Date: Wednesday, December 3, 2014

Time: 9:00am

Location: MoSE, room 3201A

Committee

Prof. Zhiqun Lin (Advisor, MSE)

Prof. Meilin Liu (MSE)

Prof. Vladimir Tsukruk (MSE)

Prof. Zhonglin Wang (MSE/ECE)

Prof. Nazanin Bassiri-Gharb (MSE&ME)

Title: Crafting Organic-Inorganic Nanocomposites via Nonlinear Block Copolymers as Nanoreactors for Capacitors and Batteries

Abstract

Organic-inorganic nanocomposites composed of polymer and nanoparticles offer a vast design space of potential material properties, depending heavily on the properties of these two constituents 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 construction of miniaturized devices. However, this is still a challenging issue and has not yet been largely explored.

 In this project, we have developed an unconventional strategy to first create in-situ all ferroelectric nanocomposites (i.e., PVDF-BaTiO₃) comprising monodisperse ferroelectric BaTiO₃nanoparticles and nanorods intimately and permanently tethered with ferroelectric polyvinylidene fluoride (PVDF) by capitalizing on rationally designed amphiphilic nonlinear block copolymer poly(acrylic acid)-block-Poly(vinylidene fluoride) (PAA-b-PVDF) as nanoreactors. The diameter of BaTiO₃ nanoparticles and the chain length of ferroelectric PVDF can be precisely tuned. Quite intriguingly, ferroelectricity is existed in PVDF-BaTiO₃ nanocomposites even with the size of BaTiO₃ nanoparticle as small as 10 nm. Moreover, we also have exploited the nanoreactor strategy noted above to craft PS-capped ZnFe₂O₄ nanocrystals by using star-like poly(acrylic acid)-block-Polystyrene (PAA-b-PS) PAA-b-PS diblock copolymer as template. The PS capping was transformed into a thin carbon layer coated on the surface of the ZnFe₂O₄ nanoparticles. The electrochemical performance of C/ZnFe₂O₄ nanocomposites as electrode was scrutinized in lithium ion batteries. Such bottom-up crafting of intimate organic-inorganic nanocomposites offers new levels of tailorability to nanostructured materials and promises new opportunities 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.