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Radiation‐absorbing hydrogel–melanin blends for ocular devices
Author(s) -
Chirila Traian V.,
Cooper Richard L.,
Constable Ian J.,
Horne Robert
Publication year - 1992
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.1992.070440405
Subject(s) - self healing hydrogels , materials science , polymer , ultraviolet , methacrylate , melanin , lens (geology) , contact lens , copolymer , chemical engineering , aqueous solution , irradiation , visible spectrum , polymer chemistry , photochemistry , optoelectronics , optics , composite material , chemistry , organic chemistry , biochemistry , physics , nuclear physics , engineering
Hydrophilic polymers and copolymers of 2‐hydroxyethyl methacrylate, with low or high crosslinking density, were synthesized and then treated in aqueous medium with epinephrine (adrenaline) at neutral or acid pH, at room temperature, and in the presence of oxygen and light. During this treatment, a melanin is formed and uniformly dispersed in polymers. The resulting slightly colored hydrogels display radiation‐absorbing properties in the ultraviolet and visible regions of the natural spectrum. This enhances significantly their value as materials for ocular devices (contact lenses, intraocular lenses) that should protect the retina of the patients without their natural lens from potential damage induced by ultraviolet and visible (violet and blue) radiation. The incorporation of common ultraviolet absorbers led to transmittances similar to that of the natural human lens, i.e., 30% or less at 450 nm, 40% or less at 500 nm, and no more than 50% at 700 nm. The two‐phase morphology of the melanized hydrogels, as investigated by TEM, revealed a very fine structure comprising melanin domains of 1 to 12 nm in size. Although no proof for a network interpenetration could be provided, it is believed that the novel blends are true sequential interpenetrating polymer networks.