Nanohybrid thin films have been wildly exploited as the devices in the applications of nanotechnologies. The inorganic-organic hybrid materials are the candidates for next-generation materials owning to their excellent material properties, such as optical, electrical, optoelectronic, mechanical, and magnetic properties. Diblock copolymers with degradable segment can be used for topographic nanopatterning through hydrolytic treatment. Sol-gel chemistry is a well-known method to synthesize various ceramic oxide compounds which has a wild range of applications. In this study, we aim to use the topographic nanopatterns as templates for the sol-gel reaction so as to fabricate Nanohybrid thin films. Polystyrene-b-poly(L-lactide) (PS-PLLA) thin films with well-oriented, perpendicular PLLA hexagonal cylinders can be prepared by spin coating. Degradable PLLA microdomains were degenerated by hydrolytic process so as to create nanoporous PS thin films (i.e., topographic nanopatterns) with well-defined cylindrical nanochannels. By taking advantage of the nanoreactor concept, the sol-gel reaction for the fabrication of inorganic oxides can be achieved via templating so as to create PS/SiO2 nanohybrid thin films.
To acquire successful templating for the sol-gel reaction, it is necessary to carry out the pore-filling process for introducing the inorganic oxide precursors into the template. Different methods have been designed and examined in order to achieve the optimized condition for the successful templating through pore-filling. The topographic nanopatterns were floated on the sol-gel solution (i.e., the mixture of TEOS, methanol and aqueous HCl solution) with the participation of small amount of water to enhance the surface tension of the solution. However, water causes the formation of large SiO2 particles before pore-filling. Subsequently, instead of direct pore-filling of the sol-gel solution with water, the nanoporous thin films were collected on Cu grid, and then the pore-filling process of the sol-gel solution followed by the sol-gel reaction using the vapor of water was carried out. The formation of templated SiO2 could be identified, suggesting that the solution was successfully driven into the nanopores by capillary force. Similar process for templated sol-gel reaction can be conducted by pore-filling the mixture of TEOS and methanol solution but without the HCl aqueous solution. Subsequently, the pore-filled template was exposed to the vapor of aqueous HCl solution. Significant improvement on the pore-filling efficiency could be achieved through this method due to the occurrence of the sol-gel reaction after pore-filling. To acquire the best efficiency of templated sol-gel reaction, the reaction rate of sol-gel process should be justified so as to alleviate the formation of SiO2 before pore-filling. Alternatively, a low-temperature process for the sol-gel reaction was used such that giving the well-defined PS/SiO2 nanohybrid thin films with high pore-filled efficiency. Consequently, well-ordered nanorods can be obtained after the degeneration of PS by UV exposure. Apart from the formation of PS/SiO2 thin films, PS/TiO2 thin film can also be prepared by similar approach. As a result, we demonstrate an easy method for the formation of nanohybrid thin films by combining the templating of nanoporous thin films resulting from degradable block copolymers and the sol-gel reaction within templates.

References

1. Brabec, C . J.; Sariciftci, N. S.; Adv. Funct. Mater. 2001, 11 , 15.
2. Moreau, W.M. Semiconductor lithography: principles and materials New York: Plenum; 1988.
3. Smith, H.I.; Schattenberg, M.L.;Hector, S.D.;Ferrera, J.Moon, E.E.; Yang, I.Y.; Burkhardt, M. microelectron engng 1996,32,143.
4. Hatzakis, M. J. Electrochem. Soc. 1969, 116, 1033.
5. Yang, P.; Wirnsberger, G.; Huang, H. C.; Cordero, S. R.; McGehee, M.D.; Scott, B.; Deng, T.; Whitesides, G. M.; Chmelka, B. F.; Buratto, S. K.; Stucky, G. D. Science 2000, 287, 465.
6. Unger, M.A.; Chou, H. P.; Thorsen, T.; Scherer, A.; Quake, S.R. Science 2000, 288, 113.
7. Dagata, J. A.; Schneir, J. H.; Harary, H.; Evans, C. J.; Postek, M. T.; Bennett, J. Appl. Phys. Lett. 1990, 56, 2001.
8. Piner, R. D.; Zhu, J.; Xu, F.; Hong, S.; Mirkin, C. A. Science 1999, 283, 661.
9. Ginger, D. S.; Zhang, H.; Mirkin, C. A. Angew. Chem. Int. Ed. 2004, 43, 30.
10. Tseng, A. A.; Notargiacomo, A.; Chen, T. P. J. Vac. Sci. Technol. B 2005, 23, 877.
11. Whitesides, G. M. ; Grzybowski, B. Science 2002, 295, 2418.
12. Philip, D.; Stoddart, J. F. Angew. Chem. Int. Ed. 1996, 35, 1155.
13. Whitesides, G. M.; Ismagilov, R. F. Science 1999, 284, 89.
14. Clark, T. D.; Tien, J.; Duffy, D. C.; Paul, K. E.; Whitesides, G. M.; J. Am. Chem. Soc. 2001, 123, 7677.
15. Jakubith, S.; Rotermund, H. H.; Engel, W.; Von Oertzen, A.; Ertl, G. Phys. Rev . Lett . 1990, 65, 3013.
16. Giersig, M.; Mulvaney, P. Langmuir, 1993, 9, 3408
17. Kresge, C.; Leonowicz, M.; Roth, W.; Vartuli, C.; Beck, J. Nature 1992, 359, 710
18. Bates, F.S.; Fredrickson, G.H. Phys today 1999, 52, 32.
19. Yang, X. M.; Peter R.D. ; Nealey , P.F.; Solak, H. H.; Cerina, F. Macromolecules 2000,33,9575
20. Bita,I.; Yang,J. K. W.; Jung,Y. S.; Ross, C. A.; Thomas E. L.,; Berggren. K. K. SCIENCE 2008, 321 , 939 (graphoepitaxy)
21. Kim, G.; Libera, M.; Macromolecules ,1998, 31, 2569
22. Thurn-albrecht, T.;Steiner, R.; DeRouchey, J.; Stafford, C.M.;Huang. E.; Bal.M.;Tuominen, M.; Hawker, C. J.; Russell T. P. Adv. Mater. 2000, 12, 787.
23. Park, M.; Harrison, C.; Chaikin P. M.; Register, R. A.; Adamson, D. H. Science 1997, 276, 1401.
24. Zalusky, A. S.; Olayo-Valles, R.; Taylor, C.J.; Hillmyer, M. A. J. Am Chem. Soc. 2001, 123, 1519.
25. Lin, Y.; Boker, A.; Hel, J.; Sill, K,; Xiang, H.; Abetz, C.; Li, X.; Wang, J.; Emrick, T.; Long, S.; Wang, Q.; Balazs, A.; Russel. T. P. Nature 2005, 434, 55.
26. Cheng, J. Y.; Ross, C. A.; Chan, V. Z. H.; Thomas, E. L.; Rob, G. H.; Lammertink, R. G. H.; Vancso, G. J. Adv.Mater. 2001, 13, 1174
27. johnson, B. J. S.; Wolf, J. H.; Zalusky, A. S.; Hillmyer, M. A. Chem. Mater. 2004, 16, 2909.
28. Russell, T. P. Curr. Opin. Colloid Interface Sci. 1996, 1, 205
29. Spatz, J. P.; MoDme,S. ; Moiler, M. Chem. Eur. J.,1996, 2, 1552
30. Lopes, W. A. ; Jaeger, H. M. NATURE , 2001, 414 , 735
31. Schubert, U. ;N. Huesing, ; Lorenz,A. Chem. Mater. 1995, 7, 2010
32. F□rster, S. ; Antonietti, M. Adv. Mater. 1998, 10, 195
33. Rao,Y. Q. ; Chen,S. Macromolecules, 2008, 41 , 4838
34. Dislich, H. Glastechn.ber. 1971, 44, 1.
35. Stein,A.; Melde, B. J.; Schroden, R. C. Adv. Mater. 2000, 12, 1403
36. Hench', L. L. ;West, J. K. Chem. Rev. 1990, 90. 33
37. Hiemenz P.C., “Principle of Colloid and Surface Chemistry”, Marcel Dekker, New York (1953)
38. Pierre A. C. , “Introduction to sol-gel processing”, Springer, London (1998)
39. Wright,J.D.; Sommerdijk, N.A. “ Sol-Gel Materials: Chemistry and Applications”, Taylor & Francis Books, London (2001)
40. Orcel, G.; Hench, L. L.; Artaki, I.; Jones, J.; Zerda, T. W. J.　Non-Cryst. Solids 1988, 105, 223.
41. Hench, L. L.; Orcel, G. J. Non-Cryst. Solids 1986, 82, 1.
42. Brinker, C. J.; Scherer, G. W. J. Non-Cryst. Solids 1985, 70, 301
43. Hegde, N. D.; Rao A.V. Journal of Sol-Gel Science and Technology 2006 38, 55
44. Tseng, W. H.; Chen, C. K,; Chiang, Y. W.; Ho, R. M.; Akasaka, S.; Hasegawa, H.; J. Am. Chem. Soc., 2009, 131 ,1356
45. Yin, Y.; Lu, Y.; Gates, B.; and Xia, Y. ;J. Am. Che. Soc. 2001, 123 ,871
46. Cui, Y.; Bjolrk, M.T.; Liddle, J.A.; Sonnichsen, C.; Boussert, B; Alivisatos, A.P. Nano lett., 2004, 4, 1093
47. Zhang,Q. ; Xu,T.; Butterfield,D.; Misner, M. J. ;D. Y. Ryu, T. E., Russell, T. P. Nano Lett., 2005 , 5,537
48. Ho, R.M.; Tseng, W.H.; Fan, H.W.; Chiang, Y. W.; Lin, C. C. ; Ko, B. T.; Huang, B.H. Polymer 2005 46 9362
49. Park,S.; Kim, B. ; Wang, J. ; Russell, T. P. Adv. Mater. 2008, 20, 681
50. Chen, C.; Zhang, H. ; Shen, L. ; Hillmyer, M. A. ; Guo, S. ; Nanotechnology 2008, 19, 365304
51. Bailey, T. S.; Rzayev, J.; Hillmyer M. A.,; Macromolecules 2006, 39, 8772
52. Lo, K. H.; Tseng, W. H,; Ho, R. M. Macromolecules, 2007, 40, 2621
53. Zhang, Q.; Gupta, S.; Emrick T.,; Russell. T. P.　J. Am. Chem. Soc. 2006, 128, 3898
54. Yan M.; Harnish B., Adv. Mater. 2003, 15, 244
55. Melde, B.J.; Burkett, S. L.; Xu, T.; Goldbach, J. T.; Russell, T. P.; Hawker, C. J.; Chem. Mater. 2005, 17, 4743