Hydrogel was moderate crosslinded, branched polymers, widely studied and applied because of the ability to absorb large quantities of water, swell quickly, soft, elastine and biologic consistence.

Polymers may consist of long chains of unbranched or branched monomers or may be cross-linked networks of monomers in two or three dimensions.

These catalyst systems are generally used to produce polyolefins having broad molecular weight distributions, especially polyethylene. Some systems are used to produce branched or block polymers.