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Green Chemistry Workshop #6: Polymers

Green Chemistry Workshop #6: Polymers. US – Thai Distance Learning Program March 17, 2010 Professor Kenneth M. Doxsee University of Oregon. The Principles of Green Chemistry. Prevention Atom Economy Less Hazardous Synthesis Designing Safer Chemicals Safer Solvents and Auxiliaries

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Green Chemistry Workshop #6: Polymers

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  1. Green Chemistry Workshop #6:Polymers US – Thai Distance Learning Program March 17, 2010 Professor Kenneth M. Doxsee University of Oregon

  2. The Principles of Green Chemistry • Prevention • Atom Economy • Less Hazardous Synthesis • Designing Safer Chemicals • Safer Solvents and Auxiliaries • Design for Energy Efficiency • Renewable Feedstocks • Reduce Derivatives • Catalysis • Design for Degradation • Real-time Analysis • Inherently Safer Chemistry

  3. Polymer Packing “Peanuts” Premise • Packing “peanuts,” made up of various polymers, can be used for simple and safe demonstrations of various chemical properties. Chemical Concepts • Polymers; carbohydrates; solubility. Image: http://www.turtlerescues.com/images/packing%20peanuts%20on%20top%20of%20inside%20box.jpg

  4. Background • Packing “peanuts,” used to protect fragile items during shipping, are available in a variety of compositions. • Varying in chemical properties – polarity, solubility, etc. – these different types of packing peanuts can be used to demonstrate these properties in simple and safe ways.

  5. Polystyrene styrene polystyrene Pink: antistatic Green: recycled content Polystyrene image: http://i.ehow.com/images/a04/cu/il/packing-peanuts-200X200.jpg

  6. Polyurethanes Alcohols react with isocyanates to form urethanes: Diols react with diisocyanates to form polyurethanes: toluene diisocyanate a polyurethane Polyurethane image: http://www.redpackaging.com/images/packing_peanuts.jpg

  7. Starch Starch image: http://cracklecdn-zoovy-1.simplecdn.net/img/bamtar/W678-H574-Bffffff/packing_peanuts/eco_packing_peanuts_shipping_supplies_zoom.jpg

  8. Materials and Procedure Polystyrene “peanuts Biodegradable “peanuts” Acetone (10 – 25 mL) Water (10 – 15 mL) Containers – beakers or jars • Add a polystyrene peanut to water, observe. • Repeat for a biodegradable, starch-based peanut. • Repeat for the two types of peanuts in acetone.

  9. Laboratory Safety Accident: An unexpected and undesirable event, especially one resulting in damage or harm. Safety glasses image from: http://facilitysigns.wordpress.com/category/signs-and-labels/

  10. Break for …. Laboratory session

  11. Results “Like Dissolves Like” Lotus flower image from: http://tsvetankapetrova.files.wordpress.com/2009/01/1663153-lotus-flower-0.jpg Lotus with droplet image from: http://www.smartgarmentpeople.com/images/page_image/ water%20droplet%20on%20lotus%20leaf%20NANOSURFACES.jpg Close-up image from: http://www.ramehart.com/goniometers/newsletters/lotus2.jpg

  12. Green Relevance Green Concepts • Consider Green Principles • #1 (prevent waste) • #3 (less hazardous reagents) • #4 (safer chemicals) • #7 (renewable feedstocks) • #10 (design for degradation) Trash image: http://www.sfgate.com/blogs/images/sfgate/green/2008/12/30/styrofoam_trash.JPG

  13. Carbohydrates Premise • Simple household materials can be used to explore concepts of polymer chemistry. Chemical Concepts • Properties of covalent compounds; carbohydrates; food chemistry; polymers; acid/base; intermolecular interactions. Sugar image: http://img.alibaba.com/photo/100383368/Sugar_Thailand_Origin.jpg

  14. Background • Pectin is the major binding component of the cell walls of plants and fruits. It is chemically a polysaccharide, consisting of a linear chain of linked molecules of galacturonic acid. • Aqueous solutions of pectin become gelatinous when treated with carbohydrates (e.g., sucrose) under suitable conditions of concentration and pH. Image: http://www.pickyourown.org/blueberry/pectin_types.jpg

  15. Chemistry Image: http://www.jbei.org/images/feedstocks/pectin_structure.png

  16. Chemistry pectin sucrose • Gelation is not a chemical reaction. • Enhanced strand-strand interaction caused by high sugar concentration (reduced water activity). • Moderate acidity also required – too many carboxylates can prevent chain aggregation. • Ca2+ can induce gelation in ‘low methoxyl’ pectin. Role of Sucrose in Pectin Gelation:  Static and Dynamic Light Scattering Experiments Macromolecules, 2002, 35 (21), pp 8147–8151

  17. pH Adjustment malic acid fruit juice (apple or white grape) malic acid Apple juice image: http://hotelminishop.com/Dole_apple.jpg Polymer swelling schematic: http://www.physik.uni-halle.de/im/1221849046_513_00_800.gif

  18. Materials & Procedure • Place water, pectin, and juice in 600 mL beaker. • Stir and heat until just about to boil. • Add sugar, heat to hard boil with constant stirring. • After 1 minute, remove from heat. • Allow to cool, removing any foam with a spoon.

  19. Laboratory Safety Accident: An unexpected and undesirable event, especially one resulting in damage or harm. Image from: http://facilitysigns.wordpress.com/category/signs-and-labels/ Hot image from: http://www.freesignage.co.uk/pdfthumbs/warning/caution_hot_liquids_warning_sign.png

  20. Break for …. Laboratory session

  21. Results

  22. Other Approaches • Polystyrene, other polymers - crosslinking. • Styrene, divinylbenzene. • Solvent-swollen polymers (e.g., rubber o-ring in THF) • Hazardous reagents. • Reagents derived from petroleum - • nonrenewable resource. • Disposal of hazardous waste. Image from: http://www.drugdeliverytech.com/Media/PublicationsArticle/000647.jpg

  23. Green Relevance Green Concepts • Consider Green Principles • #3 (prevent waste) • #4 (safer chemicals) • #5 (safer solvents) • #7 (renewable feedstocks) • #10 (design for degradation) Image from: http://hostedmedia.reimanpub.com/TOH/Images/Photos/37/exps24652_TH10525D15.jpg

  24. Analysis of Charge with Polymer Gels Premise • The “superabsorbent” polymer used in disposable baby diapers can be used as an ion exchange resin. Chemical Concepts • Properties of ionic and covalent compounds; cation analysis; solubility; polymers. Disposable diaper image: http://reflectionsofamirror.files.wordpress.com/2008/02/disposable_baby_diaper.jpg

  25. Background • Disposable baby diapers contain a small amount of a polymer that is able to absorb many times its own weight in water. Image: http://bp2.blogger.com/_PDb1K6TmuWc/SD8dET_sN6I/AAAAAAAAAKk/sAJoIUkirIk/s1600-h/04.15.08-05.29.08+002.jpg

  26. Chemistry • More highly-charged cations – e.g., Ca2+ - interact with the carboxyl groups, causing the gel to collapse. • Cations are attracted to the charged polymer chain, while anions are not.

  27. Procedure • Carefully take apart a clean disposable baby diaper, transferring the cotton (fluffy white) portion to a plastic bag. • In the bag, tear apart the cotton, shaking to separate the superabsorbent polymer grains. • Remove as much of the cotton as possible. Bag image: http://www.supplierlist.com/photo_images/66082/LDPE_Ziplock_Bag_Plastic_Bag_Packaging_Bag_Zip_loc.jpg

  28. Procedure • Hydrate about 0.5 g of polymer. • In each of six plastic cups, place water and a sample of a dye – e.g., 1 drop of food coloring (red, blue, green), methylene blue, malachite green, crystal violet. • To each cup add a portion of the polymer gel. • Let stand for 15 minutes. • While waiting, use a hot paperclip to melt small holes into the bottoms of six plastic cups. • Transfer the samples to these plastic cups, allowing liquid to drain out through the holes. • Rinse with excess water, allowing to drain. Plastic cups image: https://www.inspire4less.com/productimages/9780784725290.jpg

  29. Laboratory Safety Accident: An unexpected and undesirable event, especially one resulting in damage or harm. Safety glasses image from: http://facilitysigns.wordpress.com/category/signs-and-labels/

  30. Break for …. Laboratory session

  31. Results • Other things that can be explored (see packet): • Effect of salts on gel. • Effect of acids on gel. • Other dyes or colored ions. • Your students’ ideas.

  32. Green Relevance Green Concepts • Consider Green Principles • #1 (prevent waste) • #4 (safer chemicals) • #5 (safer solvents) • #10 (design for degradation) • #11 (real-time analysis) • #12 (inherently safer chemistry) Ion exchange image from: http://www.systemsaver.com/windsor-website/education/how-softeners-work/ion-exchange.jpg

  33. Questions and Discussion Image from: http://www.legis.state.wi.us/senate/sen11/news/images/questions.jpg

  34. ขอบคุณครับ สวัสดีครับ

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