Thermosensitives hydrogels based on poly (ethylene glycol) - I. Synthesis, characterization and release

Thermosensitives hydrogels based on poly(ethylene glycol) (PEG), diisocyanate (aromatic or aliphatic) and glycerol were prepared. The influence of the molecular weight, nature and amount of the crosslinking agent on the swelling properties and the mechanism of water transport through these hydrogels were examined. The exponential relation ship M-t/M-infinity = kt(n) was applied to calculate the exponent (n) describing the Fickian or non-Fickian behaviour of swelling polymer networks. Diffusion coefficients of an anti-inflammatory agent and network properties of hydrogels systems were calculated. The microscopic pore properties of the hydrogels were determined by SEM, which indicated an interconnected cylindrical porous structure and a few structural imperfections. The average diameter of the pores was 0.4 mu m, which depends on the molar mass of PEG. The release of the anti-inflammatory agent from hydrogels was studied by determination of the diffusion coefficient which are in the range of (0.4-10).10(-6) cm(2)/s.