The present invention provides an optical composition from which an optical article having reduced poor appearance such as cloudiness and optical strain during lens base material production can be obtained, and when a photochromic compound is added, a photochromic cured body having excellent photochromism and mechanical strength can also be formed, and a polyrotaxane used therefor. The polyrotaxane has a composite molecular structure formed of an axle molecule and a plurality of cyclic molecules clathrating the axle molecule, satisfying at least one of (X) and (Y). (X): A side chain having a secondary or tertiary hydroxyl group is introduced into at least part of the cyclic molecule of the polyrotaxane. (Y): A side chain having a group represented by -A (A is an organic group, and contains at least one hydroxyl group) is introduced into at least part of the cyclic molecule of the polyrotaxane, and a pKa of the hydroxyl group of the compound represented by H-A is 6 or more and less than 14.

A rubber composition for a tire, which does not require the addition of a compound when synthesizing rubber component and the modification of a rubber component, and a winter tire using the rubber composition are provided. The rubber composition for a tire contains fine particles of rotaxane having a straight chain molecule, acyclic molecule clathrating the straight chain molecule and blocking groups arranged at both terminals of the straight chain molecule such that the cyclic molecule does not desorb from the straight chain molecule, covered with silica; a rubber component comprising styrene-butadiene rubber; and at least one of carbon black and silica, wherein the total content of the fine particles, the carbon black and the silica (excluding silica covering rotaxane) is 70 to 150 parts by mass per 100 parts by mass of the rubber component.

The invention provides a polymerizable composition and a hydrogel obtained or obtainable from the polymerizable composition. The polymerizable composition comprises cucurbituril and a first monomer having a guest for the cucurbituril, wherein the total monomer concentration, C.sub.mon, within the polymerizable composition is at least 0.5 M. The composition may be an aqueous composition.

The invention provides a polymerizable composition and a hydrogel obtained or obtainable from the polymerizable composition. The polymerizable composition comprises cucurbituril and a first monomer having a guest for the cucurbituril, wherein the total monomer concentration, C.sub.mon, within the polymerizable composition is at least 0.5 M. The composition may be an aqueous composition.

There are provided a fiber reinforced thermoplastic resin molded article including a thermoplastic resin [A], carbon fibers [B] and a polyrotaxane [C], the thermoplastic resin [A], the carbon fibers [B] and the polyrotaxane [C] being included in amounts of 40 to 98 parts by weight, 1 to 40 parts by weight and 1 to 20 parts by weight, respectively, based on 100 parts by weight of the total content of the thermoplastic resin [A], the carbon fibers [B] and the polyrotaxane [C], wherein the carbon fibers [B] included in the molded article have a weight-average fiber length [Lw] in a range of 0.5 to 20 mm, and a ratio ([C]/[B]) of the content of the polyrotaxane [C] to that of the carbon fibers [B] is 0.04 or more and 0.5 or less; and a thermoplastic resin molded article which has excellent impact strength and also has excellent conductivity.

An electrophotographic photosensitive member, which is suppressed in occurrence of fogging and is excellent in abrasion resistance. In the electrophotographic photosensitive member, an outermost surface layer of the electrophotographic photosensitive member comprises a polymerized product of a composition comprising at least a polyrotaxane and a monomer having a polymerizable reactive group, and a chain molecule of the polyrotaxane has two blocking groups at both terminals thereof, and a (meth)acryloyloxy group of a cyclic molecule of the polyrotaxane forms a bond.

An electrophotographic photosensitive member having a support and a photosensitive layer on the support, wherein the electrophotographic photosensitive member comprises a surface layer comprising a polymerization product of a composition containing polyrotaxane and a charge transporting substance, and the polymerization product including a bond between the polyrotaxane and the charge transporting substance.

Provided is an elastomer which is suitable for application in actuators or sensors, and which exhibits an appropriately low initial elastic modulus in a low deformation region.

An elastomer composition containing the following components (A) to (D):

component (A): a polyrotaxane;

component (B): a crosslinking agent containing a second linear molecule having a molecular weight of 1,200 to 7,000, and a functional group disposed at both ends of the second linear molecule;

component (C): a double-reactive component having a reactive group at both ends; and

component (D): a single-reactive component having a reactive group at only one end, wherein at least a portion of the functional group in the component (B) is directly or indirectly bonded to the cyclic molecule in the component (A), and the elastomer composition exhibits an initial elastic modulus of 0.6 to 2 MPa.

The invention provides a polymerizable composition and a hydrogel obtained or obtainable from the polymerizable composition. The polymerizable composition comprises cucurbituril and a first monomer having a guest for the cucurbituril, wherein the total monomer concentration, C.sub.mon, within the polymerizable composition is at least 0.5 M. The composition may be an aqueous composition.

This document relates to methods for preventing or inhibiting the formation of micro-cracks and fractures in the cement of an oil well using cement compositions that contain cross-linked polyrotaxane additives. The cement compositions containing the cross-linked polyrotaxane additives exhibit increased stiffness without suffering a decrease in compressive strength, as compared to the same cement without the cross-linked polyrotaxane additive.