Nonlinear optically active copolymer

Abstract

[Problem] The present invention addresses the problem of providing: a nonlinear optically active copolymer which achieves both high glass transition temperature (Tg) and higher denseness of a nonlinear optical dye; and a nonlinear optical material which is obtained using this copolymer. [Solution] The present invention provides: a nonlinear optically active copolymer which comprises, in the same molecule thereof, at least a repeating unit A of an N-substituted maleimide skeleton represented by formula (1), and a repeating unit B represented by formula (2) and having a nonlinear optically active moiety; and an organic nonlinear optical material, a part of which is composed of this copolymer. [Chemical formula 1] (In the formula, R1 represents an alkyl group, an aralkyl group, a cycloalkyl group, an aliphatic crosslinked ring group or an aryl group; R2 represents a hydrogen atom or a methyl group; L1 represents a divalent hydrocarbon group which may contain an ether bond and / or an ester bond; L2 represents *-NHC(=O)O-, *-C(=O)NH- or *-C(=O)O- (wherein * represents a coupling end coupled to L1); and Z represents an atomic group which exhibits nonlinear optical activity.)

Description

Nonlinear Optically Active Copolymers

[0001] The present invention relates to a nonlinear optically active copolymer having an organic nonlinear optically active moiety that is used in optical information processing such as optical switches and optical modulation, optical communications, etc., and more particularly to a nonlinear optically active copolymer having a structure derived from an organic nonlinear optical compound in its side chain, and an organic nonlinear optical material using said copolymer.

[0002] In recent years, the development of various electronic devices using nonlinear optical materials has been progressing in fields such as optical information processing and optical communications. Among these nonlinear optical materials, materials that produce a first-order electro-optic effect (Pockels effect) due to a second-order nonlinear optical effect are expected to be applied to optical switches and optical modulation. Among nonlinear optical materials that exhibit the Pockels effect, inorganic nonlinear optical materials such as lithium niobate have already been put to practical use and are widely used. With the recent development of an information-oriented society, more advanced information processing is required, and there is a demand for the development of organic nonlinear optical materials that have excellent performance, such as higher nonlinear optical properties and faster response, instead of inorganic materials.

[0003] Among organic nonlinear optical materials, polymeric materials can be easily formed into films by methods such as casting, dipping, and spin coating, and are attracting attention for their ease of processing in device fabrication. Examples of such polymeric organic nonlinear optical materials include those in which an organic dye compound exhibiting a nonlinear optical effect is dispersed in a polymer matrix, and those in which an organic dye monomer is introduced into the main chain or side chain of a polymer compound. Among these, polymeric materials in which an organic dye monomer is introduced into the main chain or side chain can be formed into a film with the organic dye moiety dispersed uniformly at a high concentration, thereby enabling the development of uniform optical properties throughout the film. Therefore, such materials can be considered to be excellent materials from the perspective of practical device application.

[0004] To achieve a high nonlinear optical effect, polymer-based organic nonlinear optical materials are required to have a high glass transition temperature (Tg) and a high amount of organic dye monomer (organic dye moiety) incorporated. If the Tg is low, the molecular orientation of the organic dye moiety, which is oriented at high temperature and then fixed by cooling, gradually relaxes over time, resulting in a decrease in nonlinear optical effect. To counter this, proposals have been made to increase the Tg of the polymer by introducing units having cycloalkanes, such as adamantyl groups, into acrylic copolymers, thereby suppressing the orientation relaxation of the organic dye moiety over time (Patent Documents 1 and 2). Furthermore, Non-Patent Document 1 discloses that the nonlinear optical effect increases when the concentration of organic dye moieties exhibiting nonlinear optical effect in the polymer is high. For polymer materials with organic dye monomers incorporated into the side chains, it is important to increase the amount of organic dye monomer incorporated.

[0005] JP 2017-057415 A International Publication No. 2017 / 159815

[0006] Norman S. Allen, Photochemistry and Photophysics of Polymer Materials, John Wiley & Sons, Inc. ,2010

[0007] As described above, in polymer-based organic nonlinear optical materials, achieving a high Tg and increasing the amount of organic dye moieties introduced are important factors for improving nonlinear optical properties. However, if the proportion of monomer units (units containing an adamantyl group or the like) in the polymer that contribute to a high Tg is increased in order to achieve a high Tg, the proportion of monomer units having organic dye moieties (incorporation rate) will decrease, making it difficult to achieve both a high Tg and a high amount of organic dye moieties introduced.

[0008] An object of the present invention is to provide a nonlinear optically active copolymer that achieves both a high glass transition temperature (Tg) and densification of a nonlinear optical dye, and to provide a nonlinear optical material obtained by using the copolymer.

[0009] As a result of extensive investigations to achieve the above object, the present inventors have found that by incorporating a monomer unit derived from an N-substituted maleimide monomer, it is possible to achieve both a high Tg and a high amount of organic dye moiety introduced, and have completed the present invention.

[0010] That is, in a first aspect, the present invention relates to a nonlinear optically active copolymer containing at least a repeating unit A represented by formula [1] and a repeating unit B represented by formula [2] having a nonlinear optically active moiety in the same molecule. (In the formula, R １ represents an alkyl group having 1 to 6 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a cycloalkyl group having 4 to 8 carbon atoms, an aliphatic bridged ring group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms; R ２ represents a hydrogen atom or a methyl group; １ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond; L ２ *-NHC(=O)O-, *-C(=O)NH- or *-C(=O)O- (* is L １ and Z represents an atomic group exhibiting nonlinear optical activity.) As a second aspect, the present invention relates to a nonlinear optically active copolymer according to the first aspect, which contains 20 to 80 mol % of the repeating unit A represented by the formula [1] in the same molecule. As a third aspect, the present invention relates to a nonlinear optically active copolymer according to the first aspect, ２ *-NHC(=O)O-(* is L １ As a fourth aspect, the present invention relates to the nonlinear optically active copolymer according to the first aspect or the third aspect, wherein R １ is an alkyl group having 1 to 3 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, a cycloalkyl group having 6 to 8 carbon atoms, an aliphatic bridged ring group having 8 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. As a fifth aspect, the present invention relates to the nonlinear optically active copolymer according to any one of the first to fourth aspects, wherein Z is an atomic group having a furan ring group represented by formula [3]. (In the formula, R１０ and R １１ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a haloalkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the black dot represents a bond to the remaining structure constituting the atomic group Z that exhibits nonlinear optical activity.) As a sixth aspect, the Z is represented by formula [4] or formula [5] (in these chemical formulas, R ４ ~R ９ wherein one hydrogen atom is removed from the group consisting of: (In the formula, R ４ and R ５ each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted aryl group having 6 to 10 carbon atoms; R ６ ~R ９ 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 having 1 to 6 carbon atoms and / or a phenyl group, or a halogen atom; R １０ and R １１ each independently represents the same meaning as above, and Ar represents a divalent aromatic group represented by formula [6] or formula [7]. (In the formula, R １２ ~R １７ 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.) As a seventh aspect, the present invention provides a method for forming a compound represented by the formula [4] or [5] (in these chemical formulas, R ４ or R ５and wherein one hydrogen atom is removed). As an eighth aspect, the present invention relates to an organic nonlinear optical material comprising the nonlinear optically active copolymer according to any one of the first to seventh aspects as part of the material. As a ninth aspect, the present invention relates to an electro-optical element comprising the nonlinear optically active copolymer according to any one of the first to seventh aspects. As a tenth aspect, the present invention relates to an optical switching element comprising the nonlinear optically active copolymer according to any one of the first to seventh aspects. As an eleventh aspect, the present invention relates to a varnish comprising the nonlinear optically active copolymer according to any one of the first to seventh aspects. As a twelfth aspect, the present invention relates to a method for producing an organic nonlinear optical material, the method comprising the steps of: applying the varnish according to the eleventh aspect onto a surface of a substrate or onto the outermost surface of a single layer or multiple layers laminated on the substrate to obtain a coating film; and applying an electric field to the coating film under heating to orient atomic groups that exhibit nonlinear optical activity in the coating film.

[0011] According to the present invention, by combining a repeating unit having a nonlinear optically active moiety with a repeating unit derived from an N-substituted maleimide monomer, it is possible to provide a nonlinear optically active copolymer that achieves a high glass transition temperature (160°C or higher) and has a greater amount of the nonlinear optically active moiety introduced than conventional copolymers. The nonlinear optically active copolymer of the present invention having the above-described configuration can suppress orientational relaxation of the nonlinear optical moiety and can be used as an organic nonlinear optical material having excellent nonlinear optical properties. Furthermore, the nonlinear optically active copolymer of the present invention can be dissolved in a solvent to form a varnish, which can be easily molded, thereby achieving the effect of being suitable for use in the field of optoelectronic materials as an optical material with high handleability. Furthermore, the organic nonlinear optical material of the present invention has a large nonlinear optical constant and enables the production of easily moldable optical devices.

[0012] Polymeric materials incorporating organic dye monomers (organic dye moieties) into the main chain or side chain, including the nonlinear optically active copolymer of the present invention, do not exhibit nonlinear optical effects simply by being formed into a film. This is because the organic dye moieties exhibiting the nonlinear optical effect are completely randomly oriented in the film. To exhibit the nonlinear optical effect, a device containing the formed polymer is first heated to near the Tg of the polymer, followed by a poling process in which a voltage is applied from one direction to orient the organic dye moieties. The device is then cooled below the Tg, suppressing molecular motion while maintaining the orientation of the organic dye moieties. This allows the polymer to maintain its orientation, and only after these operations does the polymer material exhibit the nonlinear optical effect. The aforementioned Patent Document 2 discloses the effect of orientation relaxation over time, showing that a copolymer with nonlinear optical activity and a Tg of 172.5°C is resistant to orientation relaxation even after 1,000 hours or more at a high temperature of 85°C. The inventors further investigated and concluded that if the Tg of a nonlinear optically active polymer is 160°C or higher, orientation relaxation can be suppressed even after 1000 hours at the aforementioned temperature of 85°C. This 1000-hour condition at 85°C corresponds to the accelerated test condition for a 5-year lifespan, which is generally the trial period for devices. In other words, if the Tg of a nonlinear optically active polymer is 160°C or higher, orientation relaxation is suppressed, and it can be determined that it is useful as a nonlinear organic polymer material that can withstand practical use. However, as shown in Patent Document 1, for example, in the copolymer disclosed therein, the Tg can only exceed 160°C by increasing the abundance ratio of adamantyl methacrylate-derived units to 74 mol% or more. Thus, achieving a high Tg has hitherto been associated with the difficulty of increasing the concentration of organic dye moieties in the polymer.

[0013] In addition to the performance requirements for nonlinear optical materials, such as a high Tg and a high concentration of organic dye moieties, from the perspective of polymeric materials, it is desirable for the material to have good processability, as mentioned above. For example, to achieve good film-forming properties, it is desirable for the formed polymeric material to be amorphous. If the material becomes crystalline, a uniform film will not be formed, and it will be prone to unevenness or a phenomenon known as cracking, in which the film breaks in parts. In the technical field of optical materials targeted by this invention, optical signals are blocked at cracks, so the ability to form a uniform, crack-free film is an important aspect for practical application of optical devices. However, cycloalkane-based monomers such as the aforementioned adamantyl methacrylate generally tend to have poor film-forming properties when introduced at high concentrations. Patent Document 2 discloses the preparation of a varnish containing a copolymer incorporating a monomer unit having an adamantyl group, a monomer unit having a nonlinear optically active moiety, and other monomer units, and then forming a film by spin coating using the varnish as the core of an optical waveguide. However, the introduction of other monomer units may make it more difficult to achieve a high concentration of organic dye moieties.

[0014] The present inventors have therefore realized a nonlinear optically active copolymer that has a high glass transition temperature (Tg) by incorporating a monomer unit derived from an N-substituted maleimide monomer and that can be bound with a nonlinear optical dye at a high concentration, and have also discovered the advantage that the copolymer has excellent film-forming properties, leading to the completion of the present invention. The present invention will be described in detail below.

[0015] <Nonlinear Optically Active Copolymer> The nonlinear optically active copolymer of the present invention is a nonlinear optically active copolymer containing at least a repeating unit A represented by formula [1] and a repeating unit B represented by formula [2] having a nonlinear optically active moiety in the same molecule.

[0016] In the above formula [1], R １represents an alkyl group having 1 to 6 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a cycloalkyl group having 4 to 8 carbon atoms, an aliphatic bridged ring group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms. The alkyl group having 1 to 6 carbon atoms may have a branched structure, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, and n-hexyl. Examples of aralkyl groups having 7 to 12 carbon atoms include, but are not limited to, phenylmethyl (benzyl), 2-phenylethyl, 3-phenyl-n-propyl, 4-phenyl-n-butyl, 5-phenyl-n-pentyl, and 6-phenyl-n-hexyl. Examples of cycloalkyl groups having 4 to 8 carbon atoms include cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The aliphatic bridged ring group having 6 to 14 carbon atoms may have an unsaturated double bond, and examples thereof include an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, and an adamantyl group, and may also be a group in which such a bridged ring group is bonded to an alkyl group having 1 to 4 carbon atoms. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

[0017] Among these, R １ is preferably an alkyl group having 1 to 3 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, a cycloalkyl group having 6 to 8 carbon atoms, an aliphatic bridged ring group having 8 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and among these, an ethyl group, a phenylmethyl group (benzyl group), a cyclohexyl group, an adamantyl group, or a phenyl group is particularly preferred, and R １ is preferably a cyclohexyl group.

[0018] In the above formula [2], R ２ represents a hydrogen atom or a methyl group.

[0019] In the above formula [2], L １represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond. The divalent hydrocarbon group having 1 to 30 carbon atoms may be either an aliphatic group or an aromatic group, and the aliphatic group may be linear, branched, or cyclic. Among these, an aliphatic group is preferred, and an alkylene group having 1 to 6 carbon atoms is more preferred. Examples of such divalent hydrocarbon groups having 1 to 30 carbon atoms include linear aliphatic 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 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 ] Cycloaliphatic groups such as decanediyl group, adamantanediyl group, norbornanediyl group, and norbornenediyl group; and aromatic groups such as phenylene group and naphthalenediyl group.

[0020] In the above formula [2], L ２ *-NHC(=O)O-, *-C(=O)NH- or *-C(=O)O- (* is L １ It represents the bond end with. ２ is *-NHC(=O)O-(* is L １ It is preferable that the bond is a bond end with

[0021] In the above formula [2], Z represents 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 preferably a π-conjugated compound having an electron-donating group at one end of a π-conjugated chain and an electron-withdrawing group at the other end, and having a large molecular hyperpolarizability β. 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.

[0022] Among these, preferred atomic groups that exhibit nonlinear optical activity in the present invention include atomic groups having a furan ring group represented by the following formula [3].

[0023] In the above formula, R １０ , R １１ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a haloalkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and a black dot (●) represents a bond to the remaining structure constituting the atomic group Z that exhibits nonlinear optical activity.

[0024] Specific examples of the preferred atomic group (Z) that exhibits the nonlinear optical activity include an atomic group having a functional group derived from a structure represented by the following formula [4], or an atomic group having a functional group derived from a structure represented by the following formula [5]. That is, the atomic group (Z) is represented by formula [4] or formula [5] (in these chemical formulas, R ４ ~R ９ In the above, one hydrogen atom is removed from either of the groups.

[0025] In the above formula [4] or formula [5], R ４ and R ５each 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 alkyl group having 1 to 10 carbon atoms may have a branched structure or a cyclic structure, or may be an arylalkyl group. Specific examples 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, 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, and a phenethyl 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. 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. ４ or R ５ is preferably a bond obtained by removing one hydrogen atom from

[0026] In the above formula [4] or formula [5], R ６ ~R ９ 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 having 1 to 6 carbon atoms and / or a phenyl group, or a halogen atom. ４ and R ５Examples of the alkoxy group having 1 to 10 carbon atoms include groups in which the above-mentioned 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 groups in which the above-mentioned 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 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, and a triphenylsilyloxy group. Examples of the halogen atom include a fluoro group, a chloro group, a bromo group, and an iodo group.

[0027] In the above formula [4] or formula [5], R １０ and R １１ are each independently R in the formula [3] １０ and R １１that is, each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a haloalkyl 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 haloalkyl group having 1 to 5 carbon atoms may have a branched or cyclic structure and includes 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, a perfluorocyclopentyl group, etc. Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, etc.

[0028] In the above formula [4] or formula [5], Ar represents a divalent aromatic group represented by the following formula [6] or formula [7].

[0029] In the above formula [6] and formula [7], R １２ ~R １７ 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. Here, the alkyl group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, and the substituent are the same as those described above for R ４ and R ５ Examples of the groups include those exemplified in

[0030] The nonlinear optically active copolymer of the present invention may also contain repeating units (referred to as "other repeating units") other than the repeating unit A represented by the above formula [1] and the repeating unit B represented by the formula [2] having a nonlinear optically active moiety. For example, in order to adjust the content of the nonlinear optically active moiety, a repeating unit that forms a polymer matrix can be introduced into the nonlinear optically active copolymer. Furthermore, in order to contribute to improving the solvent resistance and suppressing orientation relaxation in a molded article (cured film) obtained from the copolymer, and further to enable the formation of a molded article by thermosetting, a repeating unit having a structure that can be thermoset (crosslinked) can be introduced into the nonlinear optically active copolymer. Alternatively, in order to adjust the glass transition temperature, a repeating unit containing a cycloalkane such as an adamantyl ring may be introduced into the nonlinear optically active copolymer. Considering that the nonlinear optically active copolymer of the present invention will be used as an optically active material, for example, as a core of an optical waveguide, it is desirable to select such other repeating units having a structure that does not significantly adversely affect the transparency or moldability of the copolymer.

[0031] In the repeating unit forming the polymer matrix, examples of the polymer matrix include resins such as polymethyl methacrylate, polycarbonate, polystyrene, silicone-based resins, epoxy-based resins, polysulfone, polyethersulfone, polyimide, etc. By introducing such a repeating unit forming the polymer matrix into the nonlinear optically active copolymer, the nonlinear optically active polymer of the present invention can be in a form obtained by copolymerization of the repeating unit A represented by the above formula [1], the repeating unit B having a nonlinear optically active moiety represented by formula [2], and the repeating unit of the polymer matrix.

[0032] In the repeating unit having a structure capable of being thermoset (crosslinked), a preferred example of the structure capable of being thermoset (crosslinked) is 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. The repeating unit having a structure capable of being thermoset (crosslinked) can be exemplified by the repeating unit represented by the following formula [8]. In the above formula [8], R １８ represents a hydrogen atom or a methyl group, L ３ represents 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. ３ The divalent hydrocarbon group having 1 to 30 carbon atoms in １ The same groups as those exemplified in the above can be mentioned.

[0033] In the repeating unit containing the cycloalkane, the cycloalkane is not particularly limited and may be a single ring or a condensed ring, and these rings may be bridged. Examples of the condensed ring include a bicyclo ring and a tricyclo ring. Examples of the bridged ring include dicyclopentane and adamantyl.

[0034] The weight-average molecular weight of the nonlinear optically active copolymer of the present invention, which contains at least the repeating unit A represented by the formula [1] and the repeating unit B represented by the formula [2], is not particularly limited, but is preferably 10,000 to 1,000,000. The weight-average molecular weight in the present invention is a value measured by gel permeation chromatography (polystyrene equivalent).

[0035] In the nonlinear optically active copolymer of the present invention, the proportion of the repeating unit A represented by the formula [1] in the same molecule is not particularly limited, but can be, for example, 1 to 99 mol %, or, for example, 20 to 80 mol %.

[0036] In the nonlinear optically active copolymer of the present invention, the blending ratio of the repeating unit A represented by formula [1] to the repeating unit B represented by formula [2] is not particularly limited, but can be, for example, a molar ratio of A:B=99:1 to 1:99, or 90:10 to 10:90, or 80:20 to 20:80, or 70:30 to 50:50, or 60:40 to 50:50, or 90:10 to 60:40, etc. Increasing the blending ratio of the repeating unit A represented by formula [1] can achieve a high Tg, and considering the increase in the amount of organic dye moiety (repeating unit B represented by formula [2]) introduced, the molar ratio A:B can be, for example, 80:20 to 20:80, 90:10 to 60:40, or 60:40 to 40:60. When the copolymer contains the other repeating units, the blending ratio of the repeating unit A represented by formula [1] to the other repeating units is not particularly limited, and can be, for example, a molar ratio of A:other repeating units of 99:1 to 10:90, or 80:20 to 10:90, or 75:25 to 10:90, or 60:40 to 10:90, or 95:5 to 30:70. Furthermore, in this case, the ratio of the total number of moles of the repeating unit A represented by formula [1] and the other repeating units to the number of moles of the repeating unit B represented by formula [2] can be the above-mentioned ratio.

[0037] <Method for Producing Nonlinear Optically Active Copolymer> The nonlinear optically active copolymer of the present invention, which contains at least the repeating unit A represented by formula [1] and the repeating unit B represented by formula [2], can be obtained, for example, by copolymerizing an N-substituted maleimide with a (meth)acrylic acid derivative having a functional group capable of 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 the target 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. In the present invention, the nonlinear optically active moiety is preferably introduced via an isocyanate group to obtain the repeating unit B represented by formula [2]. For example, the nonlinear optically active copolymer of the present invention can be produced by reacting an N-substituted maleimide with a (meth)acrylic acid derivative having an isocyanate group, followed by reaction with a compound having, in the same molecule, a functional group reactive with an isocyanate group and a nonlinear optically active moiety. The functional group reactive with the isocyanate group is not particularly limited, and examples thereof include groups having active hydrogen, such as a hydroxy group, an amino group, or a carboxy group, or an epoxy group capable of generating active hydrogen. Examples of the nonlinear optically active moiety include the moiety derived from the organic nonlinear optical compound described in the description of Z (an atomic group exhibiting nonlinear optical activity) in the above formula [2]. A preferred example is a moiety having a furan ring group represented by the above formula [3]. For example, examples of compounds having a functional group reactive with an isocyanate group and a nonlinear optically active moiety in the same molecule include the compounds represented by the above formula [4] and formula [5], and the hydroxy group or the like present in these compounds can react with the isocyanate group to obtain the repeating unit B represented by the above formula [2].

[0038] <Varnish> When the nonlinear optically active copolymer of the present invention is used as a nonlinear optical material, it is generally used in the form of a thin film. As a method for producing the thin film, the nonlinear optically active copolymer of the present invention is dissolved in a suitable organic solvent to form a varnish, and the varnish is applied to a substrate such as a suitable substrate (e.g., a silicon / silicon dioxide-coated substrate, a silicon nitride substrate, a substrate coated with a metal such as aluminum, molybdenum, chromium, etc., a glass substrate, a quartz substrate, an ITO substrate, etc.) or a film (e.g., a resin film such as a triacetyl cellulose film, a polyester film, or an acrylic film) by a wet coating method such as spin coating, flow coating, roll coating, slit coating, spin coating followed by slit coating, inkjet coating, printing, etc. to form a film. Note that the above varnish is also within the scope of the present invention.

[0039] The solvent used in preparing the varnish herein is one that dissolves the nonlinear optically active copolymer containing at least the repeating unit A represented by formula [1] and the repeating unit B represented by formula [2], as well as optional additives, which will be described later. The type and structure of the solvent are not particularly limited, as long as the solvent has such dissolving ability. Examples of preferred organic solvents 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 monomethyl ether. These solvents can be used alone or in combination of two or more. Among these solvents, tetrahydrofuran, cyclopentanone, chloroform, etc. are preferred from the viewpoint of high solubility of the copolymer containing at least the repeating units A and B represented by formula [1] and formula [2] and good film-forming properties. The solid content of the varnish is, for example, 0.5 to 30 mass %, or, for example, 5 to 30 mass %. The solid content here refers to the mass of the substances (nonlinear optically active copolymer and, if desired, additives described below) remaining after removing the solvent from the varnish. Therefore, the prepared varnish is preferably used after filtering using a filter with a pore size of about 0.2 μm.

[0040] In addition, when the nonlinear optically active copolymer of the present invention contains, for example, a repeating unit represented by the formula [8] as another repeating unit, it is possible to thermally cure (crosslink) a thin film (molded product) formed from the varnish. Specifically, the blocking agent protecting the isocyanate groups is dissociated (deblocked) by heating, regenerating active isocyanate groups, which then react with each other or with other curing agents (crosslinking agents) to cure (crosslink). The curing (crosslinking) temperature is not particularly limited as long as it is a temperature at which the blocking agent protecting the isocyanate groups dissociates, but is usually within the range of 100 to 300°C, preferably 120 to 250°C, and more preferably 140 to 200°C.

[0041] Furthermore, the varnish may contain, as necessary, 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 for the polymer matrix, compatibilizers, curing agents, pigments, storage stabilizers, antifoaming agents, etc., as long as the effects of the present invention are not impaired.

[0042] <Electro-optical Elements, Optical Switching Elements> The nonlinear optically active copolymer of the present invention can be used as a material for various electro-optical elements that have been proposed in the past. Representative examples of electro-optical elements include optical switching elements (optical communication elements) such as Mach-Zehnder optical modulators. In optical switching elements, a varnish containing the nonlinear optically active copolymer of the present invention is applied to a substrate such as glass or plastic, and then processed using light or electron beam lithography, wet and dry etching, or nanoimprinting to form an optical waveguide structure capable of transmitting light. Typically, an optical waveguide structure is formed by coating and laminating the varnish on a material with a lower refractive index than the varnish containing the nonlinear optically active copolymer. However, this structure is not limited to this, and the nonlinear optically active copolymer (varnish) of the present invention can also be applied to other optical waveguide structures. In a Mach-Zehnder optical modulator, a representative optical switching element, a high-frequency voltage is applied to both or one of the branched optical waveguide structures to exhibit electro-optical properties, changing the refractive index and thereby causing a phase change in the propagating light. This phase change changes the light intensity after branching and multiplexing, enabling high-speed modulation of light. Furthermore, the electro-optical element referred to here is not limited to phase and intensity modulation, but can also be used, for example, as a polarization conversion element or a branching and multiplexing element. Furthermore, the nonlinear optically active copolymer of the present invention can be used not only for communication element applications, but also for applications such as an electric field sensor that detects changes in the electric field as changes in the refractive index. An optical waveguide using a varnish containing the nonlinear optically active copolymer of the present invention as a core material can be manufactured, for example, by the method disclosed in WO 2016 / 035823.

[0043] <Organic Nonlinear Optical Material> In the present invention, a poling treatment is required to develop second-order nonlinear optical properties in a material (e.g., a thin film) prepared using a varnish containing the nonlinear optically active copolymer. Poling is a process in which a material is heated to a temperature above the glass transition temperature and below the melting point of the material, a predetermined electric field is applied, and the material is cooled while maintaining the electric field, thereby orienting the nonlinear optically active moieties (atomic groups that exhibit nonlinear optical activity) contained in the copolymer. This process allows the material to develop macroscopic nonlinear optical properties. In the present invention, simply forming a thin film of the nonlinear optically active copolymer in the form of a varnish results in random orientation of the nonlinear optically active moieties (atomic groups that exhibit nonlinear optical activity). Therefore, the nonlinear optical properties are developed by heating the material to a temperature 15°C, preferably 10°C, lower than the glass transition temperature of the nonlinear optically active copolymer or higher (approximately 120°C or higher if the nonlinear optically active copolymer does not exhibit a glass transition temperature), or lower than the melting point, and then poling is performed to develop nonlinear optical properties.

[0044] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0045] In the examples, the apparatus and conditions used for sample preparation and physical property analysis are as follows: (1) GPC (Gel Permeation Chromatography) Apparatus: Shimadzu Corporation (GPC system configuration) System controller: CBM-20A Column oven: CTO-20A Autosampler: SIL-10AF Detector: SPD-20A and RID-10A Exhaust unit: DGU-20A3 GPC column: Shodex (registered trademark) KF-804L and KF-803L Column temperature: 40°C Solvent: tetrahydrofuran Flow rate: 1 mL / min Standard sample: Five types of polystyrene with different weight average molecular weights (197000, 55100, 12800, 3950, 1260) (2) １ H NMR spectrum Apparatus: Ascend manufactured by Bruker ＴＭ 500 Solvent: deuterated chloroform (CDCl ３) Internal standard: tetramethylsilane (3) Differential scanning calorimetry (DSC): Glass transition temperature (Tg) measurement Apparatus: DSC 204 F1 Phoenix (registered trademark), manufactured by Netsch Japan Co., Ltd. Measurement conditions: under nitrogen atmosphere Heating rate: 10°C / min Temperature cycle conditions: (heating from 30°C to 200°C, cooling from 200°C to 100°C, heating from 100°C to 200°C) Determination conditions for glass transition temperature (Tg): The differential inflection point of the DSC curve at the second heating was taken as Tg. (4) Ultraviolet-visible-near-infrared absorption spectrum Apparatus: UV-3600 spectrophotometer, manufactured by Shimadzu Corporation Solvent: tetrahydrofuran (THF) Cell: 1 cm long quartz cell Measurement temperature: room temperature Measurement wavelength range: 800 nm to 300 nm (0.5 nm intervals)

[0046] The abbreviations have the following meanings: PM: N-phenylmaleimide [Imilex (registered trademark)-P, manufactured by Nippon Shokubai Co., Ltd.] CM: N-cyclohexylmaleimide [Imilex (registered trademark)-C, manufactured by Nippon Shokubai Co., Ltd.] EM: N-ethylmaleimide [Tokyo Chemical Industry Co., Ltd.] BM: N-benzylmaleimide [Tokyo Chemical Industry Co., Ltd.] Sty: styrene [Tokyo Chemical Industry Co., Ltd.] Ada: adamantyl methacrylate [Osaka Organic Chemical Industry Co., Ltd.] NCO: 2-isocyanatoethyl methacrylate [Karenz (registered trademark) MOI, manufactured by Showa Denko K.K.] Neg: 2-(2-methacryloyloxyethyloxy)ethyl isocyanate [Karenz (registered trademark) MOI-EG, manufactured by Showa Denko K.K.] AIBN: 2,2'-azobis(isobutyronitrile) [Fujifilm Wako Pure Chemical Industries, Ltd.] CPTC: 2-cyano-2-propyldodecyl trithiocarbonate [manufactured by Sigma-Aldrich] DBTDL: dibutyltin(IV) dilaurate [manufactured by Tokyo Chemical Industry Co., Ltd.] CPN: cyclopentanone THF: tetrahydrofuran

[0047] The nonlinear optical compound used in the present invention is not particularly limited, and may be selected, for example, from organic dye compounds exhibiting second-order nonlinear optical properties. [Reference Example 1] Production of Nonlinear Optical Compound (1) The following compound [EO-1] was used as the nonlinear optical compound (1) to be introduced into the side chain of the polymer. The following compound was produced by a method similar to that disclosed in X. Zhang et al., Tetrahedron Lett., 51, p. 5823 (2010).

[0048] Reference Example 2: Preparation of Nonlinear Optical Compound (2) The following compound [EO-2] was used as the nonlinear optical compound (2) to be introduced into the side chain of the polymer. The following compound was prepared by the following method. N-methyl-N-(2-hydroxyethyl)-4-aminobenzaldehyde (manufactured by Combi-Blocks, CAS No. 1201-91-8) was dissolved in ethanol, impurities were filtered off, and the solution was purified by reprecipitation with toluene. 8.96 g (50 mmol) of the purified N-methyl-N-(2-hydroxyethyl)-4-aminobenzaldehyde was dissolved in 50 mL of ethanol. Next, 15.76 g (50 mmol) of [3-cyano-4-methyl-5-phenyl-5-(trifluoromethyl)-2(5H)-furanylidene]-propanedinitrile was placed in a round-bottom flask, and 350 mL of ethanol was added. The mixture was stirred in a 65°C oil bath until [3-cyano-4-methyl-5-phenyl-5-(trifluoromethyl)-2(5H)-furanylidene]-propanedinitrile was dissolved. After dissolution, an ethanol solution of N-methyl-N-(2-hydroxyethyl)-4-aminobenzaldehyde was added dropwise little by little. After stirring for 1 hour, the reaction solution was cooled to room temperature and then stored in a refrigerator controlled at 4°C for 1 day. The reaction solution was filtered, and the filtrate was washed several times with cold ethanol. The resulting filtrate was dried under reduced pressure to obtain 22.86 g of [EO-02] in a 96% yield and with an LC purity of 99% or more. [3-cyano-4-methyl-5-phenyl-5-(trifluoromethyl)-2(5H)-furanylidene]-propanedinitrile (CAS. No. 436097-14-2) was synthesized by W. Jin, P. V. Johnston, D. L. Elder, K. T. Manner, K. E. Garrett, W. Kaminsky, R. Xu, B. H. Robinson and L. R. Dalton, Journal of Materials Chemistry C, Issue 4, 2016, pages 3119-3124.

[0049] [Examples 1 and 2] Preparation of Nonlinear Optically Active Polymers (EOP-P-50, EOP-P-60) (1) Preparation of Precursor Polymer: To a 200 mL round-bottom flask were added 6.92 g (40 mmol) of PM, 6.21 g (40 mmol) of NCO, 52.5 mg (0.32 mmol) of the polymerization initiator AIBN, 0.277 g (0.8 mmol) of the chain transfer agent CPTC, and 50 g of CPN. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an oil bath at 80°C. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (13.3 g, 89% yield) of the nonlinear optically active copolymer. The polymerization ratio of PM to NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the PM:NCO ratio was 50:50 mol %, which was the same as the monomer charging ratio.

[0050] (2) Production of Nonlinear Optically Active Copolymer 4.0 g of the obtained precursor polymer (containing approximately 12.2 mmol of isocyanate groups) was charged with 4.0 g of nonlinear optical compound (1) [EO-1] (50% by mass, 6.8 mmol, Example 1) or 6.0 g (60% by mass, 10.2 mmol, Example 2) of the compound (1) [EO-1] in each flask. Dry THF was added to the resulting mixture in an amount 25 times the mass of the solid content, and the mixture was stirred to achieve a uniform solution. 0.2 g of DBTDL (5% by mass, based on the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to induce a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxyl groups of the nonlinear optical compound (1). When the peak of the unreacted nonlinear optical compound (1) disappeared in GPC, or when no decrease in the peak was observed, methanol was added to eliminate the unreacted isocyanate groups. After the reaction was completed, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried, yielding the target nonlinear optically active copolymers EOP-P-50 (Example 1) and EOP-P-60 (Example 2) having repeating units represented by the following formulas in yields of approximately 90%. In the formulas representing the repeating units below, the numbers and symbols attached to the repeating units (50, m, 50-m, etc. in the case of Example 1) represent the molar ratio of each repeating unit (total: 100). m represents the molar ratio of the repeating units in which the isocyanate groups of the precursor polymer react with the nonlinear optical compound. The molar ratio of the repeating units in which the unreacted isocyanate groups react with methanol to eliminate the unreacted isocyanate groups is represented by subtracting m from the molar ratio of the repeating units in the precursor polymer having isocyanate groups (50 in the case of Example 1).

[0051] Examples 3 to 5 Production of Nonlinear Optically Active Polymers (EOP-C-50, EOP-E-50, EOP-B-50) Precursor polymers were produced in the same manner as in Examples 1 and 2, except that CM (Example 3), EM (Example 4), or BM (Example 5) was used instead of the PM used in Examples 1 and 2. The polymerization ratio of CM, EM, or BM to NCO in the precursor polymer was CM (or EM, BM):NCO=50:50 mol %. Subsequently, 2.0 g of nonlinear optical compound (1) was added to 2.0 g of each of the obtained precursor polymers (containing approximately 6.1 mmol of isocyanate groups) in an amount of 50% by mass, 3.4 mmol, based on the total amount of the precursor polymer and nonlinear optical compound (1), and nonlinear optical active copolymers having repeating units represented by the following formulas: EOP-C-50 (Example 3), EOP-E-50 (Example 4), and EOP-B-50 (Example 5) were obtained in a yield of approximately 90%, respectively, using the same procedures as in Examples 1 and 2.

[0052] Comparative Example 1: Preparation of Nonlinear Optically Active Polymer (EOP-Ada-50) (1) Preparation of Precursor Polymer: 2.20 g (10 mmol) of Ada, 1.55 g (10 mmol) of NCO, 13.1 mg (0.08 mmol) of AIBN, 69.1 mg (0.2 mmol) of CPTC, and 15 g of CPN were added to a 100 mL round-bottom flask, and the mixture was thoroughly bubbled with nitrogen and stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (3.8 g, yield 90%) of the nonlinear optically active copolymer. The polymerization ratio of Ada to NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the Ada:NCO ratio was 50:50 mol %, which was the same as the monomer charging ratio.

[0053] (2) Production of Nonlinear Optically Active Copolymer 2.0 g of the obtained precursor polymer (containing approximately 5.3 mmol of isocyanate groups) was charged into a flask with 2.0 g of nonlinear optical compound (1) [EO-1] (amount charged relative to the total amount of the precursor polymer and nonlinear optical compound (1): 50% by mass, 3.4 mmol), and 100 g of dry THF was added and stirred to achieve a uniform solution. 0.1 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (1). When the peak of the unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 3.8 g of the target nonlinear optically active copolymer EOP-Ada-50 having a repeating unit represented by the following formula in a yield of about 90%.

[0054] Comparative Example 2: Preparation of Nonlinear Optically Active Polymer (EOP-Ada-30) (1) Preparation of Precursor Polymer: 3.30 g (15 mmol) of Ada, 0.78 g (5 mmol) of NCO, 13.1 mg (0.08 mmol) of AIBN, 69.1 mg (0.2 mmol) of CPTC, and 15 g of CPN were added to a 100 mL round-bottom flask, and the mixture was thoroughly bubbled with nitrogen and stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (3.75 g, 88% yield) of the nonlinear optically active copolymer. The polymerization ratio of Ada to NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the ratio of Ada:NCO was 75:25 mol %, which was the same as the monomer charging ratio.

[0055] (2) Production of Nonlinear Optically Active Copolymer 2.0 g of the obtained precursor polymer (containing approximately 2.5 mmol of isocyanate groups) was charged into a flask with 0.86 g of nonlinear optical compound (1) [EO-1] (charge amount relative to the total amount of the precursor polymer and nonlinear optical compound (1): 30% by mass, 1.5 mmol), and 100 g of dry THF was added and stirred to achieve a uniform solution. 0.1 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (1). When the peak of the unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 2.9 g of the target nonlinear optically active copolymer EOP-Ada-30 having a repeating unit represented by the following formula in a yield of about 93%.

[0056] Example 6: Preparation of Nonlinear Optically Active Polymer (EOP-CS-40) (1) Preparation of Precursor Polymer: 8.96 g (50 mmol) of CM, 3.88 g (25 mmol) of NCO, 2.56 g (25 mmol) of Sty, 70.0 mg (0.4 mmol) of AIBN, 0.35 g (1.0 mmol) of CPTC, and 80 g of dried THF were added to a 300 mL round-bottom flask. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an oil bath at 80°C. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (18.5 g, yield 93%) of the nonlinear optically active copolymer. The polymerization ratio of CM, Sty, and NCO in the precursor polymer was: １ The proton ratio of H NMR was found to be CM:Sty:NCO=50:25:25 mol %, which was the same as the monomer charging ratio.

[0057] (2) Production of Nonlinear Optically Active Copolymer 10.0 g of the obtained precursor polymer (containing approximately 16.4 mmol of isocyanate groups) was charged into a flask with 6.67 g of nonlinear optical compound (1) [EO-1] (charge amount relative to the total amount of precursor polymer and nonlinear optical compound (1): 40% by mass, 11.4 mmol), and 250 g of dry THF was added. The mixture was stirred to achieve a uniform solution. 0.5 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (1). When the peak of the unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 15.9 g of the target nonlinear optically active copolymer EOP-CS-40 having a repeating unit represented by the following formula in a yield of about 90%.

[0058] Example 7: Preparation of Nonlinear Optically Active Copolymer (EOP-CA-40) (1) Preparation of Precursor Polymer: 8.96 g (50 mmol) of CM, 3.88 g (25 mmol) of NCO, 5.51 g (25 mmol) of Ada, 70.0 mg (0.4 mmol) of AIBN, 0.35 g (1.0 mmol) of CPTC, and 80 g of dry toluene were added to a 300 mL round-bottom flask. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an oil bath at 80°C. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (18.5 g, yield 93%) of the nonlinear optically active copolymer. The polymerization ratio of CM, Ada, and NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the ratio of CM:Ada:NCO was 50:25:25 mol %, which was the same as the monomer charging ratio.

[0059] (2) Production of Nonlinear Optically Active Copolymer 10.0 g of the obtained precursor polymer (containing approximately 13.2 mmol of isocyanate groups) was charged into a flask with 6.67 g of nonlinear optical compound (1) [EO-1] (40% by mass, 11.4 mmol, based on the total amount of precursor polymer and nonlinear optical compound (1)), and 250 g of dry THF was added. The mixture was stirred to achieve a uniform solution. 0.5 g of DBTDL (5% by mass based on the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxyl groups of the EO dye. When the peak of unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 15.3 g of the target nonlinear optically active copolymer EOP-CA-40 having a repeating unit represented by the following formula in a yield of about 89%.

[0060] Example 8 Production of Nonlinear Optically Active Copolymer (EOP-C-50) (1) Production of Precursor Polymer Into a 300 mL round-bottom flask were added 5.38 g (30 mmol) of CM, 4.65 g (30 mmol) of NCO, 39.4 mg (0.24 mmol) of AIBN, 20.7 mg (0.6 mmol) of CPTC, and 40 g of dry toluene. The mixture was thoroughly bubbled with nitrogen and then stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an oil bath at 80°C. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (10.2 g, yield 91%) of the nonlinear optically active copolymer. The polymerization ratio of CM to CM in the precursor polymer was １ The proton ratio of H NMR revealed that the CM:NCO ratio was 50:50 mol%, which was the same as the monomer charging ratio.

[0061] (2) Production of Nonlinear Optically Active Copolymer 8.0 g of the obtained precursor polymer (containing approximately 23.4 mmol of isocyanate groups) was charged into a flask with 8.0 g of nonlinear optical compound (2) [EO-2] (charge amount relative to the total amount of precursor polymer and nonlinear optical compound (2): 50% by mass, 16.8 mmol), and 500 g of dry THF was added and stirred to achieve a uniform solution. 0.4 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (2). When the peak of the unreacted nonlinear optical compound (2) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 13.2 g of the target nonlinear optically active copolymer EOP-C-50 having a repeating unit represented by the following formula in a yield of about 78%.

[0062] Example 9: Preparation of Nonlinear Optically Active Copolymer (EOP-CNe-50) (1) Preparation of Precursor Polymer: 5.38 g (30 mmol) of CM, 5.97 g (30 mmol) of Neg, 39.4 mg (0.24 mmol) of AIBN, 20.7 mg (0.6 mmol) of CPTC, and 50 g of dry toluene were added to a 200 mL round-bottom flask, and the mixture was thoroughly bubbled with nitrogen and stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (10.2 g, 90% yield) of the nonlinear optically active copolymer. The polymerization ratio of CM to Neg in the precursor polymer was: １ The proton ratio of H NMR revealed that the CM:Neg ratio was 50:50 mol %, which was the same as the monomer charging ratio.

[0063] (2) Production of Nonlinear Optically Active Copolymer 8.0 g of the obtained precursor polymer (containing approximately 21.1 mmol of isocyanate groups) was charged into a flask with 8.0 g of nonlinear optical compound (2) [EO-2] (charge amount relative to the total amount of precursor polymer and nonlinear optical compound (2): 50% by mass, 16.8 mmol), and 500 g of dry THF was added and stirred to achieve a uniform solution. 0.4 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (2). When the peak of the unreacted nonlinear optical compound (2) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 12.4 g of the target nonlinear optically active copolymer EOP-CNe-50 having a repeating unit represented by the following formula in a yield of about 77%.

[0064] Example 10: Preparation of Nonlinear Optically Active Copolymer (EOP-CANe-50) (1) Preparation of Precursor Polymer In a 200 mL round-bottom flask, 5.38 g (30 mmol) of CM, 3.59 g (18 mmol) of Neg, 2.64 g (12 mmol) of Ada, 39.4 mg (0.24 mmol) of AIBN, and 20.7 mg (0.6 mmol) of CPTC were added to 50 g of dry toluene. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (11.1 g, 90% yield) of the nonlinear optically active copolymer. The polymerization ratio of CM, Neg, and Ada in the precursor polymer was: １ The proton ratio of H NMR was found to be CM:Neg:Ada=50:30:20 mol %, which was the same as the monomer charging ratio.

[0065] (2) Production of Nonlinear Optically Active Copolymer 8.0 g of the obtained precursor polymer (containing approximately 12.4 mmol of isocyanate groups) was charged into a flask with 5.3 g of nonlinear optical compound (2) [EO-2] (charge amount relative to the total amount of precursor polymer and nonlinear optical compound (2): 40% by mass, 11.2 mmol), and 500 g of dry THF was added and stirred to achieve a uniform solution. 0.4 g of DBTDL (5% by mass relative to the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (2). When the peak of the unreacted nonlinear optical compound (2) disappeared or no longer decreased in GPC, methanol was added to eliminate the unreacted isocyanate groups. After completion of the reaction, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 14.4 g of the target nonlinear optically active copolymer EOP-CANe-50 having a repeating unit represented by the following formula in a yield of about 87%.

[0066] Example 11: Preparation of Nonlinear Optically Active Polymer (EOP-P31-40) (1) Preparation of Precursor Polymer: To a 200 mL round-bottom flask were added 5.19 g (30 mmol) of PM, 1.55 g (10 mmol) of NCO, 26.3 mg (0.16 mmol) of the polymerization initiator AIBN, 0.138 g (0.4 mmol) of the chain transfer agent CPTC, and 30 g of CPN. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (6.3 g, yield 92%) of the nonlinear optically active copolymer. The polymerization ratio of PM to NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the PM:NCO ratio was 75:25 mol %, which was the same as the monomer charging ratio.

[0067] (2) Production of Nonlinear Optically Active Copolymer 2.0 g of the obtained precursor polymer (containing approximately 3.0 mmol of isocyanate groups) and 1.33 g of the nonlinear optical compound (1) [EO-1] (40% by mass, 2.3 mmol, based on the total amount of the precursor polymer and the nonlinear optical compound (1)) were charged into a flask. Dry THF was added to the mixture in an amount 25 times the mass of the solid content, and the mixture was stirred to achieve a uniform solution. 0.1 g of DBTDL (5% by mass based on the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (1). Methanol was added to eliminate the unreacted isocyanate groups when the peak of the unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC. After the reaction was completed, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 2.97 g of the target nonlinear optically active copolymer EOP-P31-40 having a repeating unit represented by the following formula in a yield of about 90%.

[0068] Example 12: Preparation of Nonlinear Optically Active Polymer (EOP-P13-50) (1) Preparation of Precursor Polymer: To a 200 mL round-bottom flask were added 1.73 g (10 mmol) of PM, 4.65 g (30 mmol) of NCO, 26.3 mg (0.16 mmol) of the polymerization initiator AIBN, 0.138 g (0.4 mmol) of the chain transfer agent CPTC, and 30 g of CPN. After sufficient nitrogen bubbling, the mixture was stirred to obtain a homogeneous reaction solution. The polymerization reaction was carried out overnight in an 80°C oil bath. After confirming the synthesis of the polymer by GPC, the reaction solution was cooled to room temperature, and the polymer was precipitated using dry hexane. The precipitate was collected on a filter and dried under reduced pressure to obtain a precursor polymer (5.9 g, 89% yield) of the nonlinear optically active copolymer. The polymerization ratio of PM to NCO in the precursor polymer was: １ The proton ratio of H NMR revealed that the PM:NCO ratio was 25:75 mol %, which was the same as the monomer charging ratio.

[0069] (2) Production of Nonlinear Optically Active Copolymer 2.0 g of the obtained precursor polymer (containing approximately 9.4 mmol of isocyanate groups) and 2.0 g of the nonlinear optical compound (1) [EO-1] (50% by mass, 3.4 mmol, based on the total amount of the precursor polymer and the nonlinear optical compound (1)) were charged into a flask. Dry THF was added to the mixture in an amount 25 times the mass of the solid content, and the mixture was stirred to achieve a uniform solution. 0.1 g of DBTDL (5% by mass based on the precursor polymer) was then added. The mixture was stirred at room temperature under an inert atmosphere to cause a condensation reaction between the isocyanate groups of the precursor polymer and the hydroxy groups of the nonlinear optical compound (1). Methanol was added to eliminate the unreacted isocyanate groups when the peak of the unreacted nonlinear optical compound (1) disappeared or no longer decreased in GPC. After the reaction was completed, the THF was concentrated, and the polymer was precipitated with a large amount of methanol. The precipitate was collected on a filter and thoroughly dried to obtain 3.4 g of the target nonlinear optically active copolymer EOP-P31-20 having a repeating unit represented by the following formula in a yield of about 85%.

[0070] Table 1 below shows the types and molar ratios of the monomer components used in the preparation of the precursor polymers for the nonlinear optically active copolymers prepared in the examples and comparative examples, as well as the types of nonlinear optical compounds and the amounts of the nonlinear optical compounds charged. The amount of the nonlinear optical compound refers to the amount (mass%) of the nonlinear optical compound charged relative to the total amount (mass) of the precursor polymer and the nonlinear optical compound. Table 1 also shows the content of the structure derived from the nonlinear optical compound in the copolymer, determined from the maximum absorption intensity in the ultraviolet-visible-near-infrared absorption spectrum of the nonlinear optically active copolymer, as the introduction rate [mass%] of the nonlinear optical compound in the nonlinear optically active copolymer, and the reaction conversion rate of the nonlinear optical compound, expressed as the ratio [%] of the introduction rate [%] of the nonlinear optical compound in the nonlinear optically active copolymer to the amount [%] of the nonlinear optical compound charged. Table 1 also shows the glass transition temperatures of each of the prepared nonlinear optically active copolymers.

[0071]

[0072] As shown in Table 1, the nonlinear optically active copolymers obtained in Examples 1 to 12 all had high glass transition points (Tg) of 160°C or higher, regardless of whether various N-substituted maleimides and NCO-containing (meth)acrylic acid derivatives were used as monomer components of the precursor polymer, or whether other monomers were used. Among these, Examples 1 to 5, 8 to 9, and 12 achieved a high incorporation rate of more than 40% and a high glass transition point, regardless of the type of nonlinear optical compound. On the other hand, the comparative example had a high glass transition point when the incorporation rate of the nonlinear optical compound was as low as less than 25% (Comparative Example 2), but when the incorporation rate of the nonlinear optical compound exceeded 40%, the glass transition point fell below 140°C, making it impossible to achieve both a high glass transition point and an increased amount of nonlinear optically active moiety incorporated.

Claims

1. A nonlinear optically active copolymer comprising, in the same molecule, at least a repeating unit A represented by formula [1] and a repeating unit B represented by formula [2] having a nonlinear optically active moiety. 【Chemical 1】 (In the formula, R １ represents an alkyl group having 1 to 6 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, a cycloalkyl group having 4 to 8 carbon atoms, an aliphatic bridged cyclic group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms, R ２ represents a hydrogen atom or a methyl group, L １ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may contain an ether bond and / or an ester bond, L ２ *-NHC(=O)O-, *-C(=O)NH- or *-C(=O)O- (* is L １ represents the bond end with Z represents an atomic group that exhibits nonlinear optical activity.

2. 2. The nonlinear optically active copolymer according to claim 1, wherein the repeating unit A represented by the formula [1] is contained in the same molecule in a proportion of 20 to 80 mol %.

3. Said L ２ *-NHC(=O)O-(* is L １ (represents the bond end with The nonlinear optically active copolymers described herein are:

4. The R １ 2. The nonlinear optically active copolymer of claim 1, wherein is an alkyl group having 1 to 3 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, a cycloalkyl group having 6 to 8 carbon atoms, an aliphatic bridged cyclic group having 8 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

5. 2. The nonlinear optically active copolymer according to claim 1, wherein Z is an atomic group having a furan ring group represented by formula [3]. 【Chemistry 2】 (In the formula, R １０ and R １１ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a haloalkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the black dot represents a bond to the remaining structure constituting the atomic group Z that exhibits nonlinear optical activity.

6. The Z is represented by the formula [4] or the formula [5] (in these chemical formulas, R ４ ~R ９ 6. The nonlinear optically active copolymer according to claim 5, wherein one hydrogen atom is removed from the group represented by the formula: 【Chemistry 3】 (In the formula, R ４ and R ５ each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted aryl group having 6 to 10 carbon atoms; R ６ ~R ９ 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 having 1 to 6 carbon atoms and / or a phenyl group, or a halogen atom; R １０ and R １１ each independently represents the same meaning as above, Ar represents a divalent aromatic group represented by formula [6] or formula [7]. 【Chemistry 4】 (In the formula, R １２ ~R １７ each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, or an optionally substituted aryl group having 6 to 10 carbon atoms.

7. The Z is represented by the formula [4] or [5] (in these chemical formulas, R ４ or R ５ 7. The nonlinear optically active copolymer according to claim 6, wherein one hydrogen atom is removed from the group represented by the formula:

8. 8. An organic nonlinear optical material comprising the nonlinear optically active copolymer according to claim 1 as a part of the material.

9. 8. An electro-optical element comprising a nonlinear optically active copolymer according to any one of claims 1 to 7.

10. An optical switching element comprising a nonlinear optically active copolymer according to any one of claims 1 to 7.

11. A varnish comprising the nonlinear optically active copolymer according to any one of claims 1 to 7.

12. A method for producing an organic nonlinear optical material, comprising the steps of: applying the varnish described in claim 11 onto the surface of a substrate or onto the outermost surface of a single layer or multiple layers laminated on the substrate to obtain a coating film; and applying an electric field to the coating film under heating to orient atomic groups in the coating film that exhibit nonlinear optical activity.

Images