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6 x Research Seminars (Materials Science)

Date: Wed 28 Nov 2012, 13:30 - 15:40

Location: SEMS Seminar Room

6 x Research Seminars (Materials Science), 20 minutes for each speaker

Dr Salvatore Grasso, Nanoforce Technology Limited, Queen Mary University of London
Electro-Magnetic manipulation of advanced ceramics
The talk emphasizes the potential of electro-magnetic fields [1-3] during processing to manipulate the microstructures and properties of advanced ceramics. Magnetic field [3] (12 T, DC) is selected as tools to add novel functionalities to ceramics. The unique potentials of Spark Plasma Sintering (SPS) are highlighted by my recent research works. Special attention is given to metastability, nanosintering (high pressure compaction) and SPS modeling. The talks explain how electro-magnetic manipulation might have a significant impact on science and technology.
[1] S Grasso, Y Sakka, G Maizza, Electric current activated/assisted sintering (ECAS): a review of patents 1906–2008, Science and Technology of Advanced Materials 10 (2009) 053001
[2] S Grasso, H Yoshida, H Porwal, Y Sakka, M Reece, Highly transparent α-alumina obtained by low cost high pressure SPS accepted for publication Ceramics international
[3] S Grasso, C Hu, O Vasylkiv, T S Suzuki, S Guo, T Nishimura, Y Sakka, High-hardness B4C textured by strong magnetic field technique, Scripta Materialia 64 (2011) 256-259.

Dr Jin Geng, University of Bristol
"Stimuli-Responsive Polymeric Nanoparticles: innovations at biological and chemical interface"
Introducing a novel self-organized supramolecular system based on the tunable composition of an amphiphilic diblock copolymer. The amount of hydrophilic content can be readily modulated through a supramolecular grafting approach, thereby producing reduction- responsive micelles and vesicles of controlled sizes. This offers a new control strategy for triggered therapeutic systems through a reduction stimulus, particularly in therapeutic dosage control, biosensing and biodiagnostics.

Dr David Muñoz-Rojas, University of Cambridge
Novel architectures, novel methods & novel materials for 3rd generation solar cells
In order to make solar cell energy a real alternative to fossil fuels, 3rd generation solar cell technologies with much better cost-efficiency ratios than the established Si-based ones, must be developed. Therefore new methods, materials and cell architectures must be developed to i) minimize the use of materials, ii) reduce fabrication costs and iii) reduce material costs by using abundant elements. In my seminar I will present the work I have done in these three lines. I will first describe a new architecture for organic bulk heterojunction solar cells. Then I will introduce a novel fabrication technique, i.e. Atmospheric Atomic Layer Deposition Layer. Finally, I will talk about the use of abundant, non-toxic elements in all-oxide solar cells.

Dr C Remzi Becer, Department of Chemistry, University of Warwick
Precision in Polymer Science - from oil field chemicals to dendritic cells
Polymers are used in all areas of our lives and bring enormous benefits to advanced materials. In this lecture, we will discuss the techniques to prepare designed macromolecules and their applications in various fields such as use of stimuli-responsive polymers as kinetic hydrate inhibitors and glycopolymers to reduce the risk of HIV infection.

Dr Alexey Ganin, Department of Chemistry, University of Liverpool, L69 7ZD
Solution processed superconducting materials
The discovery of new phenomena in solids and the development of specific properties of existing functional materials, such as superconductivity, rely upon our ability to direct reaction pathways toward materials with desired structure and composition. However, as solid state reactions usually take place at high temperatures (normally >500oC) it is very difficult to control redox or exchange reaction pathways. As a result many new potentially important phases cannot be accessed or isolated in phase pure form due to their metastability. Solution based chemistry approach to synthesis of solids - with reactions accomplished close to ambient conditions - can be a viable alternative to the traditional high temperature route and can offer an additional level of control and understanding of reaction mechanisms. In my presentation I will exemplify the validity of this approach by looking at superconducting systems of alkali-metal fullerides (Cs3C60) and layered metal chalcogenides (KxFe2Se2) where the use of solution based chemistry produced novel superconducting systems unattainable (so far) in other ways.

Dr. Paul Podsiadlo, Research & Eng Co. New Jersey, USA
“Mechanics and Applications of Self-Assembled Hybrid Organic/Inorganic Nanocomposites”
In this presentation I will highlight two examples of my research on mechanics and applications of self-assembled hierarchical architectures of nanomaterials. In the first example, I will present preparation of biomimetic polymer/clay nanocomposites with record-high strength and stiffness. (Podsiadlo et al., Science, 2007) Understanding of nanoscale mechanics, the interfacial molecular interactions, and achieving efficient interfacial load transfer between the inorganic nanomaterial and organic polymer matrix are key elements for successfully harnessing the exceptional nanoscale properties for macroscale structures. The ultimate development of my work is a 90% transparent in the visible range multilayered film with 50 vol.% loading of clay nanoparticles, tensile strength of 400 MPa, and modulus of elasticity of 110 GPa. The unique layered architecture of these materials has been explored for applications in gas barriers, flame retardant coatings, as well as biomedical coatings. In the second part of my talk, I will present my recent research on characterization of collective physical properties in self-assembled nanoparticle (NP) superlattices (SL). In these novel architectures NPs self-organize into periodic structures analogous to atomic crystals, with NPs serving the roles of artificial atoms. Precise positioning of the NPs in single, binary, and even ternary assemblies leads to novel collective optical, electronic, magnetic, and even mechanical properties. I will present the first experimental results from systematic evaluation of mechanical properties of 3D SLs using nanoindentation and in situ synchrotron X-ray diffraction techniques. The nanoindentation results showed truly “crystalline” behavior of the 3D SLs, with elastic modulus and hardness being at least 2x greater when compared to random films of the same NPs. Combination of small-angle X-ray scattering and diamond anvil cell techniques revealed unusual elasticity and significantly greater bulk modulus of SLs composed of 7-nm PbS NPs stabilized with oleic acid. The bulk modulus was calculated as high as 15 GPa. These results show unique potential and opportunities for tuning interparticle interactions through application of mechanical force in these novel metamaterials.

References:
1. P. Podsiadlo et al. “Ultra-Strong and Stiff Layered Polymer Nanocomposites”, Science, 318, 80-83, 2007.
2. P. Podsiadlo et al. “LBL Assembled Laminates with Hierarchical Organization from Nano to Micro Scale: High-Toughness Nanomaterials and Deformation Imaging”, ACS Nano, 3 (6), 1564-1572, 2009.
3. P. Podsiadlo et al. “The Role of Order, Nanocrystal Size and Capping Ligands in the Collective Mechanical Response of Three-Dimensional Nanocrystal Solids”, JACS, 132, 8953-8960, 2010.
4. P. Podsiadlo et al. “High-Pressure Structural Stability and Elasticity of Self-Assembled Nanoparticle
Supercrystals”, Nano Letters, 11, 579-588, 2011.

Contact:Julia Shelton
Email:j.shelton@qmul.ac.uk

Updated by: Jonathon Hills