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Dry synthesis of softly-agglomerated, metal/ceramic nanoparticles for functional nanocomposites

English title Dry synthesis of softly-agglomerated, metal/ceramic nanoparticles for functional nanocomposites
Applicant Pratsinis Sotiris E.
Number 114095
Funding scheme Project funding (Div. I-III)
Research institution Institut für Verfahrenstechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Chemical Engineering
Start/End 01.10.2006 - 30.09.2009
Approved amount 173'172.00
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Keywords (8)

flame pyrolysis; optical application; dielectric application; nanocomposite; nanoparticle; flame spray pyrolysis; soft-/hard-agglomeration; surface modifier

Lay Summary (English)

Lay summary
From simple paints to optical lithographic suspensions for microelectronics and even medical (dental or orthopedic) nanocomposites, loosely (softly) agglomerated nanoparticles with functionalized composition are required that can be easily dispersed in a liquid or polymer matrix. In the latter state, particles can be handled and transported easily with minimal environmental impact while retaining all advantages of their nanostructure. Dry (flame) synthesis offers distinct advantages over wet-chemistry techniques for production of nanoparticles with closely controlled characteristics for its scale-up capacity, minimal process steps and limited, if any, undesired, liquid byproducts.
Though softly-agglomerated, simple oxide nanoparticles have been made in flames as little as 50 nm in diameter that are dispersed readily in polymer matrices, further reduction in size has been accompanied by formation of agglomerates that are particularly difficult to disperse even though chemical or sinter bonds are visibly absent between such particles.
At these sizes, surface forces start becoming quite strong rendering a hard-agglomerate behavior to soft-agglomerates. To control these forces it is imperative to modify the particle surface by altering and controlling its composition. In particular, for this project a distinct goal is to explore the hard- or soft-agglomerate behavior of nanoparticles made by flame-spray pyrolysis (FSP). Multi-nozzle and multi-stage FSP configurations are explored leading to closely controlled temperature profiles and particle cooling rates that have a profound effect on particle composition and extent of agglomeration.
Detailed understanding of the formation of hard- or soft-agglomerated particles by FSP is developed by systematic experimental studies and subsequent reactor designs focusing on widely used ceramic oxides as ZnO, Al2O3, SiO2 and TiO2. The investigation of the formation of hard-, preferably soft- or non-agglomerated particles is one of the main goals.
In-situ characterisation methods such as FTIR emission/transmission spectroscopy for determination of flame temperatures and PDA for droplet size and velocity field determination as well as thermophoretic sampling combined with transmission electron microscopy analysis, ultra-small or small-angle x-ray scattering and static light scattering for evolution of particle growth will be used. Collected nanoparticles will be characterized also by ex-situ techniques such as nitrogen adsorption for particle (grain) size, x-ray diffraction for crystallinity and crystallite size and dynamic light scattering in dispersions for evaluation of the degree of particle agglomeration. A further goal is to explore the incorporation of such particles into selected polymers and investigate optically the degree of particle distribution in these matrices and most importantly their mechanic, thermal, optical or dielectric properties. The introduction of surface modifiers during particle synthesis to prevent agglomeration and improve adherence of these particles to the polymer matrix will be explored.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
117349 Multifonctional reactor for benchmark evaluation of novel, flame-made nanostructured catalysts 01.07.2007 R'EQUIP
121359 Rig for design and scale-up of flame aerosol synthesis of nanostructured materials 01.07.2008 R'EQUIP
107947 Design of Nanoparticle Synthesis in Flame Sprays 01.06.2005 Project funding (Div. I-III)
126694 Flame synthesis of nanostructured materials for functional nanocomposites 01.01.2010 Project funding (Div. I-III)