Nano Science And Applications Lec 1 Q and A

What is the size range that defines nanoscience?

1 to 100 nanometers (nm)

Define Nanoscience?

the study of structures and materials at a very small scale, specifically 1 to 100 nanometers (nm)

What distinguishes the properties of materials at the nanoscale compared to larger amounts of the same material?

Unique physical, chemical, and biological properties

Define nanotechnology?

The practical use of nanoscience to design, create, and use materials, devices, and systems at the nanoscale

Involves manipulating matter at an atomic or molecular level

What is the goal of nanotechnology?

To develop new materials with enhanced properties for use in various fields like medicine, electronics, and energy

How large is one nanometer?

One billionth of a meter (10⁻⁹ m)

Besides small size, what other key aspect defines nanoscience?

Materials show new physical phenomena called quantum effects

What is a characteristic of quantum effects at the nanoscale?

They are size-dependent

They cause nanoscale materials to behave differently from macro-scaled or bulk materials

List some of the properties that can be changed in nanoscale materials due to quantum effects?

Color,Solubility,Strength Electronic conductivity,Thermal conductivity,

Magnetic behavior ,Mobility ,Chemical activities ,Biological activities

What is the approximate diameter of a human hair?

80,000 nm

What is the approximate diameter of a red blood cell?

2000 nm

What is the approximate length of 10 compact hydrogen atoms?

1 nm

What is the approximate length of a water molecule?

0.1 nm

Approximately how many gold atoms positioned adjacently equal 1 nm?

Three and a half

What gap do nanoparticles bridge?

The gap between the atomic/molecular scale and the bulk material scale

What is the size range of the atomic scale?

0.1–1 nm

What is involved at the atomic scale?

Individual atoms and small molecules

What is the size range of the nanoparticle scale?

1–100 nm

What is the size of the bulk material scale?

>100 nm

What governs the properties of materials at the bulk material scale?

Classical physics, not quantum effects

Give an example of the early use of nanomaterials?

Ancient Romans using gold and silver nanoparticles in glassmaking for colours in church windows

Who introduced the idea of manipulating atoms in the 20th century and in what lecture?

Physicist Richard Feynman in his 1959 lecture, "There’s Plenty of Room at the Bottom"

What invention in the 1980s allowed scientists to see and move atoms?

The Scanning Tunneling Microscope (STM)

What is the defining characteristic of a nanomaterial based on its dimensions?

An object with at least one dimension in the nanometer scale (approximately 1-100nm)

What are zero-dimensional (0D) nanomaterials? Provide an example

All dimensions are confined to the nanoscale Example: Nanoparticles (e.g., quantum dots)

What are one-dimensional (1D) nanomaterials? Provide examples

One dimension is in the nanoscale range, while the other two are larger than the nanoscale

Examples: Nanotubes, nanowires

What are two-dimensional (2D) nanomaterials? Provide examples

Two dimensions are in the nanoscale range, while the third dimension is larger Examples: Nanosheets, graphene

What are three-dimensional (3D) nanomaterials? Provide examples

All three dimensions are beyond the nanoscale but contain nanoscale building blocks

Examples: Nanocomposites, bulk nanomaterials

Give examples of carbon-based nanomaterials?

Examples: graphene, carbon nanotubes (CNTs), carbon nanodots

What is a Property of carbon-based nanomaterials?

High electrical and thermal conductivity mechanical strength, biocompatibility

What is a application of carbon-based nanomaterials?

Batteries, sensors, drug delivery, composites, water purification

Give examples of metal-based nanomaterials?

Gold (Au), silver (Ag), platinum (Pt), copper (Cu) nanoparticles

What is a Property of metal-based nanomaterials?

Strong surface plasmon resonance, catalytic activity, antimicrobial properties.

What is a application of metal-based nanomaterials?

Biomedical imaging, catalysis, sensors, antimicrobial coatings.

Give examples of metal oxide-based nanomaterials?

Titanium dioxide (TiO₂), zinc oxide (ZnO), aluminum oxide (Al₂O₃), silicon dioxide (SiO₂)

What is a Property of metal oxide -based nanomaterials?

High photocatalytic activity, optical transparency, chemical stability

What is a application of metal oxide -based nanomaterials?

Photocatalysis, UV-blocking coatings, environmental remediation, semiconductors

Give examples of polymer-based nanomaterials?

polymeric micelles, nanogels.

What is a Property of polymer-based nanomaterials?

Biodegradability, flexibility, chemical tunability

What is a application of polymer-based nanomaterials?

Drug delivery, tissue engineering, nanocomposites

what is the definition of composite nanomaterials?

Combination of two or more different nanomaterials to enhance properties

Give examples of composite nanomaterials?

polymer-metal composites, ceramic nanocomposites

What is a Property of composite nanomaterials?

Improved mechanical, electrical, and thermal properties

What is a application of composite nanomaterials?

Aerospace, automotive industry, energy storage, biomedical applications

What is a key characteristic of nanomaterials that makes them special?

Their properties like electrical, mechanical, thermal, and optical properties can change at the nanometer scale compared to their bulk form

How can the properties of bulk silver differ from silver nanoparticles?

Bulk silver is non-toxic, but silver nanoparticles can kill viruses

How can the conductivity of a semiconductor change at the nanoscale?

A semiconductor can become a good conductor

How do the mechanical properties of nano phase ceramics compare to bulk ceramics?

Nano phase ceramics are more ductile than bulk ceramics

How does the melting temperature of gold nanoparticles (2.5 nm) compare to bulk gold?

Gold nanoparticles (2.5 nm) melt at a much lower temperature (300˚C) than bulk gold (1064˚C)

How do the mechanical properties of carbon nanotubes compare to the bulk material?

They are better than the bulk material

What happens to the optical properties of nanoparticles when their size is changed? Provide an example.

Their optical properties alter

Example: Observed in CdSe semiconductor nanoparticles and Gold nanoparticles

What two main factors give rise to the unique properties of nanotechnology?

Small size

High surface area-to-volume ratio

How do quantum mechanics affect material behavior at the nanoscale?

It leads to novel optical, electrical, and magnetic properties

What effect does the high surface area-to-volume ratio have on the chemical reactivity of nanomaterials?

It enhances chemical reactivity and catalytic properties

How can the mechanical strength of nanomaterials compare to their bulk counterparts? Give an example.

Nanomaterials can be stronger and more durable Example: Carbon nanotubes are stronger than steel

How can quantum dots demonstrate enhanced optical properties?

They can emit different colours depending on their size

Provide an example of a nanomaterial with exceptional electrical conductivity?

Graphene

How does the surface area of nanomaterials compare to the same amount of material in bulk form?

Nanomaterials have a greater surface area

Why are nanomaterials excellent catalysts?

The increased chemical reactivity due to high surface area

Explain the concept of surface area-to-volume ratio in nanomaterials compared to bulk materials?

Nanomaterials have a much higher surface area compared to their volume A significant portion of their atoms are on the surface

If the size of a material decreases 1000 times, how does its surface area-tovolume ratio change?

The surface area-to-volume ratio increases by the same factor (1000 times)

For a cube of side length L, what is the formula for its surface area (SA)?

SA = 6L²

For a cube of side length L, what is the formula for its volume (V)?

V = L³

For a cube of side length L, what is the ratio of surface area to volume (SA/V)?

6/L

Why is a high surface area crucial for nanomaterials?

Increases Chemical Reactivity: More surface atoms are exposed, leading to faster chemical reactions

Influences Mechanical Properties: Can exhibit unique and enhanced strength, flexibility, and durability

Benefits Energy Applications: Improves the efficiency of batteries, fuel cells, and solar panels

What is one type of imperfection that tends to be reduced in nanomaterials?

Fewer imperfections

What process allows impurities and internal defects in nanomaterials to move towards the surface?

Thermal annealing

What is the result of the self-purification process in nanomaterials?

An increased level of perfection

What property of nanomaterials is contributed to by their increased perfection?

Very high chemical stability