(a)
Interpretation:
The structures of cis- and trans-polyacetylene are to be drawn.
Concept introduction:
The
(b)
Interpretation:
An explanation to show that cis- and trans-polyacetylene conduct electricity is to be stated.
Concept introduction:
The double bonds in the structures of cis- and trans-polyacetylene are present at alternative positions. These alternative positions of double bonds indicate that cis- and trans-polyacetylene are conjugated and thereby movement of electrons are possible.
(c)
Interpretation:
An explanation for the possibility to prepare anisotropic electrical conductivity (unusual behaviour) polyacetylene films is to be stated.
Concept introduction:
Anisotropic electrical conductivity of a polymer refers to the different conductivity of a polymer in different direction. Electrical conductivity, parallel to the layer of a polymer is high as compare to perpendicular to the layer of a polymer.
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Organic Chemistry (9th Edition)
- The 2000 Nobel Prize in Chemistry was awarded for work on polyacetylenes. Acetylene can be polymerized using a Ziegler–Natta catalyst. The cis or trans stereochemistry of the products can be controlled by careful selection and preparation of the catalyst. The resulting polyacetylene is an electrical semiconductor with a metallic appearance. cis-Polyacetylene has a copper color, and trans-polyacetylene is silver. It is possible to prepare polyacetylene films whose electrical conductivity is anisotropic. That is, the conductivity is higher in some directions than in others. Explain how this unusual behavior is possible.arrow_forwardExplain the general process observed for conjugated polyenes ?arrow_forwardPoly(lactic acid) (PLA) has received much recent attention because the lactic acid monomer [CH3CH(OH)COOH] from which it is made can be obtained from carbohydrates rather than petroleum. This makes PLA a more “environmentally friendly” polyester. (A more in-depth discussion of green polymer synthesis is presented in Chapter 30.) Draw the structure of PLA.arrow_forward
- When polyethylene is made by free radical polymerization, the resulting polymer has a significant amount of branching, resulting in low-density polyethylene (see Section 26.9a). When styrene undergoes free radical polymerization, on the other hand, very little branching occurs. Explain this phenomenon.arrow_forwardPoly(lactic acid) (PLA) has received much recent attention because the lactic acid monomer [CH3CH(OH)COOH] from which it is made can be obtained from carbohydrates rather than petroleum. This makes PLA a more “environmentally friendly” polyester. (A further discussion of green polymer synthesis is presented in Chapter 28.) Draw the structure of PLA.arrow_forwardPoly(lactic acid) (PLA) has received much recent attention because the lactic acid monomer [CH3CH(OH)COOH] from which it is made can be obtained from carbohydrates rather than petroleum. This makes PLA a more “environmentally friendly” polyester. Draw the structure of PLAarrow_forward
- Draw (by hand) the monomers used to synthesize poly(ethyl cyanoacrylate) and poly(octyl cyanoacrylate), and chemical structure of the repeat units of each when polymerized.arrow_forward4. Describe how the stereoisomerism affect the degree of crystallinity of a semicrystalline polymer such as polyethylene.arrow_forwardCharles Goodyear discovered that if sulfur is added to rubber and the mixture is heated, the rubber hardens, becomes more resilient, and does not melt. This process is referred to as and involves the formation of sulfur bridges between the methyl side groups on different chains. A polymerization sintering c hybridization D linking E) vulcanizationarrow_forward
- A polymerization reaction in which monomers react to form a polymer chain without net loss of atoms substitution reduction c) cross-linking D hybridization additionarrow_forward2. In your own words, explain the difference between step-reaction polymerization and chain-reaction poly- merization. What is the advantage of this terminology over the more traditional addition and condensa- tion polymerization?arrow_forwardExplain why styrene (CH2=CHPh) can be polymerized to polystyrene by all three methods of chain-growth polymerization.arrow_forward
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