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Final Exam, May 2, 2014, 100 pts Polymer Chemistry, CHEM 466, Spring 2014 Texas A&M University, College Station, TX, USA
- Choose a polymer that you find most interesting and answer the following questions.
(a) Provide its chemical structure (don't forget to include the chain ends). [5 points]
(b) Provide a retrosynthetic pathway by which the polymer structure of part (a) could be prepared. [5 points]
(c) State whether the polymerization step of your retrosynthesis in part (b) would proceed by a chain-growth or step-growth process. [2 points]
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(d) State whether your polymerization would be controlled or un-controlled. [2 points]
(e) State whether the molecular weight distribution would be expected to be narrow or broad. [ points]
(f) Draw the expected DPn vs. % monomer conversion plot on the axes below. [4 points]
DP,
0 100
% monomer conversion
(g) Describe the physical and mechanical properties characteristics and how they relate to the polymer composition and structure. [4 points]
(h) State how this polymer is used or could be used. Indicate whether it is a component of current products or under research development. [2 points]
- (a) Provide a retrosynthetic route for the preparation of the polyacetylene structure shown below. [5 points]
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(b) As we had discussed in class, hydrogenation of this polymer could lead to a linear polyethylene. Provide the structure of the polymer that would result from hydrogenation of the polymer of part (a). [5 points]
(c) Industrially, however, linear polyethylene is produced using transition metal catalysts for the polymerization of ethylene. To tune the physical and mechanical properties of linear polyethylene, we discussed a process that was developed at Dow Chemical Company and involves copolymerization of ethylene with a-olefins, e.g. octene. Describe the key mechanistic features of the reaction system that were reported in the article, Arriola, D. J.; Carnahan, E. M.; Hustad, P. D.; Kuhlman, R. L; Wenzel, T. T. Science, 2006, 372, 714-719, to obtain statistical olefin multi-block copolymers with alternating semicrystalline and amorphous segments. [5 points]
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(c) In addition to ethylene and octene, predict the components (catalysts, etc.) that were employed during the copolymerizations that led to the molecular weight data obtained by GPC analysis (below), and explain the characteristics of the polymer/copolymer samples/mixtures. In agreement with the arrows, place each answer (for components and polymer characteristics) into a separate box — on the left for the GPC trace for one sample and on the right for the other. [8 points]
(d) Give two advantages that were observed for the physical properties that resulted from the statistical multi-block copolymer structure. [4 points]
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- The following questions are related to the poly(glucose carbonate) polymer shown below (PGC(EC)) that is prepared in the presence of the organocatalyst TBD through ring opening polymerization of a cyclic carbonate monomer of glucose.
PGC(EC)
(a) Provide a retrosynthetic pathway for the preparation of this polymer (you need only to work back to the protected cyclic carbonate monomer). [4 points]
2 mol% TBD
PGC(EC)
o
OH P-\
o 6 —
(b) Provide the expected products upon hydrolytic degradation of this polymer. [4 points]
3nH 2 O
PGC(EC)
HO O-
n CO, + 2n (^) ^OH
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- For quiz #10, several students expressed interest in the chemistries of the polymers used in 'ove' gloves and bullet-proof vests. Therefore, (a) Provide the structures of the polymers. [5 points] (b) Provide retrosyntheses for the polymers. [5 points] (c) Give their tradenames. [2 points] (d) Describe the characteristics of the polymer compositions and structures that lead to high temperatures for thermal transitions and decompositions, which allow for their utilization in these applications. [5 points]
'ove' glove polymer:
~-AV"M 0
H^M
r
Bullet-proof vest polymer:
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