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Organic Polymer Chemistry Question 1 A 20.0 sample of polyester, synthesized by reacting terephthalic acid and ethylene glycol: 1/1 mole ratio, was found to contain 2.95 10³ moles of carboxylic acid groups by titration with base. (a) What the number average molecular weight of the polymer? (b) Estimate the extent of reaction that was required in order to attain this molecular weight. (c) Draw the structure of the polymer, clearly showing the repeating unit and the end groups. Question What factors determine whether cyclization or linear polymerization is the predominant reaction in step growth polymerization? Discuss the possibility of cyclization in the polymerization of the monomers shown in (a) and (b) below, when has values of 2- 10. At what stage or stages in the polymerizations is cyclization possible? (a) (b) HO-(CH2)2-OH HOOC-(CH2COOH Question Show by means of chemical equations the initial reaction product or products of the reaction of propagating poly(methyl acrylate) radicals with each the following compounds: (a) -butylmercaptan (b) isopropyl benzene (c) 2,6-di-tert-buty Iphenol (d) di-tert-buty peroxide (e) carbon tetrabromide (f) 4-benzoquinone (g) Oxygen (h) Allyl acetate Classify each of the compounds (a h) as either chain transfer agent or an inhibitor and explain your choice. Question The sodium naphthalenide polymerization of styrene is carried out in benzene and tetrahydrofurar solutions. Which solution gives the higher polymerization rate? Discuss the effect of solvent on the relative concentrations of the different types of propagating centers. Question What reaction conditions determine the relative amounts of 1,2-, cis 1,4-, and trans 1,4 polymerization in radical and anionic polymerizations of 1,3 -butadiene? Indicate the effect of solvent and counterion in these polymerizations. What polymer structures are obtained using traditional Ziegler-Natta and Metallocene catalysts? Question 6 Which the polymerization initiator or initiators can be used to polymerize each of the monomers (a-h) listed in the table below' (Note: an initiator may be suitable for more than one monomer). For each of the monomers, draw the structure of the polymer repeating unit that obtained. Polymerization initiators Monomers PhCH=CH-[Ru] (a) Propylene oxide n-butyllithium (b) 2-pyrrolidinone BF3+H2O (c) cyclooctene TiCla + Et2AICI (d) oxacyclobutane H2SO4 (e) -valerolactone NaOC2Hs (f) norbornene H2O (g) Octamethylcyclotetrasiloxane (h) Trioxane Question Describe with the aid of chemical reaction schemes how you would synthesize block copolymers with segments of the structures shown in (a) and (b): (a) tonging and Hot (b) 3-mm and Question What methods can be used to increase the polymerization rates in free radical initiated polymerizations? Discuss the impact that each method has on molecular weight of the polymer produced. Question Compare and contrast the cationic ring- opening polymerization of the three member hetrocyclic monomers ethylene oxide and aziridine. Draw structures of polymers obtained and explain why the polymers from these monomers have different chain architectures. Question 10 A sample of polystyrene, prepared by the living anionic polymerization of styrene with n- butyllithium as an initiator, was found to have number average molecular weight of was 104.000 100% g/mole complete, and what molar are: mass (a) dispersity the relative of initial 1.04. concentrations Assuming the conversion of monomer of and styrene initiator required to achieve this molecular weight; and (b) the weight average molecular weight of the sample?

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