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

Abstract 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.