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Questions and Answers
What is necessary for an anionic polymerization reaction to occur?
What is necessary for an anionic polymerization reaction to occur?
Why do living polymers commonly form in anionic polymerization?
Why do living polymers commonly form in anionic polymerization?
What type of substituent on the alkene is necessary for an anionic polymerization reaction to occur?
What type of substituent on the alkene is necessary for an anionic polymerization reaction to occur?
What is necessary to initiate anionic polymerization of methyl α-cyanoacrylate?
What is necessary to initiate anionic polymerization of methyl α-cyanoacrylate?
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What initiates the polymerization reaction when using Super Glue?
What initiates the polymerization reaction when using Super Glue?
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What is the result when using Super Glue?
What is the result when using Super Glue?
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Why is anionic polymerization necessary for the formation of some polymers?
Why is anionic polymerization necessary for the formation of some polymers?
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What is unique about the initiator in anionic polymerization?
What is unique about the initiator in anionic polymerization?
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What type of reaction occurs between molecules with a functional group at each end to form condensation polymers?
What type of reaction occurs between molecules with a functional group at each end to form condensation polymers?
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Which of the following is NOT a class of step-growth polymers?
Which of the following is NOT a class of step-growth polymers?
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What is the monomer used to form nylon 6?
What is the monomer used to form nylon 6?
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What is the starting material for the synthesis of nylon 6?
What is the starting material for the synthesis of nylon 6?
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What is the name of the polyamide formed from adipoyl chloride and 1,6-hexanediamine?
What is the name of the polyamide formed from adipoyl chloride and 1,6-hexanediamine?
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What is the process by which Dacron is made?
What is the process by which Dacron is made?
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What is the property of epoxy resins that makes them useful as adhesives?
What is the property of epoxy resins that makes them useful as adhesives?
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What is the polyester formed by the transesterification of dimethyl terephthalate with 1,4-di(hydroxymethyl)cyclohexane?
What is the polyester formed by the transesterification of dimethyl terephthalate with 1,4-di(hydroxymethyl)cyclohexane?
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What is the mechanism of polymerization of epoxides when the initiator is a nucleophile?
What is the mechanism of polymerization of epoxides when the initiator is a nucleophile?
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What is the process of hardening rubber by heating it with sulfur known as?
What is the process of hardening rubber by heating it with sulfur known as?
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What type of copolymer has a random distribution of monomers?
What type of copolymer has a random distribution of monomers?
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What is the natural rubber a polymer of?
What is the natural rubber a polymer of?
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What is the problem with natural and most synthetic rubbers?
What is the problem with natural and most synthetic rubbers?
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What is the result of heating rubber with sulfur?
What is the result of heating rubber with sulfur?
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What type of polymerization occurs in the presence of a Lewis acid?
What type of polymerization occurs in the presence of a Lewis acid?
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What is a graft copolymer composed of?
What is a graft copolymer composed of?
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Study Notes
Anionic Polymerization
- Initiator is a nucleophile that reacts with the monomer to form an anion propagating site
- Nucleophilic attack on an alkene does not occur readily due to the electron-rich nature of alkenes
- Initiator must be a very good nucleophile, such as sodium amide or butyllithium, and the alkene must contain electron-withdrawing substituents to decrease the electron density of the double bond
Mechanism of Anionic Polymerization
- Initiating step: involves the reaction of the nucleophile with the monomer
- Propagation steps: involve the reaction of the anion propagating site with additional monomers
Living Polymers
- Most common in anionic polymerization
- Chains cannot be terminated by proton loss from the polymer (as they can in cationic polymerization) or by chain combination or disproportionation (as they can in radical polymerization)
Examples of Alkenes That Undergo Anionic Polymerization
- Methyl α-cyanoacrylate (Super Glue)
Ring-Opening Polymerizations
- Some compounds can polymerize well rather than ethylene and substituted ethylenes in chain-growth polymerizations
- Epoxides undergo chain-growth polymerization
- If the initiator is a nucleophile, polymerization occurs by an anionic mechanism
- If the initiator is a Lewis acid, epoxides are polymerized by a cationic mechanism
Polymerization of Dienes
- The manufacture of rubber
- Natural rubber is a polymer of 2-methyl-1,3-butadiene (isoprene)
- Synthetic rubbers have been made by radical polymerization of dienes other than isoprene
Vulcanization
- A problem with both natural and most synthetic rubbers is that they are soft and sticky
- They can be hardened by vulcanization (heating of rubber with sulfur)
- Heating rubber with sulfur causes cross-linking of the separate polymer chains through disulfide bonds
Copolymers
- Formed from two or more different monomers
- Both chain-growth polymers and step-growth polymers can be copolymers
- Four types of copolymers:
- Alternating copolymer: the two monomers alternate
- Block copolymer: consists of blocks of each kind of monomer
- Random copolymer: has a random distribution of monomers
- Graft copolymer: contains branches derived from one monomer grafted onto a backbone from another monomer
Condensation Polymers (Step-Growth Polymers)
- Formed by the intermolecular reaction of molecules with a functional group at each end
- In most cases, a small molecule such as H2O, alcohol, or HCl is lost
- Can be formed by the reaction of a single compound with two different functional groups, A and B, or by the reaction of two different compounds
Classes of Step-Growth Polymers
- Polyamides
- Polyesters
- Epoxy Resins
- Polyurethanes
Polyamides
- Nylon 6: an example of a step-growth polymer formed from a monomer with two different functional groups
- Nylon 6 is formed from the polymerization of 6-aminohexanoic acid, which contains six carbons
- The starting material for the synthesis of nylon 6 is ε-caprolactam
Polyesters
- Polymers containing many ester groups
- Dacron is the most common polyesters polymer
- Dacron is made by the transesterification of dimethyl terephthalate with ethylene glycol
- Kodel polyester is formed by the transesterification of dimethyl terephthalate with 1,4-di(hydroxymethyl)cyclohexane
Epoxy Resins
- They are the strongest adhesives known
- They are extensively cross-linked systems
- They can adhere to almost any surface and are resistant to solvents and high temperature
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Description
This quiz covers the process of anionic polymerization, including the role of nucleophilic initiators and electron-withdrawing substituents in forming living polymers.
