Gel having interpenetrating network

A method for producing a gel having an interpenetrating network formed from a first network structure composed of a first crosslinked polymer and a second network structure composed of a second crosslinked polymer having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form and a derivative group of an acidic dissociative group, comprising a step of forming the first crosslinked polymer by polymerizing at least one noncrosslinkable compound selected from the group consisting of a compound represented by the following formula (I) and a compound represented by the following formula (II), and at least one crosslinkable compound selected front the group consisting of a compound represented by the following formula (III) and a compound represented by the following formula (IV) in a mixture comprising water and the second crosslinked polymer:

• wherein
• R1-R4 are each independently a hydrogen atom or a substituent,
• A1-A3 are each independently an acidic dissociative group, an acidic dissociative group in a salt form, or a derivative group of an acidic dissociative group,
• P is an aryl group having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form, and a derivative group of an acidic dissociative group,
• W1 is an alkylene group optionally having substituent(s), a cycloalkanediyl group optionally having substituent(s), an arenediyl group optionally having substituent(s), or a divalent group optionally having substituent(s) which is a combination of at least two selected from the group consisting of an alkylene group, a cycloalkanediyl group and an arenediyl group, and
• Q is an arenediyl group having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form, and a derivative group of an acidic dissociative group.

A method for producing a separation membrane comprising a gel having an interpenetrating network formed from a first network structure composed of a first crosslinked polymer and a second network structure composed of a second crosslinked polymer having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form and a derivative group of an acidic dissociative group, comprising

• a step of forming a coated film by applying a mixture comprising water, at least one noncrosslinkable compound selected from the group consisting of a compound represented by the following formula (I) and a compound represented by the following formula (II), and at least one crosslinkable compound selected from the group consisting of a compound represented by the following formula (III) and a compound represented by the following formula (IV), and the second crosslinked polymer to a substrate, and
• a step of forming the first crosslinked polymer by polymerizing the noncrosslinkable compound and the crosslinkable compound:
• wherein
• R1-R4 are each independently a hydrogen atom or a substituent,
• A1-A3 are each independently an acidic dissociative group, an acidic dissociative group in a salt form, or a derivative group of an acidic dissociative group.
• P is an aryl group having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form, and a derivative group of an acidic dissociative group,
• W1 is an alkylene group optionally having substituent(s), a cycloalkanediyl group optionally having substituent(s), an arenediyl group optionally having substituent(s), or a divalent group optionally having substituent(s) which is a combination of at least two selected from the group consisting of an alkylene group, a cycloalkanediyl group and an arenediyl group, and
• Q is an arenediyl group having at least one selected from the group consisting of an acidic dissociative group, an acidic dissociative group in a salt form, and a derivative group of an acidic dissociative group.