1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 2Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061 3Graduate School of the Chinese Academy of Sciences, Beijing 100049
Morphology and Wettability of [Bmim][PF6] Ionic Liquid on HOPG Substrate
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 2Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061 3Graduate School of the Chinese Academy of Sciences, Beijing 100049
We investigate the morphology and wettability of [Bmim][PF6] ionic liquid (IL) on a highly oriented pyrolitic graphite (HOPG) substrate using atomic force microscopy. Thin films, nanometer-sized droplets, and "drop-on-layer'' structures of the IL are found on the substrate. Films with a thickness of up to 2 nm (about 4 IL layers) show the solid-like behavior. In contrast, a dewetting phenomenon is observed for thicker IL films, indicating that the IL films retain liquid properties. The contact angle of a buck IL droplet on the HOPG is measured to be about 35º. The wettability of the bulk IL droplet on the HOPG is found to be quite different from that of IL films. These results indicate that the IL molecules can be organized into various micro-morphologies when they are confined to a solid substrate and show characteristic behavior at nanometer scales.
We investigate the morphology and wettability of [Bmim][PF6] ionic liquid (IL) on a highly oriented pyrolitic graphite (HOPG) substrate using atomic force microscopy. Thin films, nanometer-sized droplets, and "drop-on-layer'' structures of the IL are found on the substrate. Films with a thickness of up to 2 nm (about 4 IL layers) show the solid-like behavior. In contrast, a dewetting phenomenon is observed for thicker IL films, indicating that the IL films retain liquid properties. The contact angle of a buck IL droplet on the HOPG is measured to be about 35º. The wettability of the bulk IL droplet on the HOPG is found to be quite different from that of IL films. These results indicate that the IL molecules can be organized into various micro-morphologies when they are confined to a solid substrate and show characteristic behavior at nanometer scales.
[1] Rogers R D and Seddon K R 2003 Science 302 792 [2] Welton T 1999 Chem. Rev. 99 2071 [3] Wasserscheid P and Keim W 2000 Angew. Chem. Int. Ed. 39 3773 [4] Dupont J, de Souza R F and Suarez P A Z 2002 Chem. Rev. 102 3667 [5] Wang P, Zakeeruddin S M, Moser J E and Gratzel M 2003 J. Phys. Chem. B 107 13280 [6] Papageorgiou N, Athanassov Y, Armand M, Bonhote P, Pettersson H, Azam A and Gratzel M 1996 J. Electrochem. Soc. 143 3099 [7] Kim S K, Shin B J, Kim J H, Ahn S and Lee S Y 2008 Electrochem. Commun. 10 1625 [8] Xue B F, Wang H X, Hu Y S, Li H, Wang Z X, Meng Q B, Huang X J, Chen L Q, Sato O and Fujishima A 2004 Chin. Phys. Lett. 21 1828 [9] Chen L H, Xue B F, Liu X Z, Li K X, Luo Y H, Meng Q B, Wang R L and Chen L Q 2007 Chin. Phys. Lett. 24 555 [10] Bhushan B, Palacio M and Kinzig B 2008 J. Colloid. Interf. Sci. 317 275 [11] Nainaparampil J J, Phillips B S, Eapen K C and Zabinski J S 2005 Nanotechnology 16 2474 [12] Lynden-Bell R M, Kohanoff J and Del Popolo M G 2005 Faraday Discuss. 129 57 [13] Bhargava B L and Balasubramanian S 2006 J. Am. Chem. Soc. 128 10073 [14] Bovio S, Podesta A, Lenardi C and Milani P 2009 J. Phys. Chem. B 113 6600 [15] Carmichael A J, Hardacre C, Holbrey J D, Nieuwenhuyzen M and Seddon K R 2001 Mol. Phys. 99 795 [16] Lee B S, Chi Y S, Lee J K, Choi I S, Song C E, Namgoong S K and Lee S G, 2004 J. Am. Chem. Soc. 126 480 [17] Oldham K B, 2008 J. Electroanal. Chem. 613 131 [18] Silva F, Gornes C, Figueiredo M, Costa R, Martins A and Pereira C M 2008 J. Electroanal. Chem. 622 153 [19] Solutskin E, Ocko B M, Taman L, Kuzmenko I, Gog T and Deutsch M 2005 J. Am. Chem. Soc. 127 7796 [20] Su Y Z, Fu Y C, Yan J W, Chen Z B and Mao B W 2009 Angew. Chem. Int. Ed. 48 5148 [21] Sung J, Jeon Y, Kim D, Iwahashi T, Seki K, Iimori T and Ouchi Y 2006 Colloid. Surf. A 284 84 [22] Atkin R, El Abedin S Z, Hayes R, Gasparotto L H S, Borisenko N and Endres F 2009 J. Phys. Chem. C 113 13266 [23] Atkin R and Warr G G 2007 J. Phys. Chem. C 111 5162 [24] Yan T Y, Li S, Jiang W, Gao X P, Xiang B and Voth G A 2006 J. Phys. Chem. B 110 1800 [25] Sloutskin E, Lynden-Bell R M, Balasubramanian S and Deutsch M 2006 J. Chem. Phys. 125 174715 [26] Gannon T J, Law G, Watson P R, Carmichael A J and Seddon K R 1999 Langmuir 15 8429 [27] Law G and Watson P R 2001 Chem. Phys. Lett. 345 1 [28] Law G, Watson P R, Carmichael A J, Seddon K R and Seddon B 2001 Phys. Chem. Chem. Phys. 3 2879 [29] Baldelli S 2003 J. Phys. Chem. B 107 6148 [30] Fletcher K A and Pandey S 2004 Langmuir 20 33 [31] Bowers J, Vergara-Gutierrez M C and Webster J R P 2004 Langmuir 20 309 [32] Liu Y D, Zhang Y, Wu G Z and Hu J 2006 J. Am. Chem. Soc. 128 7456 [33] Hanke C G, Price S L and Lynden-Bell R M 2001 Mol. Phys. 99 801 [34] Ozawa R, Hayashi S, Saha S, Kobayashi A and Hamaguchi H 2003 Chem. Lett. 32 948 [35] Hayashi S, Ozawa R and Hamaguchi H 2003 Chem. Lett. 32 498 [36] Sha M L, Zhang F C, Wu G Z, Fang H P, Wang C L, Chen S M, Zhang Y and Hu J 2008 J. Chem. Phys. 128 134504 [37] Fitchett B A and Conboy J C 2004 J. Phys. Chem. B 108 20255 [38] Brochard-Wyart F, di Meglio J-M, Quere D and de Gennes P G 1991 Langmuir 7 335 [39] Troncoso J, Cerdeirina C A, Sanmamed Y A, Romani L and Rebelo L P N 2006 J. Chem. Eng. Data 51 1856 [40] Lin J, Zheng Z J, Yu J L, Bai Y L 2009 Chin. Phys. Lett. 26 086802 [41] Kang Y S and Wang H J 2009 Chin. Phys. Lett. 26 126102
2010, Vol. 27 
