Nanomaterials facts for kids

Kids Encyclopedia Facts

Nanomaterials are super tiny materials, so small that you can't see them without special microscopes! Imagine something between 1 and 100 nanometers big. A nanometer is one billionth of a meter – that's like comparing a marble to the entire Earth!

Scientists who study nanomaterials use ideas from materials science and nanotechnology. They've found that materials this small can have amazing and unique properties. For example, they might act differently with light, electricity, heat, or even be super strong.

These tiny materials are slowly starting to appear in many products we use every day.

What Are Nanomaterials?

The word "nanomaterial" means a material that has at least one part of it (like its length, width, or thickness) that is between 1 and 100 nanometers. This includes two main types:

Nano-objects: These are tiny, separate pieces of material.
Nanostructured materials: These materials have tiny structures inside them or on their surface that are in the nanoscale.

Different Kinds of Nanomaterials

Nano-objects are often grouped by how many of their dimensions (length, width, height) are in the nanoscale.

Tiny Shapes: Nano-objects

Nanoparticles: These are like tiny dots or balls, with all three dimensions in the nanoscale. Their length and width are pretty much the same.
Nanofibers: These are long and thin, like tiny threads. Two of their dimensions are in the nanoscale.
- Nanotubes: These are hollow nanofibers, like super tiny straws.
- Nanorods: These are solid nanofibers, like tiny sticks.
Nanoplates/Nanosheets: These are flat and thin, like tiny sheets of paper. Only one of their dimensions is in the nanoscale. If they are much longer than they are wide, they are called nanoribbons.

Materials with Tiny Structures: Nanostructured Materials

Nanocomposites: These are solid materials made from at least two different parts, where one part has dimensions in the nanoscale.
Nanofoams: These are like sponges, with tiny gas bubbles inside a liquid or solid material. One of the two parts (the gas or the material) is nanoscale.
Nanoporous materials: These are solid materials with tiny holes (pores) that are nanoscale.
Nanocrystalline materials: These materials are made of many tiny crystals, where a big part of these crystals are nanoscale.

Nanoporous Materials

These materials have tiny holes or pores.

Microporous materials have pores smaller than 2 nanometers.
Mesoporous materials have pores between 2 and 50 nanometers.

These materials are useful for things like separation membranes (filters) or for holding many molecules because they have a huge inner surface.

Nanoparticles

Nanoparticles are tiny particles where all three dimensions are in the nanoscale. They can also be mixed into larger materials to make nanocomposites.

Fullerenes

Fullerenes are a special type of carbon. Imagine a sheet of graphene (a super-thin carbon material) rolled up into a tube or a sphere.

Carbon nanotubes are like tiny, strong tubes. They are interesting for their strength and how they conduct electricity.
The most famous fullerene is called buckminsterfullerene (C₆₀), which looks like a tiny soccer ball. It was discovered in 1985 by scientists at Rice University.

A spinning view of C₆₀, a type of fullerene.

Scientists are still studying fullerenes for many uses, including in medicine to fight bacteria or even cancer cells. They are also being researched for their ability to resist heat and conduct electricity without resistance (superconductivity).

Metal-based Nanoparticles

These are tiny particles made of metals, semiconductors, or oxides. They have cool properties related to light and electricity, making them useful in things like optoelectronics (devices that use both light and electricity). For example, they could be used in Organic solar cells or OLEDs (lights for screens). Nanoparticles are also being studied for biomedical uses, like helping with tissue engineering, delivering medicines, or creating tiny biosensors.

What makes nanoparticles special is that their properties can change depending on their size. For example:

Tiny semiconductor particles can show "quantum confinement" effects, changing how they conduct electricity.
Some metal particles have "surface plasmon resonance" which affects how they interact with light.
Tiny magnetic materials can become "superparamagnetic".

Even common materials like copper act differently at the nanoscale. Copper nanoparticles smaller than 50 nanometers are super hard and don't bend easily like regular copper wire. Also, gold nanoparticles can look deep red or even black when mixed in a liquid, instead of shiny gold!

One-Dimensional Nanostructures

These are like super thin wires, sometimes as thin as a single atom! Carbon nanotubes are a good example. They can be used as a base to build other tiny wires.

Two-Dimensional Nanostructures

These are materials that are just one layer of atoms thick, like a super-thin sheet. The most famous one is graphene, discovered in 2004. Very thin films are also considered nanostructures, but they usually need to be on a surface and don't exist on their own.

Bulk Nanostructured Materials

Some larger materials have tiny features inside them that are nanoscale. Examples include nanocomposites and nanocrystalline materials. A cool example is "Box-shaped graphene" (BSG), which has tiny hollow channels inside it, about 1 nanometer thick.

How Nanomaterials Are Used

Nanomaterials are used in many different ways, from manufacturing to healthcare:

Paints and Filters: They can make paints stronger or help create filters that can remove tiny particles, even viruses, from water or air.
Insulation: Modern, safe insulation can use nanomaterials.
Lubricants: Adding nanomaterials to lubricants can reduce friction in moving parts, making machines run smoother.
Sunscreen: Tiny mineral particles like titanium-oxide are used in sunscreen to give better UV protection.
Sports Gear: Carbon nanotubes can make lighter sports equipment, like baseball bats.
Military: Mobile pigment nanoparticles are used to create better camouflage.
Car Catalysts: They are used in car exhaust systems (three-way catalysts) to reduce harmful pollution like nitrogen oxides.
Nanozymes: In healthcare, these are nanomaterials that act like natural enzymes, helping with things like biosensing (detecting biological substances), bioimaging (seeing inside the body), and even fighting tumors.

How Nanomaterials Are Made

Making nanomaterials usually involves controlling their size very carefully, so they have the special properties we want. There are two main ways to make them:

Building Up: Bottom-Up Methods

These methods involve putting atoms or molecules together, piece by piece, to build nanostructures.

Chaotic Processes: Imagine heating up atoms or molecules until they're in a wild, chaotic state, then suddenly cooling them down. They quickly form nanoparticles. Examples include laser ablation or burning materials.
Controlled Processes: These methods carefully deliver atoms or molecules to a specific spot, allowing the nanoparticle to grow slowly and precisely to the desired size. Examples include self-limiting growth in solutions or molecular beam epitaxy.

Breaking Down: Top-Down Methods

These methods involve taking larger materials and breaking them down into nanoparticles.

A common method is ball milling, where materials are ground into tiny pieces using tiny balls.
Another method is laser ablation, where short, powerful laser pulses are used to chip off tiny bits from a solid material.

How Scientists Study Nanomaterials

Scientists study nanomaterials to understand their unique properties.

Quantum Effects: When materials get super small (nanoscale), their electrons can behave differently. This is called "quantum confinement" and can change how the material conducts electricity or how it glows (fluorescence).
Mechanical Properties: Nanomaterials can be incredibly strong or flexible. When added to a larger material, they can make it much stiffer or more elastic. For example, adding carbon nanotubes to plastics can make them super strong and lightweight, like a replacement for metals.
Catalysts: Many nanomaterials, like zeolites, are used as catalysts in chemical reactions. They help reactions happen faster and more efficiently, which is good for the environment.

Scientists use special tools like ultramicroscopes (developed in the early 1900s) and modern techniques like light scattering and ultrasound to measure the size and properties of these tiny particles. They also study their surface charge to make sure they don't clump together.

Stronger Materials: Mechanical Properties

Nanomaterials often have much better mechanical properties (like strength and hardness) than larger materials. This is because of their tiny size and how their surfaces behave.

When nanoparticles are added to a material, they can make it much stronger by improving its internal structure. For example, adding nano-silica to cement makes the cement much stronger and more resistant to breaking.
Scientists use techniques like nanoindentation (pushing a tiny tip into the material) and AFM (a super-sensitive microscope) to measure these properties.
Crystalline metal nanomaterials: Tiny gold nanoparticles are much harder than regular gold. This is because of tiny flaws and changes in their structure that make them stronger.
Nonmetallic Nanoparticles: The strength of polymer nanomaterials can vary. Sometimes, they can clump together, which might make the material weaker.
Nanowires/Nanotubes: The strength of these tiny wires can change with their diameter, depending on the material.

Studying the mechanical properties of individual nanoparticles is tricky, but AFM and computer simulations (like molecular dynamics) are helping scientists understand them better.

Sticking and Sliding: Adhesion and Friction

How well a material sticks to something (adhesion) and how easily it slides (friction) are also important.

Nanomaterials can greatly increase a material's ability to stick to surfaces because of their large surface area and special forces like electrostatic forces.
Scientists use AFM to measure these properties. They've even observed how tiny particles like fullerenes move by rolling or sliding, which affects their ability to reduce friction (lubrication).

These properties are important for things like:

Lubrication (making things slide smoothly)
Nano-manufacturing (making tiny parts)
Coatings (protective layers)

Making Them Even: Uniformity

For high-tech products, it's important that nanomaterials are spread out evenly. If they clump together, it can cause problems like cracks or weak spots in the final product.

Imagine trying to build a wall with bricks of different sizes and shapes – it would be hard to make it strong and even. It's similar with nanomaterials.
Scientists use special liquids and additives called "dispersants" to help keep nanoparticles spread out and prevent them from clumping.
Using "monodisperse" nanoparticles (all the same size) helps create very uniform and strong materials.

Nanomaterials in the World

Nanomaterials are a hot topic! By 2018, hundreds of thousands of scientific articles had been written about nanoparticles, nanotubes, and other nanomaterials. They are also mentioned in many patents, showing how new inventions use them. Thousands of products on the market today use nanoparticles to improve their features. Things like liposomes (tiny bubbles for drug delivery), nanofibers, and aerogels are common in consumer products. The European Union has an online observatory (EUON) with a database called NanoData that provides information on patents, products, and research about nanomaterials.

Keeping Safe: Health and Safety

Since nanotechnology is quite new, scientists are still studying how exposure to nanomaterials might affect our health and what levels are safe.

Breathing Them In: Breathing in tiny nanoparticles seems to be the biggest concern. Studies on animals show that carbon nanotubes can cause lung problems, similar to asbestos.
Skin Contact and Swallowing: There are also concerns about nanomaterials touching skin or being swallowed.
Dust Explosions: Fine powders, including some nanomaterials, can also cause dust explosions.

The World Health Organization (WHO) has created guidelines to help protect workers from potential risks. They suggest:

Being Careful: Even if we're not totally sure about the risks, it's best to reduce exposure as much as possible.
Controlling Exposure: The best way to protect workers is to remove the source of exposure first. This means using engineering controls like special ventilation systems (fume hoods, gloveboxes) to keep workers away from the materials.
Personal Protective Equipment (PPE): Things like gloves, goggles, and special masks (respirators) should be used as a last resort if other controls aren't enough.
Training: Workers should be trained on how to handle, store, and dispose of nanomaterials safely.

Scientists are constantly working to understand more about the safety of nanomaterials, and these guidelines will be updated as new information becomes available.

Tiny Tools for Health: Nanoscale Diagnostics

Nanotechnology is making big waves in medicine, especially in how we see inside the body (biomedical imaging).

Nanomaterials have unique properties that allow them to be used as "imaging probes." These probes can help doctors see things more clearly, like where tumors or inflammation are located. This helps with early detection and personalized treatment.

Silica Nanoparticles

These are tiny particles made of silica (like sand). They can be solid or have tiny pores.
They are made in a special process called the Stöber process, which allows scientists to control their size.
Their surfaces are "hydrophilic" (attracted to water), which makes them great for carrying medicines or genes.
Because they have a large surface area, they can carry much more medicine than traditional methods.
They can be designed to target specific areas, like cancer tumors. Once at the tumor, they can release medicine or even be heated to damage the tumor cells.
Silica nanoparticles are also used in bioimaging because they can carry special dyes or agents that glow or show up on MRI scans, helping doctors see inside the body.

Super-Sensitive Imaging: TAS3RS

TAS3RS (Topically applied surface-enhanced resonance Raman ratiometric spectroscopy) is another new imaging technique.
It uses special nanoparticles to detect tiny tumors, even as small as 370 micrometers (that's less than half a millimeter!).
This technique looks for "Folate Receptors" (FR), which are often found in large amounts on the surface of many cancer cells.
TAS3RS is super sensitive and can be applied locally (not needing to go into the bloodstream), which avoids some safety concerns. It's also more stable than other imaging methods, meaning fewer false results.