Nanotechnology – widely applied
In the past nanotechnology sounded like science-fiction, nowadays it is fully incorporated in our daily lives. Even if we don’t always notice nano-particles – they are widely applied in chemical and downstream industries.
Nano-particles have unique physical and chemical properties due to their high surface area and nanoscale size (ranging from 1nm-100nm). The properties are dependent on the particle size and shape, allowing the possibility of tuning the material according to the required characteristics.
As shown in figure 1, the decrease of size from materials in micro-size to nano-sized, causes:
- an increase in the surface area
- anti-bacterial properties
- hardness
- electron band gap
- changes in the optical, electric and magnetic properties.
Due to these characteristics, they are suitable candidates for various commercial and domestic applications, which include catalysis, imaging, medical applications, energy-based research, and environmental applications.
Main applications of nanomaterials
- Paints & coatings
- Cosmetics
- Catalysts
- Lightening / display industry
- Energy sector: solar cells / batteries
- Membranes and filters
Cosmetics
After recognizing the estrogen-like activity of numerous organic sunscreen additives, inorganic UV absorbing pigments based on titania nanoparticles and zinc oxide were introduced at a large scale to the cosmetics industry.
There, nanoparticles were advantageous since they range below 50 nm. Visible light scattering becomes negligible, and corresponding UV protection can be realized with a reduced whitening effect that is typical on sunscreen products.
Other applications of Nanoparticles in the cosmetic industry include skin creams and lotions. These use proteins derived from stem cells or other nutrients, which are encapsulated in nanoparticles and merge with the membranes of skin cells to allow an active delivery in deeper skin layers.
Paints & Coatings
Additives containing nanoscale materials have previously been used in the production of paints and coatings. For example, barium sulfate and iron oxide as coloring pigments and synthetic amorphous silica to influence the fluidity of the product.
Today it is possible to tailor the nanostructures in the coating industry to the specific needs of the various applications. Novel nano-based coatings are used today, for instance, to functionalize surfaces, to provide protection against corrosion and dirt, to prevent biological soiling and graffiti, or to create attractive designs by special color effects. The German Paint and Printing Ink Industry Association (VdL) estimates that by 2020 about 20 % of the turnover in Germany will come from the use of nanotechnology.
Lightening
With more efficient and cheaper technologies, LED lighting and displays have allowed ultra-flat, very bright, and power-saving applications.
Most recently, quantum dots (semiconductor nanoparticles with dimensions of up to 10 nm) have become one of the most promising optoelectronic materials. Quantum dots have tunable and valuable properties. They are assumed to be the next-generation display technology.
Quantum-Dot-based materials have purer colors, longer lifetime, lower manufacturing cost, and lower power consumption. Another key advantage of the quantum dot displays is that, because Quantum Dots can be deposited on virtually any substrate, one can expect printable and flexible – even foldable – displays of all sizes.
Energy sector: solar cells, batteries
Solar cells are exposed to intense radiation – this creates a strong demand for extremely bleach resistant materials.
Further it puts severe limitations on the use of organic materials, particularly when designing organic photovoltaics. As a result, the design of increasingly or even predominantly inorganic solar cells is a major research area, and functional layers are subsequently replaced using nanoparticle-based inks.
A recent example is the so-called hole injection layers, today accessible using transition metal oxide nanoparticles.
On top of that, nanoparticles have been changing the battery industry due to the production of materials with nanopore. This allows a selective exchange and transport of some components.
Membranes and filters
Traditional manufacturing of water filtration membranes is based on the so-called phase inversion. Here, a nonsolvent is used to precipitate a polymer in the form of a pre-shaped, partially dissolved film. This elegant process suffers from huge solvent consumption and difficult process control.
Splitting up film formation and nanopore generation, recently afforded an easy to control process. First leading to a composite film that is subsequently converted into the final porous Membrane.
Catalysts
Nanomaterial-based catalysts are usually heterogeneous catalysts, broken up into metal nanoparticles – in order to speed up the catalytic process. Metal nanoparticles have a higher surface area. There is increased catalytic activity, in comparison to the analogous bulk material, because more catalytic reactions can occur at the same time.
Nanoparticle-surface supports heterogeneous catalysts, permitting the materials to be dispersed in a reaction medium and rapidly removed when isolating a product.
The surface activity of gold is undoubtedly the most prominent and outstanding example of industrial relevance.
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