Overview

Look around you. The plastic in your phone, the nylon in your clothes, the rubber in your shoes, the DNA in your cells. They are all polymers. “Poly” means many, “mer” means part. A polymer is a giant molecule made of thousands of little molecules (monomers) strung together like beads on a necklace.

Core Idea

The core idea is Chain Reaction. You take a gas (like ethylene), add a catalyst, and suddenly the molecules start grabbing hands. They form long, tangled chains. These chains are what give plastic its strength and flexibility.

Formal Definition

The study of the synthesis, characterization, and properties of polymer molecules (macromolecules).

  • Thermoplastics: Can be melted and reshaped (e.g., LEGOs).
  • Thermosets: Harden permanently when heated (e.g., Epoxy).

Intuition

  • Monomer: A single paperclip.
  • Polymer: A chain of 10,000 paperclips hooked together.
  • Cross-linking: Connecting the chains to each other (like a chain-link fence). This makes the material harder (Vulcanization).

Examples

  • Teflon (PTFE): The slipperiest substance on earth. The bond between Carbon and Fluorine is so strong that nothing can stick to it. It was discovered by accident when a gas cylinder froze.
  • Kevlar: A polymer with chains that line up perfectly straight and stiff. It is 5 times stronger than steel but light enough to wear as a vest.
  • Slime: A classic kid’s experiment. You take glue (PVA polymer) and add Borax. The Borax acts as a cross-linker, tying the glue chains together so it turns from a liquid into a rubbery blob.

Common Misconceptions

  • All polymers are synthetic: No. Cellulose (wood), Starch (potatoes), Protein (meat), and DNA are all natural polymers. Nature invented them first.
  • Plastic lasts forever: It breaks down into “microplastics,” but it doesn’t biodegrade (turn back into dirt) easily. This is the global pollution crisis.
  • Bioplastics: Polymers made from corn or bacteria that can biodegrade.
  • Copolymer: A chain made of two different types of beads (A-B-A-B).

Applications

  • 3D Printing: Most 3D printers work by melting a thermoplastic polymer (PLA or ABS) and laying it down layer by layer.
  • Hydrogels: Polymers that love water. They can absorb 500x their weight. Used in diapers and contact lenses.

Criticism / Limitations

  • Recycling: Most plastics cannot be recycled together. If you mix Type 1 (PET) with Type 2 (HDPE), the result is useless trash. This makes recycling very expensive and inefficient.

Further Reading

  • Carraher, Charles. Introduction to Polymer Chemistry.
  • Miodownik, Mark. Stuff Matters. (Chapter on Plastic).