Polymers: Crash Course Chemistry #45
TLDRThe script discusses the history and chemistry of polymers. It starts with the first commercial polymer, cellulose nitrate, used for billiard balls to replace expensive ivory. It then explains that polymers are long chains of repeating organic units called monomers. The simplest monomer, ethene, can be polymerized into polyethylene, the most common plastic today. The script explores how modifying ethene by substituting atoms creates other important polymers like PVC, polystyrene and Teflon. It describes the chemical processes of addition polymerization and condensation that build polymers. Finally, it notes biological polymers like proteins and DNA that create our bodies.
Takeaways
- 😀 The first commercial polymer, celluloid, helped save elephants by replacing ivory billiard balls
- 👍🏻 Adding chlorine to ethylene makes vinyl chloride, the building block of PVC plastic
- 🌟 Changing ethylene's hydrogen atoms creates common plastics like polypropylene and polystyrene
- ✨ Tetrafluoroethylene makes Teflon, which has very low friction due to fluorine's electronegativity
- 🔬 Addition polymerization joins monomers by breaking their double bonds to form longer chains
- 💧 Condensation polymerization joins monomers by eliminating small molecules like water
- 🧬 Nylon forms at the interface between two liquids containing monomers with reactive groups
- 🧠 Amino acids can polymerize into proteins, part of the polymers that make up your body
- 🎬 Multiple natural polymers like DNA, RNA and glycogen encode and store vital biological information
- 👍 Producing polymers commercially helped conserve elephants by reducing demand for ivory
Q & A
What was the first commercial polymer product, and what problem did it help solve?
-The first commercial polymer was celluloid, created by John Wesley Hyatt. It provided a substitute for expensive ivory billiard balls, helping save elephants from being hunted for their tusks.
What are the two main types of polymerization reactions?
-The two main types are addition polymerization and condensation polymerization. In addition polymerization, monomers are simply added together with no byproducts. In condensation polymerization, a small molecule like water is given off as a byproduct when the monomers join.
What is the difference between thermoset and thermoplastic polymers?
-Thermoset polymers form permanent chemical crosslinks during curing, so they cannot be melted and reformed. Thermoplastics can be melted and re-shaped because their polymer chains are not chemically joined.
Why is Teflon so slippery and non-stick?
-Teflon is made from polymerized tetrafluoroethylene. The fluorine atoms strongly attract electrons, making them unavailable to form even weak interactions with other molecules. This makes Teflon very frictionless and non-stick.
What are some natural polymers produced in the human body?
-Important natural polymers in the human body include proteins made from amino acids, polysaccharides used for energy storage, and nucleic acids like DNA and RNA used to encode genetic information.
What determines if a polyethylene plastic will be rigid or flexible?
-The length of the polymer chains determines the density and mechanical properties. Long chains become tightly coiled and result in rigid high-density polyethylene. Shorter chains are more flexible and make low-density polyethylene.
Why are vinyl records called vinyl?
-Vinyl records are made from polyvinyl chloride or PVC plastic. The "vinyl" name comes from the vinyl group, which is the name for the ethene functional group when it is attached to a larger molecule.
How does addition polymerization get initiated?
-Addition polymerization begins when a free radical attacks a carbon-carbon double bond. This leaves an unpaired electron which continues the chain reaction by attacking the next double bond.
What are the monomers that combine to form nylon?
-Nylon forms from a condensation reaction between hexamethylenediamine and adipic acid. The amine group of one monomer joins with the carboxylic acid of the other, releasing water.
Why can condensation polymerization continue to grow long chains?
-Because the monomers have two reactive groups, the resulting dimer molecule has a functional group on each end. This allows further monomers to join onto the chain ends.
Outlines
🎱 Darwin's Love for Billiards Led to First Synthetic Plastic
Charles Darwin loved playing billiards and owned a valuable ivory billiard ball set. Ivory billiard balls were extremely expensive, requiring a lot of rare elephant tusks. In 1867, a company offered $10,000 for a sustainable substitute, leading inventor John Wesley Hyatt to create synthetic billiard balls out of nitrocellulose. This launched the polymer industry.
🚰 Evolution of Plastics: Properties, Polymerization, and Usage
Polymers like PVC, bakelite, and nylon were developed as ivory substitutes. Their properties can be optimized by factors like chain length and additives. Ethene is polymerized into polyethylene, the most common plastic, through addition reactions. Other techniques like condensation are also used to produce important polymers like nylon and those crucial for life.
Mindmap
Keywords
💡polymer
💡monomer
💡addition polymerization
💡condensation polymerization
💡free radical
💡cross-linking
💡thermoplastic
💡thermoset
💡electronegativity
💡amino acid
Highlights
The first commercial polymer ever saved the lives of a lot of elephants.
Polyethylene is transparent and thermoplastic, meaning it can be melted and reformed, making it recyclable.
Polyethylene is the most common plastic in the world, with over 80 million tons produced per year.
Changing the substituents on the ethylene monomer brought out new properties in early plastics.
PVC stands for polyvinyl chloride, which is why records are called vinyl.
Polystyrene in foam form is called Styrofoam.
Teflon is made from polymerized tetrafluoroethylene (PTFE), making it extremely non-reactive.
Ethene polymers form through addition polymerization by simply adding monomers together without byproducts.
Free radicals kick off polymerization by attacking double bonds, propagating a chain reaction.
Nylon forms from hexamethylenediamine and adipic acid polymerizing at their interface.
Amino acids polymerize into proteins, directed by DNA and enzymes.
Other biological polymers include polysaccharides for energy storage and DNA/RNA for encoding information.
The first polymer substitute for ivory billiard balls was made using nitrocellulose and patented for profit.
The new polymer was better for mass production but still dangerous, leading to further innovation.
Polymerization propagates until two free radicals meet, consuming each other and ending the chain reaction.
Transcripts
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