Surface Adhesion and Water Drops

1. Surface Adhesion and Water Drops • Low Surface Adhesion • High Surface Adhesion Water molecules attracted to the surface more than to each other. Forming a lower water droplet, will contain less mass. Water molecules attracted to each other (hydrogen bonding) and not to the surface. Forming taller, larger water droplet, will contain more mass.

2. Important Definitions • Polymer - substances containing a large number of structural units joined by the same type of linkage. These substances often form into a chain-like structure. • polar molecule – molecules that contain a partial positive end and a partial negative end • non-polar molecule – molecules that have no partial charges • cohesive forces – the forces of attraction between the same type of molecules • adhesive forces – the forces of attraction between different types of molecules • hydrophilic – attracted to water molecules • hydrophobic – not attracted to water molecules • surfactant – a substance that is polar on one end and non-polar on the other • hydrogen bond- intermolecular attraction of hydrogen atoms that are bonded to a nitrogen, oxygen, or fluorine atom. • Wetting – the ability of a liquid to be attracted to the surface of a material

3. Six Recycled Plastics