Veritasium - Why Super Glue Is Perfect For Gluing Skin
Superglue, or cyanoacrylate, is a powerful adhesive that sets quickly due to its chemical structure, which allows it to form strong polymer chains. It was discovered accidentally during World War II when chemist Harry Coover was searching for a clear plastic. The glue's strength comes from its ability to bond with almost any surface, especially those with moisture, as water initiates the polymerization process. However, it is less effective on smooth or chemically inert surfaces like polyethylene. Superglue's medical applications include sealing wounds, as seen in the Vietnam War, where it saved lives by stopping bleeding. The development of medical superglue addressed issues like heat release and brittleness by modifying the chemical structure. Additionally, superglue's potential in recycling is being explored, as it can be depolymerized and reformed, offering a sustainable solution to plastic waste.
Key Points:
- Superglue sets quickly due to water-triggered polymerization, forming strong bonds.
- It is highly effective on porous surfaces but weak on smooth, inert materials.
- Medical superglue was developed to address heat and brittleness issues, saving lives in war.
- Superglue can be depolymerized and reformed, offering a recycling solution for plastics.
- Its discovery was accidental, highlighting the importance of open-mindedness in innovation.
Details:
1. 🔍 Discovering Superglue: A Sticky History
- A single drop of superglue can support the weight of a person by hanging from it.
- Superglue sets quickly and has a strong adhesive capability, such that one drop can lift over three tons.
- The initial discovery of superglue (cyanoacrylate) occurred during World War II when chemist Harry Coover was searching for a clear plastic to replace glass in gun sights.
- Cyanoacrylate was initially considered a nuisance due to its tendency to stick to everything it touched and was abandoned for military use.
- In 1951, Coover revisited cyanoacrylate for jet plane canopies, realizing its potential as a powerful adhesive after a laboratory accident.
- The compound was later named Eastman 910 Adhesive after it was found to bond almost anything instantly and unbreakably.
- Modern applications of superglue extend to medical uses, such as closing wounds, and industrial applications, including electronics and aerospace.
2. 🔬 Science of Superglue: Why So Sticky?
- Superglue bonds quickly and strongly to various materials, including plastic, rubber, metal, and more, due to its unique chemical composition.
- The active chemical in superglue is ethyl cyanoacrylate, which is a liquid monomer that solidifies upon reacting with itself to form long polymer chains.
- The glue works by filling the pores and crevices of surfaces, turning from liquid to solid, thereby creating a strong bond. Smooth surfaces may require sanding to increase adhesion.
- The reactivity of ethyl cyanoacrylate is due to its electron-deficient double bond attached to a nitrile group and an ester group, making it highly reactive to slightly electronegative substances.
- The polymerization process is initiated by a negative ion, causing the carbon double bond to break and form single bonds, leading to a chain reaction of monomer bonding.
- Superglue typically sets within 10 to 30 seconds, a significant improvement over adhesives available in the 1950s, which relied on drying out to bond.
- Practical applications include quick repairs in various industries, although caution is advised due to potential skin irritation and the need for ventilation during use.
- Limitations include reduced effectiveness on smooth or oily surfaces unless prepped, and potential brittleness under high stress or temperature fluctuations.
- Environmental concerns include the non-biodegradable nature of the polymers formed, suggesting a need for responsible disposal.
3. 😬 Superglue Mishaps: Stuck on You!
3.1. Scientific Mechanisms of Superglue Adhesion
3.2. Practical Implications and Mishaps
4. 💪 Superglue Strengths and Weaknesses
4.1. Strength Demonstration
4.2. Polymer Structure and Strength
4.3. Weaknesses and Brittleness
4.4. Shear and Peel Forces
5. 🚫 Superglue's Limitations: What It Won't Stick To
- Superglue does not stick to polyethylene, polypropylene, or Teflon because these materials are chemically inert, lacking reactive sites due to their non-polar nature.
- The carbon atoms in polyethylene and polypropylene do not share electrons, preventing superglue, which is electron deficient, from bonding.
- These materials are hydrophobic and non-porous, repelling both water and superglue, further inhibiting adhesion.
- Even with initiators like water, superglue cannot bond to these materials due to their hydrophobic properties.
- Manufacturers caution against using superglue on polyethylene and polypropylene, confirming its ineffectiveness on these surfaces.
- This limitation is advantageous for containment applications to avoid unwanted adhesion.
6. 🔧 Industrial Uses and Innovations
- Super glue's first industrial application was in 1956 when it was used by Mason and Hanger to assemble atomic bombs, highlighting its early and critical role.
- To adjust the properties of ethyl cyanoacrylate, companies introduced thickening agents like fumed silica, enhancing viscosity and usability.
- Acids are added to super glue formulations to prevent premature polymerization inside containers, ensuring product stability.
- Accelerators such as baking soda are used to speed up the setting time of super glue by increasing negative ions, facilitating quicker and more efficient bonding.
- The composite created by layering super glue with baking soda forms a robust material that can be drilled or sanded, useful for strengthening joints and filling gaps.
- Dissolving baking soda in water before adding super glue results in a continuous polymer thread, though this method produces a more fragile plastic.
7. 🏥 Medical Marvels: Superglue in Healthcare
- Superglue can be used underwater by slowing down polymerization with a gel cyanoacrylate, allowing for effective application and adhesion, setting the stage for its medical use.
- Coover discovered superglue's potential in medicine when it quickly sealed a cut on his son's finger, inspiring the idea to replace sutures with a more efficient solution.
- The main challenges in medical applications were heat release during setting, breakdown into toxic chemicals, and rigidity, which were overcome by modifying the alkyl chain to slow reaction and reduce heat, leading to flexible polymers.
- The US military developed Coover's medical superglue into a spray, which was life-saving in the Vietnam War by effectively stopping severe bleeding where conventional methods failed.
- A notable case involved a soldier with a liver wound, where superglue successfully stopped bleeding, demonstrating its effectiveness and potential in emergency medicine.
- Despite its battlefield success, approval for medical use was delayed until 1998 with the introduction of Dermabond, highlighting the bureaucratic challenges in medical innovation.
- The medical superglue industry has since grown into a $900-million-a-year market, reflecting its significant impact on healthcare.