A lens includes an optical unit, and a rib unit extending outwardly in a radial direction of the optical portion, wherein the rib unit includes a light transmitting region and a light blocking region, and the light blocking region is disposed in the rib unit.

Compositions that are curable by free radical redox reactions are disclosed. Free radical curing reactions between polythiols and polyalkyenyls are initiated by the reaction of metal complexes and organic peroxides. The compositions are useful as sealants.

Compositions that are curable by free radical redox reactions are disclosed. Free radical curing reactions between polythiols and polyalkyenyls are initiated by the reaction of metal complexes and organic peroxides. The compositions are useful as sealants.

Polythioether prepolymers that have a low nucleation temperature. The symmetry of the polythioether prepolymers is modified by including pendent groups extending from the backbone of the polythioether prepolymer chain and/or the symmetry is modified by including segments having a different number of —C(R).sub.2— groups between heteroatoms. The polythioether prepolymers are stable at low temperature storage conditions for an extended period of time. Compositions prepared using the low nucleation temperature polythioether prepolymers are useful as sealants.

Polythioether prepolymers that have a low nucleation temperature are disclosed. The polythioether prepolymers are stable at low temperature storage conditions for an extended period of time. Compositions prepared using the low nucleation temperature polythioether prepolymers are useful as sealants.

Provided are thionated polymers comprising one or more aromatic groups and at least one S.sub.x group, wherein x is 1-200, wherein the thionated polymer comprises about 50% by weight or less, based on the weight of the thionated polymer, of substituents on the backbone of the thionated polymer that absorb at a wavelength of about 700 to about 6200 nm. Also provided are substrates such as films, glass substrates, and optical devices comprising a thionated polymer and processes for preparing a thionated polymer described herein.

A polymerizable composition for optical materials of the present invention includes a polymer (a) comprised of one or more compounds selected from compounds represented by the following General Formulas (1) to (4), a compound (b) of which light absorption characteristics vary by sensing changes in environment; and a polymerization reactive compound (c) (except for the polymer (a)). ##STR00001##

A polymerizable composition for optical materials of the present invention includes a polymer (a) comprised of one or more compounds selected from compounds represented by the following General Formulas (1) to (4), a compound (b) of which light absorption characteristics vary by sensing changes in environment; and a polymerization reactive compound (c) (except for the polymer (a)). ##STR00001##

Hydroxyl-containing bis(alkenyl) ethers can be incorporated into the backbone of polythioether prepolymers and can be used as curing agents in thiol-terminated polythioether prepolymer compositions. Cured sealants prepared using compositions containing hydroxyl-containing bis(alkenyl) ether-containing polythioether prepolymers and/or hydroxyl-containing bis(alkenyl) ether curing agents exhibit improved physical properties such as rapid curing and compatibility with fillers suitable for use in aerospace sealant applications.

Compositions that are curable to polythioether polymers are provided, comprising: a) a dithiol monomer; b) a diene monomer; c) a radical cleaved photoinitiator; d) a peroxide; and e) an amine; where the peroxide and amine together are a peroxide-amine redox initiator. In some embodiments, the amine is a tertiary amine. In some embodiments, the amine is selected from the group consisting of dihydroxyethyl-p-toluidine, N,N-diisopropylethylamine, and N, N, N′, N″, N″-pentamethyl-diethylenetriamine. In some embodiments, the peroxide is selected from the group consisting of di-tert-butyl peroxide, methyl ethyl ketone peroxide, and benzoyl peroxide. In some embodiments, the composition may additionally comprise a polythiol monomer having three or more thiol groups.