Strategies to disperse or self-assemble nanoparticles in crosslinked polymers

R.J.J. WILLIAMS

Cancún

Congreso; International Materials Research Congress (IMRC XX); 2011

Materials Research Society

Nanoparticles (NPs) are usually stabilized with specific organic ligands to avoid coalescence and facilitate their dispersion in adequate solvents. Examples are the use of dodecanethiol to stabilize Au and Ag NPs, oleic acid to stabilize ferric oxide NPs, and the organic groups bonded to Si atoms in polyhedral oligomeric silsesquioxanes (POSS). Stabilized NPs can be dispersed in the precursors of a crosslinked polymer. However, in most cases a polymerization-induced phase separation takes place in the course of polymerization [1], leading to the segregation and self-assembly of the NPs. By an adequate selection of reaction conditions, a homogeneous solution of POSS in an epoxy-amine solvent can give place to a dispersion of POSS crystalline platelets in the final network [2], mimicking nanoclays dispersions. Gold NPs self-assembled into colloidal crystals exhibiting a 3D hexagonal close-packed structure generating highly ramified fractal structures at the air-polymer interface [3]. Phase separation of NPs can be avoided by introducing reactive groups in the organic ligands. The covalent bonding allows the trapping of NPs in the polymer network. Examples of this approach are the dispersion of multifunctional POSS [4] or Ag NPs [5] in epoxy networks. An alternative procedure to generate a uniform dispersion of NPs is the swelling of a polymeric gel with a solution of the precursors of NPs (e.g., silver nitrate or tetrachloroauric acid) followed by the in situ reduction of the cations [6]. Other possibilities of producing uniform dispersions of NPs in crosslinked polymers will be discussed in the presentation.                   [1] E.R. Soulé, J. Borrajo, R.J.J. Williams, Macromolecules 2007, 40, 8082. [2] C. Di Luca, E.R. Soulé, I.A. Zucchi, C.E. Hoppe, L.A. Fasce, R.J.J. Williams, Macromolecules 2010, 43, 9014. [3] I.A. Zucchi, C.E. Hoppe, M.J. Galante, R.J.J. Williams, M.A. López-Quintela, L. Matejka, M. Slouf, J. Plestil, Macromolecules 2008, 41, 4895. [4] J. Choi, J. Harcup, A.F. Yee, Q. Zhu, R.M. Laine, J. Am. Chem. Soc. 2001, 123, 11420. [5] I.E. dell’Erba, C.E. Hoppe, R.J.J. Williams, Langmuir 2010, 26, 2042. [6] A. Ledo-Suárez, J. Puig, I.A. Zucchi, C.E. Hoppe, M.L. Gómez, R. Zysler, C. Ramos, M.C. Marchi, S.A. Bilmes, M. Lazzari, M.A. López-Quintela, R.J.J. Williams, J. Mater. Chem. 2010, 20, 10135.