Department of Chemistry CHEM1020 General Chemistry *********************************************** Instructor: Dr. Hong Zhang Foster Hall, Room 221 Tel:

CHEM1020/General Chemistry _________________________________________ Chapter 10. (L9)-Organic Chemistry Today’s Outline..Addition polymerization addition polymerization various polymers..Polymerization equations

Chapter 10. (L9)-Organic Chemistry Types of polymerization reactions …Two general types of polymerization reactions: -addition polymerization -condensation polymerization …Addition polymerization Addition polymerization is the polymer forming process in which the polymer generated contains all the atoms from the starting monomers.

Chapter 10. (L9)-Organic Chemistry Addition polymerization …Examples of addition polymerization: Polyethylene: Made of monomers of the units from ethylene: CH 2 =CH 2 n(CH 2 =CH 2 )  (~CH 2 -CH 2 ~) n (n = ) Thus, in a sense, polyethylene is actually a giant alkane molecule with simple C-C bonding.

Chapter 10. (L9)-Organic Chemistry Addition polymerization Polymers made of derivatives of ethylene with one or more of its hydrogen replaced by another atom or a group. Examples: Polypropylene: Made of monomers of the units from propylene: CH 3 CH=CH 2 n(CH=CH 2 )  (~CH-CH 2 ~) n | | CH 3 CH 3 or ~CH 2 -CH-CH 2 -CH-CH 2 -CH~ | | | CH 3 CH 3 CH 3

Chapter 10. (L9)-Organic Chemistry Addition polymerization Polypropylene: -a tough plastic -resisting moisture, oil, and solvents -molded into hard-shell luggage or battery cases, and various kinds of appliances -packaging materials, fibers, carpets, ropes can be sterilized with steam (m.p.: 121 ºC)

Chapter 10. (L9)-Organic Chemistry Addition polymerization Polystyrene: Produced by using the ethylene with one H replaced with a benzene ring (styrene): n(C 6 H 5 CH=CH 2 )  ~(C 6 H 5 CH-CH 2 )~ -used to make transparent drinking cups with or without colors, toys, household goods -used to make Styrofoam by blowing gas into liquid styrene and then hardening into solid

Chapter 10. (L9)-Organic Chemistry Addition polymerization Vinyl polymers: Produced by using the ethylene with one H replaced with a Cl (vinyl chloride): n(CH 2 =CHCl)  ~(CH 2 -CHCl)~ or ~(CH 2 -CH-CH 2 -CH-CH 2 -CH)~ | | | Cl Cl Cl The polymer is a thermoplastic material called polyvinyl chloride (PVC); it is used to make things such as clear plastic bottles and wraps, artificial leather, floor tile, shower curtains, simulated wood (in home siding and window frames), PVC pipes

Chapter 10. (L9)-Organic Chemistry Addition polymerization Teflon: Produced by using the ethylene with all H atoms replaced with F atoms on each C (tetrafluoroethylene): n(CF 2 =CF 2 )  ~(CF 2 -CF 2 )~ or ~(CF 2 -CF 2 -CF 2 -CF 2 -CF 2 -CF 2 )~ The polymer is called polytetrafluoroethylene (PTFE or Teflon), with very exceptionally strong C-F bonding resistant to heat and chemicals a tough, inert, nonflammable material (insulation, chemical containers, tubing, connectors) non-sticky material (but its decomposition products may be bad; recent EPA story)

Chapter 10. (L9)-Organic Chemistry Polymerization equations A short-cut way to write polymerization reaction: n(CH 2 =CH 2 )  ~(CH 2 -CH 2 ) n ~ monomerspolymer We can also write the complex structural formula by providing the bonds for each C.

Chapter 10. (L9)-Organic Chemistry Plastics Many polymers are called plastics in everyday life. But, in chemistry, plastics is one that can be made to flow (soft, fluid) under heat and pressure and the material can then be shaped in a mold or other ways. Plastic products are usually made from powders. Addition polymers have the highest production quantity in the plastic industry, with polyethylene at the top of the list. More examples of polymers in Table 10.2 on pp. 285 of the textbook.

Chapter 10. (L9)-Organic Chemistry Types of molding in making plastic products -Compression molding: Heat and pressure are applied directly to the polymer powder in the mold cavity -Transfer molding: The polymer powders are first softened by heating outside the mold and then pored into the mold to harden. -Injection molding: The plastic is first melted in a heating chamber and then forced by a plunger into cold molds to set. -Extrusion molding: The melted polymer is extruded through a die in continuous form to be cut into lengths or coiled.

Chapter 10. (L9)-Organic Chemistry Quiz Time The general two types of chemical polymerization processes are (a) heating and pressing; (b) stirring and cooling; (c) stretching and kicking; (d) addition and condensation.

Chapter 10. (L9)-Organic Chemistry Quiz Time Addition polymerization is (a) the polymer forming process in which the polymer generated contains none of the atoms from the starting monomers; (b) the polymer forming process in which the polymer generated contains some of the atoms from the starting monomers; (c) the polymer forming process in which the polymer generated looses all the atoms from the starting monomers; (d) the polymer forming process in which the polymer generated contains all the atoms from the starting monomers.

Chapter 10. (L9)-Organic Chemistry Quiz Time Polyethylene is a polymer made by the process called (a) condensation polymerization; (b) subtraction polymerization; (c) elimination polymerization; (d) addition polymerization.

Chapter 10. (L9)-Organic Chemistry Quiz Time Styrofoam is made using (a) polyethylene; (b) polypropylene; (c) polystyrene; (d) polyvinyl chloride.

Chapter 10. (L9)-Organic Chemistry Quiz Time PVC is referred to the polymer called (a) polyethylene; (b) polypropylene; (c) polystyrene; (d) polyvinyl chloride.

Chapter 10. (L9)-Organic Chemistry Quiz Time The structural formula of vinyl chloride is (a) CH 2 =CH 2 ; (b) CH 2 =CHF; (c) CH 3 -CH 3 ; (d) CH 2 =CHCl.

Chapter 10. (L9)-Organic Chemistry Quiz Time Teflon is a polymer called PTFE, which means (a) polyteflonethylene; (b) polytetrafluorene; (c) polytetrafluoroethylene; (d) none of above.

Chapter 10. (L9)-Organic Chemistry Quiz Time Teflon is a polymer made of the monomer called tetrafluoroethylene, which has the structural formula as (a) CHF=CHF; (b) CH 2 F-CH 2 F; (c) CCl 2 =CF 2 ; (d) CF 2 =CF 2.