Directed Assembly of Quantum Dots in a Diblock Copolymer Matrix

Report No. ARL-TR-4204
Authors: Frederick L. Beyer; Christopher R. Ziegler; Kevin Sill; Todd Emrick; Nicholas M. Benetatos; Karen I. Winey
Date/Pages: August 2007; 20 pages
Abstract: The effect of ligand molecular weight on nanoparticle dispersion and nanocomposite morphology has been investigated. Nanoscopic particles, CdSe/ZnS quantum dots (QDs), were dispersed into the polystyrene (PS) microdomains of a microphase separated, bulk PS-poly(methyl methacrylate) block copolymer. The QDs were compatibilized with the PS-domains of the microphase separated block copolymer by the use of PS-based ligands associated with the surfaces of the QDs. A stock solution of the functionalized particles was mixed with dissolved block copolymer, and bulk samples were formed by solvent evaporation. Dispersion of the nanoparticles was determined via bright field transmission election microscopy and high-angle annular dark field scanning transmission electron microscopy. The microphase separated block copolymer morphology (lamellae) was probed using small-angle and ultrasmall-angle x-ray scattering. Although the additive particles are much larger in diameter than those considered in previous calculations and experimental work, it was found that the QDs modified with 14,000 g/mol PS ligands dispersed well in the block copolymer, while those modified with 81,000 g/mol PS ligands formed small aggregates. In these nanoparticle/polymer composites, the block copolymer retains its original morphology.
Distribution: Approved for public release
  Download Report ( 0.629 MBytes )
If you are visually impaired or need a physical copy of this report, please visit and contact DTIC.

Last Update / Reviewed: August 1, 2007