May 08, 2020 - 06:07 PM
In the absence of water, the polymer chain is very tightly twisted and piled up on itself so the water connection points are tightly buried inside the nugget.
When water is available, the molecular links on the outside of the nugget grab it and hold on through simple cross-link bonding. The more water is available, the more the polymer has to unwind to get it. It will swell 300 times the original weight of the crystal.
Each link gets larger as it hooks up to more and more water. The chain begins to swell on the outside surface and that allows more water to get farther into the polymer to available link points.
Water is cross-linked farther in and the polymer expands to make room for it. If enough water is available, this bonding and swelling continues until there are no more available places to collect water.