Abstract: A method of producing a hollow fiber membrane is provided. The method includes: extruding from a molding nozzle a membrane-forming stock solution, the membrane-forming stock solution containing a vinylidene fluoride-based resin, polyethylene glycol, and a common solvent, and having a slope (B) of 1.15 or more and less than 3.00 where the slope (B) is calculated by I=A×q?B from a scattering intensity of a small-angle X-ray; and solidifying the extruded membrane-forming stock solution in a solution containing water as a main component.

Abstract: A hollow fiber membrane contains a vinylidene fluoride-based resin and polyethylene glycol. In the hollow fiber membrane, the polyethylene glycol has a content of 1.0 part by weight or more and less than 5.0 parts by weight with respect to 100 parts by weight of the vinylidene fluoride-based resin. In a case where the hollow fiber membrane is divided in three equal parts by a line drawn from an inner surface side to an outer surface side of the hollow fiber membrane in a radial direction of a cross section perpendicular to a longitudinal direction of the hollow fiber membrane, and where polyethylene glycol normalized intensities at respective intermediate points are defined as inner surface part a, central part b, and outer surface part c, c is less than 0.3 and a is 0.5 or more.

Abstract: A microphase-separated structure comprising a block copolymer, which contains at least a block chain A consisting of a monomer A as a repeating unit and a block chain B consisting of a monomer B as a repeating unit, and a solvent, wherein the solvent has a temperature zone 1 where the block chain A and the block chain B are soluble and a temperature zone 2 where the block chain A is insoluble but the block chain B is soluble, and a structural period thereof varies by changing temperature between the temperature zone 1 and the temperature zone 2.

Abstract: [Project] To provide a microphase-separated structure which comprises a vast and visible structure showing a structural color with the use of the phase separation due to the self-assembly of a block copolymer, enables the design of a definite structural color by a convenient method and shows temperature response. [Means for Solving Problems] A microphase-separated structure comprising a block copolymer, which contains at least a block chain A consisting of a monomer A as a repeating unit and a block chain B consisting of a monomer B as a repeating unit, and a solvent, wherein the solvent has a temperature zone 1 where the block chain A and the block chain B are soluble and a temperature zone 2 where the block chain A is insoluble but the block chain B is soluble, and a structural period thereof varies by changing temperature between the temperature zone 1 and the temperature zone 2.