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Questions and Answers
What does the prefix 'poly' signify in the term polymer?
What does the term 'mer' refer to in the context of polymers?
Which of the following is an example of a polymer formed from monomers?
Which type of polymerization involves the elimination of small molecules during the process?
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In which mechanism of addition polymerization does a free radical initiator decompose spontaneously?
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Which of the following factors does NOT influence the physical properties of a polymer?
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What is an example of a mechanism used in addition polymerization?
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What is the result of addition polymerization with respect to the size of the resulting polymer?
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What is the primary mechanism of free radical polymerization termination?
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Which type of polymerization uses unstable intermediates such as cations or anions?
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Who were the pioneering scientists in the development of the Ziegler-Natta catalysts?
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What characterizes isotactic polymers in terms of molecular arrangement?
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The discovery of Ziegler-Natta catalysts significantly impacted which aspect of polymer chemistry?
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What distinguishes syndiotactic polymers from isotactic polymers?
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Which of the following polymers is described as having a soft and rubbery structure due to its random arrangement of groups?
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What type of polypropylene has all methyl groups arranged on the same side of the polymer chain?
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What substances are combined to facilitate stereospecific polymerization in the Ziegler-Natta method?
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What is the main characteristic of thermoplastic resins?
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Which type of polymerization involves two or more monomers undergoing joint polymerization?
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What defines thermosetting resins?
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What type of polymerization eliminates small molecules like H2O during the reaction?
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Which of the following is an example of a product made from condensation polymerization?
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Which statement about the degree of polymerization is true?
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What happens to thermoplastic resins upon repeated heating and cooling?
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Study Notes
Polymerization
- Polymers are large molecules formed by connecting smaller molecules called monomers.
- Polymerization is the process of joining monomers to create polymers.
- Polyethylene is an example of a polymer made from the monomer ethylene.
Types of Polymerization
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Addition Polymerization: Monomers with double or triple bonds combine without releasing small molecules.
- Polyethylene from ethylene is an example.
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Condensation Polymerization: Monomers with different functional groups combine, releasing small molecules like water.
- Nylon (polyamide) and polyester are examples.
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Copolymerization: Two or more different monomers are polymerized together.
- SBR (Styrene Butadiene Rubber) is an example.
Mechanism of Addition Polymerization
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Free radical polymerization: Involves initiation, propagation, and termination steps.
- Initiation: Initiator decomposes into free radicals, which add to monomers.
- Propagation: Free radical reacts with a monomer, continuing the chain growth.
- Termination: Collision of growing chains or with impurities.
- Ionic polymerization: Similar to free radical polymerization, but unstable intermediates are cations or anions.
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Coordination or Ziegler-Natta Polymerization: Uses catalysts (Ziegler-Natta catalysts) to control the polymer's structure.
- These catalysts were discovered by Karl Ziegler and Giulio Natta and led to stereospecific polymerization.
Stereochemistry of Polymers
- Stereospecific polymerization: Controls the spatial arrangement of groups on asymmetric carbon atoms.
- Isotactic polymers: All groups are on the same side of the polymer backbone.
- Syndiotactic polymers: Groups alternate on opposite sides of the backbone.
- Atactic polymers: Groups are arranged randomly, resulting in a softer, more elastic material.
Degree of Polymerization
- The number of repeating units in a polymer chain.
Plastics (Resins)
- A class of high polymers that can be molded into shapes using heat and pressure.
- Resins are the binders used in plastics, and the terms are often used interchangeably.
Types of Plastics
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Thermoplastic resins: Soften upon heating and harden upon cooling.
- The change is physical, not chemical, so repeated heating and cooling does not alter the material.
- Examples: Children's toys and plastic bottles.
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Thermosetting resins: Harden permanently upon heating.
- They cannot be re-softened after hardening.
- Examples: Epoxy resins and Bakelite.
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Description
Explore the fascinating world of polymerization, a crucial process in chemistry where small molecules, known as monomers, combine to form large polymer chains. This quiz covers the different types of polymerization including addition, condensation, and copolymerization, as well as the mechanisms involved, such as free radical polymerization. Test your understanding of these fundamental concepts and their real-world applications.
