Question

Match the polymers given in Column-I with the preferred mode of polymerisation followed by their monomers. Column-I Column-II (A) Nylon-6,6 (P) Free radical polymerisation (B) \(\mathrm{PVC}\) (Q) Ziegler-Natta polymerisation or coordination polymerisation (C) HDP (R) Anionic polymerisation (S) Condensation polymerisation

Short answer

The correct matching of polymers and their preferred mode of polymerisation is: (A) Nylon-6,6: Condensation polymerisation (S) (B) PVC: Free radical polymerisation (P) (C) HDPE: Ziegler-Natta polymerisation or coordination polymerisation (Q)

Step-by-step solution

Identify the polymers' structures and monomers

In order to match the polymers with the appropriate mode of polymerisation, we first need to identify the structures and monomers for each polymer: (A) Nylon-6,6 - This polymer is made from the condensation reaction of adipic acid and hexamethylenediamine. (B) PVC (Polyvinyl Chloride) - This polymer is made from the vinyl chloride monomer. (C) HDPE (High-Density Polyethylene) - This polymer is made from the polymerisation of ethylene.

Analyse the types of polymerisation involved

Now let's analyse the preferred mode of polymerisation for each of the given polymers: (A) Nylon-6,6 - The polymerisation of adipic acid and hexamethylenediamine, which are multifunctional monomers, involves the formation of a covalent bond and the release of a small molecule (water). Therefore, this type of polymerisation is called condensation polymerisation. (B) PVC (Polyvinyl Chloride) - The polymerisation of vinyl chloride involves the creation of radicals from the monomer, which then reacts with another monomer to form more radicals. Finally, vinyl chloride radicals combine to form long chains of the polymer. This type of polymerisation is called free radical polymerisation. (C) HDPE (High-Density Polyethylene) - The polymerisation of ethylene is facilitated by coordination polymerisation such as Ziegler-Natta polymerisation, which uses transition metal catalysts to provide the active centers that initiate polymerisation without forming radicals or ions.

Match the polymers with the types of polymerisation

Let's match the polymers from Column-I with their corresponding preferred mode of polymerisation from Column-II: (A) Nylon-6,6 → (S) Condensation polymerisation (B) PVC → (P) Free radical polymerisation (C) HDPE → (Q) Ziegler-Natta polymerisation or coordination polymerisation In conclusion, the correct matching of polymers and their preferred mode of polymerisation is as follows: (A) Nylon-6,6: Condensation polymerisation (S) (B) PVC: Free radical polymerisation (P) (C) HDPE: Ziegler-Natta polymerisation or coordination polymerisation (Q)

Key concepts

Condensation Polymerisation

Polymer chemistry is a fascinating field where small molecules, known as monomers, link together to form long chains or networks called polymers. One of the essential reactions in polymer chemistry is condensation polymerisation. This process involves the chemical combination of monomers with the elimination of a small molecule, usually water or methanol, as a byproduct. Condensation polymerisation is crucial in creating polymers like Nylon-6,6, where hexamethylenediamine and adipic acid combine. During the reaction, each bond formation between monomers releases a molecule of water.

Condensation polymerisation is not just about forming long chains; it's also about creating complexity in polymer structures. The diversity in monomers allows for the synthesis of polymers with different properties, which can be tailored for specific applications such as textiles, plastics, and resins. Understanding the role of condensation reactions in polymerisation greatly assists students in grasping how intricate and versatile polymer structures are produced.

Free Radical Polymerisation

Another pivotal polymerisation technique is free radical polymerisation. It’s a type of addition polymerisation where a radical initiates the reaction, and propagation occurs without the loss of any atoms or molecules from the monomers. This process is widely used in the manufacturing of commercial polymers such as polyvinyl chloride (PVC), which is derived from the monomer vinyl chloride.

In free radical polymerisation, the creation of polymer chains starts with the generation of a free radical, usually by the decomposition of a chemical initiator under heat or light. The free radical adds to a monomer, creating a new radical which then reacts with another monomer, propagating the chain reaction. This process produces polymers with characteristics that can be controlled by altering factors such as temperature, pressure, and the concentration of the initiator. It's a versatile and simple method, which explains its widespread use in the production of plastic materials.

Ziegler-Natta Polymerisation

Ziegler-Natta polymerisation stands out as a unique method of creating polymers with high stereoregularity and molecular weight. Named after the chemists Karl Ziegler and Giulio Natta who discovered this method in the 1950s, it pertains to a class of reactions known as coordination polymerisation. This process uses metal catalysts to polymerise olefins, such as ethylene and propylene, into polymers like high-density polyethylene (HDPE).

The catalyst systems often involve transition metals, which form complexes with the monomers and facilitate the polymerisation. One of the outstanding features of Ziegler-Natta catalysts is their ability to produce polymers with specific and uniform structural arrangements. By adjusting the components of the catalyst system and reaction conditions, manufacturers can tailormake polymers for different end-uses, emphasizing the exceptional versatility of this polymerisation method. Understanding these advanced catalysts enables students to appreciate the innovation and intricacy involved in modern polymer production.

Polymer Structures and Monomers

The diversity of polymers and their applications largely boils down to the structure of the polymer and the nature of the monomers used to make it. Polymer structures can range from linear to branched to cross-linked, affecting properties like strength, flexibility, and resilience. Monomers are the building blocks and can be simple like ethylene for polyethylene or more complex like caprolactam for Nylon-6.

A sound comprehension of how monomers dictate polymer properties enhances a student's ability to predict and understand the performance of the final material. For instance, monomers with functional groups capable of forming hydrogen bonds will result in polymers with higher melting points, useful in making heat-resistant materials. Moreover, the use of different monomers can lead to copolymers, which combine the properties of the constituent monomers into a versatile material. This aspect of polymer chemistry is crucial for designing new materials and for the innovative application of polymers in various industries.