What is slime and why are we so obsessed? // Brains On! Science Podcast For Kids

Episode Overview

• The episode investigates the popular trend of making homemade slime, a gooey, stretchy substance that has captivated kids everywhere.
• It delves into the chemistry of how slime is created, explaining the reaction between common household ingredients like glue and laundry detergent.
• The discussion covers the unique physical properties of slime, classifying it as a non-Newtonian fluid that exhibits characteristics of both liquids and solids.
• It also touches on the sensory appeal of slime, exploring why the sounds and feel of it are so satisfying to many people, a phenomenon related to ASMR.

Key Concepts

• Polymers: Glue is composed of long, chain-like molecules called polymers. In their liquid state, these chains can slide past one another, similar to slippery spaghetti noodles.
• Cross-linking: When a borate compound (found in laundry detergent or contact lens solution) is added to glue, it acts as a cross-linker. It chemically "grabs" onto the polymer chains, linking them together into a network and transforming the liquid glue into a gooey, thick slime.
• Non-Newtonian Fluid: Slime is a type of non-Newtonian fluid, which means its viscosity (or thickness) changes depending on the stress or force applied to it. It can flow like a liquid when handled gently but feels solid when squeezed or hit quickly.
• ASMR (Autonomous Sensory Meridian Response): The pleasant, tingly sensation that some people experience from specific auditory or visual triggers. The satisfying squishing and popping sounds of slime are a common ASMR trigger, which may explain why slime videos are so popular.

Quotes

• At 00:46 - "Slime is... sticky, stretchy, squishy, slimy." - Several young listeners describe the unique texture and properties of slime.
• At 01:52 - "How does sticky glue become slime when you add laundry detergent?" - A listener named Ava poses the central scientific question that the episode sets out to answer.
• At 03:25 - "When glue is just glue, it's just a bunch of loose spaghetti noodles all sliding past each other." - Chemist Raychelle Burks uses an analogy to explain the polymer structure of liquid glue before the cross-linking reaction occurs.

Takeaways

• Slime is created through a chemical process called cross-linking, where an activator like borate connects the long polymer chains found in glue.
• Slime is classified as a non-Newtonian fluid because its behavior changes under stress—it can act like a solid when force is applied quickly and like a liquid when it's handled slowly.
• The unique tactile sensation and sounds of slime can trigger a relaxing feeling known as ASMR, which contributes to its widespread appeal.
• Basic chemistry can be explored using simple, everyday household items, turning a kitchen into a fun science lab.