ENGR 145, Chemistry of Materials Case Western Reserve University

1
Lecture 30 Condensation Polymerization

• Reading assignment OGN 20.2, 24.1-24.2
  Callister 16.11
• Learning objectives
• To describe examples of condensation
  polymerization
• Polyesters
• Polyamides
• To understand the effects of these reactions on
  the structure and properties of the resulting
  polymer

2
Types of Polymerization Reactions

• Free radical polymerization
• Ionic polymerization
• Coordination polymerization
• Condensation polymerization

3
Condensation Polymerization

• Gives off a small molecule (often H2O) as a
  byproduct
• Stepwise polymerization
• long reaction times
• Bifunctional monomers ? linear polymers
• Trifunctional monomers ? cross-linked and network
  polymers (e.g. phenol-formaldehyde (Bakelite),
  the first synthetic plastic) (OGN p. 827)
• Examples
• Polyesters
• Nylons
• Polycarbonates

4
Condensation Reaction Esterification OGN 20.2

• Organic acid alcohol ? ester
• E.g. acetic acid ethanol ? ethyl acetate
• CH3COOH C2H5OH ? CH3COOC2H5 H2O
• Condensation reaction
• H2O molecule eliminated
• Monofunctional reactants ? product is a single
  ester, not a polyester macromolecule

5
Condensation Polymerization Esterification

• Polyesters from a hydroxy-acid
• Acid and base functionality on one monomer
• e.g., n . HO-CH2CH2CH2CH2COOH ?
• -(-CH2CH2CH2CH2COO-)n- nH2O
• General reaction
• n . HO-R-COOH ? -(-R-COO-)n- nH2O

6
Condensation Polymerization Esterification

• Polyester from a di-alcohol and a di-acid
• Example (Callister eq. 16.8)

7
Condensation Polymerization Esterification

• Another polyester PETE poly(ethylene
  terephthalate) (OGN p. 829)
• terephthalic acid ethylene glycol
• n.HOOC-C6H4-COOH n.HO-CH2CH2-OH ?
• -(-OOC-C6H4-COO-CH2CH2-)n 2nH2O

8
Condensation Polymerization Esterification

• Poly(ethylene terephthalate) (PETE)
• (-OOC-C6H4-COO-CH2CH2-)n
• Benzene ring stiffens the polymer ?
  crush-resistant fabrics (Dacron)
• In film form Mylar (audio and video tapes)
• PETE beverage bottles

9
Condensation Reaction Amides

• Amide group -NHCO-
• Generic primary amine organic acid ? amide
• Example methylamine acetic acid ? acetamide
• CH3NH2 CH3COOH ? CH3NHCOCH3
  H2O condensation
• Monofunctional reactants ? product is a single
  amide, not a polyamide macromolecule

10
Condensation Polymerization Polyamides

• Nylon 6 from polymerization of an amino acid
• acid and base groups on one monomer
• H2N-(CH2)5-COOH
• n H2N-(CH2)5-COOH ? (-(CH2)5-CONH)n nH2O
• 6-carbon monomer ? 6-carbon mer

11
Condensation Polymerization Polyamides

• Nylon 6,6 2 monomers 6-carbon diamine
  6-carbon diacid
• hexamethylene diamine adipic acid

12
Condensation Polymerization Polyamides

• Nylon 6,6 can also use adipyl chloride
• hexamethylene diamine adipyl chloride
• n H2N-(CH2)6-NH2 n ClOC-(CH2)4-COCl ?
• -(-HNOC-(CH2)4-CONH-(CH2)6-)n 2nHCl
• Note byproduct here is HCl, not H2O

13
Video Synthesis of Nylon 6,10

• Hexamethylene diamine sebacyl chloride
• H2N-(CH2)6-NH2 ClOC-(CH2)8-COCl
• Nylon 6,10 (C in diamine), (C in diacid)
• byproduct HCl
• video courtesy of Prof. John Russ, North
  Carolina State University

14
Example Problem Nylon 6,6

• Question
• Calculate the masses of hexamethylene diamine
  and adipic acid needed to produce 1000 kg of
  nylon 6,6.
• Solution
• The chemical reaction is
• nH2N-(CH2)6-NH2 nHOOC-(CH2)4-COOH ?
  -(-HNOC-(CH2)4-CONH-(CH2)6-)n 2nH2O
• The masses are in proportion to molecular
  weights. Per mer of nylon 6,6
• C6H16N2 C6H10O4 ? C12H22O2N2
  2H2O
• 721628 721064 ?
  144223228 2x18
• 116 146 ? 226 36
• 116x103kg 146x103kg 103 kg
• 226 226
• 513 kg HMDA 646 kg adipic acid Note 159
  kg of H2O byproduct

15
Applications of Nylon Plastics
16
Applications of Polymers OGN 24.1-2 Callister
16.11
17
Applications of Polymers OGN 24.1-2 Callister
16.11