Synthesis and characterisation of hydrogels based on poly(vinyl pyrrolidone)

Poly(vinyl pyrrolidone) (PVP) hydrogels were crosslinked by using gamma irradiation technique. The effects of the PVP concentration and the absorbed dose on gel content were investigated. Equilibrium swelling study was performed to calculate molecular weight between crosslinks of swollen gel using Flory Rhenner theory. The oxygen effect was studied through the yield of crosslinking Gx which was deducted from the gel–sol analysis performed with the GelSol95 program. Systematic analysis of the influence of the dose and the concentration showed that the gel fraction increased with increasing dose and PVP concentration. The highest degree of swelling of PVP hydrogels was obtained at doses near the gelation point. The polymer concentration of 7% seems to be the most adequate to obtain an appreciable gel content, even at low irradiation doses. The crosslinking process is affected by the presence of oxygen in the solution. The microbe penetration tests showed that this hydrogel constitutes a good barrier against bacteria.