Podcast
Questions and Answers
What happens to the concentration of monomer over time?
What happens to the concentration of monomer over time?
- It decreases gradually (correct)
- It remains constant
- It fluctuates randomly
- It increases rapidly
What is the primary characteristic of step growth polymerization?
What is the primary characteristic of step growth polymerization?
- Oligomers react together to form longer chains (correct)
- Monomers react in a single step
- The reaction is reversible
- Chain growth is rapid and continuous
What is the main difference between linear and branched polymers?
What is the main difference between linear and branched polymers?
- Branched polymers have a network structure
- Branched polymers have a backbone with short branches (correct)
- Linear polymers have a single chain structure
- Linear polymers have cross-links
What is the main characteristic of cross-linked polymers?
What is the main characteristic of cross-linked polymers?
What is the primary factor that determines the physical properties of a polymer?
What is the primary factor that determines the physical properties of a polymer?
What is the primary type of force that holds polymer chains together?
What is the primary type of force that holds polymer chains together?
What are the regions of a polymer where the chains are highly ordered called?
What are the regions of a polymer where the chains are highly ordered called?
What happens to the density of a polymer when it has substituents or branches that prevent close packing?
What happens to the density of a polymer when it has substituents or branches that prevent close packing?
What type of polymers have both ordered crystalline regions and amorphous noncrystalline regions?
What type of polymers have both ordered crystalline regions and amorphous noncrystalline regions?
What is the reason thermosetting polymers cannot be remelted by heating?
What is the reason thermosetting polymers cannot be remelted by heating?
What happens to the polymer chains when elastomers are stretched?
What happens to the polymer chains when elastomers are stretched?
What type of polymers are rubber and spandex examples of?
What type of polymers are rubber and spandex examples of?
What type of polymerization is involved in the formation of addition polymers?
What type of polymerization is involved in the formation of addition polymers?
What is the common monomer used to form vinyl polymers?
What is the common monomer used to form vinyl polymers?
Why do elastomers return to their original state after the stretching force is removed?
Why do elastomers return to their original state after the stretching force is removed?
What is the characteristic of thermoplastic polymers that allows them to be molded when heated?
What is the characteristic of thermoplastic polymers that allows them to be molded when heated?
What is the purpose of molecule XY in radical polymerization?
What is the purpose of molecule XY in radical polymerization?
Why is head-to-tail addition favored in radical polymerization?
Why is head-to-tail addition favored in radical polymerization?
What type of bond is required for molecule XY to react with the growing chain?
What type of bond is required for molecule XY to react with the growing chain?
What is the role of the initiator in radical polymerization?
What is the role of the initiator in radical polymerization?
Why does head-to-head addition occur when Z is small?
Why does head-to-head addition occur when Z is small?
What is the effect of a phenyl substituent on the radical?
What is the effect of a phenyl substituent on the radical?
What type of cleavage occurs in radical polymerization?
What type of cleavage occurs in radical polymerization?
What is the result of chain transfer in radical polymerization?
What is the result of chain transfer in radical polymerization?
What is the role of the initiator in anionic polymerization?
What is the role of the initiator in anionic polymerization?
What type of shift can occur in the propagating site during cationic polymerization?
What type of shift can occur in the propagating site during cationic polymerization?
What is the characteristic of the monomers that undergo cationic polymerization?
What is the characteristic of the monomers that undergo cationic polymerization?
What is the type of carbocation formed at the propagating site before rearrangement?
What is the type of carbocation formed at the propagating site before rearrangement?
What is the reason for the difficulty in nucleophilic attack on an alkene in anionic polymerization?
What is the reason for the difficulty in nucleophilic attack on an alkene in anionic polymerization?
What is the characteristic of the initiator in anionic polymerization?
What is the characteristic of the initiator in anionic polymerization?
What is the purpose of the electron-withdrawing substituent in anionic polymerization?
What is the purpose of the electron-withdrawing substituent in anionic polymerization?
What is the result of a 1,2-hydride shift in the propagating site during cationic polymerization?
What is the result of a 1,2-hydride shift in the propagating site during cationic polymerization?
What is the functional group that reacts with the carboxylic acid group in the formation of nylon?
What is the functional group that reacts with the carboxylic acid group in the formation of nylon?
What is the name of the polyamide formed from the polymerization of 6-aminohexanoic acid?
What is the name of the polyamide formed from the polymerization of 6-aminohexanoic acid?
What is the common name of the polyester polymer formed by the transesterification of dimethyl terephthalate with ethylene glycol?
What is the common name of the polyester polymer formed by the transesterification of dimethyl terephthalate with ethylene glycol?
What is the characteristic of epoxy resins that makes them resistant to solvents and high temperature?
What is the characteristic of epoxy resins that makes them resistant to solvents and high temperature?
What is the functional group that defines a polyurethane?
What is the functional group that defines a polyurethane?
What is the starting material for the synthesis of nylon 6?
What is the starting material for the synthesis of nylon 6?
What is the name of the polyamide formed from two different bifunctional monomers—adipoyl chloride and 1,6-hexanediamine?
What is the name of the polyamide formed from two different bifunctional monomers—adipoyl chloride and 1,6-hexanediamine?
What is the reaction that forms Kodel polyester?
What is the reaction that forms Kodel polyester?
Flashcards are hidden until you start studying
Study Notes
Polymerization
- The concentration of monomer decreases gradually until it is depleted during polymerization.
Classification of Polymers: Growth
- Step growth: Chains have at least two growth points, forming oligomers that react to give longer chains, associated with condensation polymerization.
- Chain growth: Associated with addition polymerization.
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.
Classification of Polymers: Physical Properties
- Physical properties of polymers are a result of individual chain arrangement.
- Regions of highly ordered chains (crystallites) are interspersed with amorphous, noncrystalline regions.
- Polymers classified according to properties:
- Thermoplastic polymers: Have both ordered crystalline and amorphous noncrystalline regions, can be molded when heated.
- Thermosetting polymers: Cross-linked, rigid, and cannot be remelted by heating.
- Elastomers: Flexible, can be stretched and return to original state, have some cross-linking.
Addition Polymers
- Formed from ethylene or substituted ethylenes (vinyl polymers).
- Radical polymerization:
- Termination steps: Chain transfer, may occur by reaction with a molecule XY.
- Favored head-to-tail addition due to steric hindrance and stabilization by substituents.
- May undergo head-to-head or tail-to-tail addition in some cases.
- Cationic polymerization:
- Mechanism involves chain-initiating, chain-propagating, and termination steps.
- Carbocation intermediates can undergo rearrangement by 1,2-hydride or 1,2-methyl shift.
- Best monomers have substituents that stabilize the positive charge.
Anionic Polymerization
- Initiator is a nucleophile that reacts with the monomer to form an anion propagating site.
- Nucleophilic attack on an alkene requires a very good nucleophile and electron-withdrawing substituents on the alkene.
Classes of Step-Growth Polymers
- Polyamides
- Polyesters
- Epoxy resins
- Polyurethanes
Polyamides
- Nylon 6: Formed from 6-aminohexanoic acid, a polyamide.
- Nylon 66: Formed from adipoyl chloride and 1,6-hexanediamine.
- Starting material for nylon 6 synthesis is ε-caprolactam.
Polyesters
- Containing many ester groups.
- Dacron: Made by transesterification of dimethyl terephthalate with ethylene glycol.
- Kodel polyester: Formed by transesterification of dimethyl terephthalate with 1,4-di(hydroxymethyl)cyclohexane.
Epoxy Resins
- Strongest adhesives known, extensively cross-linked systems.
- Adhere to almost any surface, resistant to solvents and high temperature.
- Epoxy cement: Consisting of a low-molecular-weight prepolymer and a hardener that react to form a cross-linked polymer.
Polyurethanes
- Containing urethane (carbamate) groups.
- Formed by reaction of a prepolymer with a hardener.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
