CHM Lab Polymers

CHM Lab Polymers - Investigation of Polymers CHM 11500 Fall...

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Investigation of Polymers CHM 11500 Fall 2011 1 Investigation of Polymers During this activity you will prepare and investigate two polymers: 1. cross-linked poly(vinyl alcohol) 2. nylon prepared by the condensation of adipoyl chloride and 1,6-diaminohexane Read the information on polymers in your textbook, pp. 461-466, and in your lecture notes. It is important that you understand the following terms and skills: Terms: monomer polymer degree of polymerization viscosity branched polymers cross-linked polymers Skills: calculate the molar mass of a polymer chain, the molar mass of a polymer repeat unit, or the number of repeat units identify the repeat unit of a polymer chain understand the difference between a condensation reaction and an addition reaction INTRODUCTION Cross-linked Poly(vinyl alcohol) Abstracted in part from J. Chem. Educ. , 1986, 63 (1), p 57. Poly(vinyl alcohol) is the polymer formed by the addition polymerization of vinyl alcohol, H 2 C=CHOH. vinyl alcohol Most vinyl polymers are not soluble in water. Polyvinyl alcohol (PVA) is soluble, however, because it has hydroxy (-OH) groups, which can form hydrogen bonds with water. This allows PVA to interact with polar water molecules and makes PVA soluble. (Nevertheless, you will still need to utilize patience in dissolving the PVA in water.) addition polymerization poly(vinyl alcohol) - PVA
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Investigation of Polymers CHM 11500 Fall 2011 2 Sodium tetraborate (borax), Na 2 B 4 O 7 10 H 2 O, dissolves in water to form a mixture of boric acid, B(OH) 3 , and borate ion, B(OH) 4 . Borate ion is tetrahedral and can form hydrogen bonds between adjacent PVA polymer molecules with any of its four hydroxyl groups. This crosslink is formed by relatively strong hydrogen bonds, which are constantly forming and dissociating. In this lab you will have the opportunity to observe how cross-linking changes the properties of a polymer. Nylon The nylon you will prepare in this experiment is formed by the condensation polymerization of 1,6-diaminohexane, H 2 N(CH2) 6 NH 2 ,and adipoyl chloride, ClOC(CH 2 ) 4 COCl, an acid chloride. The condensation proceeds with elimination of 2 molecules of HCl.
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Investigation of Polymers CHM 11500 Fall 2011 3 PRELAB As part of your individual preparation for lab, answer the following questions in your lab notebook before going to lab. The copy of your answers on perforated pages from your lab notebook is due at the beginning of lab. 1. Describe the difference between a monomer and a polymer. 2. Write a structural formula showing all atoms and bonds for a portion of a poly(vinyl alcohol) (PVA) chain that contains four monomers. Circle the repeat unit (one monomer). 3.
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CHM Lab Polymers - Investigation of Polymers CHM 11500 Fall...

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