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Experiment 26*:

Experiment 26*:. SYNTHESIS AND ANALYSIS OF COMMERCIAL POLYMERS. Objectives:. To carry out step-wise condensation polymerizations to prepare a polyamide and a set of polyesters. To compare the solubility of various synthetic and natural polymers in water, acetone, and toluene.

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Experiment 26*:

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  1. Experiment 26*: SYNTHESIS AND ANALYSIS OF COMMERCIAL POLYMERS

  2. Objectives: • To carry out step-wise condensation polymerizations to prepare a polyamide and a set of polyesters. • To compare the solubility of various synthetic and natural polymers in water, acetone, and toluene. • To determine the length of the polyamide polymer formed during the synthesis.

  3. Natural vs. Synthetic Organic Polymers • Proteins • hair, skin, tissue • Polysaccharides • cellulose, starch • Polynucleotides • DNA, RNA • Nylons • Polyesters • Acrylics • Polyvinyls • Plastic sheeting and plumbing materials • Polystyrenes • Insulating materials

  4. Natural Polymers RNA

  5. Classifications of Synthetic Polymers • Synthetic polymers are classified by their method of synthesis. Synthetic Method Chain-growth Step-growth Addition polymerization Condensation polymerization polystyrenes Polyamides Polyesters

  6. Addition Polymerization • Two molecules combine to form long chain polymer. • Can be linear or branched. • INITIATION: Initiator adds to C=C of styrene, yields reactive intermediate. • PROPAGATION: Reactive intermediate reactions with a second molecule of styrene, yields another reactive intermediate. • TERMINATION: Cycle continues until two reactive intermediates combine to end polymerization.

  7. Condensation Polymerization—Polyamides • Two molecules undergo addition accompanied by the loss of a small molecule as a by product. • Each bond forms independently of others. diamine Diacid chloride

  8. Condensation Polymerization—Linear Polyester Sodium acetate diol anhydride

  9. Condensation Polymerization—Cross-Linked Polyester Sodium acetate triol anhydride

  10. Properties of Polymers— Chain Structures Linear Cross-linked Branched Elastic & flexible Rigid & Brittle

  11. OVERVIEW • Synthesize polyamide via interfacial polymerization and determine length of fiber formed. • Synthesize linear and cross-linked polyesters. • Compare transparency, elasticity, and hardness of synthesized polymers to other provided synthetic and natural polymers. • Compare solubility of natural and synthetic polymers in various organic solvents.

  12. SYNTHESIS—Nylon 6,10 • Pour sebacoyl chloride slowly into a solution of hexamethylene diamine. • With tweezers, grab the film which forms at the interface of the two layers and pull up slowly. • Secure the end of the fiber around a large test tube and rotate until no more fiber is produced. KEEP TRACK OF REVOLUTIONS! • Rinse nylon in beaker of tap water, remove from test tube, and set aside for product analysis.

  13. SYNTHESIS—Linear and Cross-Linked Polyesters • Cover watch glasses with foil and label. • Place phthalic anhydride and sodium acetate in center of watch glass and mix solids with glass rod. • Add glycerol to one, ethylene glycol to the other. • Heat and mix with glass rod until mixture becomes clear and boils. • Remove from heat and cool to RT. • Remove polymer from foil and set aside for product analysis.

  14. ANALYSIS—NYLON FIBER LENGTH • Measure the diameter of the test tube used to collect the nylon fiber. • Determine the length of the fiber produced using the following formula: Nylon produced (mm) = (Diameter of test tube) * ( p ) * ( # test tube revolutions) * Where p = 3.14

  15. Table 26.1: Nylon Fiber Analysis

  16. ANALYSIS—SOLUBILITY TESTING • Label 18 small test tubes 1A-F, 2A-F, and 3A-F. • Measure 3 mL of the appropriate solvent to the test tubes. • Add a small amount of the polymer as indicated in Table 26.2. • Shake to mix the contents completely. • Record the solubility of each polymer in Table 26.2.

  17. 1 A 1 B 1 C 1 D 1 E 1 F 2 A 2 B 2 C 2 D 2 E 2 F 3 A 3 B 3 C 3 D 3 E 3 F ANALYSIS—SOLUBILITY TESTING 1 = Acetone A-F = Polymer type 2 = Toluene A-F = Polymer type 3 = Methanol A-F = Polymer type

  18. Table 26.2: Physical Property and Solubility Results

  19. SAFETY • Sebacoyl chloride, hexamethylenediamine, and sodium hydroxide are CORROSIVE! • Hexane, ethylene glycol, and toluene are TERATOGENIC! • Toluene, acetone, hexane, and methanol are highly FLAMMABLE!

  20. WASTE • All liquid waste generated throughout the course of the synthesis and solubility testing can be placed in the “LIQUID WASTE” container. • Solid polymer waste and aluminum foil can be placed in the YELLOW SOLID WASTE CAN at the front of the room.

  21. CLEANING • All glassware used during this experiment requires cleaning with SOAP, WATER, BRUSH followed by a final rinse with WASH ACETONE. • DO NOT return any glassware to lab drawer dirty or wet !

  22. IN LAB QUESTION(The following question should be answered in the laboratory notebook.) • Differentiate between a chain growth addition reaction and the step growth condensation reactions used to produce the polymers described in this experiment. • Give an example of a polymer produced using each method.

  23. IN LAB QUESTION(The following question should be answered in the laboratory notebook.) • List the intermolecular forces present in polystyrene, toluene, and nylon. Explain, in terms of IMF, why polystyrene is soluble in toluene, but nylon 6,10 is not.

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