chm325h-m2008 - UNIVERSITY OF TORONTO Faculty of Arts and...

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Unformatted text preview: UNIVERSITY OF TORONTO Faculty of Arts and Science APRIL-MAY EXAMINATIONS 2008 CHEM 325HS DURATION: 120 MINUTES NO AIDS ALLOWED Duration - 2 hours NOTE THAT CLEAR DIAGRAMS AND CONCISE INF ORMATIVE ANSWERS ARE ESSENTIAL FOR SCORING HIGH MARKS IN THIS EXAMINATION ANSWER QUESTIONS IN SECTION A AND B IN SEPARATE EXAMINATION BOOKS TOTAL MARKS: 120 Page 1 of 3 SECTION A ANSWER 3 QUESTIONS FROM QUESTIONS 1-4 1. (20 marks) Explain how IR—spectroscopy is used to characterize polymer (a) crystallinity (b) hydrogen bonding (c) miscibility with another polymer (d) degradation Give appropriate examples and draw schematic diagrams of the corresponding spectra. 2. (20 marks) Films produced from poly(methyl methacrylate) (PMMA) frequently crack. Describe 3 methods to improve the mechanical properties of PMMA. In each case, explain the reason for the enhancement. 3. (20 marks) Write polymerization reactions used for the synthesis of (a) poly(butyl acrylate) (b) a block copolymer of polystyrene and polyacrylic acid with PDI=1 . 1. (c) poly(ethy1ene terephthalate) Choose one polymer and write reactions for all stages of the process of polymerization 4. (20 marks) Use a polymer of your choice and explain how you would choose an appropriate solvent for it. Explain advantages and limitations of the solubility parameter approach. Support your answer by appropriate equations. SECTION B ANSWER 3 QUESTIONS FROM QUESTIONS 1-7 1. (20 marks) Explain the origin of the color and therrnochromic behavior of Wolfram’s salts {[M(en)2][M’(en)2C12]}X4 in chloroform solution, where M, M’ = Ni, Pd, Pt, en = ethylenediarnine and X is the anionic phospholipids: cfla'ccflz)”_1 ' CH,{CH2)M- o’ ‘o‘ 1§(n*12,16] (20 marks) Provide a simple configuration coordinate description (energy vs distortion coordinate) of Day and Robbins classification of mixed valence compounds and use it to explain the Verwey semiconductor-metal transition observed in the temperature dependence of the electrical conductivity in the inverse Spinel Fe304. (20 marks) Describe the origin, nature and manifestation of the Peierls effect, the metal—nonmetal transition and charge density waves observed in the layered tantalum disulfide TaSz. (20 marks) Elaborate on pertinent details behind the statement that the doping of silicon is chemically and physically distinct to doping in polyacetylene and polypyrrole. (20 marks) Provide synthesis and structure, bonding and band structure, molecule and polymer material relations between S4N4 and SzNz and (SN)x that enables rationalization of the metallic properties and transition to superconducting properties at low temperatures for polythiazyl (SN)X. (20 marks) Tetrathiofulvalene-tetracyanoquinodimethane TTF-TCNQ is metallic at RT and becomes semiconducting below 60K. Explain this observation and describe what chemical modifications of this basic system can be used to make it a low temperature superconductor rather than a semiconductor. (20 Marks) Describe the synthesis, component materials assembly and physico- chemical principles that underpin the operation of two of the following: (a) all—polymer battery comprised of a cathode and anode both made of polyacetylene and an electrolyte comprised of a polyethyeleneoxide—salt composite (b) Schottky type semiconductor-metal junction solar cell based on a thin film of polyacetylene deposited on n-doped silicon wafer (c) all-polyacetylene optical waveguide (d) all poly-acetylene electrical capacitor ...
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This note was uploaded on 01/05/2012 for the course CHM 325 taught by Professor - during the Spring '11 term at University of Toronto- Toronto.

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chm325h-m2008 - UNIVERSITY OF TORONTO Faculty of Arts and...

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