Lesson 1

Basic Polymer Concepts

  • A polymer is a long-chain molecule composed of repeating units of identical structure.

  • Polymers are formed by joining repeating units together.

  • A monomer (or mer) is the simple molecular unit that can chemically bond with other molecules to form a long chain, serving as the building block of a polymer.

Polymer Nomenclature

  • Polymers are typically named after the monomer from which they originate, using the prefix "poly".

  • For example, polyethylene is derived from the monomer ethylene.

  • Example: Ethylene monomer forms polyethylene, which is used in packaging films.

Polymers vs. Plastics

  • Polymers can be either synthetic or natural.

  • Plastics are synthetic or man-made polymers.

  • The term "plastics" cannot be applied to natural polymers.

Polymer Classification - Based on Nature

  • Polymers can be classified as natural or synthetic.

Natural Polymers

  • Naturally occurring organic compounds.

  • Extracted from organic sources like algae, plants, and animals.

Synthetic Polymers

  • Man-made polymers.

  • Derived from petrochemical products, such as petroleum oil.

Properties Comparison

  • Natural polymers are harder to modify and control.

  • Synthetic polymers can be easily modified to achieve desirable properties under controlled conditions.

  • Natural polymers are easily degraded by biological processes.

  • Synthetic polymers degrade very slowly and are hardly degraded by microorganisms.

Polymer Classification - Based on Composition

  • Polymers can be classified as organic or inorganic.

Organic Polymers

  • Mainly consist of carbon and hydrogen atoms, often with oxygen, nitrogen, and sulfur.

Inorganic Polymers

  • Polymeric structure is primarily non-carbon based.

  • Common backbones are made of silicon, phosphorus, and boron.

Inorganic Polymers Example

  • Polysiloxane is a typical inorganic polymer.

  • Its backbone consists of alternating silicon and oxygen atoms.

  • Polysiloxane is hydrophobic, chemically stable, and unreactive.

  • Polydimethylsiloxane (PDMS) is a popular polysiloxane used to make silly putty.

  • Other examples include polyphosphazene and polysilane.

Homopolymers and Copolymers

  • Polymers can be homopolymers or copolymers.

Homopolymers

  • Polymers composed of only one repeating unit.

Copolymers

  • Polymer chains containing more than one repeating unit.

  • Example: Ethylene-vinyl acetate copolymer

Types of Copolymers

  • Random Copolymer

  • Alternating Copolymer

  • Block Copolymer

  • Graft Copolymer

Random Copolymer

  • Repeating units are arranged randomly along the chain molecule, resulting in varied properties.

Alternating Copolymer

  • Ordered arrangement of the two repeating units along the polymer chain, providing more uniform properties.

Block Copolymer

  • Chain consists of relatively long sequences (blocks) of each repeating unit chemically bound together giving unique phase separation and mechanical properties.

Graft Copolymer

  • Sequences of one monomer (repeating unit) are grafted onto the backbone of another monomer type creating branched structures with tailored properties.