Polymer Chemistry

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Polymers are giant molecules (also called macromolecules) that are essential to our existence¹. They are important chemicals in our bodies (proteins, poly(nucleic acids)), in plants (starch, cellulose), and in our everyday lives (fibers, plastics, elastomers).

Polymers are made by transforming small molecules (monomers) into molecules with very large molecular weights. Athough the chemical properties of polymers are similar to those of analogous small molecules, their physical properties are quite different. Every polymer has its own characteristics, but most polymers have the following general properties⁶.

1. Polymers can be very resistant to chemicals.

2. Polymers can be both thermal and electrical insulators.

3. Generally, polymers are light in weight with varying degrees of strength.

4. Polymers can be processed in various ways to produce thin fibers or intricate parts.

Several key parameters determine the properties of a polymer⁸.

• Chemical Composition
• Molecular Weight Distribution
• Topology
• Isomerism
• Morphology

This resource will concentrate on these parameters and their influence on polymer properties. Links to other useful polymer chemistry sites are listed below.

Useful Polymer Chemistry Sites

• Macrogalleria
• Life Cycle of a Plastic Product
• Introduction to Polymers

Key Parameters

• Chemical Composition
  • Polymerization Reactions
    • Chain Polymerization
    • Step Polymerization
  • Pendant Groups
  • Stiffening Groups
  • Intermolecular Forces
• Molecular Weight Distribution
  • Degree of Polymerization
  • Molecular Weight Averages
  • Chain Entanglement
  • Threshold Molecular Weight
  • Commercial Polymer Range
• Topology
  • Linear
  • Nonlinear (Branched)
  • Network
• Isomerism
  • Structural Isomerism
  • Sequence Isomerism
    • Head-to-Tail or Head-to-Head
  • Stereoisomerism (Tacticity)
  • Isotactic
  • Syndiotactic
  • Atactic
• Morphology
  • Classification of Polymers
    • Thermoplastics
    • Thermosets
    • Elastomers
  • Polymer Crystallinity
    • Crystalline
    • Amorphous
    • Semi-Crystalline
  • Crystallization Tendency
    • Structural Regularity
      
    • Degree of Polymerization
      
    • Intermolecular Forces
      
    • Pendant Groups
      
    • Processing
      
      • Rate of Cooling
      • Orientation

Polymer Properties

• Transitions
  • Glass Transition
  • Factors Influencing T_g
  • Melting Point
• Mechanical Properties
  • Stress-Strain Curves
  • Tensile Strength
  • % Elongation-to-Break
  • Young's Modulus
  • Toughness
  • Typical Materials
• Experimental Methods
  • Tensile Testing
• DSC
• Density