Problem 119 - A Complete Resource Book in Chemistry for JEE Main

Question

The polymer containing strong intermolecular forces e.g., hydrogen bonding is [2010] (a) Teflon (b) nylon 6,6 (c) polystyrene (d) natural rubber

Step-by-Step Solution

Answer

Nylon 6,6.

Step 1: Understanding Intermolecular Forces

Intermolecular forces are forces of attraction between molecules. These include hydrogen bonding, dipole-dipole interactions, and dispersion (Van der Waals) forces. Among these, hydrogen bonding is particularly strong and occurs in molecules where hydrogen is directly bonded to highly electronegative atoms such as oxygen, nitrogen, or fluorine.

Step 2: Analyze Each Polymer

Let's analyze each polymer to see if they contain groups that can form strong intermolecular forces like hydrogen bonding. - **Teflon (PTFE):** Made from tetrafluoroethylene, consisting mainly of carbon-fluorine bonds which are non-polar and do not participate in hydrogen bonding.- **Nylon 6,6:** Contains amide groups \((-CONH-)\) in its backbone. The hydrogen attached to the nitrogen is capable of forming hydrogen bonds with carbonyl oxygens of another chain.- **Polystyrene:** Made from styrene, largely consists of non-polar hydrocarbons which do not form hydrogen bonds.- **Natural rubber:** Composed mainly of isoprene units, and does not contain functional groups capable of hydrogen bonding.

Step 3: Identify the Polymer with Hydrogen Bonding

From the analysis in Step 2, it is clear that nylon 6,6 contains amide groups that allow it to form hydrogen bonds. This makes it the polymer with strong intermolecular forces due to hydrogen bonding.

Step 4: Conclusion

Considering the nature of the intermolecular forces and the chemical structure of each polymer, nylon 6,6 has the strongest intermolecular forces because of its potential for hydrogen bonding.

Key Concepts

Hydrogen Bonding

Hydrogen bonding is a crucial concept in the realm of intermolecular forces. It is a specific type of dipole-dipole interaction that is significantly stronger than typical dipole-dipole attractions or dispersion forces. These bonds occur when a hydrogen atom is covalently bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. This setup leads to a partial positive charge on the hydrogen, which then strongly attracts the lone pairs of electrons on nearby electronegative atoms, forming a hydrogen bond.

Key features of hydrogen bonds include:

• Being stronger than other types of intermolecular forces but weaker than covalent or ionic bonds.
• Playing a significant role in determining the properties of substances, such as boiling and melting points.
• Being essential for the structure and function of biological macromolecules like proteins and nucleic acids.

In polymers such as nylon 6,6, hydrogen bonding substantially enhances the material's mechanical properties by reinforcing the interaction between polymer chains. This results in a material with high tensile strength and durability, making hydrogen bonding a vital concept in polymer chemistry.

Nylon 6,6

Nylon 6,6 is a type of synthetic polymer known for its versatility and high strength. This polymer is composed of repeating units of hexamethylene diamine and adipic acid, leading to a structure that includes amide linkages \( -CONH- \). These amide groups are key in enabling hydrogen bonding between the polymer chains, which drastically change its properties.

Here are some characteristics of nylon 6,6 influenced by its ability to form hydrogen bonds:

• High melting point due to the strong intermolecular forces.
• Increased resistance to abrasion and wear.
• Good elasticity and resilience, making it suitable for textiles and plastic products.

Nylon 6,6's ability to form hydrogen bonds extensively contributes to its application in a wide range of industries. From heavy-duty engineering components to common household items, its strength and durability make it ideal for various uses. The hydrogen bonds also contribute to its stability in various environmental conditions, which is crucial for long-term applications.

Polymer Chemistry

Polymer chemistry is the branch of chemistry that focuses on the synthesis, characterization, and properties of polymers. Polymers are large molecules made up of repeating units called monomers, which are covalently bonded to form a long chain. The type of monomers and the nature of the bond formation define the polymer's properties.

In the context of polymers like nylon 6,6, several important concepts include:

• Intermolecular Forces: These forces (including hydrogen bonding, dipole interactions, and Van der Waals forces) significantly affect the physical properties of polymers.
• Functional Groups: The presence of functional groups like amides influences the polymer's ability to form environmentally resistant and structurally strong materials.
• Polymerization Methods: Processes like step-growth and chain-growth polymerization determine the polymer's architecture and chain length.

Understanding these elements is crucial because they directly impact the material's behavior and its applicability. This foundation in polymer chemistry enables the development of new materials with tailored properties, meeting the specific needs of various industrial and consumer applications. In essence, polymer chemistry sheds light on how materials are formed and why they behave the way they do, driving innovation across multiple sectors.