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Permeability and partition coefficient of aqueous sodium chloride in soft contact lenses
Author(s) -
Guan L.,
Jiménez M. E. González,
Walowski C.,
Boushehri A.,
Prausnitz J. M.,
Radke C. J.
Publication year - 2011
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.33336
Subject(s) - aqueous solution , partition coefficient , diffusion , chemistry , contact lens , materials science , analytical chemistry (journal) , sodium , thermodynamics , chromatography , optics , organic chemistry , physics
Transport of physiologic saline through soft contact lenses is important to on‐eye behavior. Using a specially designed Stokes‐diaphragm cell, we measure aqueous NaCl permeabilities through commercial soft contact lenses at 35°C. The permeabilities increase exponentially with the water content of the lenses spanning a range from 10 −7 to 10 −5 cm 2 /s. Equilibrium partition coefficients are obtained by the back‐extraction of lenses initially immersed in 1 M aqueous NaCl. Partition coefficients also increase with lens water content but over a smaller range, from 0.1 to 0.7. Because the partition coefficient values are smaller than the water content of the lenses, ideal theory is not followed. Donnan exclusion, bound water, and excluded volume are proposed explanations. The diffusion coefficients of aqueous NaCl through soft contact lenses increase with increasing lens water content following free‐volume theory. Aqueous NaCl diffusivities in the lower water‐content lenses are smaller than the diffusion coefficient of NaCl in water by factors up to 100 indicating very tortuous diffusion paths. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011