Mechanical characteristics of poly(2-hydroxyethyl methacrylate) hydrogels crosslinked with various difunctional compounds

Poly(2-hydroxyethyl methacrylate) hydrogels were prepared in the presence o f 30 wt% water using two series of crosslinking agents including divinylic (ethyleneglycol dimethacrylate, 1,4-butanediol dimethacrylate, 2,3-dihydrox ybutanediol 1,4-dimethacrylate) and diallylic (1,5-hexadiene-3,4-diol and 1 ,5-hexadiene) compounds, over a concentration range between 0.1 and 5 mol%. The resulting polymers were swollen in water to yield homogeneous transpar ent hydrogels. These hydrogels were characterised in terms of equilibrium s welling in water, tensile properties and compression stress-strain measurem ents. The influences of the nature and the concentration of crosslinking ag ent on the swelling behaviour and the mechanical properties of these hydrog els were investigated. The crosslinking efficiency of two representative ag ents (ethyleneglycol dimethacrylate and 1,5-hexadiene-3,4-diol) was quantif ied by compression experiments. A much lower crosslinking efficiency (0.013 ) was observed for 1,5-hexadiene-3,4-diol than for ethyleneglycol dimethacr ylate (0.336). It is suggested that the low crosslinking efficiency of dial lylic agents is responsible for a trend in properties different from that d isplayed by the gels crosslinked with dimethacrylates. A comparison was mad e to the similar effect observed previously in heterogeneous PHEMA hydrogel s. (C) 2001 Society of Chemical Industry.