Introduction to Nanochemistry and Self-Assembly, Exams of Chemistry

Download Introduction to Nanochemistry and Self-Assembly and more Exams Chemistry in PDF only on Docsity! ANGELA A. TAPING BSCE-1 ANSWER SHEET REVIEW QUESTIONS: 1. Define nanochemistry. Explain with the help of suitable examples how the properties of nanomaterials differ from those of the same materials in bulk size. ● Nanochemistry is the science of nanoparticles or particles whose size varies from 1 to 10 nm in at least one dimension. Nanochemistry exploits this size range for various chemical reactions and chemical purposes, which would not be possible otherwise at the bulk level. The properties of nanomaterials are very different from those of the bulk material. Nanoparticles can't be seen with the naked eye. However, we can see the particles in the bulk materials. Nanomaterials and bulk materials vary in that nanoparticles have a size of 1-100 nm range in at least one dimension, whereas bulk materials have a size greater than 100 nm in all dimensions. 2. What do you understand by the term ‘self-assembly’? Explain the fundamental principles of self-assembly. ● Self-assembly is the spontaneous formation of ordered aggregates by components that are either independent or coupled. If the right circumstances are present, self-assembly may occur with components ranging in size from molecule to macroscopic. Self- assembly is a natural idea that motivates both technological innovation and how we collaborate. Self-assembly, a basic biological design process in which an organized structure appears to create itself from a disorderly collection of smaller pieces, is one of life's most fascinating aspects. 3. What are molecular self-assembly and material self-assembly? Explain. ● Molecular self-assembly is the process of molecules assembling themselves without the need for external forces. Reversible non- covalent interactions such as Van der Waals forces, hydrogen bonds, metal-ligand connections, ℼ-ℼ interactions, and others driving factors underlying molecular self-assembly. Intermolecular and intramolecular molecular self-assembly are both possible. Folding is caused by intramolecular self-assembly, and the phrase molecular self-assembly actually refers to intramolecular self-assembly. The assembling of various nanosized pieces leads to material self- assembly. Organic, inorganic, and polymeric chemical components with well-defined functionalities integrate into electronics, photonic, mechanical, analytical, and chemical systems for nanotechnological applications in material self-assembly. 4. What do you understand by mesoscale self-assembly (MESA)? Write down the different methods used to construct MESA and also compare MESA with molecular self-assembly. Mesoscale self-assembly (MESA) can range in size from 10 nm to 10 mm (1cm). MESA's components are larger than molecules, therefore they may use a variety of additional interactions outside molecular self-assembly forces, such as capillary, electrostatic, magnetic, optical, gravitational, and fluidic shear. The methods used to construct MESA are as follows: By capillary interactions, self-assembly by spontaneous folding, Hierarchical self-assembly, Templated self-assembly, By changing solvent polarity, By adsorption, and Dynamic self-assembly. COMPARISON OF MOLECULAR AND MESOSCALE SELF-ASSEMBLY Molecular self-assembly Mesoscale self-assembly The size of molecules is small in the range of few nanometers. Component size is bigger in mesoscale self-assembly and varies from 10 nm to 10 mm (1cm). Reversible non-covalent interactions such as Van der Waals forces, hydrogen bonds, metal-ligand bonds, - interactions ℼ ℼ guide the self-assembly. Electrical and magnetic interactions do not support molecular self-assembly. Apart from the forces of molecular self- assembly, the additional forces responsible for mesoscale self-assembly are capillary, magnetic, optical, fluidic shear, electrical and gravitational. The components of self- assembled structures move and interact to form assemblies. In molecular self- assembly, thermal motion is sufficient to bring the molecules in contact. As the components are larger in size, apart from thermal motion, molecular contact in MESA requires motion by external sources such as shaking or stirring. The components of molecular self- assembly are molecules and the properties of individual molecules and the self-assembled structure vary significantly. In MESA, the individual component makes the final structure. The function desired in the final structure must exist in the component. The components assemble by balancing both attractive and repulsive forces. Complementary shape of interacting components assists self-assembly. As the components assemble by balancing both attractive and repulsive forces. The complementary shape of interacting components assists self- assembly. Templating or use of guides to control Owing to their bigger size the self-