Ian Wark Research Institute
ARC Special Research Centre
ARC Special Research Centre
Research Area: Nanomaterials, polymer science
Supervisors: Prof Namita Roy Choudhury and
Dr Naba Dutta
Description: Nanomaterials, particularly nanoclusters of metals and semiconductors, which exhibit size dependent optical, magnetic, electronic and catalytic properties due to their quasi zero space have been heralded as the next generation of building block for designing new materials. The utilization of such harmonized nanomaterials (HNM) will have a major impact in catalytic, sensor, optical, electronic, opto-electronic, electroceramic, and structural ceramic material applications. However, the incorporation of nano-sized inorganic particles into a polymeric matrix represents one of the most difficult problems in the fabrication of such nanocomposites. Template mediated mineralisation has emerged as a popular technique to control precisely the particle size, distribution, morphology using polymers, micelles, zeolites, colloidal assemblies and so forth. This program will produce 'novel nanomaterials’, using “Bottom Up” approach of building material, component and entire product molecule-by-molecule, even atom-by-atom. The molecular building block approach gives us precise control over structure, consequently on performance. To achieve proposed targets we will develop a fundamental strategy called “Organic Template Mediated Hybrid” or so called biomimetic approach. The hybrid is generally the collective name for crystals, liquid crystals, thin films, etc including organic/inorganic, host-guest supramolecular material, self assembled monolayers, layered inorganic/organic compounds, nanocomposites, which can be formed by hybridization of organic compounds, polymers, and inorganic materials, metals at a molecular level. Unlike other methods, which use process parameter as the main variable to control particle size, appropriate control of nanoparticle size will be achieved through control of template size. Successful outcome has the potential to solve the size control problem in nano-fabrication.
Methodology: The best example of HNM (harmonized nanomaterial) is a self-organized, molecularly ordered nanostructure in living entity. We will choose various unique templates with defined architecture and reactivity, which are suitable for complexing and functionalization with several ligands. Different organic based templates or cores with different architecture {such as cubic, spherical, torroidal) will be used in this program. Knowledge of the template sizes will be exploited to form nanoparticles of predictable sizes. The concept of using them as precise nanoreactors (diameter between 1 to 15 nm) involves organization of small molecules or ions followed by their immobilization/stabilization as guest material. Such pre-organization can occur by acid-base interaction, salt formation, and complex formation through ligand-metal interaction. As these molecules are highly symmetrical, they can contain a large number of regularly spaced internal and external functional groups. The interior and the exterior can be designed to be hydrophilic or hydrophobic. Due to the availability of large number of binding sites within such architecture, many possible overlapping equilibrium processes may occur by any guest-host mechanism, such as complex formation by ligand/metal-ion interactions, acid-base, donor-acceptor interaction, etc. We will endeavor to develop a family of harmonized organic-inorganic hybrid nanomaterials suitable for use as dielectric insulator material, optical limiter. The ability to fabricate advanced material based on nonfunctional template has been limited due to their poor solubility and tendency to cluster. While alloying some of the templates can result in significant improvement in some properties, more dramatic property modification is expected when functionalized templates are copolymers or crosslinked through flexible spacer to a monomer. By prefunctionalising the templates with flexible spacer or ligand, it is possible to molecularly disperse and compatibilise the template in a monomer. Nanomaterial in well-defined matrix, more specifically quantum-confined clusters will be grown within the template architecture. The template will be functionalized with reactive side groups to make them soluble and molecularly disperse in a matrix for subsequent preparation of the hybrid. With heterostructure it will be possible to engineer the electrical, optical and mechanical properties of the materials. Through proper choice of composition, thickness or doping, one can control the interaction between electrons and photons or the conductivity.
There are various ways to prepare HNM eg self assembled monolayer, spin coating, Langmuir Blodgett (LB) film, layer by layer or thin stacked layer, etc. The behavior of a small quantity of self-assembling molecules is strongly influenced by the way they are attached to the surface. Surface forces predominate in small or ultrathin assemblies and thus in practice; the behavior of nano assemblies can be more readily manipulated. The structure of most of the reported template bound polymers are unclear or only a matter of speculation. Thus detailed characterization is a crucial issue and an insight into the size, shape, interface, thickness, diffusion and distribution to be precisely determined through very unique and powerful characterization methods that have not been applied to this class of materials before.
The proposed program will represent a synthetic approach to make the template-mediated film or hybrid and a major characterization plan to understand the family of newly developed materials. The basic components of the project are:
- design and synthesis of multifunctional templates
- immobilization of the templates on a matrix or a substrate
- structure and morphology evaluation by SAXS and Atomic Force Microscopy
- investigation on the interface, buried interface, diffusion/self-diffusion and thickness of the thin film by neutron reflectometry
- evaluation of dielectric property.
Funding: International students should apply for an International Postgraduate Research Scholarship (IPRS) and a UniSA President’s Scholarship (UPS). To be eligible for UPS, applicants must have a supervisor willing to nominate them for consideration.
Australian students should apply for an Australian Postgraduate Award (APA) and a UniSA Australian Postgraduate Research Award
(USAPRA).
