What are nanomaterials?
13.02.2023Nanomaterials are all those materials with a particle size of less than 100 nm in at least one of its dimensions. Although scientists have not reached a unanimous agreement on the definition of these materials, they do agree that they are characterized by their small size, measured in nanometers.
To give you an idea of its size: a nanometer is one billionth of a meter!
Something very curious about nanomaterials is that their physicochemical properties are different from those they have when they are micro or macroscopic in size, for example, mercury shows a non-metallic behavior when the nanocrystals are smaller than 2 nm, this is because when we reduce the size of a material we are increasing its surface area, so it has more space to interact with other atoms and/or molecules, both to attract (Van der Waals interactions, Hydrogen Bridges, electrostatic interactions , etc.) as to repel due to the interaction between its electronic clouds.
Origin of nanomaterials
The first ideas and concepts behind nanoscience and nanotechnology appeared in the work entitled “There´s plenty of room at the bottom” of physicist Richard Feynman at the meeting of the American Physical Society at the California Institute of Thechnology (CalTech) on December 29, 1959. This scientific conference marked the beginning of the nanomaterial era, since Feyman described a process in which scientists could manipulate and control individual atoms and molecules, and the revolution that this would entail.
Decades later, Professor Norio Taniguchi coined the term nanotechnology, although it was not until 1981 when modern nanotechnology began to be discussed thanks to the development of the tunnel effect microscope by G. Binnig and H. Rohrer (IBM Zurich), which allowed see individual atoms for the first time.
Properties of nanomaterials
As the size is reduced to the nanometric scale, the exposed surface area increases and this favors the greater interaction between nearby atoms and molecules, giving rise to various interactions, attractions and repulsions that cause surface, electronic and quantum effects that affect to the optical, electric and magnetic behaviors of the materials.
This means that with a very small amount of nanomaterial the properties of other materials can be modified and significantly improved, providing great potential and added value. An example of this will be polymers doped with carbon nanotubes, which make the doped material have a lightness, mechanical strength and functionality superior to metals.
Types of nanomaterials and applications
Nanomaterials can be grouped into different classifications, but one of the most important is according to their dimensions:
• Nanomaterials of dimension 0: All its dimensions are within the nanoscale. 0D nanomaterials are considered nanoparticles. Within this group are fullerenes, inorganic nanomaterials such as Au and Ag nanoparticles, nanowires, nanodiamonds or quantum-dots.
Fullerenes have potential application in medicine as they can be used as transport for drug release since they have good biocompatibility, are selective, retain biological activity and their size is small enough to be diffused.
Carbon quantum-dots are carbon semiconductor nanostructures studied to replace conventional quantum-dots since they have the same fluorescence properties to be applied as biosensors but are biocompatible and their toxicity is much lower.
• One-dimensional nanomaterials: Two dimensions are within the nanoscale. This classification includes nanotubes and carbon nanofibers.
The latter are applied as additives for example in polymer matrices to improve some of its properties.
They also improve the electrical conductivity in adhesives and paints without modifying their rheological properties and prevent corrosion of the materials that are coated. Its electrical conductivity properties allow them to be used in the construction of anodes and cathodes and in the formulation of conductive inks that can be used in the construction of flexible electronic circuits.
• Two-dimensional nanomaterials: In these nanomaterials one of the three dimensions is within the nanoscale. They are sheet-shaped materials. Among them are graphene, nanofilms, and nanocoatings.
Within this group, graphene is the most representative material and with the greatest potential for application in different fields such as medicine, where its application is investigated as a drug transport and release system or as a biosensor. In the energy sector since graphene can increase the life of a traditional lithium battery, charging it faster and keeping it running longer. In the electronic sector, this material can be introduced in the touch screens of the devices to improve their properties or in the electrical circuits of the computers to increase their processing speed. Its application is also studied as a filtration system since graphene oxide can form a membrane that acts as a barrier against liquids and gases allowing water purification.
• Three-dimensional nanomaterials:Materials that have no dimension in the nanoscale. Within this classification are nanostructured materials, nanoparticle dispersions and multi-nanolayers. In this sense, tungsten oxide has been investigated as a material for the photoelectrochemical generation of hydrogen. The surface of the nanostructured semiconductor material absorbs solar energy and acts as an electrode for water electrolysis.
How are nanomaterials made?
• Top-down: The Top-Down strategy consists in the manufacture of nanomaterials from larger-scale materials that are reduced to reach the nanometric scale. This method offers reliability and complexity in the devices, but it has associated high energy costs, greater imperfection on the surface of the structure and pollution problems.
This technique is used for example in the microelectronic materials industry or in lithography where materials are exposed to light such as ions or electrons to achieve the desired sizes.
• Bottom-up: The Bottom-Up strategy consists of the construction of structures, atom by atom, or molecule by molecule. The degree of miniaturization achieved by this technique is higher than that which can be achieved with the top-down strategy because thanks to microscopes there is a great capacity to place individual atoms and molecules in a certain place.
This type of technique can be subdivided into three groups: Chemical synthesis, Positional assembly and Self-assembly.
What is expected from nanotechnology and nanoscience?
Nanotechnology can create new materials and devices that can be used for a wide range of applications in fields as diverse as nanomedicine, nanoelectronics, biomaterials, energy production and consumer products. This will mean a great technological and environmental revolution.
Safety and health at work with nanomaterials
The information currently available on the effects of nanomaterials on human health is very limited for most nanomaterials, and since they do not behave like the same material on their micro or macrometric scale, their effects cannot be extrapolate to the nanometric scale, for this reason it is very important to continue researching to expand knowledge in this regard.
But you should not be afraid of nanomaterials since 90% are of natural origin caused by volcanic activity, fires and pollen.
From the normative point of view there is no specific regulation for its use either at European or international level, although there are recommendations and manuals for the use of nanomaterials. Currently, the regulations for the prevention of occupational hazards in matters of health protection and safety of workers against risks of chemical agents are applied, and the European regulation regarding the registration, evaluation, authorization and restriction of chemical substances and preparations (REACH) on classification, labeling and packaging of substances and mixtures (known as the CLP regulation).
From Phi 4 Technology one of our main objectives is the continuous training of our workers, which makes us very competitive and allows us to give our customers the best solutions in the market. All this accompanied by exhaustive controls of production and quality, which guarantees both the safety of our workers and compliance with the most restrictive present and future laws.