Polymerization Reactions Organic Chemistry: Polymerization Reactions Today’s Objectives: Define, illustrate, and give examples of monomers, polymers, and polymerization in living and non-living systems STS: 2) Illustrate how science and technology are developed to meet societal needs and expand human capabilities STS: 3) Illustrate how science and technology have both intended and unintended consequences Section 10.5 (pg. 445-459)

Polymerization Polymers are large molecules made of chains of monomers, small molecules that link together. Polymerization is the formation of polymers from these small units Polymers can occur naturally (proteins, carbohydrates) and can be synthesized (nylon, Teflon, polyethylene) They play an integral part in the function of life systems and have revolutionized the way society functions

Addition Polymerization Many plastics (synthetic polymers) are made by this process The polymerization process is initiated with a free radical (a species with an unpaired electron). The free radical attacks and breaks the double bond forming a new free radical that attacks another monomer

Addition Polymerization always results in one product, the polymer Requires unsaturated hydrocarbon monomers and bond saturation occurs when the polymer is made Common polymers produced by addition polymerization:

Things to know about addition polymers… The polymer names end in –ene (i.e. polystyrene, polypropene). Does this mean they have double bonds? No, the double bonds are saturated by adjacent monomers, as the polymer is made. The name refers to the starting monomer (i.e. polyethene is started by the monomer ethene) What properties make Teflon a good product for non-stick materials? Teflon is made up of C-F bonds which are very strong (not C-H bonds). These very strong bonds make the Teflon highly unreactive (non-sticking), it has a high melting point and it has a slippery surface

Condensation Polymerization Monomers combine to form a polymer and a bi-product. Each time a bond forms between monomers, small molecules, such as water, ammonia, or HCl are “condensed” out. The polymerization of nylon: For condensation polymerization to occur, monomers must be bifunctional, meaning they have at least two functional groups. If they only had one functional group, then only one bond would form.

Condensation Polymerization Condensation polymerization also produces natural polymers, called proteins. Amino acids (monomers) polymerize to make peptides (short chains of amino acids) or proteins (long chains of amino acids)

Comparison of Addition and Condensation Polymerization Needs a double or triple bond in the monomer Produces only one product, the polymer Needs bifunctional monomers (have two functional groups) Produces two products: the polymer and the biproduct (water, ammonia or HCl)

Polyester When a carboxylic acid reacts with an alcohol in an esterification reaction, a water molecule is eliminated and a single ester molecule is formed. This esterification reaction can be repeated so many esters are joined in a long chain… a polyester This is created using a dicarboxylic acid (an acid with a carboxyl group at each end) and a diol (an alcohol with a hydroxyl group at each end) The ester linkages are formed end to end between alternating acid and alcohol molecules

Polyester: Dacron Another example of a polyester: Note the two carboxyl groups in the dicarboxylic acid and the two hydroxyl groups in the polyalcohol that start the chain reaction

Natural Polymer Examples Starch, wood, silk, DNA

Today’s homework What is coming up tomorrow? Review for unit test Pg. 448 #2-4 Pg. 452 #13 Pg. 455 #16, 17 Due tomorrow What is coming up tomorrow? Review for unit test

Chemistry 30 Organic Review Learning Tip Pg. 441 Unit Exam Chemistry 30 Organic Review