Hydrogelsrepresent a class of highwater content polymerswith physical or chemical crosslinks.Their physical
properties are similar to soft tissues. Cross linking is a stabilization process in polymer chemistry which leads to
multidimensional extension of polymeric chain resulting in network structure. Cross-link is a bond which links one polymer
chain to other.It can be ionic or covalent.Crosslinking changes a liquid polymerinto ‘solid’ or‘gel’ by restricting the ability
of movement. When polymer chains are linked together by cross-links, they lose some of their ability to move asindividual
polymer chains. A liquid polymer (where the chains are freely flowing) can be turned into a ‘solid’ or ‘gel’ by cross-linking
the chainstogether. Crosslinking increasesthe molecular mass of a polymer. Cross-linked polymers are important because
they are mechanically strong and resistant to heat, wear and attack by solvents. However, the drawback associated with
cross-linked polymers is that they are relatively inflexible when it comes to their processing properties because they are
insoluble and infusible.