1. Practical Application of Intermolecular Forces
A Study of Adhesives
By Babi Hijau (Photo taken by own) [Public domain], via Wikimedia Commons

2. Intermolecular Forces
Forces between molecules
Permanent dipoles
Induced dipoles
van der Waals or London Dispersion forces
Hydrogen bonds

3. Applications
Determines various physical properties of a molecular solid
Melting point
Boiling point
Vapor pressure
Adhesive force of glue

4. An adhesive is a substance that sticks to the surface of an object such that two surfaces become bonded.
In order for an adhesive to bond (hold together) to the substrate, there must be several types of molecular interaction between the adhesive and both substrates.
By Amirreza Saharkhiz (Own work) [CC BY-SA 3.0 ( via Wikimedia Commons

5. The adhesive will “wet” or cover the substrate, when the Intermolecular forces between the glue and the substrate are stronger than the Intermolecular forces between the glue and glue.
Why does the Elmer’s glue stick to this piece of paper? Glue hardens when there is a loss of water from the formula. Exposure to the atmosphere will cause the water to evaporate and make the glue harden.
By Mk2010 (Own work) [CC BY-SA 3.0 ( or GFDL ( via Wikimedia Commons

6. For an adhesive to wet a surface, the adhesive should have a lower surface tension, than the solid’s surface energy (or critical surface tension),
A shows a fluid with very little wetting, while C shows a fluid with more wetting. A has a large contact angle, and C has a small contact angle.
By MesserWoland (own work created in Inkscape) [GFDL ( CC-BY-SA-3.0 ( or CC BY-SA ( via Wikimedia Commons

7. Adhesive Curing
Theilr’s Flickr account – Creative Commons Attribution
Once the adhesive is applied to the substrate, it will begin to cure, or form a permanent bond Different Adhesives have different mechanisms in which the curing takes place

8. So HOW do glues compare?
In the following lab you will investigate the differences in the adhesive ability of some different types of glues
By Selena Wilke (Own work) [Public domain], via Wikimedia Commons