It is wonderful if you can find something you love to do in your youth which is big enough to sustain your interest through all your adult life. Because, whatever it is, if you do it well enough people will pay you to do what you want to do anyway. – Feynman It is wonderful if you can find something you love to do in your youth which is big enough to sustain your interest through all your adult life. Because, whatever it is, if you do it well enough people will pay you to do what you want to do anyway. – Feynman

Polymers - the nightmare begins I am inclined to think that the development of polymerization is, perhaps, the biggest thing that chemistry has done, where it has the biggest effect on everyday life I am inclined to think that the development of polymerization is, perhaps, the biggest thing that chemistry has done, where it has the biggest effect on everyday life LORD TODD President of the Royal Society of London LORD TODD President of the Royal Society of London

What are polymers? Why important ? What are polymers? Why important ? Long chain molecules Extraordinary range of physical properties Many (not all) are cheap Long chain molecules Extraordinary range of physical properties Many (not all) are cheap

Question: if chain has a molecular weight of 420,000, how many ethylene units does it contain ? Question: if chain has a molecular weight of 420,000, how many ethylene units does it contain ? A. 30,000 B. 15,000 C. 150,000 A. 30,000 B. 15,000 C. 150,000 Because only 200 ethylene units in this chain (200 - mer), molecular weight only 5,600 (= 28 x 200). Ethylene Polyethylene C C H H 2 2 = = C C H H 2 2 [ [ - - C C H H C C H H ] ] n n Check out chain of beads at right. Imagine each bead is an ethylene unit; How big is n ?

Commercially produced polyethylenes often have MWs of hundreds of thousands. If ethylene unit is 1" instead of a few angstroms Length of fully stretched out MW 420,000 chain is almost 1/4 mile! Commercially produced polyethylenes often have MWs of hundreds of thousands. If ethylene unit is 1" instead of a few angstroms Length of fully stretched out MW 420,000 chain is almost 1/4 mile! [ [ - - C C H H C C H H ] ] = 1 inch

Some Basic Chemistry: Single and Double Bonds Some Basic Chemistry: Single and Double Bonds CCC –– – – H H HHCH 4 CC C –– – – H H HC – – – H H HC2H6C2H6 CC C – – – H H C – – H H –C2H4C2H4

Functional groups - small groups of atoms held together in specific arrangement by covalent bonds Responsible for principal chemical properties of molecule Functional groups - small groups of atoms held together in specific arrangement by covalent bonds Responsible for principal chemical properties of molecule Some Basic Chemistry: Functional Groups Some Basic Chemistry: Functional Groups CH 2 =CH 2 Ethylene R–OHR–C–OH = O R–C–O–R + Alcohol Carboxylic Acid Ester = O R–NH 2 R–C–OH R–C–NH–R + Carboxylic Acid Amine Amide = O = O

Some Basic Chemistry: Condensation Reactions Some Basic Chemistry: Condensation Reactions Acetic Acid Ethyl Alcohol or Ethanol reversible reaction Ester linkage O Ethyl Acetate O CH 3 - C - OH + CH 3 - CH 2 - OH CH 3 - C - O - CH 2 - CH 3 + H 2 O

Except, reaction goes step-wise Now…to make a Polymer The molecules are monofunctional: + + To make linear chains need bifunctional molecules:

O O O O HO - C - (CH 2 ) n - C - O - (CH 2 ) m - OH + H 2 O O O O O Polyester - step 1 HO - C - (CH 2 ) n - C - OH + HO - (CH 2 ) m - OH Dimer Monomers

Polyester HO - C - (CH 2 ) n - C - OH O O O O HO - C - (CH 2 ) n - C - O - (CH 2 ) m - OH + O O O O HO - C - (CH 2 ) n - C - O - (CH 2 ) m - O - C - (CH 2 ) n - C - OH O O O O O O O O - H 2 O Trimer M 1 + M 1 M 2 M 2 + M 1 M 3 M 2 + M 2 M 4 M 3 + M 1 M 4 M 4 + M 1 M 5 M 3 + M 2 M 5 M 5 + M 1 M 6 Etc. Reacting diacid & dialcohol give polyester!

Nylons H 2 N - (CH 2 ) 6 - NH 2 + HO - C - (CH 2 ) 4 - C - OH O O H 2 N - (CH 2 ) 6 - N - C - (CH 2 ) 4 - C - OH + H 2 O O O O O O O Adipic Acid Hexamethylene Diamine Amide Group H H

Nylon 6,6 - N - (CH 2 ) 6 - N - C - (CH 2 ) 4 - C - O O O O n n H H H H “I am making the announcement of a brand new chemical textile fiber ---derivable from coal, air and water -- and characterized by extreme toughness and strength -- ” Charles Stine V.P. for research, Du Pont, 1938 “I am making the announcement of a brand new chemical textile fiber ---derivable from coal, air and water -- and characterized by extreme toughness and strength -- ” Charles Stine V.P. for research, Du Pont, 1938

Nylon “I am making the announcement of a brand new chemical textile fiber ---derivable from coal, air and water -- and characterized by extreme toughness and strength -- ” Charles Stine V.P. for research, Du Pont, 1938 “I am making the announcement of a brand new chemical textile fiber ---derivable from coal, air and water -- and characterized by extreme toughness and strength -- ” Charles Stine V.P. for research, Du Pont, 1938

Nylon May “Nylon Day” Four million pairs go on sale throughout US Supply exhausted in 4 days.

Nylon Parachute WWII

Post WWII stocking sale, San Francisco.

Assignment: Review today's classnotes a. what is a polymer? b. molecular weight c. chemical bonding d. functional groups e. polymerization f. polyesters g. nylons Read: chapter 14 Assignment: Review today's classnotes a. what is a polymer? b. molecular weight c. chemical bonding d. functional groups e. polymerization f. polyesters g. nylons Read: chapter 14