Question

Vinyl chloride \(\left(\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}\right),\) undergoes copolymerization with 1,1 -dichloroethylene, \(\left(\mathrm{H}_{2} \mathrm{C}=\mathrm{CCl}_{2}\right)\), to form a polymer commercially known as Saran. Draw the structure of the polymer, showing the repeating monomer units.

Short answer

-[(CH2-CHCl)-(CH2-CCl2)]-

Step-by-step solution

Identify the Monomers

The two monomers involved in the copolymerization to form Saran are vinyl chloride \(\left(\mathrm{H}_{2} \mathrm{C}=\mathrm{CHCl}\right)\) and 1,1-dichloroethylene \(\left(\mathrm{H}_{2} \mathrm{C}=\mathrm{CCl}_{2}\right)\). Each of these monomers has a double bond that will open up during polymerization.

Understand the Copolymerization Process

In copolymerization, the two different monomers react with each other, and their double bonds break to form a long chain. The bond formation alternates the vinyl chloride and 1,1-dichloroethylene units.

Draw the Repeating Unit

To derive the structure of the copolymer, draw the two monomer units with open bonds: connect the carbon of the vinyl chloride (bearing one \(\mathrm{H}\), \(\mathrm{Cl}\), and the other open for connection) and the carbon of the 1,1-dichloroethylene (bearing two \(\mathrm{Cl}\) and open on one end for connection).

Illustrate the Polymer Structure

The repeating unit of the polymer Saran would look like this: -[\mathrm{CH}_2-\mathrm{CHCl}-\mathrm{CH}_2-\mathrm{CCl}_2]-_n, where \(n\) indicates the number of repeating units. This shows the alternating sequence of two different monomers.

Key concepts

Vinyl Chloride

Vinyl chloride, a key player in the copolymerization process, is an organic compound represented by the chemical formula \( \text{C}_2\text{H}_3\text{Cl} \). It contains a vinyl group, which is essentially a simple alkene consisting of a pair of carbon atoms connected by a double bond. This double bond is crucial as it allows vinyl chloride to undergo chemical reactions more easily, including polymerization.

In the creation of polymers, these double bonds open up and allow connections with other molecules, such as 1,1-dichloroethylene, to form long chains.

• Vinyl chloride is a gas at room temperature.
• It's widely used in the production of PVC (polyvinyl chloride).
• During polymerization, the chlorine atom of vinyl chloride plays a vital role in determining the properties of the final polymer, often increasing its strength and chemical resistance.

Polymer Structure

The structure of a polymer is made up of multiple repeating units that bind together, much like repeating links forming a chain in a necklace. This structure gives polymers their unique properties, such as flexibility, strength, and durability. When discussing vinyl chloride, its polymer structure greatly influences its application in industries.

In the specific case of Saran, the polymer is constructed from two monomers: vinyl chloride and 1,1-dichloroethylene. The alternating connection of these monomers leads to a structurally unique polymer that holds many useful properties.

• Polymers can be crystalline, amorphous, or a mix, affecting transparency and rigidity.
• Strong intermolecular forces due to chlorine atoms contribute to the stability of the polymer structure.
• The alternating pattern impacts the polymer's flexibility and resistance to chemicals.

Repeating Monomer Units

In copolymerization, the repeating monomer units are crucial to forming a polymer's backbone. They are the simplest repeating structures that make up the entire polymer chain, giving it distinct characteristics. For Saran, these repeating units come from two different monomers: vinyl chloride and 1,1-dichloroethylene.

When you draw the repeating unit of Saran, it comprises sections of polyvinyl chloride and segments of the polymer formed from 1,1-dichloroethylene. The polymer chain is configured as: \[[\mathrm{CH}_2-\mathrm{CHCl}-\mathrm{CH}_2-\mathrm{CCl}_2]_n\]

• The subscript \( n \) indicates that this pattern repeats potentially thousands of times to create the macromolecule, which is the full polymer.
• These repeating units govern the properties like melting temperature, flexibility, and strength of the polymer.
• Altering the proportion or sequence of repeating units can lead to polymers with varied characteristics.

Chemistry Education

Chemistry education plays a pivotal role in understanding complex concepts like copolymerization. By learning about the chemical behaviors of compounds such as vinyl chloride, students gain insights into real-world applications and innovations.

Educators strive to break down these intricate subjects into easy-to-digest segments, because an understanding of polymer chemistry can lead to advancements in materials science, environmental solutions, and various industrial applications. The specific study of polymer structures and reactions, like the formation of Saran, is essential to grasp larger chemical engineering concepts.

• Hands-on experiments with simple polymerization processes can solidify theoretical knowledge.
• Visualization tools and molecular models help students see the repeat patterns of polymer chains.
• Understanding these concepts can lead to exploration in fields like biodegradable plastics and renewable resources.