1. Hydrogels

2. What are they?
A hydrogel is a solid, jelly-like material that can vary from soft and weak to hard and tough. By weight, gels are mostly liquid, yet they behave like solids.
Gels consist of a solid three-dimensional network that spans the volume of a liquid medium and ensnares it through surface tension effects

3. How do they Work Many hydrogels are polymers of carboxylic acids.
When the polymer chains are in solution, they
tend to coil up. 
When these polymers are put into water, the
hydrogen atoms react and come off as positive ions.
This leaves negative ions along the length of the polymer chain.
This leaves negative ions along the length of the polymer chain.

4. 1 – Making a Hydrogel
Cross-linking of alginates with calcium chloride.
Molecular gastronomy - Spherification

5. 2 – Properties of hydrogels
Action of salt and sugar on hair gel
If the ionic concentration of the solution is increased the polymer will collapse in on itself again.

6. 3 – Hydrogels in Action Extracting a hydrogel from nappies
You will be amazed how much water the material from one nappy can hold

7. 4 –Fighting Fires
Testing the fire-retardant property of your nappy hydrogel.
There are already products on the market using this technology