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Polymer Chemistry: Step-Growth Polymers
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Polymer Chemistry: Step-Growth Polymers

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Questions and Answers

What is the primary characteristic of step growth polymerization?

  • Oligomers react together to give longer chains (correct)
  • Chain growth is associated with addition polymerization
  • It forms highly crystalline polymers
  • It involves the gradual depletion of monomers
  • What is the primary reason for the reduced density of a polymer?

  • Presence of substituents or branches (correct)
  • Short chain length
  • Strong Van der Waals forces
  • High degree of crystallinity
  • What type of polymerization is associated with chain growth?

  • Step growth polymerization
  • Condensation polymerization
  • Addition polymerization (correct)
  • Free radical polymerization
  • What is the term for regions of a polymer with highly ordered chains?

    <p>Crystallites</p> Signup and view all the answers

    What is the primary function of Van der Waals forces in polymers?

    <p>To hold the individual chains together</p> Signup and view all the answers

    What is the result of having highly ordered polymer chains?

    <p>An increase in density, hardness, and resistance to heat</p> Signup and view all the answers

    What type of polymer has short branches connected to the main chain?

    <p>Branched polymer</p> Signup and view all the answers

    What is the primary characteristic of a cross-linked polymer?

    <p>Covalently bonded linking units between chains</p> Signup and view all the answers

    What is the mechanism by which epoxides are polymerized when the initiator is a Lewis acid?

    <p>Cationic mechanism</p> Signup and view all the answers

    What is the main problem with natural and most synthetic rubbers?

    <p>They are too soft and sticky</p> Signup and view all the answers

    What type of polymerization reaction is involved in the formation of condensation polymers?

    <p>Step-growth polymerization</p> Signup and view all the answers

    What is the purpose of vulcanization in rubber production?

    <p>To create a harder and more flexible material</p> Signup and view all the answers

    What type of copolymer has a random distribution of monomers?

    <p>Random copolymer</p> Signup and view all the answers

    What is the main difference between homopolymers and copolymers?

    <p>Homopolymers are formed from one monomer, while copolymers are formed from two or more monomers</p> Signup and view all the answers

    What is the result of heating rubber with sulfur in the vulcanization process?

    <p>The formation of a harder and more flexible material</p> Signup and view all the answers

    What is the name of the process by which a polymer is formed from a single compound with two different functional groups?

    <p>Condensation polymerization</p> Signup and view all the answers

    What is the primary characteristic of a step-growth polymer?

    <p>It is formed from a monomer with two different functional groups</p> Signup and view all the answers

    What is the reaction mechanism involved in the synthesis of nylon 6?

    <p>Condensation reaction</p> Signup and view all the answers

    What is the starting material for the synthesis of nylon 6?

    <p>ε-caprolactam</p> Signup and view all the answers

    What is the primary characteristic of epoxy resins?

    <p>They are extensively cross-linked systems and can adhere to almost any surface</p> Signup and view all the answers

    What is the reaction mechanism involved in the synthesis of Dacron?

    <p>Transesterification reaction</p> Signup and view all the answers

    What is the primary characteristic of polyurethanes?

    <p>They contain a urethane group, which is a compound with an OR group and an NHR group bonded to the same carbonyl carbon</p> Signup and view all the answers

    What is the primary difference between nylon 6 and nylon 66?

    <p>Nylon 6 is formed from a single monomer, while nylon 66 is formed from two different monomers</p> Signup and view all the answers

    What is the primary application of epoxy resins?

    <p>They are used as adhesives and coatings</p> Signup and view all the answers

    Study Notes

    Step-Growth Polymers

    • Contain two functional groups (A and B) in each monomer
    • Examples: Polyamides, Polyesters, Epoxy Resins, Polyurethanes

    Polyamides

    • Formed from monomers with different functional groups (carboxylic acid and amino)
    • Nylon 6: formed from 6-aminohexanoic acid (contains six carbons)
    • Nylon 66: formed from adipoyl chloride and 1,6-hexanediamine (each with six carbons)

    Polyesters

    • Contain many ester groups
    • Dacron: formed by transesterification of dimethyl terephthalate with ethylene glycol
    • Kodel polyester: formed by transesterification of dimethyl terephthalate with 1,4-di(hydroxymethyl)cyclohexane

    Epoxy Resins

    • Strong adhesives with extensive cross-linking systems
    • Can adhere to almost any surface and resist solvents and high temperatures
    • Formed by reacting a low-molecular-weight prepolymer with a hardener

    Polyurethanes

    • Contain urethane (carbamate) groups
    • Formed by reaction of isocyanate and alcohol groups

    Addition Polymers

    • Ring-Opening Polymerizations: epoxides polymerize through cationic mechanism
    • Polymerization of Dienes: natural rubber is a polymer of 2-methyl-1,3-butadiene (isoprene)
    • Synthetic rubbers: made by radical polymerization of dienes other than isoprene
    • Vulcanization: heating rubber with sulfur causes cross-linking of polymer chains through disulfide bonds

    Copolymers

    • Formed from two or more different monomers
    • Types: alternating, block, random, and graft copolymers

    Condensation Polymers (Step-Growth Polymers)

    • Formed by intermolecular reaction of molecules with functional groups at each end
    • Can be formed by reaction of a single compound with two different functional groups or two different compounds

    Classification of Polymers

    Structure

    • Linear polymers: continuous chain of repeating units
    • Branched polymers: short branches connected to the main chain
    • Cross-linked polymers: covalently bonded linking units between chains

    Physical Properties

    • Physical properties result from arrangement of individual chains
    • Chains held together by Van der Waals forces
    • Crystallites: regions of highly ordered polymer chains
    • Amorphous regions: randomly oriented chains between crystallites
    • Density, hardness, and heat resistance increase with crystallinity

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    Description

    This quiz covers the characteristics and examples of step-growth polymers, including polyamides, polyesters, epoxy resins, and polyurethanes.

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