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Polymerization. Section 7. Polymerization. The process of chemically linking monomers together to form macromolecules In our discussion we will not include natural polymers Essentially there are two types of polymerization Addition Polymerization Condensation Polymerization.

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  • The process of chemically linking monomers together to form macromolecules
  • In our discussion we will not include natural polymers
  • Essentially there are two types of polymerization
    • Addition Polymerization
    • Condensation Polymerization
addition polymerization
Addition Polymerization

The entire monomer molecule becomes part of the polymer

  • A polymerization where unsaturated monomers combine without rearrangement of their structure
  • This is sometimes referred to as vinyl or chain polymerization
  • This process is essentially a three step process
  • The monomer is added to the polymer outright
addition step 1
Addition- Step 1
  • Step 1 is called initialization (I)
    • An initiator through the application of thermal energy breaks down to form two radicals
addition step 2
Addition- Step 2
  • Step 2 is called growth
    • This is where a radical is combined with a monomer forming a two unit (mer) molecule
    • This radical-monomer is then combined with a second monomer adding it in a linear arrangement.
    • This continues until it reached the final step
addition step 3
Addition- Step 3
  • Step 3 is called termination
    • Chains that are propagating along are terminated by either having the two ends of growing chains meet and quench the reaction or by having a monomer donate a proton to the growing chain thereby quenching the reaction
addition examples
Addition Examples
  • Example 1: Polyethylene (PE)

C8- gasoline C12- oil C18- wax

C100- low MW PE C1000- MDPE C3000- HDPE

addition examples8
Addition Examples
  • Example 2: Polyvinylchloride (PVC)
    • Illustrates head-to-tail polymerization
    • Clear, toxic monomer
    • Degrades need melt point ?? Needs plasticizers
    • Plastisol is common combination of LMW PVC & WAX, DOP
    • People hate to mold it



  • Note: Head-to-tail addition is favored because the one configural form (a) of the adding chain is more stable than the other configural form (b) of the monomer added to the chain, which is made and unmade

Examples: PE, PP, PS, PVC

addition examples10
Addition Examples
  • Example 3: Polystyrene (PS)
    • clear

C2H3C6H5 Polystyrene

addition examples11
Addition Examples
  • Example 4: Teflon® (PTFE)
    • Never melts because of F-F interaction
addition examples12
Addition Examples
  • Example 5: PAN
  • Rayon- Cellulose Acetate; Orlon
  • Fiber and Films
polypropylene coordination polymerization
Polypropylene Coordination Polymerization
  • This is a special type of configurational polymerization that results in a molecule being added in only one manner
  • Specific form of a polymer made
  • Ex. PP
  • The way pendant groups are arranged along the backbone chain of a polymer
  • Heavily pertains to vinyl polymers
  • This is where the side groups are all on the same side of the carbon atoms
  • Like Cis
  • This is where the carbon side groups are on alternating sides of the carbon chain
  • Desirable
  • Like Trans
  • This is where there is no regular or repeated method to the arrangements on the side groups of the carbon chain
condensation polymerization
Condensation Polymerization

Part of the monomer molecule (a small molecule) is kicked

out when the monomer becomes part of the polymer

  • Also known as step polymerization
  • This is the process where a chemical combination of two molecules takes place with the subsequent elimination of a small molecule (usually water or HCl gas)
  • The resulting larger molecule is the combination of the other components of the original two molecules
  • This is essentially a single step process




Acid (RCOOH) + Alcohol (R1- OH) R-C-O-R1


Acid (RCOOH) + R – NH2 RCOO – NH – R1

condensation polymerization19
Condensation Polymerization
  • Two functional groups are needed per molecule
  • These groups can be the same or different
  • They can be the same for each molecule and the number of functional groups on a molecule is referred to as its functionality
condensation examples
Condensation Examples
  • Examples:
  • Acid plus alcohol equals yield as ester plus water
  • An acid plus an amine gives an amino acid plus water
condensation examples21
Condensation Examples
  • Nylon- It’s a di acid plus a diamine and it yields a polyamide

HOOC(CH2)4 COOH + H2N – (CH2)6 – NH2


condensation examples22
Condensation Examples
  • Example 1: Nylon 6,6

Note: The nomenclature for nylon is based on the number of carbon atoms in each of the two monomers that make up the nylon molecules

condensation examples23
Condensation Examples
  • Polyester- this is a diacid plus a dialcohol and yielding a polyester


Or from diacids

Terephthalic Acid


condensation examples24
Condensation Examples
  • Polyester
    • Note: If both R1 and R2 are aliphatic the product is too soft
    • If both are aromatic the product is too hard
    • For PET one is ethyl or butyl and R2 is phenyl
    • This results in polyethylene terephthatic

Aromatic: possessing thermal stability, a tendency to undergo electrophilic substitution rather than addition reactions, and resistance to oxidation

Aliphatic: used to describe non-aromatic hydrocarbons with no ring structures present

condensation examples25
Condensation Examples
  • Polycarbonate- this is carbonic acid and a phenolic diol



You might say that an addition polymer is like a good friend who accepts everything about you, the pleasant and the unpleasant alike.

But a condensation polymer is more like a snotty social club that says, "Sure you can join, but only if you ditch

those friends of yours".

polymerization comparison

Only growth reaction adds units to the chain


Any two species can react

Polymerization Comparison
polymerization comparison28
Polymerization Comparison


2. Monomer Concentration

Addition2. Monomer concentration

polymerization comparison29

2. Highpolymer formed early


2. Molecular weight rises steadily

Polymerization Comparison
polymerization comparison30

3. As time increases high conversions but no effect on molecular weight


3. As time increases it gives higher and higher molecular weights

Polymerization Comparison
polymerization comparison31

4. At any time there is only monomer, highpolymer and a small amount of initiator


4. At any time during the reaction there are small polymers, as well as intermediate size polymers, plus monomers present

Polymerization Comparison

Polymerization Comparison


4. Molecular Weight %


4. Molecular Weight %

where do polymers get their names
Where do polymers get their names?

1. Their name based on the organic material they are derived from

Ex. Cellulose acetate

2. They are named after the monomers that make them

Ex. Ethylene, propylene, and urea

3. They are named for their chemical name

Ex. Polypropylene and polyethylene

where do polymers get their names34
Where do polymers get their names?

4. They get their name from a contraction of their chemical name

Ex. Vinyl, acrylic, oelfin

5. Names can be based on their initials

Ex. PS, ABS, PP, and PE

6. They get their names from trade names

Ex. Bakelite, Lexan, Teflon, and Nylon

classification of polymers grades
Area of application

Polymer Properties

Method of fabrication

Filler and addition type

Food grade or medical grade

High heat or High impact

Extrusion or injection

Glass filled or mica filled/addition

Classificationof Polymers (Grades)

Thereare 1000 grades of PE


Plastics are bought by weight and sold by volume

Density = Mass/Volume Density= D= ρ (rho)


ρ= M/V therefore M= V* ρ

Specific Volume

ρ = 1/(SV)