JNTU B.Pharmacy IV NANO TECHNOLOGY Previous Question Paper (July-2021 - R17)

Nanotechnology is the branch of science, engineering, and technology conducted at the nanoscale, typically ranging from 1 to 100 nanometers. It involves the design, characterization, production, and application of structures, devices, and systems by manipulating matter at the atomic, molecular, and macromolecular levels to exploit unique physical, chemical, and biological properties that differ significantly from those of bulk materials.

The history of nanotechnology can be traced through several key milestones:

• Conceptual Origins: The foundation was laid in 1959 by physicist Richard Feynman in his famous lecture, "There's Plenty of Room at the Bottom," where he theorized the possibility of manipulating individual atoms and molecules.
• Terminology: The term "nanotechnology" was first coined in 1974 by Norio Taniguchi, a professor at the Tokyo University of Science, to describe the precision manufacturing of materials at the nanometer scale.
• Molecular Nanotechnology: In the 1980s, K. Eric Drexler popularized the concept through his book "Engines of Creation," which explored the potential for self-replicating molecular machines and advanced nanotechnology.
• Instrumentation Breakthroughs: The invention of the Scanning Tunneling Microscope (STM) in 1981 by Gerd Binnig and Heinrich Rohrer at IBM allowed scientists to visualize and manipulate individual atoms for the first time, providing the necessary tools to transition from theory to practice.
• Discovery of Nanomaterials: The discovery of fullerenes (C60) in 1985 by Kroto, Smalley, and Curl, followed by the discovery of carbon nanotubes by Sumio Iijima in 1991, opened new frontiers in material science and electronics.
• Modern Era: Since the late 1990s and early 2000s, nanotechnology has evolved into a multidisciplinary field, leading to the development of nanomedicine, high-efficiency catalysts, quantum dots, and advanced nanocomposites, supported by significant global research initiatives such as the National Nanotechnology Initiative (NNI) in the United States.

Nanomaterials exhibit unique properties primarily due to two fundamental factors: the Quantum Confinement Effect and the Surface-to-Volume Ratio. As particle size decreases to the nanometer scale, the electronic energy levels become discrete rather than continuous, altering optical, electrical, and magnetic behaviors. Simultaneously, a significantly higher percentage of atoms reside on the surface compared to the bulk material, leading to increased surface energy, higher chemical reactivity, and enhanced catalytic properties.

Nanomaterials are classified based on their dimensionality, which refers to the number of dimensions that are outside the nanometer range:

1. Zero-Dimensional (0D) Nanomaterials: All three dimensions are in the nanoscale (e.g., quantum dots, nanoparticles, and nanoclusters). These materials exhibit quantum confinement in all directions.
2. One-Dimensional (1D) Nanomaterials: Two dimensions are in the nanoscale, while the third dimension is larger (e.g., nanotubes, nanowires, and nanorods). These are primarily used in electronics and structural reinforcement.
3. Two-Dimensional (2D) Nanomaterials: One dimension is in the nanoscale, while the other two are in the macroscale (e.g., thin films, graphene sheets, and nanocoatings). These are critical for surface-sensitive applications and sensors.
4. Three-Dimensional (3D) Nanomaterials: None of the dimensions are in the nanoscale, but they are composed of nanostructured building blocks (e.g., bulk materials made of nanocrystalline grains, dendrimers, and porous structures).