Chapter Questions
What monomer would you use to form each of the following polymers?
Draw a segment of polystyrene that contains two head-to-head, two tail-to-tail, and two head-to-tail linkages.
Show the mechanism for the formation of a segment of poly(vinyl chloride) that contains three units of vinyl chloride and is initiated by hydrogen peroxide.
Polyethylene can be used for the production of beach chairs as well as beach balls. Which of these items is made from more highly branched polyethylene?
List the following groups of monomers in order from most able to least able to undergo cationic polymerization:
List the following groups of monomers in order from most able to least able to undergo anionic polymerization:
Explain, using resonance structures, why Super Glue is formed by anionic polymerizarion.
Why does methyl methacrylate not undergo cationic polymerization?
Which monomer and which type of initiator would you use to synthesize each of the following polymers?
Explain why, when propylene oxide undergoes anionic polymerization, nucleophilic attack occurs at the less substituted carbon of the epoxide, but when it undergoes cationic polymerization, nucleophilic attack occurs at the more substituted carbon.
Show the polymerization of 2,2 -dimethyloxirane bya. an anionic mechanism.b. a cationic mechanism.
Draw a short segment of gutta-percha.
a. Draw three segments of the polymer that would be formed from 1,4 -polymerization of 1,3 -butadiene in which all the double bonds are trans.b. Draw three segments of the polymer that would be formed from 1,2 -polymerization of 1,3 -butadiene.
Draw four segments of SAN, an alternating copolymer.
a. Draw a short segment of nylon $4 .$b. Draw a short segment of nylon 44 .
Write an equation that explains what will happen if a scientist working in the laboratory spills an aqueous solution of sulfuric acid on her nylon 66 hose.
What happens to polyester slacks if aqueous $\mathrm{NaOH}$ is spilled on them?
a. Propose a mechanism for the formation of the prepolymer formed by bisphenol A and epichlorohydrin.b. Propose a mechanism for the reaction of the prepolymer with the hardener.
Propose a mechanism for the formation of Melmac.
Explain why, when a small amount of glycerol is added to the reaction mixture of toluene2,6 -diisocyanate and ethylene glycol during the synthesis of polyurethane foam, a much stiffer foam is obtained.
a. Draw the structure of a short segment of PHB.b. Draw the structure of a short segment of PHBV with alternating monomers.
Draw short segments of the polymers obtained from the following monomers. In each case, indicate whether the polymerization is a chain-growth or a step-growth polymerization.
Draw the repeating unit of the step-growth polymer that will be formed from each of the following pairs of monomers:
Draw the structure of the monomer or monomers used to synthesize the following polymers, and indicate whether each is a chain-growth polymer or a step-growth polymer.
Draw short segments of the polymers obtained from the following compounds under the given reaction conditions:
A chemist carried out two polymerization reactions. One flask contained a monomer that polymerizes by a chain-growth mechanism, and the other flask contained a monomer that polymerizes by a step-growth mechanism. When the reactions were terminated early in the process and the contents of the flasks analyzed, it was found that one flask contained a high-molecular-weight polymer and very little material of intermediate molecular weight. The other contained mainly material of intermediate molecular weight and very little high-molecular-weight material. Which flask contained which product? Explain.
Quiana is a synthetic fabric that feels very much like silk.a. Is Quiana a nylon or a polyester?b. What monomers are used to synthesize it?
If a peroxide is added to styrene, the polymer known as polystyrene is formed. If a small amount of 1,4 -divinylbenzene is added to the reaction mixture, a stronger and more rigid polymer is formed. Draw a short section of this more rigid polymer.
A particularly strong and rigid polyester used for electronic parts is marketed under the trade name Glyptal. It is a polymer of terephthalic acid and glycerol. Draw a segment of the polymer and explain why it is so strong.
Draw a short segment of the polymer formed from cationic polymerization of 3,3 -dimethyloxacyclobutane.
Which monomer would give a greater yield of polymer: 5-hydroxypentanoic acid or 6-hydroxyhexanoic acid? Explain your choice.
When acrylic acid undergoes chain growth cationic polymerization, a polymer with two types of repeating units is obtained. Draw the structures of the repeating units.
Why do vinyl raincoats become brittle as they get old, even if they are not exposed to air or to any pollutants?
An alternating copolymer of styrene and vinyl acetate can be turned into a graft copolymer by hydrolyzing it and then adding ethylene oxide. Draw the structure of the graft copolymer.
How could head-to-head poly(vinyl bromide) be synthesized?
Delrin (polyoxymethylene) is a tough self-lubricating polymer used in gear wheels. It is made by polymerizing formaldehyde in the presence of an acid catalyst.a. Propose a mechanism for formation of a segment of the polymer.b. Is Delrin a chain-growth polymer or a step-growth polymer?