Nanomaterials are all those materials with a particle size smaller than 100 nm in at least one of their 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 their size: a nanometer is one billionth of a meter! A very curious fact about nanomaterials is that their physicochemical properties are different from those of the same material when it is micro- or macroscopic in size. For example, mercury shows non-metallic behavior when nanocrystals are smaller than 2 nm. This is because when we decrease the size of a material, we increase its surface area, which means it has more space to interact with other atoms and/or molecules, both to attract (Van der Waals interactions, hydrogen bonds, electrostatic interactions, etc.) and to repel due to the interaction between their electron clouds.

 

Origin of nanomaterials

The first ideas and concepts behind nanoscience and nanotechnology appeared in the work titled “There’s plenty of room at the bottom” by physicist Richard Feynman at the American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959. This scientific conference marked the beginning of the era of nanomaterials, as Feynman described a process in which scientists could manipulate and control individual atoms and molecules, and the revolution this would entail. Decades later, Professor Norio Taniguchi coined the term nanotechnology, although it was not until 1981 that modern nanotechnology began to be discussed thanks to the development of the scanning tunneling microscope by G. Binnig and H. Rohrer (IBM Zurich), which allowed scientists to see individual atoms for the first time.

Properties of nanomaterials

As size is reduced to the nanometer scale, the exposed surface area increases, favoring greater interaction between nearby atoms and molecules. This gives rise to various interactions, attractions, and repulsions that cause surface, electronic, and quantum effects affecting the optical, electrical, and magnetic behavior of materials. This means that with a very small amount of nanomaterial it is possible to significantly modify and improve the properties of other materials, giving them great potential and added value. An example of this is polymers doped with carbon nanotubes, which make the doped material lighter, mechanically stronger, and more functional than metals.

Types of nanomaterials and applications

Nanomaterials can be grouped into different classifications, but one of the most important is based on their dimensions:

Zero-dimensional nanomaterials:

All their dimensions are within the nanoscale. 0D nanomaterials are considered nanoparticles.
This group includes fullerenes, inorganic nanomaterials such as Au and Ag nanoparticles,
nanoclays, nanodiamonds, or quantum dots.

Fullerenes have potential applications in medicine as a delivery vehicle for drug release
because they have good biocompatibility, are selective, retain biological activity, and are small enough
to diffuse.

Carbon quantum dots are carbon-based semiconductor nanostructures studied as substitutes for conventional quantum dots,
since they show the same fluorescence properties for use as biosensors,
but are biocompatible and much less toxic.

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 polymeric matrices to improve certain properties.

They also improve electrical conductivity in adhesives and paints without altering their rheological properties
and prevent corrosion of coated materials. Their 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-like materials;
among them are graphene, nanofilms, and nanocoatings.

Within this group, graphene is the most representative material and has the greatest potential for application
in different fields such as medicine, where its application as a transport and drug delivery system
or as a biosensor is being investigated.

In the energy sector, graphene can extend the life of a traditional lithium battery,
charging it faster and keeping it running longer.

In the electronics sector, this material can be introduced into the touch screens of devices
to improve their properties or into computer circuits to increase their processing speed.

Its application as a filtration system is also being studied, since graphene oxide can form a membrane
that acts as a barrier against liquids and gases, enabling water purification.

Three-dimensional nanomaterials:

Materials that have no dimension in the nanoscale. This classification includes nanostructured materials,
nanoparticle dispersions, and multi-nanolayers.

In this regard, tungsten oxide has been investigated as a material for photoelectrochemical hydrogen generation.
The surface of the nanostructured semiconductor material absorbs solar energy and also acts as an electrode
for water electrolysis.

How are nanomaterials manufactured?

Top-down:

The Top-Down strategy consists of manufacturing nanomaterials from larger-scale materials
that are reduced until they reach the nanoscale. This method offers reliability and
complexity in devices, but involves high energy costs, greater
surface imperfections, and contamination issues.

This technique is used, for example, in the microelectronics industry or in lithography,
where materials are exposed to light, ions, or electrons to achieve the desired sizes.

Bottom-up:

The Bottom-Up strategy consists of building structures atom by atom or molecule by molecule.
The degree of miniaturization achieved with this technique is greater than what can be achieved with the Top-Down strategy,
since thanks to microscopes there is great capacity to place individual atoms
and molecules in a specific location.

This type of technique can be further subdivided into three groups:

• Chemical synthesis
• Positional assembly
• Self-assembly

What is expected from nanotechnology and nanoscience?

Nanotechnology is capable of creating 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.

Safety and health in working with nanomaterials

The information currently available on the effects of nanomaterials on human health is very limited for most of them. Since they do not behave the same way as the same material at the micro or macroscopic scale, their effects cannot be extrapolated to the nanoscale. For this reason, it is very important to continue researching to expand knowledge in this regard.

But nanomaterials should not be feared, as 90% are of natural origin, generated by volcanic activity, fires, and pollen.

From a regulatory point of view, there is no specific regulation for their use at either the European or international level, although there are recommendations and manuals for working with nanomaterials. Currently, occupational risk prevention regulations apply in terms of protecting the health and safety of workers against the risks of chemical agents, as well as the European regulation on 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).

At Nanomate, one of our main objectives is the continuous training of our employees, which makes us highly competitive and allows us to offer our clients the best solutions on the market. All this is accompanied by thorough production and quality controls, which ensure both the safety of our workers and compliance with current and future restrictive legislation.