An expert is someone who has made all of the possible mistakes in a very narrow field of study

– Niels Bohr

An expert is someone who has made all of the possible mistakes in a very narrow field of study

– Niels Bohr

NylonsNylons

H2N - (CH2)6 - NH2 + HO - C - (CH2)4 - C - OH H2N - (CH2)6 - NH2 + HO - C - (CH2)4 - C - OH

OO

H2N - (CH2)6 - N - C - (CH2)4 - C - OH + H2O H2N - (CH2)6 - N - C - (CH2)4 - C - OH + H2O

OOOO

OO

Adipic AcidAdipic AcidHexamethylene DiamineHexamethylene Diamine

Amide GroupAmide Group

HH

Nylon 6,6Nylon 6,6 - N - (CH2)6 - N - C - (CH2)4 - C -- N - (CH2)6 - N - C - (CH2)4 - C -

OO OO

nn66 66

HH HH

“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

NylonNylon

“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

NylonNylon

May 15 1940 - “Nylon Day” Four million pairs go on sale

throughout US Supply exhausted in 4 days.

May 15 1940 - “Nylon Day” Four million pairs go on sale

throughout US Supply exhausted in 4 days.

Nylon Parachute WWII

Nylon Parachute WWII

Post WWII stocking sale, San Francisco

Post WWII stocking sale, San Francisco

PolyurethanesPolyurethanes

Reaction does not involve splitting out of a small moleculeReaction does not involve splitting out of a small molecule

O = C = N - (CH2)6 - N = C = O + HO - (CH2)2 - OH O = C = N - (CH2)6 - N = C = O + HO - (CH2)2 - OH

O = C = N - (CH2)6 - N - C - O - (CH2)2 - OH O = C = N - (CH2)6 - N - C - O - (CH2)2 - OH

OO

Hexamethylene DiisocyanateHexamethylene Diisocyanate Ethylene GlycolEthylene Glycol

Urethane LinkageUrethane Linkage

HH

usw.usw.

Linear & branched polymersex: polyethylene

Linear & branched polymersex: polyethylene

LinearLinear

Branched - short branches

Branched - short branches

Linear & branched polymersex: polyethylene

Linear & branched polymersex: polyethylene

~~~CH2 - CH - CH2 - CH2.

~~~CH2 - CH - CH2 - CH2.

C4H9C4H9--

~~~CH2 - CH - CH2 - CH2 - CH2 - CH2.

~~~CH2 - CH - CH2 - CH2 - CH2 - CH2.

C4H9C4H9--

Formation of short chain branches in polyethylene

Formation of short chain branches in polyethylene

~~~CH2 - CH ~~~CH2 - CH

CH2 - CH2CH2 - CH2

CH2CH2..

CH2HCH2H

~~~CH2 - CH ~~~CH2 - CH

CH2 - CH2CH2 - CH2

CH2CH2.CH2.CH2HH

CH2 = CH2CH2 = CH2

CH2 = CH2CH2 = CH2

Low density polyethylene (LDPE)(short branches)

Low density polyethylene (LDPE)(short branches)

Other types of branchingOther types of branching

shortshort longlong starstar

Branching suppresses or prevents chain movement & "crystallization" in polymers

Branching suppresses or prevents chain movement & "crystallization" in polymers

Branching Branching

Another way to make chains branchAnother way to make chains branch

Use multifunctional (f>2) monomersUse multifunctional (f>2) monomers

OHOH

+ CH+ CH22OO**

**

**

OHOH

CHCH22OHOH

OHOHCHCH22

OHOH

CHCH22

CHCH22

OH

CHCH22

OHOH

OHOHOHOH

CHCH22

CHCH 22

The phenol + formaldehyde rxn The phenol + formaldehyde rxn

Network formationNetwork formationFurther reaction under heat & pressure builds up densely cross-linked network. This is Bakelite, a thermosetting polymer. Once reaction is complete, material cannot be reheated and/or reformed

Further reaction under heat & pressure builds up densely cross-linked network. This is Bakelite, a thermosetting polymer. Once reaction is complete, material cannot be reheated and/or reformed

BakeliteBakelite

Bakelite telephoneBakelite telephone

Bakelite microphoneBakelite microphoneBakelite cameraBakelite camera

Clear Bakelite itemsClear Bakelite items

Bakelite radioBakelite radio

Phenolic resin/celluloid clockPhenolic resin/celluloid clock

Bakelite - Material of a Thousand UsesBakelite - Material of a Thousand Uses

Crosslinking Crosslinking

Take linear polymer chains & link using covalent bonds

Crosslinking Crosslinking

Ex: rxn of natural rubber or poly(isoprene)Ex: rxn of natural rubber or poly(isoprene)

with sulfur - interconnects the chains by reacting with the double bonds

(vulcanization)

with sulfur - interconnects the chains by reacting with the double bonds

(vulcanization)

H

CH2 -

CH3-

C = C- CH2

--

-H

CH2 -

CH3-

C = C CH2

--

-H

CH2 -

CH3-

C = C CH2

--

-

Crosslinking Crosslinking

Assignment:

Review today's classnotesa. nylonsb. polyurethanesc. branchingd. networkse. Bakelitef. crosslinkingg. vulcanization

Read: chapter 14

Assignment:

Review today's classnotesa. nylonsb. polyurethanesc. branchingd. networkse. Bakelitef. crosslinkingg. vulcanization

Read: chapter 14