Problem 104 - A Complete Resource Book in Chemistry for JEE Main

Question

Polymerisation is the process by which monomers are converted into polymers. Both polymers and macromolecules are high molecular mass substances but still they have one important difference. For example, polythene and chlorophyll are macro molecules but polythene alone is a polymer because it has a repeating structural unit. Polymers are classified on the basis of structure, synthesis and molecular force existing between the polymer molecules. Which of the following cannot be used as a plasticizer? (a) (b) (c) Tricresyl phosphate (d) Di- \(\mathrm{n}-\) octyl phthalate

Step-by-Step Solution

Answer

The answer cannot be determined without options (a) and (b).

Step 1: Understanding Plasticizers

Plasticizers are compounds added to materials to increase flexibility, transparency, durability, and longevity. They work by embedding themselves between the polymer chains, reducing the intermolecular forces and allowing them to move more freely.

Step 2: Evaluating the Options

We need to analyze each given option to determine which cannot act as a plasticizer. Plasticizers are typically low-volatility, organic liquids or solids that are compatible with the polymer matrix they are intended for.

Step 3: Analyzing Tricresyl Phosphate

Tricresyl phosphate is known to be used as a plasticizer. It brings good flexibility and flame-resistance properties to various synthetic materials.

Step 4: Analyzing Di-n-octyl Phthalate

Di-n-octyl phthalate is commonly used as a plasticizer in producing flexible plastics and is effective with polymer materials due to its ability to reduce stiffness.

Step 5: Identify Missing Options

Since options (a) and (b) are not provided, they cannot be evaluated here. If these options were specified with chemical compounds unable to serve as plasticizers, one of them could potentially be the answer.

Key Concepts

Plasticizers

Plasticizers are a vital component in the production of flexible plastics. These are substances added to polymers to make them more flexible, pliable, or softer. Imagine having a rigid material that needs to bend without breaking. That's where plasticizers come in handy. They integrate within the polymer chains, reducing the forces that hold the chains together tightly.
This action allows the chains to slide past each other easily, giving the material its desired flexibility.

Key reasons to use plasticizers include:

• Increasing the product's ductility
• Enhancing flexibility and workability
• Improving the material's impact resistance
• Prolonging the life of the product by preventing it from becoming brittle over time

Common plasticizers, such as Tricresyl phosphate and Di-n-octyl phthalate, are frequently used due to their effective performance in enhancing the physical properties of polymers.

Polymers classification

Polymers, the large molecules formed by bonding many smaller units called monomers, come in various types. These classifications depend on different criteria: their origin, structure, synthesis process, and their intermolecular forces. Understanding how polymers are classified helps in selecting the right type for specific applications.

Polymers can be categorized as:

• Based on Origin:
  • Natural (e.g., proteins, cellulose)
  • Synthetic (e.g., nylon, polystyrene)
• Based on Structure:
  • Linear polymers - made up of long, straight chains
  • Branched polymers - have side chains branching off from the main chain
  • Cross-linked polymers - networks formed when chains connect at various points
• Based on Synthesis: Addition or condensation polymerisation
• Based on Intermolecular Forces:
  • Elastomers
  • Fibers
  • Thermoplastics
  • Thermosetting plastics

These classifications aid manufacturers in choosing the right polymer with appropriate characteristics for diverse applications, from clothing to industrial materials.

Macromolecules

Macromolecules are substantial complex molecules with high molecular mass formed from the polymerization of smaller subunits. While all polymers are macromolecules, not every macromolecule is a polymer. This distinction helps in better understanding different biological and synthetic materials.

Let's explore this distinguishing feature:

• Polymers: These are a category of macromolecules with a repeating structural unit, meaning their structure consists of repeated sequences of monomers linked together, like a long chain. Examples include polythene and polystyrene.
• Non-polymer macromolecules: These are large molecules that do not have repeating units. For example, proteins and DNA are macromolecules but do not consist of repeating monomer units. Instead, they have a more complex and unique sequence such as different amino acids in proteins.

In the realm of chemistry and materials science, differentiating between these types encourages advancements in fields like biotechnology, where understanding macromolecules such as DNA or proteins is essential.