7944
Langmuir 2003, 19, 7944-7947
Flux-Assisted Self-Assembly of Monodisperse Colloids Ludovico Cademartiri,* Alessandra Sutti, and Gianluca Calestani Dipartimento di Chimica Generale, Inorganica, Chimica Analitica, Chimica Fisica, Parco Area delle Scienze, 17a, I-43100 Parma, Italy
Chiara Dionigi and Petr Nozar CNRsISMNsBologna, Via Gobetti, 101, I-40129 Bologna, Italy
Andrea Migliori CNRsIMNsBologna, Via Gobetti, 101, I-40129 Bologna, Italy Received March 20, 2003. In Final Form: June 30, 2003 We have developed a novel method to grow ordered layers of monodisperse colloids on a flat substrate. The evaporation of the colloidal suspension in the presence of the inclined substrate is strengthened by an external gas flux directed on the meniscus. The meniscus oscillations caused by the gas flux have an evident effect on the ordering of the spheres on the substrate. Thick films (more than 150 layers in a single-step deposition) of large area single crystals (∼1 cm2) can be obtained in a very short time (∼1 cm/h maximum growth rate) and from very diluted suspensions (up to 0.022% volume fraction).
Introduction 1,2
Since the pioneering works of Yablonovitch and John, the possibility of localizing electromagnetic waves through a periodically modulated dielectric constant has drawn a lot of interest.3-18 One of the possible ways to obtain such a modulation of the dielectric constant is the deposition of monodisperse colloids to obtain opal-like4,9,16,19-21 or “inverse opal”19,22-25 structures (by using the opal-like * Corresponding author. Fax: +390521905557.
[email protected].
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(1) John, S. Phys. Rev. Lett. 1987, 58, 2486-89. (2) Yablonovitch, E. Phys. Rev. Lett. 1987, 58, 2059-62. (3) Bardosova, M.; Tredgold, R. H. J. Mater. Chem. 2002, 12, 283542. (4) van Blaaderen, A.; Ruel, R.; Wiltzius, P. Nature 1997, 385, 32124. (5) Busch, K.; John, S. Phys. Rev. E 1998, 58, 3896-908. (6) Busch, K.; John, S. Phys. Rev. Lett. 1999, 83, 967-70. (7) Figotin, A.; Klein, A. J. Opt. Soc. Am. 1998, 15, 1423-35. (8) Ho, K. M.; Chan, C. T.; Soukoulis, C. M. Phys. Rev. Lett. 1990, 65, 3152. (9) Jiang, P.; Bertone, J. F.; Hwang, K. S.; Colvin, V. L. Chem. Mater. 1999, 11, 2132-40. (10) Leung, K. M.; Liu, Y. F. Phys. Rev. Lett. 1990, 65, 2646. (11) Lin, S.-Y.; Chow, E.; Hietala, V.; Villeneuve, P. R.; Joannopoulos, J. D. Science 1998, 282, 274-76. (12) Mekis, A.; Chen, J. C.; Kurland, I.; Fan, S.; Villeneuve, P. R.; Joannopoulos, J. D. Phys. Rev. Lett. 1996, 77, 3787-90. (13) Moroz, A.; Sommers, C. J. Phys.: Condens. Matter 1999, 11, 997-1008. (14) Nozar, P.; DiDomenico, D.; Dionigi, C.; Losurdo, M.; Muccini, M.; Taliani, C. Adv. Mater. 2002, 14, 1023-27. (15) Ozin, G. A.; Yang, S. M. Adv. Funct. Mater. 2001, 11, 95. (16) Rengarajan, R.; Jiang, P.; Larrabee, D. C.; Colvin, V. L.; Mittleman, D. M. Phys. Rev. B 2001, 64, 205103. (17) Vlasov, Y. A.; Bo, X.-Z.; Sturm, J. C.; Norris, D. J. Nature 2001, 414, 289-93. (18) Yang, S. M.; Miguez, H.; Ozin, G. A. Adv. Funct. Mater. 2002, 12, 425-31. (19) Scott, R. W. J.; Yang, S. M.; Chabanis, G.; Coombs, N.; Williams, D. E.; Ozin, G. A. Adv. Mater. 2001, 13, 1468. (20) Snoeks, E.; van Blaaderen, A.; van Dillen, T.; van Kats, C. M.; Brongersma, M. L.; Polman, A. Adv. Mater. 2000, 12, 1511. (21) Velikov, K. P.; van Blaaderen, A. Langmuir 2001, 17, 4779-86. (22) Blanco, A.; Chomsky, E.; Grabtchak, S.; Ibisate, M.; John, S.; Leonard, S. W.; Lopez, C.; Meseguer, F.; Miguez, H.; Mondia, J. P.; Ozin, G. A.; Toader, O.; Driel, H. M. v. Nature 2000, 405, 437.
structure as a matrix to be infiltrated and then removed by calcination or chemical etching). The deposition of monodisperse colloids to give an ordered fcc lattice can be obtained by a variety of approaches,3,4,9,26-32 but the most popular and efficient seems to be the evaporation-induced self-assembly of the particles on a vertical substrate described in the article of Jiang et al.9 The theoretical background of this deposition method is treated in a number of articles28,33-40 and starts from the assumption that the meniscus of the suspension in contact with the substrate is quiet. The theory of the evaporation-induced self-assembly of the particles on the substrate is mainly focused on two aspects. The first, developed mainly by Nagayama et (23) Holland, B. T.; Blanford, C. F.; Do, T.; Stein, A. Chem. Mater. 1999, 11. (24) Juarez, B. H.; Rubio, S.; Sanchez-Dehesa, J.; Lopez, C. Adv. Mater. 2002, 14, 1486. (25) Soten, I.; Miguez, H.; Yang, S. M.; Petrov, S.; Coombs, N.; Tetreault, N.; Matsura, N.; Ruda, H. E.; Ozin, G. A. Adv. Funct. Mater. 2002, 12, 71. (26) Burmeister, F.; Schafle, C.; Keilhofer, B.; Bechinger, C.; Boneberg, J.; Leiderer, P. Adv. Mater. 1998, 10, 495. (27) Campbell, M.; Sharp, D. N.; Harrison, M. T.; Denning, R. G.; Turberfield, A. J. Nature 2000, 404. (28) Dimitrov, A. S.; Nagayama, K. Chem. Phys. Lett. 1995, 243, 462-68. (29) O ¨ zbay, E.; Tuttle, G.; Sigalas, M.; Soukoulis, C. M.; Ho, K. M. Phys. Rev. B 1995, 51, 13961. (30) Trau, M.; Saville, D. A.; Aksay, I. A. Science 1996, 272, 706. (31) Ye, Y.-H.; LeBlanc, F.; Hache´, A.; Truong, V.-V. Appl. Phys. Lett. 2001, 78, 52. (32) Gates, B.; Dong, Q.; Xia, Y. Adv. Mater. 1999, 11, 466-69. (33) Dimitrov, A. S.; Dushkin, C. D.; Yoshimura, H.; Nagayama, K. Langmuir 1993, 10, 432-40. (34) Denkov, N. D.; Velev, O. D.; Kralchevsky, P. A.; Ivanov, I. B.; Yoshimura, H.; Nagayama, K. Langmuir 1992, 8, 3183-90. (35) Dushkin, C. D.; Nagayama, K.; Miwa, T.; Kralchevsky, P. A. Langmuir 1993, 9, 3695-701. (36) Kralchevsky, P. A.; Nagayama, K. Langmuir 1994, 10, 23. (37) Kralchevsky, P. A.; Paunov, V. N.; Denkov, N. D.; Ivanov, I. B.; Nagayama, K. J. Colloid Interface Sci. 1993, 155, 420-37. (38) Kralchevsky, P. A.; Paunov, V. N.; Ivanov, I. B.; Nagayama, K. J. Colloid Interface Sci. 1992, 151, 79. (39) Paunov, V. N.; Kralchevsky, P. A.; Denkov, N. D.; Nagayama, K. J. Colloid Interface Sci. 1993, 157, 100-12. (40) Nagayama, K. Colloids Surf., A 1995, 109, 363-74.
10.1021/la034485r CCC: $25.00 © 2003 American Chemical Society Published on Web 08/07/2003
Self-Assembly of Monodisperse Colloids
al.,28,33-35,40 involves the role of evaporation in the motion of the particles toward the meniscus. The latter involves what is considered to be the driving force of the selfassembly: Kralchevsky et al.36-38 demonstrate the existence of a strong attractive interaction between two colloidal particles partially immersed in a liquid, in particular when these particles are next to a solid surface which forces them to bend the meniscus. The attraction is generated by the deformation of the meniscus region caused by the emerging spheres. While this force is probably the driving one for the growth of thin samples (1-3 layers), it is difficult to consider it as such for the growth of films 150 layers thick in which the vast majority of the spheres are still completely submerged when they pack into the growing crystal. The first works on the ordered deposition of colloidal particles were done using inclined substrates which were slowly drawn upward out of the suspension and resulted in one layer (or a few layers) of ordered particles.28 Generally larger grain sizes were obtained by keeping the substrate still and in a vertical position, leaving to the evaporation of the liquid phase the role of moving downward the meniscus. In this case photonic crystals of great quality and controllable thickness (more than 100 layers if multiple coatings were applied) were obtained.9 In all these works great attention has been paid to keeping the meniscus region quiet (mainly by using antivibration setups) and to keeping the deposition slow by limiting the evaporation rate. On the other hand, Yang et al.18 showed that it is possible to grow highly ordered crystals on patterned substrates by stirring the bulk of the suspension. Anyway, even in this case, the agitation was carefully set in order to not disturb the meniscus. The growth of photonic crystals in nonstationary conditions has been reported by Gates et al.32 The perturbation they use is an externally induced liquid flux which forces the packing in a confined geometry. In this paper we report the results of a new deposition method, which implies the perturbation of the evaporating meniscus. The method, consisting of a gas flux assisted deposition on an inclined substrate, has demonstrated to be efficient and allows the single-step deposition of highly ordered thick films of polystyrene spheres in a short time and from very diluted suspensions. Experimental Methods Polystyrene colloids have been synthesized by a surfactantfree emulsion polymerization reaction as described elsewhere.41 The mean diameter of the spheres used was 390 nm, and the polydispersity (defined as the standard deviation of the diameter distribution) has been evaluated by atomic force microscopy and scannning electron microscopy to be
