Table 1.
Formation mechanisms of polymer hydrogels.
Polymer Network Type | Gelation Means | Mechanisms or Agents Involved |
---|---|---|
Chemical networks | Chemically induced free radical polymerization | Thermal initiation Redox initiation Photo (UV) initiation |
Radiation induced free radical polymerization | γ-radiation Electron beam radiation |
|
Non-polymerizable cross-linking agents | Ethylenediamine tetraacetic dianhydride Citric acid anhydride Glutaraldehyde Ethylenediamine Epichlorohydrin Urea |
|
Physical networks | Electrostatic interactions | Multivalent metal ions (Ca2+, Cu2+, Mg2+, Fe2+, Ba2+, Al3+, Fe3+) Polyelectrolytes |
Semi-interpenetrating network | Chain entanglements via hydrogen bonds and Van der Waals interactions |