The effect of hydrogen bonding on diffusion across model membranes: consideration of the number of H-bonding groups

The diffusion of a series of phenols across simple silicone membranes impregnated with either octanol or toluene was studied. These solvents are taken up and saturate the membrane. The presence of the solvents in a solid membrane allows them to interact with any permeant that cross the membrane. This membrane was used to simulate a bio-membrane, e.g. the skin, capable of hydrogen bonding with the permeant. As the number of H-bonding groups was increased the flux across both the octanol and toluene impregnated membranes decreased. However, deconvolution of the data showed that for the octanol impregnated membrane the diffusion coefficient (D-m) decreased significantly with the number of H-bonding groups. This was not the case for the toluene impregnated membrane. Furthermore the spatial configuration of the -OH groups around the aromatic ring had a significant effect on the decrease in D-m. These findings have considerable implications in understanding the absorption of permeants across bio-membranes capable of H-bonding. (C) 2001 Elsevier Science B.V. All rights reserved.