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Superparamagnetic Triblock/Fe2O3 Nanofibers

Guojun Liu* and Xiaohu Yan

Department of Chemistry, University of Calgary,
Calgary, Alberta T2N 1N4 CANADA

This is an abstract for a presentation given at the
Ninth Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is available on the web.


Block copolymers self-assemble in bulk forming various intricate nanometer-sized block segregation patterns.1 Block-segregated solids of diblock copolymers have been processed chemically in the past to yield nanofibers,2, 3, 4, 5 nanospheres,6 nanochannels in thin films,7, 8 inorganic nanoparticles in polymer matrices,9, 10, 11, 12 and photolithographic masks with nanometer-sized patterns.13 Linear triblocks AnBmCl, where A, B, and C denote different monomers, are far richer in block segregation patterns than diblocks. Despite this, there have been only a few reports of nanostructure preparation from block-segregated triblock solids. Here we report the preparation of polymer/Fe2O3 hybrid nanofibers from processing films of a triblock copolymer polystyrene-block-poly(2-cinnamoyloxyethyl methacrylate)-block-poly(t-butyl acrylate) or PS-b-PCEMA-b-PtBA. Also to be reported will be the superparamagnetism of the hybrid nanofibers and their alignment in magnetic fields.

structural  formula

The preparation involved the self-assembly of the blocks in thin films into concentric PCEMA and PtBA cylinders dispersed in the matrix of PS (A-->B of Scheme 1). The cylindrical structures were then locked in by photo-crosslinking the PCEMA shells (B-->C). Dissolving the films in THF yielded individual nanofibers with PS coronas, PCEMA middle layers, and PtBA cores (C-->D). Nanotubes with poly(acrylic acid)- or PAA-lined cores were obtained after cleaving the t-butyl groups from PtBA (D-->E). Producing Fe2O3 nanoparticles in the PAA cores yielded solvent-dispersible superparamagnetic block copolymer/inorganic hybrid nanofibers (E-->F).

Scheme I
Scheme I


  1. For a review on triblock morphologies, see, for example, F. S. Bates, G. H. Fredrickson Phys. Today 1999, February issue, 32.
  2. a) Liu, G.; Ding, J.; Qiao, L.; Guo, A.; Gleeson, J. T.; Dymov, B.; Hashimoto, T.; Saijo, K. Chem. Eur. J. 1999, 5, 2740. b) Liu, G.; Qiao, L.; Guo, A. Macromolecules 1996, 29, 5508-5510.
  3. Massey, J.; Power, K. N.; Manners, I. Winnik, M. A. J. Am. Chem. Soc. 1998, 120, 9533.
  4. Won, Y.-Y., Davis, H.T. and Bates, F.S., Science 1999, 283, 960.
  5. Zhang, L.; Eisenberg, A. Science 1995, 268, 1728.
  6. Ishizu, K.; Fukutomi, T. J. Polym Sci: Part C: Polym Lett. 1988, 26, 281.
  7. a) Liu, G.; Ding, J.; Hashimoto, T.; Saijo, K.; Winnik, F. M.; Nigam, S. Chem. Mater. 1999, 11, 2233. b) Liu, G.; Ding, J.; Guo, A.; Herfort, M.; Bazett-Jones, D. Macromolecules 1997, 30, 1851.
  8. Lee, J.-S.; Hirao, A.; Nakahama, S. Macromolecules 1989, 22, 2602.
  9. Boontongkong, Y.; Cohen, R.E.; Rubner, M.F. Chem. Mater. 2000, 12, 1628.
  10. Fink, Y.; Urbas, A.M.; Bawendi, G.G.; Joannopoulos, J.D.; Thomas, E.L. Lightwave Technol. 1999, 17, 1963.
  11. Hashimoto, T.; Tsutsumi, K.; Funaki, Y. Langmuir 1997, 13, 6869.
  12. Templin, M.; Franck, A.; DuChesne, A.; Leist, H.; Zhang, Y.M.; Ulrich, R.; Schadler, V.; Wiesner, U. Science 1997, 278, 5344.
  13. Park, M.; Harrison, C.; Chaikin, P.M.; Register, R.A.; Adamson, D.H. Science 1997, 276, 1401.

Abstract in RTF format 25,419 bytes

*Corresponding Address:
Guojun Liu
Department of Chemistry, University of Calgary
2500 University Dr., NW, Calgary, Alberta T2N 1N4 CANADA
Phone: 403-220-5343
Fax: 403-289-9488


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