Course Code: CHM-DSC-351
Paper Name: Advance Materials
Nanoscience and nanotechnology involve the study and manipulation of matter at the atomic and molecular scale.
Nanoparticle: A microscopic particle with at least one dimension less than 100 nanometres.
The emergence of this field presents both unique challenges and opportunities due to the drastic change in properties when transitioning from bulk materials to the nanoscale.
Nanomaterials are classified based on their dimensions:
| Classification | Dimensions at Nanoscale | Examples |
|---|---|---|
| Zero-Dimensional (0D) | All three dimensions < 100 nm | Quantum dots, Nanoparticles |
| One-Dimensional (1D) | Two dimensions < 100 nm | Nanowires, Nanorods, Carbon Nanotubes |
| Two-Dimensional (2D) | One dimension < 100 nm | Ultrathin films, Graphene, Multilayered materials |
| Three-Dimensional (3D) | Bulk nanostructured materials | Polycrystalline materials with nano-sized grains |
Carbon at the nanoscale exhibits extraordinary mechanical, electrical, and thermal properties.
The transition from micro/macro scale to the nano scale introduces two fundamental effects:
As the size of a particle decreases, a much higher percentage of its atoms are located on the surface rather than in the bulk. This significantly increases the surface energy and chemical reactivity.
When the size of a material reaches the nanoscale, its electronic and optical properties are governed by quantum mechanics. For example, the band gap of semiconductors increases as the particle size decreases.
Nanomaterials are utilized across various industries due to their enhanced properties:
Q: What is the primary difference between bulk and nanomaterials?
A: Bulk materials have constant physical properties regardless of size, while nanomaterials exhibit size-dependent properties due to surface and quantum effects.
Q: Define a Quantum Dot.
A: It is a 0D semiconductor nanostructure that confines electrons in all three spatial dimensions, leading to discrete energy levels.
Q: Why are nanomaterials more reactive?
A: Due to the very large surface-to-volume ratio, leaving many surface atoms with "dangling bonds" ready to participate in reactions.