Polyelectrolyte complexes: Permeability to water and potential uses in ophthalmology

Abstract

synopsisComplexes from poly(vinylbeneyltrimethylammonium chloride) and polystyrenesulfonate are transparent, water-insoluble materials which offer interesting possibilities in ophthalmology for contact lenses and surgical implants. The permeability to water of a series of neutral polyelectrolyte complex membranes was determined. The measurements were carried out at relatively low pressure gradients (20-900 mm. Hg). The results are in good agreement with previously reported data obtained at higher pressures (6.9 atm. and higher). The refractive index of the complexes was also determined, and apparently a linear relationship exists between the refractive index and the amount of water in the complex: 70% water, nD 1.40; 45% water, nD 1.48; 35% water, nD 1.51. A polyelectrolyte complex membrane 0.09 mm. thick containing 60% water at equilibrium swelling will have a similar permeability to water as the endothelium of the cornea (1.55 X lo-" cm.a/secAyne) a t 35°C. The same membrane, but with a thickness of 0.03 mm., will have a permeability similar to that of the whole corneal stroma (4.9 X 10-'1 cm.*/sec.dyne). At 0.21 mm. thickness the membrane will have a permeability similar to that of the epithelium (0.67 x 10-11 cm.J/sec.dyne).

Glass Transitions in Hydrated Polyelectrolyte Complexes

“…The simultaneous-addition method minimizes the variation in PEC compositions due to kinetic trapping of regions rich in one PE . Kinetic control of PEC composition is revealed by order-of-mixing experiments. , Michaels and co-workers avoided order-of-mixing issues by either using dilute solutions in water (<0.01 M based on the repeat unit) or dissolving all PEC components in terniary solvents comprising water, salt, and an organic solvent (commonly acetone). , The resulting one-phase materials could be cast as clear films, which probably contributed to Michaels’ motivation for securing several patents and establishing a company called Amicon. − Among the potential uses for PECs, also cited in his reviews, were membranes for filtration, fuel cells and batteries, medical implants, sensors, and contact lenses, which are currently proposed as possible applications. , Refojo reported water permeability measurements of PVBTA/PSS while considering potential uses in ophthalmology but noted problems on autoclaving . Any stresses built up in PEC articles or membranes will be relieved by shrinkage or deformation in water once T g is reached …”

“…2, 28 Refojo reported water permeability measurements of PVBTA/PSS while considering potential uses in ophthalmology but noted problems on autoclaving. 51 Any stresses built up in PEC articles or membranes will be relieved by shrinkage or deformation in water once T g is reached. 52 The most stoichiometric PVBTA/PSS samples had T g s that were slightly higher than the boiling point of water.…”