2.1 Hydrogel Synthesis
The water-soluble monomer used in this work was the sodium salt (Na-AMPS) of 2-acrylamido-2-
methylpropanesulfonic acid (AMPS). An aqueous solution of Na-AMPS was prepared by dissolving AMPS in
distilled water (40% w/v), cooling in an ice-bath, and then neutralizing to pH 7 by sodium hydroxide solution with
stirring. Then 1.0% by mol N,N’-methylene-bis-acrylamide (NMBA) was added as a crosslinking agent together
with 0.1% by mole of 4,4-azo-bis(4-cyanopentanoic acid) as photoinitiator stirred until homogeneous and each
solution poured into a vertical glass mould that was covered one side with Teflon release liners.
Photopolymerisation was carried out at room temperature for 10 mins using a commercially available UV lamp.
Finally, the hydrated hydrogel sheet was removed from the mould and its properties were studied.