Question

Polyacrylonitrile is a polymer of acrylonitrile, \(\mathrm{CH}_{2}=\mathrm{CHCN} .\) Write an equation for the synthesis of this polymer.

Short answer

Polymerization: \( n(\mathrm{CH}_{2}=\mathrm{CHCN}) \rightarrow ( -\mathrm{CH}_{2}-\mathrm{CHCN}- )_{n}.\)

Step-by-step solution

Understand the Monomer Structure

The monomer acrylonitrile has the chemical structure \( \mathrm{CH}_{2}=\mathrm{CHCN} \). It contains a carbon-carbon double bond and a nitrile group (\( \mathrm{CN} \)).

Define Polymerization Type

Polyacrylonitrile is formed through a polymerization process called addition polymerization, where monomers add together without the loss of any small molecules.

Illustrate the Addition Polymerization

During addition polymerization, the double bond in the monomer opens up, allowing the monomers to link together in a long chain. The repeat unit for polyacrylonitrile is \(-\mathrm{CH}_{2}-\mathrm{CHCN}-\).

Write the Polymerization Equation

The polymerization can be represented by the equation: \[ \mathrm{n} \left( \mathrm{CH}_{2}=\mathrm{CHCN} \right) \rightarrow \left( -\mathrm{CH}_{2}-\mathrm{CHCN}- \right)_{n} \]Here, \( n \) represents the number of monomer units that have been polymerized.

Key concepts

Understanding Acrylonitrile

Acrylonitrile, represented by the chemical formula \( \mathrm{CH}_{2}=\mathrm{CHCN} \), is a crucial organic compound used in the creation of polymers. This molecule contains a double bond between two carbon atoms (\( \mathrm{C}=\mathrm{C} \)) and a nitrile group (\( \mathrm{CN} \)). The presence of a carbon-carbon double bond is critical in polymerization processes as it allows for the linking of multiple monomers.

Acrylonitrile is a versatile chemical that serves as a building block in various industrial applications. When describing its physical characteristics, it appears as a colorless, volatile liquid with a faint odor that closely resembles garlic.

In terms of applications, acrylonitrile is essential in manufacturing synthetic fibers, plastics, and elastomers. These materials are widely used in textiles, automotive manufacturing, and various consumer and industrial goods.

• The molecule undergoes addition polymerization, which is essential in forming the polymer polyacrylonitrile.
• It's critical for producing resins, which are used in products like acrylic fibers.

Formation of Polyacrylonitrile

Polyacrylonitrile is a synthetic polymer made through the polymerization of multiple acrylonitrile monomers. This process results in the formation of a long-chain molecule where each unit is identical to the previous. The formula for polyacrylonitrile is typically represented as \( (-\mathrm{CH}_{2}-\mathrm{CHCN}-)_{n} \).

The polymerization process occurs via addition polymerization, where the double bonds in acrylonitrile monomers open up and connect to one another, forming what are known as polymer chains. This chain reaction continues until it forms long, repeating units of polyacrylonitrile.

Polyacrylonitrile is known for its high strength and thermal stability, making it an excellent choice for producing fibers used in applications like carpets, clothing, and as a precursor for carbon fiber production.

• It exhibits properties such as durability and stability.
• Plays a crucial role in producing carbon fiber, a key component in aerospace and automotive industries.

Significance of the Nitrile Group

The nitrile group, \( \mathrm{CN} \), is a functional group present in organic compounds and polymers, characterized by a carbon triple-bonded to a nitrogen atom. This strong bond imparts unique properties to molecules like acrylonitrile and consequently to the polymers they form.

In polyacrylonitrile, the presence of nitrile groups contributes significant chemical and thermal resistance. The strength of the triple bond in \( \mathrm{CN} \) ensures that polymers display remarkable durability. This is especially important in environments where high temperature and chemical resistance are crucial.

Nitrile groups also influence the solubility and the ability of acrylonitrile to form cohesive, solid polymers. These properties significantly increase the material’s usability in a wide range of products.

• Enhances strength and heat resistance in polyacrylonitrile.
• Assures longevity and reliability in many polymer applications.