Question

Nylon-6 is (a) A step growth polymer (b) A copolymer (c) An addition polymer (d) A condensation polymer

Short answer

Nylon-6 is a condensation polymer (option (d)).

Step-by-step solution

Identify Keywords

Read the options and identify key terms such as 'step growth polymer,' 'addition polymer,' and 'condensation polymer'. Understand their definitions: step growth polymers are formed through the gradual stepwise reaction between functional groups, condensation polymers are a type of step growth polymer that release small molecules as by-products, and addition polymers are formed by the addition of monomers in a chain without by-products.

Understand Nylon-6 Formation

Recall that Nylon-6 is produced from the monomer caprolactam, which undergoes a process called ring-opening polymerization. This involves opening the ring with the addition of a water molecule, which leads to the formation of the polymer chain with the elimination of a small molecule as a by-product.

Link Definitions to Nylon-6

Determine if the process described for Nylon-6 matches the definitions. The creation of Nylon-6 through the loss of a small molecule (water) aligns with the characteristics of a condensation polymer, which is a type of step growth polymer involving the elimination of small molecules.

Eliminate Incorrect Options

Eliminate options based on the understanding of the characteristics of Nylon-6. Since Nylon-6 is not formed by merely adding monomers in a chain (i.e., it's not an addition polymer) and involves the loss of a small molecule, option (c) can be eliminated. Option (b) can also be eliminated as Nylon-6 is synthesized from a single type of monomer, making it a homopolymer rather than a copolymer.

Choose the Correct Option

From the understanding that Nylon-6 forms by releasing small molecules and follows stepwise reactions, classify it as a step growth and condensation polymer. Since option (d) correctly identifies it as a condensation polymer, select this as the answer.

Key concepts

Step Growth Polymerization

Step growth polymerization is a process in which polymers are formed through the reaction of monomers containing functional groups. This happens in a stepwise manner, meaning monomers can react with each other or with longer chains, resulting in a gradual buildup of the polymer.
This type of polymerization often requires high conversion of monomers to achieve high molecular weights.
Some key features include:

• Reaction of monomers with two functional groups, such as hydroxyl (-OH) and carboxyl (-COOH).
• Slow initial reaction rates, increasing as more monomers are integrated.
• Can involve both small molecules and oligomers reacting to form larger structures.

Step growth polymers are typically characterized by the formation of new molecules from these functional group reactions, which distinguishes them from addition polymers where monomers join without by-product formation.

Condensation Polymerization

Condensation polymerization is a specific type of step growth polymerization where small molecules, such as water, are released as by-products during the formation of the polymer. This process is common for polymers requiring two different functional groups for the reactions, like polyesters or polyamides.
Nylon-6 is a classic example. It is produced from caprolactam, which undergoes ring-opening polymerization involving the removal of water.
This process emphasizes the following:

• Loss of small molecules (e.g., water, methanol) in the process.
• Often utilized for forming polyamides and polyesters.
• Requires precision control to manage by-product removal for optimal polymer properties.

These features are critical in distinguishing condensation polymerization from addition polymerization, where no by-products are generated.

Ring-Opening Polymerization

Ring-opening polymerization (ROP) is a fascinating process used to create polymers from cyclic monomers. Unlike linear monomers in other polymerization types, ROP involves 'opening' cyclic structures to allow them to connect in longer chains.
The process for Nylon-6 involves breaking the ring of caprolactam and linking the molecules to form a polymer chain.
Key aspects include:

• Use of cyclic monomers that offer different properties in the resulting polymer.
• Often associated with the production of high-performance polymers, like Nylon-6.
• In some cases, catalysts or initiators may be employed to aid the reaction.

ROP is unique in its ability to transform cyclic structures into functional materials with specified mechanical and thermal properties, making it a popular choice for advanced material design.