24 Questions
What is the characteristic of condensation polymers?
Formed by the intermolecular reaction of molecules with a functional group at each end
What is the byproduct of the reaction that forms a condensation polymer?
A small molecule such as H2O, alcohol, or HCl
What type of step-growth polymer is formed by the reaction of a single compound with two different functional groups?
Polyamides
What is the starting material for the synthesis of nylon 6?
ε-caprolactam
What is the name of the polyester polymer formed by the transesterification of dimethyl terephthalate with ethylene glycol?
Dacron
What is the characteristic of epoxy resins?
They are extensively cross-linked systems
What is the name of the polyamide polymer formed by the reaction of adipoyl chloride and 1,6-hexanediamine?
Nylon 66
What is the type of reaction that forms nylon 6?
Polycondensation
What is the primary mechanism by which epoxides undergo polymerization when initiated by a nucleophile?
Anionic mechanism
Which type of polymerization is involved in the production of natural rubber?
Radical polymerization
What is the primary purpose of vulcanization in rubber production?
To create cross-linking between polymer chains
What is the characteristic of an alternating copolymer?
The two monomers alternate
What type of polymerization is involved in the production of synthetic rubbers?
Radical polymerization
What is the characteristic of a graft copolymer?
Branches derived from one monomer grafted onto a backbone from another monomer
What is the primary reason why anionic polymerization requires a very good nucleophile?
Because the alkene has a high electron density
What is the characteristic of an alkene that allows it to undergo anionic polymerization?
The presence of electron-withdrawing substituents
What is the primary difference between anionic and cationic ring-opening polymerization?
The type of initiator used
Why do living polymers commonly occur in anionic polymerization?
Because the chains cannot be terminated by proton loss or chain combination
What is the characteristic of a block copolymer?
Blocks of each kind of monomer
What type of polymerization is initiated by surface-absorbed water in Super Glue?
Anionic polymerization
What is the role of a nucleophilic group on the surface of the skin in the polymerization of Super Glue?
It initiates anionic polymerization
Why is butyllithium a suitable initiator for anionic polymerization?
Because it is a strong nucleophile
What is the typical outcome of anionic polymerization in the absence of chain termination?
Formation of a high-molecular-weight polymer
Why do alkenes with electron-withdrawing substituents undergo anionic polymerization more readily?
Because they have a lower electron density
Study Notes
Condensation Polymers (Step-Growth Polymers)
- Formed by intermolecular reaction of molecules with a functional group at each end, resulting in the loss of a small molecule such as H2O, alcohol, or HCl.
- 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, one with two A functional groups and the other with two B functional groups.
Classes of Step-Growth Polymers
- Polyamides
- Polyesters
- Epoxy Resins
- Polyurethanes
Polyamides
- Nylon 6 is an example of a step-growth polymer formed from a monomer with two different functional groups, resulting in the formation of an amide.
- 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.
- Nylon 66 is an example of a step-growth polymer formed by two different bifunctional monomers, adipoyl chloride and 1,6-hexanediamine.
Polyesters
- Polymers containing many ester groups.
- Dacron is the most common polyester polymer, 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, being extensively cross-linked systems.
- They can adhere to almost any surface and are resistant to solvents and high temperature.
Addition Polymers
Ring-Opening Polymerizations
- Some compounds can polymerize well, rather than ethylene and substituted ethylenes, in chain-growth polymerizations.
- Epoxides undergo chain-growth polymerization, which can occur by an anionic or cationic mechanism.
Polymerization of Dienes
- The manufacture of rubber involves the polymerization of 2-methyl-1,3-butadiene (isoprene).
- Synthetic rubbers can be made by radical polymerization of dienes other than isoprene.
- Natural and synthetic rubbers can be hardened by vulcanization, which involves heating rubber with sulfur, resulting in cross-linking of the separate polymer chains through disulfide bonds.
Copolymers
- Formed by the polymerization of two or more different monomers.
- Can be classified into four types: alternating, block, random, and graft copolymers.
Anionic Polymerization or Living Polymers
- The initiator is a nucleophile that reacts with the monomer to form an anion propagating site.
- The mechanism involves an initiating step and propagation steps.
- Living polymers are most common in anionic polymerization because the chains cannot be terminated by proton loss or by chain combination or disproportionation.
- Examples of alkenes that undergo anionic polymerization include methyl α-cyanoacrylate, which is used to make Super Glue.
Learn about condensation polymers, also known as step-growth polymers, formed through intermolecular reactions of molecules with functional groups at each end.
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