Slow release from gels in various solvents: a fluorescence study

A novel in situ steady state fluorescence experiment was performed for studying slow release processes in gels formed by free radical cross-linking copolymerization of methyl methacrylate and ethylene glycol dimethacrylate. Gels were prepared at 75 °C with pyrene (Py) as a fluorescence probe. After drying these gels, slow release experiments were performed in various solvent with different molar-volume, V and solubility parameters, δ at room temperature by real-time monitoring of the Py fluorescence intensity. Slow release diffusion coefficients (D) were measured and found to be in between 0.23×10−6 and 2.06×10−6 cm2 s−1 depending on the solvent used.