381201 event 1424706281 1475891299 MSE PhD Proposal: Yanjie He
Date: Friday, Feb 27,2015
Location: Love, room 210
Time: 01:00 PM

Committee Members
Prof. Lin, Zhiqun (Advisor, MSE)
Prof. Dong Qin (MSE)
Prof. Vladimir Tsukruk (MSE)
Prof. Meisha Shofner (MSE)
Prof. Yuling Deng (ChemE)

Title: Nanostructured Materials with Well-Controlled Dimensions,
Compositions and Architectures via Precise Molecular Design and Their
Applications in Energy Harvesting

Abstract

Star-like and bottlebrush-like copolymers composed of distinct polymeric
blocks offer versatile and robust strategies for producing nanostructured
materials with complex morphologies which cannot be synthesized through
conventional methods. The resulting organic-inorganic nanocomposites
consisting of functional polymers and nanostructured inorganic materials
provide a vast design space of potential material properties, depending
heavily on the properties of these two components and their spatial
arrangement. The ability to place polymers in intimate contact with
functional nanoparticles, that is, stable chemical interaction without the
dissociation of surface capping polymers, provides a means of preventing
nanoparticles from aggregation and increasing their dispersibility in
nanocomposites, and promises opportunities to explore new properties and
construct miniaturized devices. However, this is still a challenging issue
and has not yet been largely explored.
 In this proposal, we aim to develop an unconventional strategy to first
craft hollow lead telluride (PbTe) nanoparticles with varied size and shell
thickness by using star-like triblock copolymers PS-b-PAA-b-PS as
nanoreactors, which are expected to exhibit enhanced thermoelectric
properties due to preferential scattering of phonon without suppressing
transport of electrons. Based on such a similar rationale, we have proposed
another means of in-situ crafting organic-inorganic nanocomposites
comprising monodisperse thermoelectric PbTe nanoparticles or nanorods
intimately and permanently tethered with thermoelectric poly(3
4-ethylenedioxythiophene) (PEDOT) (i.e., PEDOT-PbTe) by capitalizing on
rationally designed amphiphilic nonlinear block copolymer poly(acrylic
acid)-block- poly(3 4-ethylenedioxythiophene) (PAA-b-PEDOT) as nanoreactors.
Furthermore, we have exploited the nanoreactor strategy noted above to
create polystyrene-capped magnetoelectric BaTiO3/CoFe2O4 core/shell
nanocrystals by capitalizing on star-like poly(4-vinyl pyridine)-b-poly(tert
butyl acrylate)-b-polystyrene (P4VP-b-PtBA-b-PS) triblock copolymers as
template. The intimate and permanent PS capping on the surface core/shell
nanocrystals will facilitate the selective incorporation of these
nanoparticles into PS nanodomains in PS-b-PMMA diblock copolymer during the
co-assembly of BaTiO3/CoFe2O4 core/shell nanocrystals and PS-b-PMMA thin
film, thereby leading to the formation of nanocomposites with hierarchical
distribution of ME nanoparticles in diblock copolymer matrix. In addition,
we further extend polymeric nanoreactor strategy to produce hollow
conjugated polymeric nanoparticles and nanotubes. Such bottom-up crafting of
intimate organic-inorganic nanocomposites offers new levels of tailorability
to nanostructured materials for achieving exquisite control over the surface
chemistry and properties of nanocomposites with engineered functionality for
diverse applications in energy conversion and storage, catalysis,
electronics, nanotechnology, and biotechnology.

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