Discussing about the fundamental principles of polymer chemistry emphasising on the type of reactions for making polymers.

1. Organic Chemistry V
Introduction to Polymer Chemistry
Indra Yudhipratama

2. Outline
 Defining the terms in polymer
 Type of polymers
 Polymer synthesis (Polymerisation) and the properties of its
product
 Addition polymerisation
 Polyalkenes
 Condensation polymerisation
 Polyesters
 Polyamides
 Enhancing the polymers

3. Introduction
 Polymers in daily life
 All of those are synthetic polymers.
 Mother nature also produces polymers.

4. Defining Polymer
 Polymers  Poly (many) + mer (unit)
 Hence polymer is a macromolecule that is built from
smaller unit (monomer)
 Proteins are built from many amino acids. Proteins are
polymers, amino acids are the monomers
 A polymer can be built from the same monomer
Homopolymer e.g. Poly(tetrafluoroethene)
 Also can be built from different monomers Copolymer
e.g. ABS (Acrylonitrile-Butadiene-Styrene)

5. Type of Polymers
Poly(tetrafluoroethene) ABS

6. Polymerisation
 Addition polymerisation
 Involving radicals chemistry
 Three main steps:
 Initiation
 An initiator is required to start reaction
 Propagation
 The chain is propagated to form a long chain
 Termination
 Reacts with another radical species to stop the reaction

7. Addition Polymerisation
 E.g. Synthesis of Poly(chloroethene) or PVC
 Initiation step
 Propagation step
 Termination step

9. Addition Polymerisation
 The product of addition polymerisation
 From alkene alkane, hence stronger in structure.
 More rigid/solid structure
 The products could have different arrangement:
 Regular structure provides rigid, tough, heat resistant polymers.
Known as Isotactic
 Commonly used for food containers, hospital equipments.

10. Addition Polymerisation
 The product could have different arrangement:
 Irregular structure provides more flexible and softer polymers.
Known as atactic.
 Used as sealants and coatings.
 Third type, the functional group alternates between one side and
others, known as syndiotactic. This also has regular structure.

11. Condensation Polymerisation
 Producing small molecules as side products.
 Commonly water is the small molecules, hence the process known as
condensation.
 Polyester formation
 Difunctional groups are required to form condensation polymers.
 Dicarboxylic acids with diols to form polyesters

12. Polyesters
Polyesters in daily life
 Poly(ethylene terephtalate) or known as PET.
 The monomers are phtalic acid and ethane-1,2-diol.
 A rigid structure due to benzene rings.
 Used as plastic bottle

13. Polyamides
 Has amide linkage, occur in nature e.g. proteins.
 Formed from amino acids
 Synthesised in laboratory from diacyl chlorides and diamines
 Problem in synthesis with dicarboxylic acids and diamines

14. Polyamides
 Polyamides in daily life
 Nylon
 Two types of nylon:
 Nylon-6
 Synthesised from caprolactam

15. Polyamides
 Two types of nylon:
 Nylon-6,6
 Synthesised from hexane-1,6-dioic acid and 1,6-diaminohexane
 Long alkyl chain gives the flexibility of nylon.
 Strong structure of polyamides due to hydrogen bonding and amide
bonds
 No strong hydrogen bonding in polyesters

16. Enhancing the Polymers’ Properties
 Some polymers are synthesised to meet the
market requirements.
 Properties of polymers determine its
function on the market
 Example: Hardness, hydrophilicity
 Changing the monomers would change the
properties of polymers
 Some methods to change the hardness of
the polymers:
 Using cross-linker
 Shortening the monomer chain
 Using the aromatic functional group

17. Enhancing the Polymers’ Properties
 Forming crosslink
 Natural rubber (rubber band) vs Tyres
 Both of them are poly(isoprene)
 Tyres manufacturing using sulphur as
cross-linker
 Vulcanisation process
 Bind different polymer chains
covalently

18. Enhancing the Polymers
 Vulcanisation process
 Sulphur as cross-linker
 The covalent bonds of sulphur keeps the shape

19. Enhancing the Polymers
 Forming crosslink
 Manipulating the monomers
 Difunctional monomers are used
 Case of contact lenses
 Can be polymerised at both ends
 Forming polymer networks 
hydrogels

20. Enhancing the Polymers
 Shortening the monomers
 Case of pacemaker (polyurethanes)
 Polyurethanes are copolymer
 Consists of different monomers
 Shorter chain (blue) gives the rigidity while the longer chain (red)
gives the flexibility over the pacemaker
 The flexibility over sp3 carbon chain (free rotation)

21. Enhancing the Polymers
 Using aromatic functional group
 Case of Nylon vs Kevlar
 The planar structure of benzene
ring causes the polymer can be
packed more closely.
 Increase rigidity of the polymer

22. Inorganic Polymers
 Non-carbon based polymers can
also be synthesised
 Silicone
 Si-based polymers
 PDMS
Poly(dimethylsiloxane)
 Hydrophobic liquid
polymer with highly
flexible chains
 Widely used in shampoo
formulation
 Known as dimethicone

23. Inorganic Polymers
 Silicone hybrid
 Used in contact lenses
 Combined with carbon-based polymers