Copolymer, nonlinear optical material, and electro-optic element

Abstract

The purpose of the present invention is to provide a copolymer capable of forming a crack-free film and having a nonlinear optically active moiety, and to provide a nonlinear optical material and an electro-optic element that contain the copolymer. This copolymer is characterized by comprising a repeating structural unit (A) represented by formula (1) and having an adamantyl group, and a repeating structural unit (B) having a nonlinear optically active moiety. (In the formula: R1 represents a hydrogen atom or a methyl group; W1 represents -O-, -S-, or -NH-; L1 represents a single bond, a divalent C1-30 hydrocarbon group optionally containing an ether bond and / or an ester bond, or *-L2-NHC(=O)O- (* represents an end bonded to W1); L2 represents a divalent C1-30 hydrocarbon group optionally containing an ether bond and / or an ester bond; Ad represents an adamantyl group optionally substituted with a C1-5 alkyl group; R2 represents a C1-10 alkoxy group bonded to any carbon atom constituting the adamantyl group; and n represents an integer of 1-15.)

Description

Copolymers, nonlinear optical materials, and electro-optical elements

[0001] The present invention relates to a copolymer having a nonlinear optically active moiety.

[0002] In recent years, in the fields of optical information processing, optical communications, etc., various optoelectronic devices using materials containing fluorescent dyes or nonlinear optical materials have been developed. Among these, nonlinear optical materials are materials that exhibit a polarization response proportional to the square, cube, or higher order terms of the magnitude of the electric field of light, and those that produce the first-order electro-optic effect (Pockels effect), which is a second-order nonlinear optical effect, are being considered for applications such as optical switches and optical modulation.

[0003] Conventionally, lithium niobate and potassium dihydrogen phosphate have been put to practical use as inorganic nonlinear optical materials and are widely used. However, in recent years, organic nonlinear optical materials have attracted attention because of their advantages over these inorganic nonlinear optical materials, such as high nonlinear optical performance, low material costs, and high mass productivity, and active research and development is being conducted toward their practical use.

[0004] Known methods for fabricating devices using organic nonlinear optical materials include, for example, a method using a single crystal of a compound having nonlinear optical properties (nonlinear optical compound), a vapor deposition method, and an LB film method. Other methods include introducing a structure having nonlinear optical properties into the main chain or side chain of a polymer compound, or dispersing a nonlinear optical compound in a polymer matrix. Polymer systems, in particular, have the advantage of being easy to process, since films can be formed by methods such as casting, dipping, and spin coating.

[0005] For example, Patent Document 1 proposes a nonlinear optically active copolymer containing at least a repeating unit A of a specific structure having an adamantyl group and a repeating unit B of a specific structure having a nonlinear optically active moiety in the same molecule. It also describes that the nonlinear optically active copolymer has sufficient orientation properties and can suppress thermal orientation relaxation of the nonlinear optical material.

[0006] International Publication No. 2017 / 159815

[0007] In devices using nonlinear optical materials, it is important to evaluate absorption loss at the wavelengths used. Thick films formed from nonlinear optical materials are preferable because they allow for more accurate evaluation of absorption loss in wavelength bands with low absorption than thinner films. However, as films become thicker, they are more susceptible to cracking, which leads to scattering loss and makes accurate evaluation of absorption loss difficult. Therefore, films formed using nonlinear optical materials must be thick and crack-free. Furthermore, in the fabrication process of devices using nonlinear optical materials, films are often formed not only on flat surface structures but also on various textured surface structures, which increase the likelihood of crack formation due to stress (strain) caused by the textured surface structures. Therefore, the development of nonlinear optical materials that are less susceptible to cracking is required.

[0008] It has been found that the nonlinear optically active copolymer described in Patent Document 1 is prone to cracking when formed into a film, and that cracking becomes particularly likely as the film becomes thicker.

[0009] The present invention has been made in view of the above problems, and aims to provide a copolymer having a nonlinear optically active moiety that can form a crack-free film, and a nonlinear optical material and an electro-optical element that contain the copolymer.

[0010] The present inventors have conducted extensive research to solve the above-mentioned problems and have found that by introducing a repeating structural unit containing an adamantyl group having an alkoxy group having 1 to 10 carbon atoms into a polymer having a nonlinear optically active moiety and forming a film using the polymer, it is possible to form a film free from cracks even when the film is thick. The present invention was completed based on this finding and through further research.

[0011] That is, the present invention provides the following aspects: Item 1. A copolymer comprising a repeating structural unit (A) having an adamantyl group represented by the following formula (1), and a repeating structural unit (B) having a nonlinear optically active moiety: (In the formula, R 1 represents a hydrogen atom or a methyl group, W 1 represents —O—, —S—, or —NH—; L 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O- (* is W 1 represents the bond end with 2 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, Ad represents an adamantyl group which may be substituted with an alkyl group having 1 to 5 carbon atoms, R 2 represents an alkoxy group having 1 to 10 carbon atoms bonded to any carbon atom constituting the adamantyl group, and n represents an integer of 1 to 15. Item 2. The copolymer according to Item 1, wherein the repeating structural unit (B) includes a repeating structural unit (B1) represented by the following formula (2-1) and / or a repeating structural unit (B2) represented by the following formula (2-2): (In the formula, R 3 represents a hydrogen atom or a methyl group, W 2 represents —O—, —S—, or —NH—; L 3 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, or *-L 4 -NHC(=O)O- (* is W 2 represents the bond end with 4represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, and Z represents an atomic group which exhibits nonlinear optical activity. Item 3. The copolymer according to Item 1 or 2, wherein the content of the repeating structural unit (A) is 5 to 95 mol % and the content of the repeating structural unit (B) is 5 to 95 mol %. Item 4. The copolymer according to Item 3, further comprising a repeating structural unit (C) having a structure different from the repeating structural unit (A) and the repeating structural unit (B), and wherein the content of the repeating structural unit (C) is 90 mol % or less. Item 5. A composition comprising the copolymer according to any of Items 1 to 4, and a solvent. Item 6. A nonlinear optical material comprising the copolymer according to any of Items 1 to 4. Item 7. A nonlinear optical material comprising the copolymer according to Item 1 and / or a polymer which comprises a repeating structural unit (A) having an adamantyl group represented by the following formula (1) and which does not contain a repeating structural unit (B) having a nonlinear optically active moiety, and a nonlinear optically active compound: (In the formula, R 1 represents a hydrogen atom or a methyl group, W 1 represents —O—, —S—, or —NH—; L 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O- (* is W 1 represents the bond end with 2 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, Ad represents an adamantyl group which may be substituted with an alkyl group having 1 to 5 carbon atoms, R 2 represents an alkoxy group having 1 to 10 carbon atoms bonded to any carbon atom constituting the adamantyl group, and n represents an integer of 1 to 15. Item 8. An electro-optical element comprising the copolymer according to any one of items 1 to 4 or the nonlinear optical material according to item 6 or 7.

[0012] The copolymer of the present invention can form a crack-free film whether the film thickness is thin or thick because the repeating structural unit (A) contains an adamantyl group having an alkoxy group having 1 to 10 carbon atoms. Thick, crack-free films formed using copolymers having nonlinear optically active moieties are highly preferred because they allow accurate evaluation of absorption losses at the wavelengths used in devices containing such films. Furthermore, the copolymer of the present invention, which can form crack-free films, can broaden the scope of application to devices using nonlinear optical materials.

[0013] Furthermore, the copolymer of the present invention has high solubility in common membrane-forming solvents, and a highly concentrated membrane-forming solution can be obtained, which has the advantage of facilitating the formation of thick membranes.

[0014] Furthermore, the copolymer of the present invention has a large electro-optic coefficient (r) and is superior in electro-optic effect to conventional copolymers having nonlinear optically active moieties.

[0015] Because the copolymer of the present invention has the above-mentioned characteristics, it is suitable for use as a material for electro-optical elements such as optical switches, optical modulators, phase shifters, and terahertz wave generating / detecting elements. Furthermore, there are various types of optical switches, optical modulators, phase shifters, and terahertz wave generating / detecting elements, and in the element manufacturing process, films are often formed not only on flat surface structures but also on various uneven surface structures, and films on uneven surface structures are more susceptible to cracking due to stress (strain) caused by the structure. Therefore, the copolymer of the present invention can broaden the scope of application to the electro-optical elements.

[0016] In the present invention, (meth)acrylate means acrylate and / or methacrylate, (meth)acrylic means acrylic and / or methacrylic, (meth)acryloyl means acryloyl and / or methacryloyl, and (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0017] 1. Copolymer The copolymer of the present invention is characterized by comprising a repeating structural unit (A) having an adamantyl group represented by the following formula (1) and a repeating structural unit (B) having a nonlinear optically active moiety: (In the formula, R 1 represents a hydrogen atom or a methyl group, W 1 represents —O—, —S—, or —NH—; L 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O- (* is W 1 represents the bond end with 2 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, Ad represents an adamantyl group which may be substituted with an alkyl group having 1 to 5 carbon atoms, R 2 represents an alkoxy group having 1 to 10 carbon atoms bonded to any carbon atom constituting the adamantyl group, and n represents an integer of 1 to 15.

[0018] The copolymers of the present invention may be random copolymers or block copolymers.

[0019] <Repeating structural unit (A)> The copolymer of the present invention contains a repeating structural unit (A) having an adamantyl group represented by the above formula (1). The repeating structural unit (A) may contain one type or two or more types.

[0020] R in formula (1) 1 is a hydrogen atom or a methyl group, preferably a methyl group.

[0021] W in formula (1) 1 is —O—, —S— or —NH—, preferably —O—.

[0022] L in formula (1) 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O-. The "*" represents W 1The L 2 is a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond. 1 and L 2 In the formula (I), the divalent hydrocarbon group having 1 to 30 carbon atoms is not particularly limited and may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. The aliphatic hydrocarbon group may be linear, branched, or cyclic. Of these, an aliphatic hydrocarbon group is preferred, and an alkylene group having 1 to 6 carbon atoms is more preferred.

[0023] Examples of divalent hydrocarbon groups having 1 to 30 carbon atoms include linear aliphatic hydrocarbon groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, octane-1,8-diyl, decane-1,10-diyl, icosane-1,20-diyl, and triacontane-1,30-diyl; branched aliphatic hydrocarbon groups such as methylethylene, 1-methyltrimethylene, and 2,2-dimethyltrimethylene; cyclopentane-1,3-diyl, cyclohexane-1,4-diyl, and tricyclo[5.2.1.0]diyl. 2,6 ] Examples thereof include cyclic aliphatic hydrocarbon groups such as decanediyl, adamantanediyl, norbornanediyl, and norbornenediyl groups; and aromatic hydrocarbon groups such as phenylene, toluenediyl, and naphthalenediyl groups.

[0024] L in formula (1) 1 is preferably a single bond.

[0025] In formula (1), Ad is an adamantyl group optionally substituted with an alkyl group having 1 to 5 carbon atoms. The alkyl group having 1 to 5 carbon atoms is not particularly limited and may be linear, branched, or cyclic, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, a neopentyl group, and a cyclopentyl group. Ad may have one alkyl group having 1 to 5 carbon atoms, or two or more alkyl groups having 1 to 5 carbon atoms.

[0026] Ad in formula (1) is preferably an adamantyl group that is not substituted with an alkyl group having 1 to 5 carbon atoms.

[0027] R in formula (1) 2 is an alkoxy group having 1 to 10 carbon atoms bonded to any carbon atom constituting the adamantyl group. In formula (1), n ​​is an integer of 1 to 15. From the viewpoint of increasing the glass transition temperature (Tg), the number of carbon atoms in the alkoxy group is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. From the viewpoint of ease of production and fully achieving the effects of the present invention, n is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, even more preferably an integer of 1 to 3, and particularly preferably 1. When n is an integer of 2 or greater, the number of carbon atoms in each alkoxy group may be the same or different.

[0028] <Repeating structural unit (B)> The copolymer of the present invention contains a repeating structural unit (B) having a nonlinear optically active moiety. The repeating structural unit (B) may contain one type or two or more types.

[0029] The repeating structural unit (B) is not particularly limited as long as it has a nonlinear optically active moiety. The nonlinear optically active moiety refers to an atomic group that exhibits nonlinear optical activity. The atomic group that exhibits nonlinear optical activity refers to an atomic group derived from an organic nonlinear optical compound. The organic nonlinear optical compound is not particularly limited, and includes known compounds such as π-conjugated compounds having an electron-donating group at one end of a π-conjugated chain and an electron-withdrawing group at the other end, and those with a large molecular hyperpolarizability β are preferred. Examples of electron-donating groups include dialkylamino groups, and examples of electron-withdrawing groups include cyano groups, nitro groups, and fluoroalkyl groups.

[0030] In the copolymer of the present invention, the repeating structural unit (B) having a nonlinear optically active moiety preferably includes a repeating structural unit (B1) represented by the following formula (2-1) and / or a repeating structural unit (B2) represented by the following formula (2-2): (In the formula, R3 represents a hydrogen atom or a methyl group, W 2 represents —O—, —S—, or —NH—; L 3 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, or *-L 4 -NHC(=O)O- (* is W 2 represents the bond end with 4 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, and Z represents an atomic group which exhibits nonlinear optical activity.

[0031] R in formulas (2-1) and (2-2) 3 is a hydrogen atom or a methyl group, preferably a methyl group.

[0032] W in formulas (2-1) and (2-2) 2 is —O—, —S— or —NH—, preferably —O—.

[0033] L in formulas (2-1) and (2-2) 3 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, or *-L 4 -NHC(=O)O-. The "*" represents W 2 The L 4 is a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond. 3 and L 4 In the formula (I), the divalent hydrocarbon group having 1 to 30 carbon atoms is not particularly limited and may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. The aliphatic hydrocarbon group may be linear, branched, or cyclic.

[0034] Examples of divalent hydrocarbon groups having 1 to 30 carbon atoms include linear aliphatic hydrocarbon groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, octane-1,8-diyl, decane-1,10-diyl, icosane-1,20-diyl, and triacontane-1,30-diyl; branched aliphatic hydrocarbon groups such as methylethylene, 1-methyltrimethylene, and 2,2-dimethyltrimethylene; cyclopentane-1,3-diyl, cyclohexane-1,4-diyl, and tricyclo[5.2.1.0]diyl. 2,6 ] Examples thereof include cyclic aliphatic hydrocarbon groups such as decanediyl, adamantanediyl, norbornanediyl, and norbornenediyl groups; and aromatic hydrocarbon groups such as phenylene, toluenediyl, and naphthalenediyl groups.

[0035] L in formulas (2-1) and (2-2) 3 is preferably an aliphatic hydrocarbon group having 1 to 30 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms, still more preferably an alkylene group having 1 to 4 carbon atoms, and particularly preferably an alkylene group having 2 to 4 carbon atoms.

[0036] Z in formulas (2-1) and (2-2) represents an atomic group that exhibits nonlinear optical activity. The atomic group is an atomic group derived from an organic nonlinear optical compound. The organic nonlinear optical compound is not particularly limited and includes known compounds, such as π-conjugated compounds having an electron-donating group at one end of a π-conjugated chain and an electron-withdrawing group at the other end. Examples of the electron-donating group include a dialkylamino group, and examples of the electron-withdrawing group include a cyano group, a nitro group, and a fluoroalkyl group.

[0037] Z in the formulas (2-1) and (2-2) is preferably an atomic group represented by the following formula (3-1) or (3-2). (In the formula, R 4 is —O— or —NR 5 represents -, and R 5 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R 6 and R 7each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the symbol * represents a bond to the remaining structure constituting the atomic group Z that exhibits nonlinear optical activity.

[0038] Z in formula (2-1) and (2-2) is preferably an atomic group having a functional group derived from a compound represented by the following formula (4-1) or (4-2), that is, R 8 ~R 20 It is preferable that the group is an atomic group obtained by removing one or two hydrogen atoms from any one of the above. (In the formula, R 4 is —O— or —NR 5 represents -, and R 5 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R 6 and R 7 each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R 8 and R 9 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 6 to 10 carbon atoms which may have a substituent; R 10 ~R 13 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxy group, an alkoxy group having 1 to 10 carbon atoms, an alkylcarbonyloxy group having 2 to 11 carbon atoms, an aryloxy group having 4 to 10 carbon atoms, an arylcarbonyloxy group having 5 to 11 carbon atoms, a silyloxy group having an alkyl group and / or a phenyl group having 1 to 6 carbon atoms, or a halogen atom, and Ar represents a divalent organic group represented by the following formula (5), (6), or (7): (In the formula, R 14 ~R 20each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 6 to 10 carbon atoms which may have a substituent, the substituent may be a group capable of reacting with an isocyanate group, and the symbol * represents a bond.

[0039] R in formulas (3-1), (3-2), (4-1) and (4-2) 4 is —O— or —NR 5 - and R 5 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. 4 is preferably —O—.

[0040] R in formulas (3-1) and (4-1) 6 and R 7are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogenated alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The alkyl group having 1 to 5 carbon atoms may have a branched structure or a cyclic structure, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, a neopentyl group, and a cyclopentyl group. The halogenated alkyl group having 1 to 5 carbon atoms may have a branched structure or a cyclic structure, and examples thereof include a fluoromethyl group, a trifluoromethyl group, a bromodifluoromethyl group, a 2-chloroethyl group, a 2-bromoethyl group, a 1,1-difluoroethyl group, a 2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, a 2-chloro-1,1,2-trifluoroethyl group, a pentafluoroethyl group, a 3-bromopropyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,2,3,3,3-hexafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropan-2-yl group, a 3-bromo-2-methylpropyl group, a 2,2,3,3-tetrafluorocyclopropyl group, a 4-bromobutyl group, a perfluoropentyl group, and a perfluorocyclopentyl group. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

[0041] R in formulas (3-1) and (4-1) 6 and R 7 are each independently preferably a halogenated alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms, more preferably a trifluoromethyl group or a phenyl group.

[0042] R in formulas (4-1) and (4-2) 8 and R 9are each independently a hydrogen atom, an alkyl group of 1 to 10 carbon atoms which may have a substituent, or an aryl group of 6 to 10 carbon atoms which may have a substituent. The alkyl group of 1 to 10 carbon atoms may have a branched structure or a cyclic structure, or may be an arylalkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a neopentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, an n-octyl group, an n-decyl group, a 1-adamantyl group, a benzyl group, or a phenethyl group. Examples of the aryl group of 6 to 10 carbon atoms include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group. Examples of the substituent include an amino group, a hydroxy group, a carboxy group, an epoxy group, an alkoxycarbonyl group such as a methoxycarbonyl group or a tert-butoxycarbonyl group, a silyloxy group such as a trimethylsilyloxy group, a tert-butyldimethylsilyloxy group, a tert-butyldiphenylsilyloxy group or a triphenylsilyloxy group, and a halogen atom such as a fluoro group, a chloro group, a bromo group or an iodo group. 8 or R 9 Preferably, the bond is derived from a group capable of reacting with an isocyanate group contained in

[0043] R in formulas (4-1) and (4-2) 8 and R 9 are each independently preferably an alkyl group having 1 to 10 carbon atoms which may have a substituent, more preferably an alkyl group having 1 to 5 carbon atoms which may have a substituent, and even more preferably an alkyl group having 1 to 3 carbon atoms which may have a substituent. The substituent is preferably a hydroxy group.

[0044] R in formulas (4-1) and (4-2) 10 ~R 13are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxy group, an alkoxy group having 1 to 10 carbon atoms, an alkylcarbonyloxy group having 2 to 11 carbon atoms, an aryloxy group having 4 to 10 carbon atoms, an arylcarbonyloxy group having 5 to 11 carbon atoms, a silyloxy group having an alkyl group and / or a phenyl group having 1 to 6 carbon atoms, or a halogen atom. Examples of the alkyl group having 1 to 10 carbon atoms include the above-mentioned R 8 and R 9 Examples of the alkoxy group having 1 to 10 carbon atoms include a group in which the alkyl group having 1 to 10 carbon atoms is bonded via an oxygen atom. Examples of the alkylcarbonyloxy group having 2 to 11 carbon atoms include a group in which the alkyl group having 1 to 10 carbon atoms is bonded via a carbonyloxy group. Examples of the aryloxy group having 4 to 10 carbon atoms include a phenoxy group, a benzyloxy group, a naphthalene-2-yloxy group, a furan-3-yloxy group, and a thiophen-2-yloxy group. Examples of the arylcarbonyloxy group having 5 to 11 carbon atoms include a benzoyloxy group, a 1-naphthoyloxy group, a furan-2-carbonyloxy group, and a thiophene-3-carbonyloxy group. Examples of the silyloxy group having an alkyl group having 1 to 6 carbon atoms and / or a phenyl group include a trimethylsilyloxy group, a tert-butyldimethylsilyloxy group, a tert-butyldiphenylsilyloxy group, a triphenylsilyloxy group, etc. Examples of the halogen atom include a fluoro group, a chloro group, a bromo group, an iodo group, etc.

[0045] R in formulas (4-1) and (4-2) 10 ~R 13 are each independently preferably a hydrogen atom or an aryloxy group having 4 to 10 carbon atoms, more preferably a hydrogen atom or a benzyloxy group.

[0046] R in formulas (5) to (7) 14 ~R 20are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 6 to 10 carbon atoms which may have a substituent, and the substituent may be a group which can react with an isocyanate group. 8 and R 9 Examples of the groups include those exemplified in

[0047] Ar in formula (4-1) and (4-2) is a divalent organic group represented by formula (5), (6) or (7), preferably a divalent organic group represented by formula (6), and R in formula (6) 18 and R 19 is preferably a hydrogen atom.

[0048] <Repeating structural unit (C)> The copolymer of the present invention may contain a repeating structural unit (C) having a structure different from the repeating structural units (A) and (B) in order to adjust the content of the nonlinear optically active moiety, Tg, etc., to improve the solvent resistance and suppress orientation relaxation in a molded article (e.g., a cured film) obtained using the copolymer of the present invention, or to enable the formation of a molded article by thermal curing. The repeating structural unit (C) may contain one type or two or more types.

[0049] Considering that the copolymer of the present invention is used as an optically active material, for example, as a core of an optical waveguide, it is desirable to select the repeating structural unit (C) such that it does not adversely affect the transparency or moldability of the copolymer.

[0050] Examples of the repeating structural unit (C) include structural units derived from monomers such as alkyl (meth)acrylates, alkoxy group-containing (meth)acrylates, alicyclic group-containing (meth)acrylates, aryl group-containing (meth)acrylates, hydroxy group-containing (meth)acrylates, epoxy group-containing (meth)acrylates, carboxy group-containing (meth)acrylates, and isocyanate group-containing (meth)acrylates.

[0051] Examples of alkyl(meth)acrylates include methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, sec-butyl(meth)acrylate, n-pentyl(meth)acrylate, n-hexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-octyl(meth)acrylate, and n-octyl(meth)acrylate. methyl (meth)acrylate, methyl ...

[0052] Examples of alkoxy group-containing (meth)acrylates include 2-methoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and ethyl carbitol (meth)acrylate.

[0053] Examples of alicyclic group-containing (meth)acrylates include cyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and adamantyl (meth)acrylate.

[0054] Examples of the aryl group-containing (meth)acrylate include aryl group-containing (meth)acrylates having 6 to 15 carbon atoms, such as phenyl (meth)acrylate, benzyl (meth)acrylate, and phenoxyethyl (meth)acrylate.

[0055] Examples of hydroxy group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate.

[0056] Examples of epoxy group-containing (meth)acrylates include glycidyl (meth)acrylate and epoxycyclohexyl (meth)acrylate.

[0057] Examples of carboxy group-containing (meth)acrylates include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxybutyl (meth)acrylate, and carboxypentyl (meth)acrylate.

[0058] Examples of the isocyanate group-containing (meth)acrylate include (meth)acryloyloxyethyl isocyanate.

[0059] Examples of the repeating structural unit (C) include structural units derived from monomers such as 2-(meth)acryloyloxyethylsuccinic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, vinyl acetate, vinyl propionate, styrene, α-methylstyrene, N-vinylcaprolactam, cyclohexylmaleimide, phenylmaleimide, cyclohexylmaleimide, phenylmaleimide, methylmaleimide, ethylmaleimide, n-butylmaleimide, laurylmaleimide, and silicone-containing monomers.

[0060] Examples of the repeating structural unit (C) include structural units derived from resins such as poly(meth)acrylate, polycarbonate, polystyrene, silicone-based resin, epoxy-based resin, polysulfone, polyethersulfone, and polyimide. By introducing these repeating structural units that form a polymer matrix into the copolymer of the present invention, it is possible to obtain a form in which the repeating structural unit (A), the repeating structural unit (B), and the repeating structural unit (C) of the polymer matrix are copolymerized.

[0061] In order to enable the formation of a molded article by thermosetting, a repeating structural unit (C) having a structure capable of being thermoset (crosslinked) may be introduced into the copolymer of the present invention. The structure capable of being thermoset (crosslinked) may be, for example, an isocyanate group protected with a blocking agent. The blocking agent is not particularly limited as long as it can be dissociated (deblocked) by heating to regenerate an active isocyanate group, and examples thereof include phenols such as phenol, o-nitrophenol, p-chlorophenol, o-, m-, or p-cresol; alcohols such as methanol, ethanol, isopropanol, n-butanol, 2-ethoxyhexanol, 2-N,N-dimethylaminoethanol, 2-ethoxyethanol, and cyclohexanol; active methylene group-containing compounds such as dimethyl malonate, diethyl malonate, and methyl acetoacetate; oximes such as acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, cyclohexanone oxime, acetophenone oxime, and benzophenone oxime; lactams such as ε-caprolactam; pyrazoles such as pyrazole, 3,5-dimethylpyrazole, and 3-methylpyrazole; and thiols such as dodecanethiol and benzenethiol.

[0062] Examples of the repeating unit having a structure capable of being thermoset (crosslinked) include a repeating structural unit represented by the following formula (8). (In the formula, R 21 represents a hydrogen atom or a methyl group, L 4represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, and Y represents an isocyanate group protected with a blocking agent.

[0063] L in formula (8) 4 In the formula, the divalent hydrocarbon group having 1 to 30 carbon atoms includes the above-mentioned L 2 and L 3 The same groups as those exemplified in the above are included.

[0064] <Content of Each Repeating Structural Unit> In the copolymer of the present invention, the contents of the repeating structural units (A) and (B) in the copolymer of the present invention (based on 100 mol % of all repeating structural units) are not particularly limited. However, from the viewpoint of suppressing the occurrence of cracks in a film even when the film is thick and from the viewpoint of film formability, the content of the repeating structural unit (A) is preferably 5 to 95 mol %, and the content of the repeating structural unit (B) is preferably 5 to 95 mol %, more preferably 20 to 90 mol %, and the content of the repeating structural unit (B) is more preferably 10 to 50 mol %, and even more preferably 35 to 85 mol %, and the content of the repeating structural unit (B) is more preferably 15 to 20 mol %.

[0065] Furthermore, when the copolymer of the present invention contains the repeating structural unit (C) in addition to the repeating structural units (A) and (B), from the viewpoint of improving the electro-optical effect and suppressing the occurrence of cracks in the film even when the film is thick, the content of the repeating structural unit (C) in the copolymer of the present invention (based on 100 mol % of all repeating structural units) is preferably 90 mol % or less, more preferably 1 to 50 mol %, even more preferably 2 to 10 mol %, and particularly preferably 3 to 5 mol %.

[0066] <Copolymer Morphology> Examples of the morphology of the copolymer of the present invention include linear, crosslinked, and network-like morphologies. When the copolymer of the present invention contains, for example, the repeating structural unit (B2) represented by the formula (2-2), the copolymer has a crosslinked or network-like morphology. By using a crosslinked or network-like copolymer of the present invention, the occurrence of cracks in the film during film formation can be more effectively suppressed. Furthermore, by forming the copolymer of the present invention into a crosslinked or network-like morphology, the glass transition temperature can be increased, thereby suppressing thermal-induced orientation relaxation of the nonlinear optically active moiety and suppressing thermal-induced deterioration of the electro-optical effect.

[0067] <Weight-average molecular weight of copolymer> The weight-average molecular weight of the copolymer of the present invention is not particularly limited, but is, for example, 10,000 to 200,000, and from the viewpoint of solubility, is preferably 10,000 to 150,000, more preferably 10,000 to 100,000. The weight-average molecular weight in the present invention is a value measured by gel permeation chromatography (polystyrene equivalent).

[0068] <Glass Transition Temperature of Copolymer> The glass transition temperature (Tg) of the copolymer of the present invention is not particularly limited, but the midpoint of Tg is preferably 130 to 200°C, more preferably 150 to 200°C, from the viewpoint of suppressing the occurrence of cracks in the film even when the film is thick, and from the viewpoint of heat resistance.

[0069] <Viscosity of Copolymer> The viscosity of the copolymer of the present invention is not particularly limited, but for example, in a 20 wt % cyclohexanone solution (25°C), it is usually about 20 to 400 cP, and from the viewpoint of coatability, it is preferably 20 to 300 cP, more preferably 20 to 200 cP.

[0070] <Method for Producing Copolymer> The method for producing the copolymer of the present invention is not particularly limited, and any known production method may be used. For example, the copolymer can be obtained by copolymerizing a (meth)acrylic acid derivative and / or a (meth)acrylamide derivative having an alkoxyadamantyl group with a (meth)acrylic acid derivative having a functional group for introducing a nonlinear optically active moiety, and then reacting the functional group with a compound having a nonlinear optically active moiety. Examples of functional groups for introducing a nonlinear optically active moiety include an isocyanate group, a hydroxy group, a carboxy group, an epoxy group, an amino group, a halogenated allyl group, and a halogenated acyl group. For example, the copolymer of the present invention can be obtained by reacting a (meth)acrylic acid derivative and / or a (meth)acrylamide derivative having an alkoxyadamantyl group with a (meth)acrylic acid derivative having an isocyanate group, and then reacting the resulting mixture with a compound having a functional group reactive with an isocyanate group and a nonlinear optically active moiety in the same molecule. The functional group reactive with an isocyanate group is not particularly limited, and examples thereof include groups having active hydrogen, such as a hydroxy group, an amino group, and a carboxy group, as well as an epoxy group capable of generating active hydrogen. Examples of the nonlinear optically active moiety include the moieties derived from the organic nonlinear optical compounds mentioned in the description of Z (the atomic group exhibiting nonlinear optical activity) in the formulas (2-1) and (2-2), and preferably the atomic group represented by the formula (3). Examples of compounds having a functional group reactive with an isocyanate group and a nonlinear optically active moiety in the same molecule include compounds represented by the formulas (4-1) and (4-2). The hydroxy group or amino group present in the compound can react with the isocyanate group to obtain the repeating structural unit (B1) represented by the formula (2-1) or the repeating structural unit (B2) represented by the formula (2-2).

[0071] <Applications of the Copolymer> The copolymer of the present invention is suitable for use as a material for electro-optical elements such as optical switches, optical modulators, and phase shifters. In addition to applications in communication elements, the copolymer of the present invention can also be used in applications such as electric field sensors that detect changes in electric field as changes in refractive index.

[0072] 2. Composition The composition of the present invention comprises the copolymer of the present invention and a solvent.

[0073] The solvent is not particularly limited as long as it can dissolve or disperse the copolymer of the present invention, and examples thereof include tetrahydrofuran, methyltetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl acetate, cyclohexanol, 1,2-dichloroethane, chloroform, toluene, chlorobenzene, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, chlorobenzene, and propylene glycol methyl ether. These solvents can be used alone or in combination of two or more. Among these solvents, at least one selected from the group consisting of tetrahydrofuran, cyclopentanone, and chloroform is preferred from the viewpoints of high solubility of the copolymer of the present invention and good coatability.

[0074] The content of the copolymer of the present invention in the composition is not particularly limited, and is usually about 3 to 30% by weight, and from the viewpoints of coatability and facilitating the formation of a thick film using a high-concentration composition, it is preferably 3 to 25% by weight, more preferably 3 to 20% by weight. Note that the prepared composition is preferably used after filtering to remove insoluble matter using a filter with a pore size of about 200 nm or the like.

[0075] The composition of the present invention may contain additives such as antioxidants such as hydroquinone, ultraviolet absorbers such as benzophenone, rheology modifiers such as silicone oil and surfactants, adhesion aids such as silane coupling agents, crosslinkers, compatibilizers, curing agents, pigments, storage stabilizers, and antifoaming agents, as needed, as long as the effects of the present invention are not impaired.

[0076] 3. Nonlinear Optical Material <Nonlinear Optical Material A> Nonlinear optical material A of one embodiment of the present invention contains the copolymer of the present invention.

[0077] In the nonlinear optical material A of the present invention, the content of the copolymer of the present invention is not particularly limited, but is usually 85% by weight or more, preferably 90 to 100% by weight, more preferably 95 to 100% by weight, and even more preferably 99 to 100% by weight.

[0078] The nonlinear optical material A of the present invention may further contain a nonlinear optically active compound. As the nonlinear optically active compound, known inorganic nonlinear optically active compounds and / or organic nonlinear optically active compounds can be used without any particular limitation, and organic nonlinear optically active compounds are preferred.

[0079] Examples of inorganic nonlinear optically active compounds include lithium niobate, potassium dihydrogen phosphate, and zinc telluride, etc. These may be contained alone or in combination of two or more.

[0080] Examples of the organic nonlinear optically active compound include the compounds represented by the formulas (4-1) and (4-2), the compounds described in U.S. Patent No. 6,067,186, JP-A-2004-501159, WO 2011 / 024774, WO 2023 / 021921, "Organic Materials for Nonlinear Optics" (edited by the Chemical Society of Japan, Quarterly Chemistry Review No. 15 (1992)), "Organic Nonlinear Optical Materials" (edited by the Chemical Society of Japan, Quarterly Chemistry Review No. 15 (1992)), and the like. Examples of such compounds include compounds exhibiting second-order nonlinear optical effects described in "Recent Technologies of Optical Organic Materials for Information and Communications" (edited by Toshikuni Kaino, CMC Publishing (2007)), and "Molecular Nonlinear Optics" (ed. J. Zyss, Academic Press (1994)). These compounds may be contained alone or in combination of two or more.

[0081] The organic nonlinear optically active compound is not particularly limited as long as it exhibits a second-order nonlinear optical effect, but is preferably a compound having a conjugated chemical structure and further having an electron-donating group and an electron-withdrawing group in the molecule. Examples of the conjugated chemical structure include aromatic compounds such as benzene, naphthalene, anthracene, perylene, biphenyl, indene, and stilbene, heterocyclic compounds such as furan, pyran, pyrrole, imidazole, pyrazole, thiophene, thiazole, pyridine, pyridazine, pyrimidine, pyrazine, quinoline, and coumarin, and chemical structures in which these compounds are bonded to each other via a carbon-carbon unsaturated bond or a nitrogen-nitrogen unsaturated bond.

[0082] Examples of the electron-donating group include an amino group which may be substituted with an alkyl group, an aryl group, or an acyl group, an alkoxy group, an allyloxy group, and a thioether group. Examples of the electron-withdrawing group include a nitro group, a cyano group, a dicyanovinyl group, a tricyanovinyl group, a halogen atom, a carbonyl group, a sulfone group, a perfluoroalkyl group, a tricyanovinylfuran group, and a tricyanofuran group.

[0083] The organic nonlinear optically active compound is preferably a compound represented by the above formula (4-1) and / or (4-2).

[0084] When the nonlinear optical material A of the present invention contains a nonlinear optically active compound, the content of the nonlinear optically active compound may be adjusted appropriately depending on the application of the nonlinear optical material A, etc.

[0085] The nonlinear optical material A of the present invention may further contain a polymer (hereinafter also referred to as "polymer X") that contains a repeating structural unit (A) having an adamantyl group represented by the formula (1) above, but does not contain a repeating structural unit (B) having a nonlinear optically active site.

[0086] The polymer X may be a homopolymer consisting of the repeating structural unit (A), or may be a copolymer containing the repeating structural unit (A) and the repeating structural unit (C). When the polymer X is a copolymer, the polymer X may be a random copolymer or a block copolymer.

[0087] When the nonlinear optical material A of the present invention contains the polymer X, the content of the polymer X may be adjusted appropriately depending on the application of the nonlinear optical material A, etc.

[0088] The nonlinear optical material A of the present invention may contain additives such as antioxidants such as hydroquinone, ultraviolet absorbers such as benzophenone, rheology modifiers such as silicone oil and surfactants, adhesion aids such as silane coupling agents, crosslinkers, compatibilizers, curing agents, pigments, storage stabilizers, and antifoaming agents, as necessary.

[0089] <Nonlinear Optical Material B> A nonlinear optical material B according to another embodiment of the present invention comprises the polymer X and the nonlinear optically active compound.

[0090] In the nonlinear optical material B of the present invention, the contents of the polymer X and the nonlinear optically active compound may be adjusted appropriately depending on the application of the nonlinear optical material B, etc.

[0091] The nonlinear optical material B of the present invention may contain the above-mentioned additives, if necessary.

[0092] <Form of nonlinear optical material> The form of the nonlinear optical material of the present invention is not particularly limited, but is usually in the form of a film.When the nonlinear optical material of the present invention is in the form of a film, the method for producing this film is not particularly limited, and for example, the raw material of the nonlinear optical material of the present invention is dissolved or dispersed in the solvent to form a composition (preferably a solution), and this composition is applied to a suitable substrate (for example, silicon / silicon dioxide coated substrate, silicon nitride substrate, metal (for example, aluminum, molybdenum, chromium, etc.) coated substrate, glass substrate, quartz substrate, ITO substrate, etc.) or a film (for example, triacetyl cellulose film, polyester film, acrylic film, etc. resin film) or other substrate by spin coating, dip coating, spray coating, bar coating, flow coating, gravure coating, roll coating, etc. to form a film.

[0093] The formed film is then subjected to a poling treatment to develop second-order nonlinear optical properties. Poling is a process in which the copolymer or nonlinear optically active compound of the present invention is heated to a temperature near the glass transition temperature, a predetermined electric field is applied in that state, and the film is cooled while maintaining the electric field, thereby orienting the nonlinear optically active moieties (atomic groups that develop nonlinear optical activity) contained therein. This process enables the film (nonlinear optical material) to develop macroscopic nonlinear optical properties.

[0094] When the nonlinear optical material of the present invention is in the form of a film, its thickness is not particularly limited, but is usually about 0.1 to 10 μm, preferably 0.3 to 3.0 μm, and more preferably 0.5 to 2.0 μm. Since the nonlinear optical material of the present invention contains the copolymer of the present invention and / or the polymer X, cracks are unlikely to occur even when the film is thick.

[0095] <Physical Properties of Nonlinear Optical Material> The refractive index (n) of the nonlinear optical material of the present invention is not particularly limited, but is, for example, usually about 1.5 to 1.7 at a wavelength of 1308 nm, and usually about 1.5 to 1.7 at a wavelength of 1532 nm.

[0096] The electro-optic coefficient (r) of the nonlinear optical material of the present invention is not particularly limited, but is, for example, usually about 85 to 105 pm / V at a wavelength of 1308 nm, and usually about 50 to 75 pm / V at a wavelength of 1550 nm.

[0097] The figure of merit (n 3 r) is not particularly limited, but is, for example, usually about 370 to 470 pm / V at a wavelength of 1308 nm, and usually about 225 to 300 pm / V at a wavelength of 1550 nm.

[0098] 4. Electro-optical Devices The electro-optical device of the present invention comprises the copolymer of the present invention or the nonlinear optical material of the present invention. The copolymer of the present invention is suitable for use as a material for various electro-optical devices. Examples of electro-optical devices include optical switches, optical modulators, and phase shifters.

[0099] Representative examples of electro-optical elements include optical switching elements (optical communication elements) such as Mach-Zehnder optical modulators. In optical switching elements, a composition (solution) containing the copolymer of the present invention can be applied to a substrate such as glass or plastic, followed by processing using light or electron beam lithography, wet or dry etching, or nanoimprinting to form an optical waveguide structure capable of transmitting light. Typically, an optical waveguide structure is formed by applying and laminating a composition (solution) containing the copolymer of the present invention onto a material having a refractive index smaller than that of the composition (solution) containing the copolymer of the present invention. However, the present invention is not limited to this structure, and the composition (solution) containing the copolymer of the present invention can also be applied to other optical waveguide structures.

[0100] In a Mach-Zehnder optical modulator, a high-frequency voltage is applied to either or both of the branched optical waveguide structures to produce electro-optical properties, which changes the refractive index and causes a phase shift in the propagating light. This phase shift changes the light intensity after branching and combining, enabling high-speed modulation of light.

[0101] The electro-optical element of the present invention is not limited to phase and intensity modulation, but can also be used as, for example, a polarization conversion element, a wave splitting element, and a wave combining element.

[0102] An optical waveguide using the copolymer of the present invention as a core material can be produced, for example, by the method disclosed in WO 2016 / 035823.

[0103] The present invention will be described below with reference to examples, but the present invention is not limited to these examples in any way.

[0104] In the examples and comparative examples, the abbreviations are as follows: AdOMe: 3-methoxy-1-adamantyl methacrylate AdOEt: 3-ethoxy-1-adamantyl methacrylate MOI: 2-isocyanatoethyl methacrylate (manufactured by Showa Denko K.K., Karenz MOI (registered trademark)) AdMA: 1-adamantyl methacrylate (manufactured by Osaka Organic Chemical Industry Ltd., Adamantate M-104) DCPMA: dicyclopentanyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) AIBN: 2,2'-azobis(isobutyronitrile) (manufactured by Tokyo Chemical Industry Co., Ltd.) DBTDL: dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.) THF: tetrahydrofuran

[0105] Synthesis Example 1 [Synthesis of AdOMe] 118 g of 3-hydroxy-1-adamantyl methacrylate (Adamantate HM, manufactured by Osaka Organic Chemical Industry, Ltd.), 1000 g of toluene, and 76 g of triethylamine were placed in a 2000 mL four-neck flask equipped with a Dean-Stark type flow divider and a stirrer, and the mixture was cooled to 5°C or below. 69 g of methanesulfonyl chloride was added dropwise thereto, and the mixture was allowed to react for 1 hour. Thereafter, 600 g of water was added, and a separation operation was performed to separate the organic layer. The resulting organic layer was washed with 500 g of 3% hydrochloric acid and then with 500 g of water, and the solvent was then concentrated to obtain 140 g of 3-methanesulfonyloxy-1-adamantyl methacrylate.

[0106] 22 g of the obtained 3-methanesulfonyloxy-1-adamantyl methacrylate, 140 g of methanol, and 12 g of triethylamine were added to a 500 mL four-neck flask equipped with a Dean-Stark type flow divider and a stirrer, and the reaction was carried out at 65°C for 30 hours. The obtained reaction solution was concentrated, and after distilling off the methanol, 25 g of hexane, 10 g of toluene, and 50 g of water were added, and a separation operation was performed to separate the organic layer. The obtained organic layer was washed with 50 g of 2% hydrochloric acid and then with 50 g of water, and the solvent was concentrated to obtain a concentrated solution. The obtained concentrated solution was purified by distillation to obtain 17 g of AdOMe, a colorless, transparent liquid.

[0107] Synthesis Example 2 [Synthesis of AdOEt] AdOEt was synthesized in the same manner as in Synthesis Example 1, except that ethanol was used in place of methanol in Synthesis Example 1 to react with 3-methanesulfonyloxy-1-adamantyl methacrylate.

[0108] Production Example 1 [Production of Nonlinear Optically Active Compound] The following compound [FTC-OH] was used as the nonlinear optically active compound. The compound [FTC-OH] was produced by a method similar to that disclosed in X. Zhang et al., Tetrahedron Lett., 51, p. 5823 (2010).

[0109] Production Example 2 [Production of Nonlinear Optically Active Compound] The following compound [FTC-OH2] was used as the nonlinear optically active compound. The compound [FTC-OH2] was produced by a method similar to that disclosed in X. Piao et al., J. Polim. Sci., A, Polym. Chem., 49, p. 47 (2011).

[0110] Example 1 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 8.863 g (35.4 mmol) of AdOMe, 1.350 g (8.70 mmol) of MOI, and 0.354 g (2.16 mmol) of AIBN were dissolved in 20 ml of dehydrated toluene. The resulting solution was added dropwise over 20 minutes to 20 ml of dehydrated toluene heated to 70°C. The mixture was then stirred at 72-75°C for 2 hours. After allowing the mixture to cool to room temperature (approximately 23°C), the resulting reaction mixture was added dropwise to 500 ml of dehydrated IPE (isopropyl ether) to precipitate a polymer. The precipitate was filtered, washed successively with dehydrated IPE and dehydrated hexane, and dried under reduced pressure at 70°C to obtain 8.41 g of a white powder intermediate having repeating structural units derived from AdOMe and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.15 g of the intermediate (0.98 mmol as isocyanate groups), 0.525 g (0.76 mmol) of the nonlinear optically active compound [FTC-OH] prepared in Preparation Example 1, and approximately 100 ml of DBTDL were dissolved in 40 ml of dehydrated THF and stirred at 50-55°C for 2 hours. Approximately 5 ml of methanol was then added, and the mixture was further stirred at 50-55°C for 1 hour. The resulting reaction mixture was precipitated with 450 ml of IPE, and the precipitate was filtered. The crude product was added to 150 ml of THF and dissolved by heating at 60°C. The precipitate was then dispersed in 1500 ml of IPE and reprecipitated. The precipitate was filtered, washed, and then dried under reduced pressure at 70°C to obtain 1.22 g of a dark reddish-brown powder copolymer having the following repeating structural units (A1), (B1), and (C1). The following formula shows, from the left, the repeating structural units (A1), (B1), and (C1).

[0111] Example 2 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 8.910 g (33.7 mmol) of AdOEt, 1.359 g (8.76 mmol) of MOI, and 0.355 g (2.16 mmol) of AIBN were dissolved in 20 ml of dehydrated toluene. The resulting solution was added dropwise over 20 minutes to 20 ml of dehydrated toluene heated to 70°C. The mixture was then stirred at 72-75°C for 2 hours. After allowing the mixture to cool to room temperature (approximately 23°C), the resulting reaction mixture was added dropwise to 500 ml of dehydrated IPE to precipitate a viscous polymer. After removing the supernatant, 600 ml of dehydrated IPE was added to solidify the polymer. After removing the supernatant, the mixture was dried under reduced pressure at 45°C to obtain 6.31 g of a white powder intermediate having repeating structural units derived from AdOEt and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.17 g of the intermediate (0.998 mmol as isocyanate groups), 0.525 g (0.76 mmol) of the nonlinear optically active compound [FTC-OH] prepared in Preparation Example 1, and approximately 100 mg of DBTDL were dissolved in 40 ml of dehydrated THF and stirred at 50-55°C for 2 hours. Approximately 5 ml of methanol was then added, and the mixture was further stirred at 50-55°C for 1 hour. The resulting reaction mixture was precipitated with 450 ml of IPE and 450 ml of MeOH, and the precipitate was filtered. The crude product was washed with IPE:THF 10:1, then IPE, and finally MeOH, and then dried under reduced pressure at 70°C to obtain 1.31 g of a dark reddish-brown powder copolymer having the following repeating structural units (A2), (B1), and (C1). The following formula shows the repeating structural units (A2), (B1), and (C1) from left to right.

[0112] Example 3 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 4.49 g (17.9 mmol) of AdOMe, 3.96 g (18.0 mmol) of AdMA, 1.29 g (8.31 mmol) of MOI, and 0.25 g (1.52 mmol) of AIBN were dissolved in 20 ml of dehydrated toluene. The resulting solution was added dropwise to 20 ml of dehydrated toluene heated to 70°C over 20 minutes. The mixture was then stirred at 72-75°C for 2 hours. After allowing the mixture to cool to room temperature (approximately 23°C), the resulting reaction mixture was added dropwise to 450 ml of dehydrated IPE to precipitate a polymer. The precipitate was filtered, washed successively with dehydrated IPE and dehydrated hexane, and dried under reduced pressure at 70°C to obtain 7.06 g of a white powder intermediate having repeating structural units derived from AdOMe, AdMA, and MOI. (2) Preparation of Copolymer Having Nonlinear Optically Active Moieties Under an argon atmosphere, 1.25 g of the intermediate (1.07 mmol as isocyanate group), 0.558 g (0.808 mmol) of the nonlinear optically active compound [FTC-OH] produced in Production Example 1, and about 100 mg of DBTDL were dissolved in 45 ml of dehydrated THF and stirred at 50 to 55° C. for 2 hours. Then, about 5 ml of methanol was added, and the mixture was further stirred at 50 to 55° C. The mixture was stirred for 1 hour. The resulting reaction mixture was precipitated with 450 ml of IPE, and the precipitate was filtered. The crude product obtained after washing with IPE:THF (10:1), then IPE, and finally MeOH was added to 100 ml of THF and dissolved by heating at 60°C. The resulting product was dispersed in 1,000 ml of IPE for reprecipitation. The precipitate was filtered, washed with IPE:THF (10:1), then IPE, and finally MeOH, and then dried under reduced pressure at 70°C to obtain 1.47 g of a dark reddish-brown powder copolymer having the following repeating structural units (C2), (A1), (B1), and (C1). The following formula shows the repeating structural units (C2), (A1), (B1), and (C1) in order from the left.

[0113] Example 4 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 8.87 g (35.4 mmol) of AdOMe, 1.42 g (9.15 mmol) of MOI, and 0.354 g (2.16 mmol) of AIBN were dissolved in 18 ml of dehydrated toluene and stirred at 70° C. for 2 hours. After cooling to room temperature (approximately 23° C.), the resulting reaction mixture was added to 450 ml of dehydrated IPE to precipitate a polymer. The precipitate was filtered, washed successively with dehydrated IPE and dehydrated hexane, and then dried under reduced pressure at 70° C. to obtain 8.91 g of a white powder intermediate having repeating structural units derived from AdOMe and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.15 g of the intermediate (1.02 mmol as isocyanate groups), 0.525 g (0.76 mmol) of the nonlinear optically active compound [FTC-OH] prepared in Preparation Example 1, and approximately 100 mg of DBTDL were dissolved in 40 ml of dehydrated THF and stirred at 50-55°C for 2 hours. Approximately 5 ml of methanol was then added, and the mixture was further stirred at 50-55°C for 1 hour. The resulting reaction mixture was precipitated with 450 ml of IPE, and the precipitate was filtered. The crude product was added to 50 ml of THF, heated to 60°C, dissolved, and dispersed in 500 ml of IPE for reprecipitation. The precipitate was filtered, washed, and then dried under reduced pressure at 70°C to obtain 1.28 g of a dark reddish-brown powder copolymer having the following repeating structural units (A1), (B1), and (C1). The following formula shows, from the left, the repeating structural units (A1), (B1), and (C1).

[0114] Example 5 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 4.65 g (18.6 mmol) of AdOMe, 4.13 g (26.6 mmol) of MOI, and 0.222 g (1.35 mmol) of AIBN were dissolved in 14.5 ml of dehydrated toluene and stirred at 70° C. for 2 hours. After cooling to room temperature (approximately 23° C.), the reaction mixture was added to 370 ml of dehydrated IPE to precipitate a polymer. The precipitate was filtered, washed with dehydrated IPE, and dried under reduced pressure at 70° C. to obtain 7.05 g of a white powder intermediate having repeating structural units derived from AdOMe and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.53 g of the intermediate (4.63 mmol as isocyanate groups), 0.841 g (1.17 mmol) of the nonlinear optically active compound [FTC-OH2] prepared in Preparation Example 2, 0.421 g (1.34 mmol) of DR1 (Disperse Red 1), and approximately 160 mg of DBTDL were dissolved in 90 ml of dehydrated THF and stirred at 55-56°C for 2 hours. Then, 5.3 ml of methanol and approximately 60 mg of DBTDL were added, and the mixture was further stirred at 53-55°C for 1 hour. The resulting reaction mixture was precipitated with 1050 ml of IPE, and the precipitate was filtered. The resulting precipitate was washed with IPE:THF (12:1), then with IPE, and finally with hexane, and then dried under reduced pressure at 70°C to obtain 2.55 g of a copolymer in the form of a dark brown powder having the following repeating structural units (A1), (B2), (C1), and (C4). The following formula shows the repeating structural units (A1), (B2), (C1), and (C4) in order from the left.

[0115] Comparative Example 1 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 8.38 g (38.0 mmol) of AdMA, 1.258 g (8.11 mmol) of MOI, and 0.387 g (2.16 mmol) of AIBN were dissolved in 20 ml of dehydrated toluene. The resulting solution was added dropwise over 20 minutes to 20 ml of dehydrated toluene heated to 70°C. The mixture was then stirred at 72-75°C for 2 hours. After allowing the mixture to cool to room temperature (approximately 23°C), the resulting reaction mixture was added dropwise to 450 ml of dehydrated IPE to precipitate a polymer. The precipitate was filtered, washed sequentially with dehydrated IPE and dehydrated hexane, and dried under reduced pressure at 70°C to obtain 6.74 g of a white powder intermediate having repeating structural units derived from AdMA and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.24 g of the intermediate (1.04 mmol as isocyanate groups), 0.554 g (0.802 mmol) of the nonlinear optically active compound [FTC-OH] prepared in Preparation Example 1, and approximately 100 mg of DBTDL were dissolved in 40 ml of dehydrated THF and stirred at 50-55°C for 2 hours. Approximately 5 ml of methanol was then added, and the mixture was further stirred at 50-55°C for 1 hour. The resulting reaction mixture was precipitated with 500 ml of IPE. The precipitate was filtered, washed, and then dried under reduced pressure at 70°C to obtain 1.49 g of a dark reddish-brown powder copolymer having the following repeating structural units (C2), (B1), and (C1). The following formula shows the repeating structural units (C2), (B1), and (C1) from left to right.

[0116] Comparative Example 2 (Preparation of Copolymer) (1) Preparation of Intermediate Under an argon atmosphere, 7.58 g (34.4 mmol) of AdMA, 0.85 g (3.86 mmol) of DCPMA, 1.25 g (8.12 mmol) of MOI, and 0.25 g (1.52 mmol) of AIBN were dissolved in 20 ml of dehydrated toluene. The resulting solution was added dropwise over 20 minutes to 20 ml of dehydrated toluene heated to 70°C. The mixture was then stirred at 72-75°C for 2 hours. After cooling to room temperature (approximately 23°C), the resulting reaction mixture was added dropwise to 450 ml of dehydrated IPE to precipitate a polymer. The precipitate was filtered, washed sequentially with dehydrated IPE and dehydrated hexane, and dried under reduced pressure at 70°C to obtain 6.77 g of a white powder intermediate having repeating structural units derived from AdMA, DCPMA, and MOI. (2) Preparation of a Copolymer Having a Nonlinear Optically Active Moiety: Under an argon atmosphere, 1.25 g of the intermediate (1.05 mmol as isocyanate groups), 0.557 g (0.806 mmol) of the nonlinear optically active compound [FTC-OH] prepared in Preparation Example 1, and approximately 100 mg of DBTDL were dissolved in 40 ml of dehydrated THF and stirred at 50-55°C for 2 hours. Approximately 5 ml of methanol was then added, and the mixture was stirred at 50-55°C for an additional 1 hour. The resulting reaction mixture was precipitated with 500 ml of IPE, and the precipitate was filtered. The crude product obtained by washing with IPE:THF (10:1), then IPE, and finally MeOH was added to 100 ml of THF and dissolved by heating at 60°C. The crude product was then dispersed in 1,000 ml of IPE and reprecipitated. The precipitate was filtered, washed with IPE:THF (10:1), then with IPE, and finally with MeOH, and then dried under reduced pressure at 70°C to obtain 1.49 g of a dark reddish-brown powder copolymer having the following repeating structural units (C2), (C3), (B1), and (C1). The following formula shows the repeating structural units (C2), (C3), (B1), and (C1) in that order from the left.

[0117] Next, the following various measurements and evaluations were carried out using the copolymers produced in Examples 1 to 5 and Comparative Examples 1 and 2. The results are shown in Tables 1 and 2.

[0118] (1) Measurement of weight-average molecular weight: Apparatus: HLC-8200GPC manufactured by Tosoh Corporation; Column: Shodex (registered trademark) GPC KF-804L + KF-805L manufactured by Showa Denko K.K.; Column temperature: 40°C; Solvent: THF; Detector: UV (254 nm); Calibration curve: Standard polystyrene.

[0119] (2) Measurement of Glass Transition Point (Tg) Apparatus: Photo-DSC 204 F1 Phoenix (registered trademark) manufactured by NETZSCH Measurement conditions: under nitrogen atmosphere Heating rate: 30°C / min (-50 to 250°C)

[0120] (3) Measurement of Viscosity Using a viscometer (HVROC-L, manufactured by RHEOSENSE), the viscosity of a solution prepared by dissolving the copolymer in cyclohexanone at a concentration of 20% by weight was measured.

[0121] (4) Evaluation of Solubility A solution of the copolymer in cyclohexanone at a concentration of 20 wt % was placed in a plastic disposable syringe equipped with a syringe filter (Acrodisc, 13 mm, 0.2 μm, PTFE) having a hole diameter of 0.2 μm, and the piston was pressed. The solubility was evaluated based on the feel when the piston was pressed, using the following criteria: A: The syringe filter was held in one hand, and filtering was easily achieved with almost no resistance by simply pressing the piston lightly with the thumb of the hand holding the syringe filter (easy filtering with one hand). B: Filtering was possible with one hand without difficulty, although there was some resistance. C: Filtering was possible, but there was a great deal of resistance, and it was difficult to press the piston with the thumb of the hand holding the syringe filter.

[0122] (5) Measurement of Film Thickness A solution prepared by adjusting the copolymer concentration in cyclohexanone to 20 wt % was applied in a predetermined amount onto a cleaned substrate (quartz glass) using a spin coater 1H-DX2 manufactured by Mikasa Co., Ltd., and then vacuum dried at a temperature near the glass transition temperature (Tg) for 1 hour to prepare a thin film and a thick film, respectively. The film thickness of the thin film and thick film was measured using a stylus profiling system (Dektak XT manufactured by BRUKER Co., Ltd.).

[0123] (6) Evaluation of cracks Using a stereomicroscope (Nikon Solutions, NIKON ECLIPSE L150) equipped with an eyepiece (×10) and an objective lens (×5), the thin and thick films prepared above were observed for the presence or absence of cracks.

[0124] (7) Measurement of refractive index and electro-optic coefficient A solution of the copolymer in cyclohexanone at a concentration of 20% by weight was applied to a cleaned substrate (quartz glass) using a spin coater 1H-DX2 manufactured by Mikasa Co., Ltd., and then vacuum dried at a temperature near the glass transition temperature (Tg) for 1 hour to prepare a thin film with a thickness of approximately 3 μm. The refractive index of the prepared thin film (wavelengths of 1308 nm and 1532 nm) was measured using a prism coupler 2010 / M manufactured by Metricon Co., Ltd. The electro-optic coefficient of the prepared thin film was measured in the same manner as described in the reference paper "Transmission ellipsometric method without an aperture for simple and reliable evaluation of electro-optic properties", Toshiki Yamada and Akira Otomo, Optics Express, vol. 21, pages 29240-48 (2013). The laser light source used was a DFB laser 81663A (wavelengths 1308 nm and 1550 nm) manufactured by Agilent Technologies.

[0125]

[0126]

[0127] As shown in Tables 1 and 2, it was confirmed that the copolymers (Examples 1 to 5) containing a repeating structural unit (A) having an alkoxyadamantyl group were capable of forming crack-free films whether the film thickness was thin or thick. On the other hand, the copolymer (Comparative Example 1) containing a repeating structural unit having an adamantyl group and the copolymer (Comparative Example 2) containing a repeating structural unit having an adamantyl group and a repeating structural unit having a dicyclopentanyl group caused cracks in the film whether the film thickness was thin or thick. Furthermore, the films formed using the copolymers obtained in Examples 1 to 5 had higher performance indices (n 3 It was confirmed that the electro-optical effect was excellent and the optical properties were high.

[0128] The copolymer of the present invention is suitable for use as a material for electro-optical elements such as optical switches, optical modulators, phase shifters, and terahertz wave generating / detecting elements. In addition to communication element applications, the copolymer of the present invention can also be used in applications such as electric field sensors that detect changes in electric field as changes in refractive index. Furthermore, in the fabrication process of these elements, films are often formed not only on flat surface structures but also on various textured surface structures. Films on textured surface structures are more susceptible to cracking due to structural stress (strain). Therefore, the copolymer of the present invention can be used in a wider range of electro-optical elements.

Claims

1. A copolymer comprising a repeating structural unit (A) having an adamantyl group represented by the following formula (1), and a repeating structural unit (B) having a nonlinear optically active site: (In the formula, R 1 represents a hydrogen atom or a methyl group; W 1 represents -O-, -S- or -NH-; L 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O- (* is W 1 ), L 2 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, Ad represents an adamantyl group which may be substituted with an alkyl group having 1 to 5 carbon atoms, R 2 represents an alkoxy group having 1 to 10 carbon atoms bonded to any of the carbon atoms constituting the adamantyl group, and n represents an integer of 1 to 15.

2. The copolymer according to claim 1, wherein the repeating structural unit (B) includes a repeating structural unit (B1) represented by the following formula (2-1) and / or a repeating structural unit (B2) represented by the following formula (2-2): (In the formula, R 3 represents a hydrogen atom or a methyl group; W 2 represents -O-, -S- or -NH-; L 3 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, or *-L 4 -NHC(=O)O- (* is W 2 ), L 4 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, and Z represents an atomic group which exhibits nonlinear optical activity.

3. The copolymer according to claim 1, wherein the content of the repeating structural unit (A) is 5 to 95 mol %, and the content of the repeating structural unit (B) is 5 to 95 mol %.

4. The copolymer according to claim 3, further comprising a repeating structural unit (C) having a structure different from the repeating structural unit (A) and the repeating structural unit (B), and the content of the repeating structural unit (C) is 90 mol % or less.

5. A composition comprising the copolymer of claim 1 and a solvent.

6. A nonlinear optical material comprising the copolymer of claim 1.

7. A nonlinear optical material comprising the copolymer according to claim 1 and / or a polymer containing a repeating structural unit (A) having an adamantyl group represented by the following formula (1) and not containing a repeating structural unit (B) having a nonlinear optically active site, and a nonlinear optically active compound. (In the formula, R 1 represents a hydrogen atom or a methyl group; W 1 represents -O-, -S- or -NH-; L 1 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain a single bond, an ether bond and / or an ester bond, or *-L 2 -NHC(=O)O- (* is W 1 ), L 2 represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, Ad represents an adamantyl group which may be substituted with an alkyl group having 1 to 5 carbon atoms, R 2 represents an alkoxy group having 1 to 10 carbon atoms bonded to any of the carbon atoms constituting the adamantyl group, and n represents an integer of 1 to 15.

8. An electro-optical element comprising the copolymer according to claim 1 or the nonlinear optical material according to claim 6 or 7.