Abstract/Details

Directed self -assembly of nanoparticles at interfaces


2005 2005

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Abstract (summary)

The fabrication of functional nanostructured materials for sensing, encapsulation and delivery requires practical approaches to self-assembly on multiple length scales and the synthesis of tough yet permeable structures. Here, ligand-stabilized nanoparticles assembled into three-dimensional constructs at fluid-fluid interfaces driven by the reduction in interfacial energy were investigated. Studies on the dynamics of the nanoparticles and the self-assembled structures formed at the interface, using fluorescence photobleaching methods and in-situ grazing incidence small angle x-ray scattering, suggest a liquid-like behavior and ordering at the interfaces. Cross-linking of the nanoparticle assembly using functional ligands, affords robust membranes that maintain their integrity even when they are removed from the interface. These composite membranes, nanometers in thickness, are elastic yet permeable. Combining other self-assembly processes on different length scale, i.e. "breath figures", with the self-assembly of nanoparticles at the oil-water interfaces lead to the formation of hierarchically structured nanoparticle arrays. The assembly of virus and other biological complexes at fluid interfaces was also investigated where interfacial assembly rendered an easy route to direct and assemble the bioparticles into 2-D and 3-D constructs with hierarchical ordering. These assemblies enable the potential use of the bioparticles as a natural supramolecular building block to obtain materials with well-defined biofunctionalities.

Also, the organization of inorganic nanostructures within self-assembled organic or biological templates is receiving the attention of scientists interested in developing functional hybrid materials. Recent theoretical arguments have suggested that synergistic interactions between self-organizing particles and a self-assembling matrix material can lead to hierarchically ordered structures. Here we show that mixtures of diblock copolymers and either cadmium selenide- or ferritin- based nanoparticles exhibit cooperative, coupled self-assembly on the nanoscale. In thin films, the copolymers assemble into cylindrical domains, which dictate the spatial distribution of the nanoparticles; segregation of the particles to the interfaces mediates interfacial interactions and orients the copolymer domains normal to the surface, even when one of the blocks is strongly attracted to the substrate. Organization of both the polymeric and particulate entities is thus achieved without the use of external fields, opening a simple and general route for fabrication of nanostructured materials with hierarchical order.

Indexing (details)


Subject
Polymers
Classification
0495: Polymers
Identifier / keyword
Pure sciences, Diblock copolymers, Directed self-assembly, Nanoparticles, Self-assembly
Title
Directed self -assembly of nanoparticles at interfaces
Author
Lin, Yao
Number of pages
91
Publication year
2005
Degree date
2005
School code
0118
Source
DAI-B 66/11, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780542382901, 0542382903
Advisor
Russell, Thomas P.
University/institution
University of Massachusetts Amherst
University location
United States -- Massachusetts
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3193918
ProQuest document ID
304996009
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304996009
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