On Line Activity Polymers: Preparation of Nylon Rope A polymer is a large molecule, a macromolecule, composed of many repeated subunits. These subunits are also known as monomers. A different monomer, or combination of monomers, is used to manufacture each type or family of polymers. There are two broad classifications of polymers, addition and condensation, depending on the method of synthesis. 1. Addition Polymers are formed by a reaction in which monomer units simply add to one another to form a long chain polymer. The monomers usually contain C-C double bonds. Examples of synthetic addition polymers include polystyrene (Styrofoam), polytetrafluoroethylene (Teflon), polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride (PVC), and polymethyl methacrylate (Plexiglass). + Linear + Branched + + 2. Condensation polymers are formed with the elimination of a small molecule (such as water, ammonia, or HCl) as a by-product. Familiar examples of synthetic condensation polymers include polyesters, polyamides (nylon), polyurethanes, and epoxy resin. O O + OH HO O OH HO O O O HO OH + H2O O O O Some polymers are crosslinked into a 3-dimensional structure with tremendous rigidity. Rubber is an example of a crosslinked structure. Reaction of a dicarboxylic acids, or one of it’s derivatives, with a diamine leads to a linear polyamide. Comercially, nylon 6-6 (so called because each monomer has six carbons) is made from adipic acid and hexamethylenediamine. In this experiment, you will use the acid chloride instead of the diacid. The acid chloride is dissolved in cyclohexane, and this is added carefully to hexamethylenediamine dissolved in water. The liquids do not mix and two layers will form. The polymer can then be drawn out continuously to form a long strand of nylon. O Cl NH2 Cl + Adipoyl chloride H 2N Hexamethylenediamine O O H N N H O Nylon 6-6 Procedure Safety Information: 1. Hexamethylenediamine – Extremely hazardous in case of skin and eye contact. 2. Sodium hydroxide – Extremely hazardous in case of skin and eye contact. Do not breathe vapors, or ingest. 3. Adipoyl chloride – Extremely hazardous in case of skin and eye contact. Very hazardous in case of ingestion, of inhalation. 4. Cyclohexane – Slightly hazardous in case of skin contact, of eye contact, of ingestion, of inhalation. Preparation of Nylon 6-6: Pour 10 mL of a 5% aqueous solution of hexamethylenediamine (1,6hexanediamine) into a 50 mL beaker. Add 10 drops of 20% sodium hydroxide solution. Carefully add 10 mL of a 5% solution of adipoyl chloride in cyclohexane to the solution by pouring it down the wall of the slightly tilted beaker. Two layers will form, and there will be an immediate formation of a polymer film at the liquid-liquid interface. Using a copper wire hook, gently free the walls of the beaker from polymer strings. Then hook the mass at the center and slowly raise the wire so that polyamide forms continuously, producing a rope that can be drawn out for many feet. The strand can be broken by pulling it faster. Rinse the rope several times with water and lay it on a paper towel to dry. With the piece of wire, vigorously stir the remainder of the two phase system to form additional polymer. Decant the liquid and wash the polymer thoroughly with water. Allow the polymer to dry. View the JoVE video on Polymerization (embedded on Canvas). To complete this Activity, answer these questions and submit the assignment on Canvas (your instructor may have a separate PDF available on Canvas) and take the quiz. Questions: 1. Provide some examples of natural condensation polymers. Show the reactions. 2. What type of polymer classification does the formation of Nylon 6-6 fall into? 3. Draw the structure of the polymer produced from the monomer vinylidene chloride (CH2CCl2). 4. Kel-F is an addition polymer with the following partial structure. What is the monomer used to prepare it? F F F F Cl F F Cl 5. Kodel is a condensation polymer made from terephthalic acid and 1,4cylcohexanedimethanol. Draw the structure of the resulting polymer. O O HO OH Terephthalic acid HO OH 1,4-Cyclohexanedimethanol
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