Water-Soluble Polymer (green)

This green film with kidney bean-shaped bubbles is a bit of a mysterious object. It is a composite of an ordinary green plastic film, which has been laminated with a semi-translucent, powdery, water-soluble polymer made from polyvinyl alcohol (PVA). It’s hard to imagine a use that would require an insoluble film and a water-soluble film in combination, since one is often used to protect goods from water, and the other does completely the opposite. 

The water solubility of the clear film can be controlled by tweaking the structure of the polymer. If the polymer chain is acetate-heavy, the material will be very soluble and will dissolve even in cold water, whereas if alcohol groups replace those acetate groups, the material will only dissolve in hot water. These soluble films have been put to a number of uses often with the purpose of containing chemicals like detergents and fertilizers until they need to be used. They are used in agriculture so that, by spraying them with water, farmers can release fertilizers and other chemicals without having to come into direct contact with them. Another benefit of this bubble wrap-like material is that incompatible chemicals can be placed in each pouch, side by side, and they only mix when the water soluble plastic dissolves.