According to the present invention, there can be provided a photocurable composition comprising a sulfur (a) having a cyclic structure represented by the following formula (1), an episulfide compound (b), and a photopolymerization initiator (c), wherein the content of the sulfur (a) is 1 to 28 parts by mass, with respect to the total mass (100 parts by mass) of the sulfur (a) and the episulfide compound (b):

##STR00001##

A curable composition for forming a high refractive index optical material including an episulfide compound, a cyclic disulfide compound, and a reducing agent, and an optical material comprising a cured product of the curable composition.

A curable composition for forming a high refractive index optical material including an episulfide compound, a cyclic disulfide compound, and a reducing agent, and an optical material comprising a cured product of the curable composition.

The present application provides a composition for an optical material containing a compound (a) and/or a compound (b) and a compound (c) which are described below. The proportion of the compound (a) and/or the compound (b) is 0.001-30.0% by mass. The compound (a) is a compound represented by formula (1). The compound (b) is a compound represented by formula (2). The compound (c) is an episulfide compound. ##STR00001##

The present application provides a composition for an optical material containing a compound (a) and/or a compound (b) and a compound (c) which are described below. The proportion of the compound (a) and/or the compound (b) is 0.001-30.0% by mass. The compound (a) is a compound represented by formula (1). The compound (b) is a compound represented by formula (2). The compound (c) is an episulfide compound. ##STR00001##

The invention provides a polymer comprising two or more residues of formula III or IV or salts thereof: wherein dash line, X, Y, Q, L, M, n, R.sup.1, R.sup.2, R.sup.a, R.sup.b, R.sup.c and R.sup.d have any of the values defined in the specification, as well as synthetic intermediates and synthetic methods useful for preparing the compounds. The polymer is useful to treat contaminated water by chelating metal.

##STR00001##

A composition for a high refractive index, and low dispersion resin for a close-contact double layer-type composite diffractive optical element that is highly photocurable and provides a high productivity, and a close-contact double layer-type composite diffractive optical element using such composition are provided. A composition for a high refractive index, and low dispersion resin for a close-contact double layer-type composite diffractive optical element includes a thiol compound represented by general formula (1) or an oligomer synthesized by use of a thiol compound represented by general formula (1) (A component); and an ene compound including two or more polymerizable unsaturated bonds (B component). (In the formula, p represents an integer of 2 to 5; X.sub.p and Z.sub.p independently represent a hydrogen atom or a mercaptomethyl group; a ratio of sulfur atoms in a molecule is 40 to 80% by mass; and the number of thiol groups is 3 or larger.)

The present specification relates to a block polymer and a polymer electrolyte membrane including the same, a membrane-electrode assembly including the polymer electrolyte membrane, a fuel cell including the membrane-electrode assembly and a redox flow battery including the polymer electrolyte membrane.

The present specification relates to a block polymer and a polymer electrolyte membrane including the same, a membrane-electrode assembly including the polymer electrolyte membrane, a fuel cell including the membrane-electrode assembly and a redox flow battery including the polymer electrolyte membrane.

An improved process for preparing a conductive polymer dispersion is provided as is an improved method for making capacitors using the conductive polymer. The process includes providing a monomer solution and shearing the monomer solution with a rotor-stator mixing system comprising a perforated stator screen having perforations thereby forming droplets of said monomer. The droplets of monomer are then polymerized during shearing to form the conductive polymer dispersion.