Self-diffusion measurements of organic molecules in PDMS and water in sodium alginate membranes

The self-diffusion of some organic molecules in silicone rubber and of wate r and water-ethanol mixtures in sodium alginate membranes was investigated to obtain information on the transport behavior in these systems. The tempe rature dependence of self-diffusion was examined by the pulsed field gradie nt NMR technique. The experimental data confirm the homogeneous amorphous n ature of PDMS and the affinity of silicone rubber to apolar solvents. The i nterrelations between solvent and polymer structures of the sodium alginate membrane varying the temperature have been obtained using differential sca nning calorimetric. The results have been compared with the trend of self-d iffusion coefficients, and structure modifications of the membranes have be en evidenced. The overall results confirm the potentialities of the techniq ue used in measuring transport parameter in polymeric membranes. (C) 1999 J ohn Wiley & Sons, Inc.