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What is the primary characteristic of step growth polymerization?
What is the primary reason for the reduced density of a polymer?
What type of polymerization is associated with chain growth?
What is the term for regions of a polymer with highly ordered chains?
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What is the primary function of Van der Waals forces in polymers?
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What is the result of having highly ordered polymer chains?
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What type of polymer has short branches connected to the main chain?
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What is the primary characteristic of a cross-linked polymer?
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What is the mechanism by which epoxides are polymerized when the initiator is a Lewis acid?
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What is the main problem with natural and most synthetic rubbers?
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What type of polymerization reaction is involved in the formation of condensation polymers?
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What is the purpose of vulcanization in rubber production?
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What type of copolymer has a random distribution of monomers?
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What is the main difference between homopolymers and copolymers?
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What is the result of heating rubber with sulfur in the vulcanization process?
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What is the name of the process by which a polymer is formed from a single compound with two different functional groups?
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What is the primary characteristic of a step-growth polymer?
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What is the reaction mechanism involved in the synthesis of nylon 6?
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What is the starting material for the synthesis of nylon 6?
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What is the primary characteristic of epoxy resins?
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What is the reaction mechanism involved in the synthesis of Dacron?
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What is the primary characteristic of polyurethanes?
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What is the primary difference between nylon 6 and nylon 66?
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What is the primary application of epoxy resins?
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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.