Problem 187 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

Polymer obtained by condensation polymerisation is (a) PVC (b) teflon (c) polythene (d) phenol-formaldehyde resin

Step-by-Step Solution

Answer

(d) Phenol-formaldehyde resin is obtained by condensation polymerization.

Step 1: Understanding Condensation Polymerization

Condensation polymerization is a type of polymerization where monomers join together and simultaneously release small molecules, often water or methanol. This contrasts with addition polymerization, where monomers simply add together without the loss of any molecule.

Step 2: Analyze the Options

Let's analyze each option based on how they are synthesized: (a) PVC (Polyvinyl chloride) is formed by addition polymerization of vinyl chloride. (b) Teflon (polytetrafluoroethylene) is formed by addition polymerization of tetrafluoroethylene. (c) Polythene (polyethylene) is formed by addition polymerization of ethylene. (d) Phenol-formaldehyde resin is formed by the reaction of phenol with formaldehyde, releasing water.

Step 3: Identify Condensation Polymer

Among the options, phenol-formaldehyde resin is obtained through condensation polymerization because it involves the release of water molecule during the formation of the polymer.

Key Concepts

Phenol-Formaldehyde Resin

Phenol-formaldehyde resin is a synthetic polymer made through the reaction of phenol and formaldehyde. This process is known for creating a thermosetting plastic, commonly used in making adhesives, coatings, and molded products.

• Thermosetting Plastic: Once phenol-formaldehyde resin is formed, it cannot be melted or reshaped. This makes the resin very stable and durable.
• Uses: Often used in electrical insulators, laminates, and as a binder for plywood.

One notable feature of this polymer is the strong cross-linking of its molecules, which provides its heat resistance and mechanical strength. The chemical reaction involves the formation of a complex network structure, ensuring that the resulting material is rigid and tough. This is why phenol-formaldehyde is widely used in demanding industrial applications.

Polymerization Mechanisms

Understanding polymerization mechanisms is essential for classifying how various synthetic polymers are produced. The two main types are condensation polymerization and addition polymerization.

• Condensation Polymerization: It involves the binding of monomers with the simultaneous loss of small molecules like water or methanol. Phenol-formaldehyde resin is a classic example.
• Addition Polymerization: A simpler process where monomers add to each other without the loss of any atoms. Examples include PVC and Teflon.

By analyzing the products formed and studying their structures, chemists can manipulate these mechanisms to create polymers with desired properties for various uses. This understanding is pivotal for advancements in materials science.

Polymer Chemistry

Polymer chemistry is the branch of chemistry focusing on the synthesis and properties of polymers. It encompasses various techniques and processes aimed at designing materials with specific characteristics.

• Types of Polymers: Includes natural polymers like proteins and synthetic ones like nylon and plastic.
• Applications: Polymers have vast applications, from everyday household products to high-performance materials in aerospace.

The field is well-regarded for innovative development in creating new plastics, rubbers, and fibers that enhance our daily lives. With ongoing research, polymer chemistry continues to be at the forefront of technological progress, finding new sustainable materials that balance performance with environmental considerations.