Effect of molar size and solubility parameter of solvent molecules on swelling of a gel: a fluorescence study

Gels were swollen in various solvents with different molar volume V and sol ubility parameter delta. In situ steady state fluorescence (SSF) measuremen ts were performed for swelling experiments in gels formed by free radical c rosslinking copolymerization (FCC) of methyl methacrylate (MMA) and ethylen e glycol dimethacrylate (EGDM). Gels were prepared at 75 degreesC with pyre ne (Py) as a fluorescence probe. After drying these gels, swelling and slow release experiments were performed in various solvents with different V an d delta at room temperature by time monitoring of the Py fluorescence inten sity. The Li-Tanaka equation was used to produce time constant tau (1) valu es. Cooperative diffusion coefficients (D-c) were measured and found to be strongly correlated to the molar volume of the solvents used. Solvent uptak e and degree of swelling were found to be dependent on the solubility param eter of the solvent. (C) 2000 Society of Chemical Industry.