Introduction to Polymers: Classification, Properties, and Applications, Lecture notes of Applied Chemistry

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2024 - 2025 ODD Semester

UCB00 9 - CHEMISTRY

Polymers

A brief outline:

➢ Introduction and Definition of Polymers, Polymerization and Degree of Polymerization ➢ Polymers vs Macromolecules and Classification of Polymers ➢ Classification based on Origin ➢ Classification based on Monomer: Homopolymer and Copolymer ➢ Classification on the basis of chain structure ➢ Classification based on Type of Polymerization Reaction ➢ Addition Polymerization vs Condensation Polymerization ➢ Classification based on Polymer Behavior w.r.t. Temperature ➢ Average Molecular Weights of Polymers ➢ Tacticity in Polymers ➢ Dispersity of Polymers ➢ Thermoplastics vs Thermosetting Polymers ➢ Polydispersity Index and Average Molecular Weights of Polymers ➢ Conducting Polymers ➢ Inorganic Polymers ➢ Biodegradable Polymers

2024 - 2025 ODD Semester Polymers ➢ A polymer is a long-chain molecule which contains covalently-linked repeating units i.e. monomers ➢ For example: DNA is a polymer formed from all nucleotides as monomers ➢ Similarly, Polythene, Poly-vinylchloride, Nylon- 6 , 6 etc. are polymers Macromolecules ➢ A macromolecule is a giant molecule that may or may not contain repetitive monomer units. ➢ For example, triglycerides (fat) are macromolecules which are made up of glycerol backbone and several long-chain fatty acids.

Polymers vs Macromolecules

So, all polymers are macromolecules but not all macromolecules are polymers Polymers and Macromolecules are often used synonymously but on a strict basis,

2024 - 2025 ODD Semester

Classification of Polymers

Origin ➢ Natural ➢ Synthetic Monomer Composition ➢ Homopolymer ➢ Copolymer Polymerization Reaction ➢ Addition ➢ Condensation Thermal Behavior ➢ Thermoplastic ➢ Thermosetting

Classification of Polymers

Typically, polymers can be classified based on several parameters. Here, we have shown a broad classification of polymers

2024 - 2025 ODD Semester UCB009 (Chemistry)

DNA (the genetic material)

Wool (made from cross-linked proteins called keratin)

Natural Polymers

Polymer

Protein

Amino acids: Monomers

Amide bond linkages: Polyamides

Monomer Chemical Structure (Extra Info)

2024 - 2025 ODD Semester

Polymers: Classification based on Origin

Synthetic Polymers: These are prepared in the lab artificially.

Examples: polyethylene, polyvinylchloride, Nylon, Bakelite etc.

Synthetic polymers can be further classified into Organic and Inorganic polymers

2024 - 2025 ODD Semester

Polymers: Classification based on Monomer Composition

Monomer Composition

Identical Monomers  Homopolymer e.g. Poly-ethene, Poly-vinyl chloride

A-A-A-A-A-A-A-A-A-A- 

Arrangement of Monomeric Units Non-identical Monomers  More than 1 type of Monomer  Heteropolymer / Copolymer e.g. Nylon-6,6; Dacron polyester Homopolymer

2024 - 2025 ODD Semester UCB009 (Chemistry) :Two different Monomers

Types of Copolymers: Arrangement of Monomer Units

Monomeric units arranged alternatively Monomeric units arranged randomly Monomeric units arranged in blocks Random copolymer Alternating copolymer Block copolymer Graft copolymer Branch Main Chain A-A-A-A-B-A-B-B-A-B-A-B-B-A- A-B-A-B-A-B-A-B-A-B-A-B-A-B- A-A-A-A-A-A-B-B-B-B-B- A-A-A-A-A-A-A-A-A-A-A-A-A-A- B B B B The backbone is formed from one type of monomer The branches are formed from other types of monomer B B B B B Note: Either alphabetical or schematic B representation can be used

2024 - 2025 ODD Semester

Polymers: Classification based on Type of Polymerization Reaction

Polymerization Reaction Condensation Polymerization e.g. Nylon-6,6; Dacron Addition (Chain) Polymerization e.g. Poly-ethene, Poly-vinyl chloride

2024 - 2025 ODD Semester

**1. Initiation

2. Propagation
3. Termination**

Addition Polymerization: Sequence of Steps

➢ Addition polymerization, also known as chain polymerization, is a chemical process that joins small-chain monomers into long-chain polymers. ➢ This process is initiated by a chemical catalyst, also known as an initiator e.g. Benzoyl peroxide, Azo-bis-isobutyronitrile (AIBN)

2024 - 2025 ODD Semester n = 1000 - 2000 Low Density Poly-Ethylene (LDPE) How does the Degree of Polymerization affect Addition Polymers? n = 10,000 – 100, High Density Poly-Ethylene (HDPE) Ultra High Molecular Weight Poly-Ethylene (UHMWPE) n = 2 – 3 million Joint Replacement Gears

2024 - 2025 ODD Semester

Addition Polymers/Homopolymer: Examples and their applications

S. No. Names of Polymers Names of Monomer Applications 1 Polyethylene Ethylene Bottles, plastic bags, toys 2 Polypropylene (PP) Propylene Membrane filters, electronics, construction 3 Polyvinylchloride (PVC) Vinylchloride Pipes, flooring 4 Polystyrene Styrene Packaging foams, disposable medical 5 Polytetrafluoroethylene (PTFE i.e. Teflon) Tetrafluoroethylene Non-sticky surfaces, electrical insulation 6 Polyacrylonitrile Acrylonitrile Blankets, clothing, rugs

2024 - 2025 ODD Semester Condensation Polymers: Examples Ester linkage Amide linkage

2024 - 2025 ODD Semester Real-life examples of Condensation Polymers: Extra Info