Question

Write the monomers used for getting the following polymers. (i) Polyvinyl chloride (ii) Teflon (iii) Bakelite

Short answer

(i) Vinyl chloride, (ii) Tetrafluoroethylene, (iii) Phenol and formaldehyde.

Step-by-step solution

Identifying Polyvinyl Chloride Monomer

Polyvinyl chloride (PVC) is derived from the polymerization of the monomer vinyl chloride. The chemical structure of vinyl chloride is realized as \\( CH_2=CHCl \). Thus, the monomer used for PVC is vinyl chloride.

Identifying Teflon Monomer

Teflon, also known as polytetrafluoroethylene (PTFE), is made from the monomer tetrafluoroethylene. The chemical structure of tetrafluoroethylene is \\( CF_2=CF_2 \). Therefore, the monomer used for Teflon is tetrafluoroethylene.

Identifying Bakelite Monomers

Bakelite is a phenol-formaldehyde resin, which is made from two monomers: phenol \( C_6H_5OH \) and formaldehyde \( CH_2O \). These two compounds undergo a condensation reaction to form Bakelite. Thus, the monomers used for Bakelite are phenol and formaldehyde.

Key concepts

Monomers

A monomer is a simple molecule that can bind chemically to other molecules to form a polymer. Think of monomers as the building blocks of larger structures called polymers, similar to how individual bricks make up a wall. These small but vital compounds are the starting point for creating an array of different materials around us.

Monomers have the unique ability to link together in long chains through processes like polymerization. This connection occurs via various types of chemical bonds, often producing materials with diverse properties. A single type of monomer can create a polymer through repeated linking, resulting in a homopolymer. However, combining different monomers can produce copolymers, leading to materials with varied characteristics. Understanding the chemistry and structure of different monomers is the first step in grasping how common materials are created.

Vinyl Chloride

Vinyl chloride is a critical monomer used in the production of polyvinyl chloride (PVC), a material prevalent in construction but also found in everyday objects.

• Chemical Structure: Vinyl chloride is represented by the chemical formula \( CH_2=CHCl \).
• Uses: It's primarily used to make PVC, which is found in pipes, medical devices, and even clothing.
• Characteristics: Vinyl chloride is a colorless gas with a mild, sweet odor that is usually stored and transported in its liquid form under pressure.

Vinyl chloride undergoes addition polymerization to form PVC. This process involves the opening of its double bond, allowing it to link with other vinyl chloride molecules to create long, repeating chains. Despite its toxic nature, when polymerized, the resulting PVC is stable and versatile.

Tetrafluoroethylene

Tetrafluoroethylene is another fascinating monomer renowned for its role in making Teflon, or polytetrafluoroethylene (PTFE).

• Chemical Structure: This monomer is denoted as \( CF_2=CF_2 \).
• Properties: Tetrafluoroethylene is a colorless, odorless gas that is highly reactive, allowing for easy polymerization.
• Uses: Teflon, created from tetrafluoroethylene, is famous for its non-stick properties and is commonly used in cookware but also in various industrial applications.

Through polymerization, the carbon-fluorine bonds in tetrafluoroethylene form a robust chain, giving Teflon its unique resistance to heat and chemical reactions, making it invaluable in both the kitchen and the industry.

Phenol-Formaldehyde Resin

Phenol-formaldehyde resin, commonly referred to as Bakelite, is an early and important synthetic plastic. This resin is developed through a condensation reaction between two specific monomers: phenol and formaldehyde.

• Chemical Structures: Phenol is represented as \( C_6H_5OH \), while formaldehyde has the formula \( CH_2O \).
• Reaction Process: The reaction between phenol and formaldehyde leads to the formation of a hard, heat-resistant polymer commonly known as Bakelite.
• Uses: Bakelite, noted for its electrical non-conductivity, is widely used in manufacturing electrical switches, handles, and various molded objects.

This process, unlike addition polymerization, is an example of condensation polymerization, where each step produces a small byproduct. The interplay of cross-linking between polymer chains provides Bakelite with its rigid, durable properties, marking its significance in industrial advancement.