[Synthesis and compression strength of hydrogels]

The purpose of the present investigation was the synthesis of crosslinked polymers and the assay of the effect of the monomer ratio to the compression values. Hydrogels were made by free radical photoinitiation from 2-hydroxyethyl metachrylate (HEMA) monomer, poly(ethylene glycol) dimethacrylate (PEG-DMA) crosslinker and sodium anthraquinone-2-sulphonate initiatior. The concentration of HEMA and PEG-DMA was 30 %, and their ratio was varied to obtain gels with different crosslinking density. It was found, that increasing the amount of the crosslinker in the gels, the force of the deformation increased, however the elasticity decreased. The lowest difference was found between the molar ratio of 50% HEMA: 50% PEG-DMA and the 75% HEMA: 25% PEG-DMA gels. Compression strength was strongly influenced on the ratio of the crosslinking agent. The smallest compression strength was found at the lowest amount of PEG-DMA (90% HEMA: 10% PEG-DMA) (0.0475 MPa +/- 0.0117) and the highest value was found at the highest amount of the PEG-DMA (10% HEMA: 90% PEG-DMA) (0.1366 MPa +/- 0.0546). The values of the compression strength at gels with similar composition was not significantly different. On the base of the present investigations the elasticity of the materials could be calculated from the ratio of monomers. It could be an important parameter in the further applications of the gels as a local delivery system in the parodontology.