Nanomaterials are coming into use in healthcare, electronics, cosmetics, catalysis and other areas, because they bring novel mechanical, electrical, thermal, optical, electrochemical, catalytic properties differing markedly from that of the component materials.
Nanostructures are not simply another step in the miniaturization of materials. They often require very different production approaches. There are several processes to create nanomaterials, classified as ‘top-down’ and ‘bottom-up’., which are explored at Nanotec.
Self-Assembled Monolayers (layers that are one atom or molecule deep) are also routinely made and used in chemistry. The formation and properties of these layers need to be understood from the atomic level upwards, even in quite complex layers (such as lubricants). Advances are being made in the control of the composition and smoothness of surfaces, and the growth of films.
Furthermore, engineered surfaces with tailored properties such as large surface area or specific reactivity are used routinely in a range of applications such as in fuel cells, sensing and catalysts. The large surface area provided by nanoparticles, together with their ability to self assemble on a support surface, could be of use in all of these applications. Main topics in the focus are:
- Metallic Plasmonic Nanosystems
- Molecular Architectures at Interfaces
- High Charge Mobility Columnar Mesophases
- Organic/inorganic Nanocomposites
- Nanotextured Materials
Metallic Plasmonic Nanosystems
- Design, growth and investigation of plasmonic nanostructures coupled to semiconductors, ceramics, glass and plastics by MBE, thermal evaporation and plasma sputtering
- Synthesis of plasmonic systems alternative to nobel metals
- Design and synthesis of novel multifunctional multi-metallic core-shell nanoparticles supported on various substrates combining plasmonic/catalytic (e.g. Ag/Pd) and plasmonic/magnetic (e.g Au/Co) functionalities
- Development of Biochemical sensing exploting SERS mechanism
- Design of Enhanced light-matter interaction coupling semiconductors
- Tailoring of surface energy of support at the interface nanoparticle/substrate to tune nanoparticle shape and plasmonic response
- Post growth processing by annealing and plasmas to tailor optical and plasmonic properties
- Development of system for liquid and phase-change plasmonics
- Exploitation of plasmonics in localized catalysis
Molecular Architectures at Interfaces
The interfaces between bulk media are often site of reactions and phenomena which are distinct from the bulk substances and frequently dominate the macroscopic properties of the entire system. Understanding how molecules adsorb and react with these surfaces has potential applications in industrial processes and everyday life. Catalyses, combustions, lubrication, adhesion, wetting, electrochemical reactions are only few examples of phenomena of industrial interest which are governed by interfacial properties. Polymer surfaces and interfaces play an increasingly important role in modern electronic and optoelectronic technologies (i.e. organic transistors, OLED), as well as in biomedical applications (i.e., biocompatibility). Surface-specific IR and visible sum-frequency generation (SFG) vibrational spectroscopy is a powerful and versatile in situ surface probe which permits identification of surface molecular species and provides information about orientation of functional groups at the surface. SFG is non destructive, highly sensitive, and has good spatial, temporal, and spectral resolution. Because the technique works in real time under water and protein solutions it is also very well suited for studying biomaterials and biointerfaces.
High Charge Mobility Columnar Mesophases
Molecularly organized supramolecular materials are promising candidates for applications in organic opto-electronics since the properties of functional materials can be enhanced when they have a well-organized internal structure. Within this frame, the ability of liquid crystals to self-organize in mesophases to obtain functional architectures is frequently exploited and, in particular, the properties of columar liquid crystals are exploited since they are able to stack spontaneously into columns to give one-dimensional structures of π-conjugated organic molecules. This organization reflects in a long-range π-orbital overlap that allows, after suitable charge injection, intracolumnar charge carrier mobilities with high values comparable to those of amorphous silicon. These properties make columnar liquid crystals very attractive materials for use as organic semiconductors.
Study and characterization of novel columnar liquid crystal based on innovative molecular and supramolecular architectures ;
Studies of discotic mesophases whit ambipolar electrical conductivity;
Development of high mobility columnar mesophases with suitable mechanical and physical properties for application in devices (OFET, Photovoltaics etc.)
Organic-inorganic nanocomposites consisting of metal or metal oxide nanoparticles embedded in an organic matrix combine unique properties offered by both organic and inorganic components on a nanoscale level and are, therefore, attractive materials for a large number of applications in the field of catalysis (e.g., Pt, ZnO, TiO2), sensing, optical filters, antibacterial metal (Ag, Cu) delivery systems, plasmonic devices.
Plasma nanotexturing is a quite fast method to address biomimetic properties to simple raw materials such as polymer or glass. It can be driven via bottom up approach or a top down one: in the first case the adsorbed precursors can organize in a hierarchical way leading to a micro/nanotextured coating, in the latter subtractive etching, assisted by the random arrival of inhibitors, leads to the formation of pillars. After nanotexturing, the chemistry of the surface can be tuned by a suitable plasma deposited coatings, to become more hydrophobic or hydrophilic or functionalized. Nanotextured surfaces give access to unique properties such as water and oil repellency, antireflectivity (moth eye effect), superhydrophilicity and anti-fog.
- Nanotexturing of surfaces can be obtained by plasma rough etching of polymers with O2 fed plasma or in the case of silicon based materials (Si, SiO2 but even silicone) with fluorine producing plasmas
- transfer of a pattern produced by exposing a micro-featured (i.e. TEM copper grid) or nano-featured mask (i.e. colloidal lithography)
- deposition of teflon-like coatings in soft plasma conditions (i.e. modulated/pulsed discharges)
- aerosol-assited cold plasma deposition of nanocomposite coatings consisting of inorganic nanoparticles embedded in an organic matrix and showing hierarchical multiscale surface texture.