Intermolecular Forces: Polymers

or

Fun with Chemistry!

"I just want to say one word to you -- just one word -- 'plastics.'"

Advice to Dustin Hoffman's character, Ben, in The Graduate

Definition

•Plastic is broadly defined as–Any inherently formless material that can be molded or modeled under heat or pressure

•Amazingly versatile•Usually formed from “polymers”

Polymers: Introduction

• Polymer: High molar mass molecule made up of a small repeating unit (monomer).– A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-

• Monomer: Low molar mass compound that can be connected together to give a polymer

• Oligomer: Short polymer chain• Copolymer: polymer made up of 2 or

more monomers– A-B-A-B-A-B-A-B-A-B-A-B-A-B

As early as…

• Go back as far as the Old Testament– References of:

• Fillers• Adhesives• Coatings

• Greek word plastikos• First natural plastics

– Tortoise shell– Tree resins– Shellac

• Insect secretion

Good Ol’ Enoch Noyes

• b. 1760• Opened business with the use of

natural polymers• Made combs out of organic proteins

(Keratin and Albuminoid) derived from animal horns, hoofs, an tortoise shells

Types of Polymers• Polymer Classifications

– Thermoset: cross-linked polymer that cannot be melted (tires, rubber bands, most difficult to recycle)

– Thermoplastic: Meltable plastic– Elastomers: Polymers that stretch and

then return to their original form: often thermoset polymers

– Thermoplastic elastomers: Elastic polymers that can be melted (soles of tennis shoes)

Natural Rubber

• Natural rubber: mainly polyisoprene

isoprenen

polyisoprene

SS

SS

SS

Sulfur crosslinking

Charles Goodyear, 1839

• Tends to be sticky when hot, brittle when warm

• Does not reform when stretched

Ebonite bracelet from 1880

1851: Hard Rubber— 20-30% Sulfur

Types of Polymers

• Polymer Families– Polyolefins: made from olefin (alkene)

monomers– Polyesters, Amides, Urethanes, etc.:

monomers linked by ester, amide, urethane or other functional groups

– Natural Polymers: Polysaccharides, DNA, proteins

Common PolyolefinsMonomer Polymer

Ethylene

H3CCH3

nRepeat unitPolyethylene

CH3

CH3n

CH3 CH3 CH3 CH3 CH3 CH3CH3Propylene

Polypropylene

PhCH3

n

Ph Ph Ph Ph Ph PhPhStyrene

Polystyrene

ClCH3

n

Cl Cl Cl Cl Cl ClClVinyl Chloride

Poly(vinyl chloride)

F2C CF2

Tetrafluoroethylene

F3C

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

F2C

CF2

CF3

nPoly(tetrafluoroethylene): Teflon

Polyesters, Amides, and Urethanes

Monomer Polymer

CO2HHO2CHO

OHO O

HO OH2C

H2C O

nTerephthalic acid

Ethyleneglycol

Poly(ethylene terephthalate

HO OH

O O

4H2N NH24

Adipic Acid 1,6-Diaminohexane Nylon 6,6HO N

HNH

H

O O

4 4n

CO2HHO2C

Terephthalic acid

NH2H2N

1,4-Diamino benzene

Kevlar

O

HO

OHN

HN H

n

HOOH

Ethyleneglycol

H2COCN NCO

4,4-diisocyantophenylmethaneSpandex

H2C

HN

HN

O

HO

O

OH2C

H2C O H

n

Urethane linkage

H

Ester

Amide

DNA: A Natural Polymer

Some notes on qualitative data

This type of data is just as important to product development as quantitative data.

Color, consistency, smell, viscosity, bounciness, feel, appearance, sheer strength, remoldability, etc

Physical characteristics and properties

Author Assignments

None. Work together to present one complete report