOLAYERS (SAM);

SULFUR COMPOUNDS;

EID: 0032120268     PISSN: 07437463     EISSN: None     Source Type: Journal    
DOI: 10.1021/la980404t     Document Type: Article

References (23)

1. Ulman, A. An Introduction to Ultrathin Organic Films; Academic Press: Boston, MA, 1991.
2. Ulman, A. Chem. Rev. 1996, 96, 1533.
3. (a) Evans, S. D.; Sharma, R.; Ulman, A. Langmuir 1991, 7, 156.
4. (b) Ulman, A.; Evans, S. D.; Shnidman, Y.; Sharman, R.; Eilers, J. E. Adv. Colloid Interface Sci. 1992, 39, 175.
5. (a) Hautman, J.; Klein, M. L. Phys. Rev. Lett. 1991, 67, 1763.
6. (b) Hautman, J.; Bareman, J. P.; Mar, W.; Klein, M. L. J. Chem. Soc., Faraday Trans. 1991, 87, 2031.
7. Leung, T. Y. B.; Schreiber, F.; Schwartz, P.; Ulman, A.; Scoles, G. In preparation.
8. Quon, R. A.; Ulman, A.; Vanderlick, T. K. In preparation.
9. S = 3.400 ± 0.05. Using these gold substrates, SAMs of biphenyl thiols show contact angle hysteresis of ≤6°. In comparison, the same SAMs on gold substrates prepared at room temperature without annealing show contact angle hysteresis of ≤20°. All substrates were cleaned using argon plasma for 30 s immediately before immersion into the thiol solution.
10. Details of synthesis, purification and analysis of 4′-substituted-4-mercaptobiphenyl will be published elsewhere. Ethanol (anhydrous) and trifluoroacetic anhydride were obtained from Aldrich and used as received.
11. Some precautions were taken to reduce errors associated with solution preparation. First, 0.1 mM stock solutions of the two thiols were prepared in ethanol, bubbled with nitrogen, and stored in the refrigerator. Second, nine pieces of gold were cut from same batch of gold substrates. Finally, nine solutions of 0%, 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5%, and 100% II mixed with I were prepared out of stock solution. All stock solutions were saved for no longer than 2 weeks. Errors were established after repetition of experiments and measurements.
12. Thickness was estimated by ellipsometry using a Rudolph Research AutoEL ellipsometer (He-Ne laser, angle of incidence 70°). Measurements of three separate points were carried out on each sample, using an assumed refractive index of 1.462.
13. -1.
14. 3a The jar was sealed, and the SAMs were allowed to react with the anhydride vapor for 18 h. The samples were removed from the jar, blown by a jet of dry nitrogen to remove adsorbed anhydride, and immediately studied by FTIR spectroscopy.
15. Redington, R. L. Spectrochim. Acta 1975, 31A, 1699.
16. Bertilsson, L.; Liedberg, B. Langmuir 1993, 9, 141.
17. Kang, J. F.; Jordan, R.; Ulman, A.; Kurth, D. G. Submitted for publication.
18. Contact angles were determined at room temperature by the sessile drop method using a Rame-Hart model 100 goniometer, equipped with a high-resolution CCD-IRIS color video-camera (Sony) connected to a computer. To measure the advancing and receding angles, a 20 μL droplet was formed at the end of blunt-ended needle of a syringe. Obtained images of the droplet were evaluated using NIH software. Advancing and receding angles were measured by tilting the sample stage. Thus, the tilt angle was increased until the droplet started to move on the surface and immediately decreased to a point where the droplet stopped moving. Maximum advancing and minimum receding contact angles for water were found at a tilt angle of ∼40°.
19. (a) Baxter, S.; Cassie, A. B. D. Text. Ind. 1945, 36, T57.
20. (b) Cassie, A. B. D.; Baxter, S. Trans. Faraday Soc. 1944, 40, 546.
21. (c) Dettre, R. H.; Johnson, R. H., Jr. Symp. Contact Angle, Bristol, 1966.
22. Ulman, A.; Evans, S. D.; Shnidman, Y.; Sharma, R.; Eilers, J. E.; Chang, J. C. J. Am. Chem. Soc. 1991, 113, 1499.
23. Wu, S. Polymer Interface and Adhesion; Marcel Dekker: New York, 1982.