Problem 117 - Chemistry The Central Science In Si Units

Question

Teflon is a polymer formed by the polymerization of \(\mathrm{F}_{2} \mathrm{C}=\mathrm{CF}_{2}\). (a) Draw the structure of a section of this polymer. (b) What type of polymerization reaction is required to form Teflon?

Step-by-Step Solution

Answer

Teflon is formed by addition polymerization from tetrafluoroethylene, with a structure of \(-\mathrm{CF}_2-\mathrm{CF}_2-\).

Step 1: Understand the Monomer

Identify the chemical formula of the monomer supplied, which is \(\mathrm{F}_2\mathrm{C} = \mathrm{CF}_2\), commonly known as tetrafluoroethylene. This serves as the repeating unit in the polymer.

Step 2: Identify Polymer Structure

Recognize that the polymerization linkage involves the opening of the double bonds. The polymer section can be represented with single bonds connecting the carbon atoms, each carbon being bonded to two fluorine atoms. The repeating unit in its polymerized form is \( -\mathrm{CF}_2-\mathrm{CF}_2- \).

Step 3: Repeat the Unit

Draw the structure with several repeating units. The conventional representation for Teflon shows a chain of carbon atoms each bonded to two fluorine atoms: \[-\mathrm{CF}_2-\mathrm{CF}_2-\mathrm{CF}_2-\mathrm{CF}_2-\].

Step 4: Determine the Polymerization Reaction Type

Recognize that Teflon is formed through an addition polymerization reaction. This type involves the process where monomers with double bonds open up and connect to form long polymer chains without the loss of any other atoms.

Key Concepts

Teflon

Teflon is a well-known synthetic polymer that finds extensive use due to its non-stick properties. It is made from tetrafluoroethylene monomers, with a chemical formula of \(F_2C=CF_2 \). These monomers link together to form a long chain polymer. Each monomer unit turns into a repeating unit in the trademark structure of Teflon: \( -CF_2-CF_2- \), which consists primarily of carbon and fluorine atoms.

Upon polymerization, Teflon's structure becomes extremely stable because of the strong bonds between carbon and fluorine. This gives Teflon its famed resistance to heat, chemicals, and electrical conductivity. The slickness of Teflon arises from its smooth molecular surface, which results in very low friction against other materials, making it a popular choice for non-stick cookware as well as various industrial applications.

• Non-reactive due to strong \(C-F\) bonds
• High melting point
• Commonly used in cookware and electrical insulation

Addition Polymerization

Addition polymerization is a fundamental chemical reaction used to produce polymers like Teflon. This type of polymerization involves the linking of monomer units without the loss of any small molecules. In the case of Teflon, the process starts with tetrafluoroethylene molecules. The double bond between carbon atoms opens up or "breaks" to allow monomers to connect and create a long chain.

• Initiation: Typically begins with a chemical initiator that helps break the double bonds.
• Propagation: As the process continues, more and more monomers add to the growing chain, extending it significantly.
• Termination: Eventually, the reaction stops, typically when no more monomer is available or the chain reacts with another chain.

Addition polymerization is crucial for producing numerous everyday materials, from plastics to synthetic fibers, offering versatile applications in various fields.

Monomer Structures

Understanding monomers, the building blocks of polymers, is key to grasping how materials like Teflon are formed. Each monomer must have a certain structure allowing it to chemically bond with others. For Teflon, the monomer tetrafluoroethylene has the structure \(F_2C=CF_2 \), which includes a double bond between two carbon atoms, each bonded to two fluorine atoms.

This double bond is pivotal in polymerization because it allows the monomers to react and link together to form a chain. When the double bond breaks, each carbon atom forms a new single bond with another carbon atom in a different monomer, thus continuing the chain.

• Tetrafluoroethylene has a symmetrical structure.
• The presence of fluorine gives strength and stability to the monomer.
• Able to form extensive networks through addition polymerization.

Monomer structure affects not only the polymerization process but also the properties of the final polymer, such as strength, flexibility, and resistance to external conditions.