Self-assembly of nanoparticles dispersed in polymers

R. J. J. WILLIAMS

Santiago de Chile

Simposio; 10th International Conference on Frontiers of Polymers and Advanced Materials; 2009

Universidads de Chile

SELF-ASSEMBLY OF NANOPARTICLES DISPERSED IN POLYMERS   R.J.J. Williams, INTEMA (Univ. Mar del Plata-CONICET) , Mar del Plata, Argentina   williams@fi.mdp.edu.ar     Nanoparticles (NPs) stabilized by organic ligands can be homogeneously dispersed in appropriate monomers. In the course of polymerization phase separation of NPs can take place leading to their self-assembly into a variety of morphologies. For example, hierarchical aggregates of 2-nm gold NPs on different length scales were in situ generated at the surface of a bridged silsesquioxane during the process of film formation by solvent evaporation and polycondensation1. Small bcc crystals (20 nm) were first generated that were self assembled into compact micrometer-sized spherical particles followed by their aggregation at the surface forming fractal structures (Fig. 1). The surface percolation of NPs in fractal structures can be the basis of useful applications.      On the other hand, a convenient way to keep the dispersion of individual NPs in the crosslinked polymer is to employ organic ligands with polymerizable groups. An example will be described where water-soluble Ag NPs stabilized with 11-mercaptoundecanoic acid (MUA) were converted into DGEBA (diglycidylether of bisphenol A)-soluble NPs by reaction of MUA with PGE (phenyl glycidylether). Homopolymerization of DGEBA initiated by a tertiary amine led to an epoxy network containing homogeneously dispersed silver NPs as revealed by the constancy of the plasmon band location. Transfer reactions involving the hydroxyl groups present in the stabilizing organic ligands enabled the covalent bonding of NPs in the network structure. The resulting materials might find applications as antimicrobial coatings.         Fig.1. TOM image of the surface of a crosslinked silsesquioxane film containing 1 wt % of 2- nm gold nanoparticles hirarchically self-assembled into fractal structures   1. M. L. Gómez, C. E. Hoppe, I. A. Zucchi, R. J. J. Williams, M. I. Giannotti and M. A.   López-Quintela, Langmuir, 25, 1210 (2009).