Polymers. One of the most remarkable and useful polymers known is Teflon, formed via polymerization of tetrafluoroethylene as shown below:

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1 Experimet 8 Chem 276 Fall Semester 2010 Page 1 of 5 Polymers Itroductio A polymer is a gigatic chailike molecule made by coectig may small molecules, kow as moomers. The process by which polymers are formed is kow as polymerizatio. Today our culture is iudated with polymers materials used i everythig ragig from Ziploc baggies ad cell phoes to car parts ad satellites. I fact, it would ow be difficult to eve imagie life without sythetic polymers. Polymers are so useful because scietists are able to develop ad produce polymer materials with may differet properties. A polymer ca be rigid, flexible, trasparet, opaque, hard, soft, elastic, stiff ad resistat to chemicals. Scietists are able to maipulate the properties of a polymer by choosig which moomers are used ad how these moomers are chemically coected. e of the most remarkable ad useful polymers kow is Teflo, formed via polymerizatio of tetrafluoroethylee as show below: (NH 4 ) 2 S 2 8 High pressure Tetrafluoroethylee F 3 C CF 3 Teflo Teflo is resistat to virtually all chemicals, forms a surface which is o-stick, ad maitais these properties over a temperature rage of -270 to 385 Celsius. The buildig you are workig i today, Malcolm Refrew Hall, is amed after a former UI chemistry professor who published the first paper o Teflo i 1946 ad (with DuPot) itroduced this useful material to the world. Prof. Refrew still lives i Moscow ad recetly celebrated his 100 th birthday.

2 Experimet 8 Chem 276 Fall Semester 2010 Page 2 of 5 Aother example of a useful polymer is polystyree. substituted bezee called styree. It is formed via polymerizatio of simple 2 Tert-butyl bezoyl peroxide H 3 C(H 5 C 6 )HC CH 2 CH 2 CH 2 (C 6 H 5 ) Heat C H 2 Styree Polystyree This type of polymerizatio is kow as a additio reactio because two styree moomers are added together resultig i the removal of the double bod. Both tert-butyl bezoyl peroxide ad heat are eeded to start this reactio. Polystyree is a hard ad trasparet polymer which is ideal for food cotaiers. Polystyree ca also be readily foamed to create packig material or thermal isulators. Styrofoam is the trade ame give to foamed polystyree. A secod type of polymerizatio reactio is kow as a codesatio reactio. I a codesatio reactio two moomers react to form a polymer with the elimiatio of a small molecule (such as H). Nylo 6-6 is sythesized usig a codesatio polymerizatio reactio. The moomers adipoyl chloride ad hexamethylee diamie react to form the polymer with the elimiatio of H as show below. H 2 N NH 2 hexamethylee diamie + adipoyl chloride C(CH 2 ) 4 C NH (CH 2 ) 6 NH C (CH 2 ) 4 C NH (CH 2 ) 6 NH 2 + H ylo 6-6 Your task today will be to prepare two polymers: polystyree ad Nylo 6-6. Take care to follow the procedure carefully as you will be graded o the quality of your fial products.

3 Experimet 8 Chem 276 Fall Semester 2010 Page 3 of 5 Procedure Polystyree 1. Fill a 250 ml beaker ¾ of the way full with sad ad place o a hot plate i the fume hood to set up a 140 Celsius sad bath. 2. Measure 10 ml of styree ito a large test tube. 3. Add 10 drops of tert-butyl peroxybezoate to the polystyree ad mix. 4. Place the mixture i the sad bath ad heat. Does the mixture chage color durig reactio? 5. ce you begi oticig bubbles, remove the test tube from the sad bath. Do ot over heat. Whe the bubbles are o loger are formig, place the test tube back ito the sad bath. Agai remove test tube if the solutio begis to bubble. 6. Cotiue heatig util the mixture is syrupy i cosistecy. 7. Pour the syrupy mixture oto a watch glass ad allow it to solidify. 8. The test tube ca be brought to LabServices ad be exchaged for a ew test tube. 9. Peel the polystyree from the watch glass ad ote its physical properties. Nylo Ito a 50 ml beaker add 2 ml of 20% NaH ad 10 ml of a 5% aqueous solutio of hexamethylee diamie ad mix. 2. Measure 10 ml of a 5% adipoyl chloride solutio i cyclohexae. 3. Beig careful ot to mix, slowly pipet the 5% adipoyl chloride solutio o top of the aqueous solutio i the 50 ml beaker. 4. You should see two differet liquid layers with ylo 6-6 beig formed at the iterface. 5. Usig forceps grasp the ylo at the iterface at its ceter ad slowly lift the solid from the solutio. Liftig up to fast will cause the ylo to break. 6. As the polymer is lifted begi to roll the ylo aroud a stir rod. New ylo will cotiue to form at the iterface. (Try to get at least a three foot piece.) 7. Wash the ylo with cold water ad dry with paper towels. 8. Note the physical properties of the polymer.

4 Experimet 8 Chem 276 Fall Semester 2010 Page 4 of 5 Report/Questios: 1. Show your polymers to your TA. You will receive a grade for the overall quality of both of your products. Polystyree /3 Nylo 6-6 /3 2. Describe the characteristics of each polymer: a) Polystyree b) Nylo What would occur if you overheated polystyree?

5 Experimet 8 Chem 276 Fall Semester 2010 Page 5 of 5 4. Styrofoam cups are made of polystyree. Compare the desity of the polystyree you made with the desity of a Styrofoam cup. How do we accout for the differece i desity? 5. Show the complete arrow-pushig mechaism for the base catalyzed codesatio reactio to form the amide bods of Nylo 6-6.