JP6091232B2 - Initiator-modified nanorods and production method thereof, grafted nanorods and production method thereof, grafted nanorod-dispersed liquid crystal, grafted nanorod-dispersed liquid crystal alignment film, polarizing optical element, and cap agent-modified nanorod - Google Patents

Description

  The present invention relates to an initiator-modified nanorod and a production method thereof, a grafted nanorod and a production method thereof, a grafted nanorod-dispersed liquid crystal, a grafted nanorod-dispersed liquid crystal alignment film, a polarizing optical element, and a cap agent-modified nanorod.

  Conventionally, as a technique for orienting nanoparticles such as nanorods, a technique for dissolving or dispersing particles whose surface characteristics are modified in a liquid crystal matrix and orienting using the alignment characteristics of the liquid crystal matrix is known. Yes. For example, in Japanese Patent Application Laid-Open No. 2010-144032 (Patent Document 1), a nanorod such as zinc oxide coated with a fluid organic surfactant in a nematic liquid crystal as a host is used as a dopant as a nanorod formulation for a liquid crystal display. The formulation contained as is described. However, in the formulation described in Patent Document 1, since the orientation of the nanorods is uniquely governed by the orientation of the liquid crystal matrix, it is difficult to sufficiently control the orientation of the nanorods. In addition, such a method has a problem that it is difficult to control the alignment over a wide region because the liquid crystal may form a domain.

  Also, for example, in Japanese Patent Application Laid-Open No. 2006-291016 (Patent Document 2), metal nanorods in which liquid crystal compatible molecules are bonded to the surface by metal ion reduction or ligand exchange are dissolved or dispersed in a liquid crystal medium. A method is described. However, the types of nanorods and liquid crystal compatible molecules that can be used in the method described in Patent Document 2 are limited, and it is difficult to control the coating amount of each liquid crystal compatible molecule on the surface of the nanorods. For this reason, it has been difficult to sufficiently control the orientation of the nanorods.

  On the other hand, as a method for modifying the surface properties such as hydrophilicity and adhesiveness of the substrate surface, a method of polymerizing monomers starting from the substrate surface to form a polymer chain directly bonded to the substrate (grafting) is known. It has been. This method is attracting attention as a method for modifying a base material in which the bond between the base material and the polymer chain is strong and the type of the polymer chain can be selected regardless of the type of the base material. Moreover, in such a method, the method of adjusting the density of the polymer chain grafted is examined for the purpose of controlling the surface characteristics of the obtained base material to a higher degree.

For example, Zhiyi Bao and two others, Macromolecules, 2006, 39, p. In 5251-5258 (Non-Patent Document 1), when modifying the surface of a base material made of gold (Au) or silica (SiO ₂ ) with PMMA (poly methyl methacrylate) or PHEMA (poly (2-hydroxyethyl) methacrylate). The surface density of the ATRP initiator serving as the starting point of polymerization can be obtained by simultaneously coating the base material surface with an ATRP initiator (α-bromopropionyl bromide, etc.) and a compound having no polymerization initiating ability (α-methylpropionyl bromide, etc.). A method of controlling is described. Kenichi Nagase, 5 others, Langmuir, 2008, 24, p. In 511-517 (Non-patent Document 2), when the surface of silica beads is modified with PIAAm (poly (N-isopropylamide)), an ATRP initiator and a compound having no ability of initiating polymerization (Phenethyltrichlorosilane) are used on the surface of the silica beads. The method of controlling the surface density of the ATRP initiator by the action of a silane coupling agent containing) is described.

JP 2010-144032 A JP 2006-291016 A

Zhiyi Bao and two others, Macromolecules, 2006, 39, p. 5251-5258 Kenichi Nagase, 5 others, Langmuir, 2008, 24, p. 511-517

  However, the present inventors have found that nanorods may aggregate when the methods described in Non-Patent Documents 1 and 2 are applied to surface modification of nanoparticles such as nanorods. Furthermore, in the methods described in Non-Patent Documents 1 and 2, the initiator coating amount cannot be directly quantified and controlled, and it is difficult to highly control the amount of polymer to be grafted. The present inventors have found that it is still insufficient as a method for highly controlling the orientation by applying to surface modification.

  The present invention has been made in view of the above-described problems of the prior art, and is capable of highly controlling the initiator coating amount and capable of directly quantifying the initiator coating amount in a non-destructive manner. Nanorod production method, initiator modified nanorod obtained by the method and capable of highly controlling the density of polymer chains to be grafted, grafted nanorod obtained using the initiator modified nanorod, and method for producing the same An object of the present invention is to provide a grafted nanorod-dispersed liquid crystal, a grafted nanorod-dispersed liquid crystal alignment film, a polarizing optical element, and a cap agent-modified nanorod.

  As a result of intensive studies to achieve the above object, the present inventors have found that a part of the surface of the nanorod is bonded to a part of the surface of the nanorod having an average aspect ratio within a specific range. Obtaining a cap agent-modified nanorod having the cap agent bound thereto, by binding an initiator having a polymerization initiating group to the surface of the nanorod to which the cap agent is not bound, to the surface of the nanorod. It was found that the initiator coating amount can be controlled in the obtained initiator-modified nanorod by sequentially performing the step of obtaining the initiator-modified nanorod to which the initiator is bound. In addition, according to such a method, the coating amount of the initiator that is the starting point of polymerization can be directly quantified and controlled in a non-destructive manner, so that the density of polymer chains polymerized on the obtained initiator-modified nanorods can be increased. The present inventors have found that it is possible to control to the present, and have completed the present invention.

That is, the method for producing the initiator-modified nanorods of the present invention includes:
Obtaining a cap agent-modified nanorod in which the cap agent is bonded to a part of the surface of the nanorod by binding the cap agent to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more;
After the step of obtaining the capping agent-modified nanorod, the capping agent and the initiator are bound to the surface of the nanorod by binding an initiator having a polymerization initiator group to the surface of the nanorod that is not bound to the capping agent. Obtaining a modified initiator-modified nanorod;
It is characterized by including.

  As a method for producing the initiator-modified nanorod of the present invention, before the step of obtaining the cap agent-modified nanorod, the coupling agent is bonded to the surface of the nanorod by bonding the coupling agent to the surface of the nanorod. The method further includes a step of obtaining a coupling agent-modified nanorod, and the cap agent and the initiator are preferably bonded to the surface of the nanorod through the coupling agent.

Moreover, as a manufacturing method of the initiator modified nanorods of the present invention,
The coupling agent has a functional group A capable of binding to the surface of the nanorod, and a functional group B not binding to either the surface of the nanorod or the functional group A,
The cap agent has a functional group C1 capable of binding to the functional group B;
The initiator further has a functional group C2 capable of binding to the functional group B;
In the step of obtaining the coupling agent-modified nanorod, the coupling agent is bonded to the surface of the nanorod via the functional group A;
In the step of obtaining the cap agent-modified nanorod, the cap agent is bonded to the functional group B of a part of the coupling agent on the surface of the coupling agent-modified nanorod via the functional group C1;
In the step of obtaining the initiator-modified nanorod, it is more preferable that the initiator is bonded to the unreacted functional group B remaining on the coupling agent on the surface of the cap agent-modified nanorod via the functional group C2.

  Furthermore, in the method for producing initiator-modified nanorods of the present invention, the average diameter of the nanorods in the minor axis direction is preferably 1 to 100 nm, and the polymerization initiating group is a living radical polymerization initiating group. preferable.

The initiator-modified nanorod of the present invention is obtained by the method for producing an initiator-modified nanorod of the present invention. In the initiator-modified nanorod of the present invention, the coating amount of the initiator is preferably 0.3 to 1.0 nm ⁻² in terms of the number of molecules per 1 nm ² .

  Further, the method for producing a grafted nanorod of the present invention provides a grafted nanorod having a polymer chain grafted by polymerizing a polymerizable monomer starting from the polymerization initiation group of the initiator-modified nanorod of the present invention. It is characterized by this. Furthermore, the grafted nanorod of the present invention is obtained by the method for producing a grafted nanorod of the present invention.

  The grafted nanorod-dispersed liquid crystal of the present invention is characterized in that the grafted nanorod of the present invention is dispersed in a matrix containing a low-molecular liquid crystal compound. As the grafted nanorod-dispersed liquid crystal of the present invention, it is preferable that the low molecular liquid crystal compound and the polymer chain grafted to the grafted nanorod are both nematic or smectic in the liquid crystal state.

  Furthermore, the grafted nanorod-dispersed liquid crystal alignment film of the present invention is obtained by aligning the grafted nanorod-dispersed liquid crystal of the present invention. The polarizing optical element of the present invention is characterized by using the grafted nanorod-dispersed liquid crystal alignment film of the present invention.

  Further, the cap agent-modified nanorod of the present invention is a region where the cap agent is bonded to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more, and the cap agent is not bonded to the surface of the nanorod. It is characterized by having. In the cap agent-modified nanorod of the present invention, a coupling agent is bonded to the surface of the nanorod, the cap agent is bonded to the nanorod through the coupling agent, and the cap agent is bonded. It is preferable that the coupling agent is exposed in a region that is not.

  The reason why the above object is achieved by the present invention is not necessarily clear, but the present inventors speculate as follows. That is, in the method for producing an initiator-modified nanorod of the present invention, first, the coating with the initiator is performed after the coating with the capping agent. The amount can be controlled to a higher degree. Therefore, it is possible to highly control the density of polymer chains polymerized on the obtained initiator-modified nanorods. Further, since the coating amount can be quantified even without destruction, the control accuracy can be further improved. On the other hand, in the method in which the substrate surface is simultaneously coated with the initiator and the compound having no polymerization initiating ability as in the methods described in Non-Patent Documents 1 and 2, the coating amount of the initiator is determined from the charging ratio. As a method for highly controlling the density of polymer chains polymerized into nanorods, it can only be indirectly calculated or quantified by peeling off the coated compound, and cannot be accurately quantified nondestructively. It was insufficient.

  In addition, since the method for producing an initiator-modified nanorod of the present invention coats the cap agent and the initiator stepwise, the cap agent and the initiator can be freely selected, It is easy to optimize the reaction, and it is possible to obtain initiator-modified nanorods whose surface is uniformly coated with the initiator. On the other hand, in the conventional methods as described in Non-Patent Documents 1 and 2, since the substrate surface may not be uniformly coated with the initiator, polymerization inhibition may occur when the monomer is polymerized. In addition, when such a method is applied to the surface modification of a nanoparticle such as a nanorod, the present inventors infer that the nanorod may be aggregated due to an unmodified surface remaining.

  According to the present invention, the initiator coating amount can be highly controlled, and the initiator coating amount can be directly quantified in a non-destructive manner. Initiator-modified nanorods capable of highly controlling the density of polymer chains to be grafted, grafted nanorods obtained using the initiator-modified nanorods and methods for producing the same, grafted nanorod-dispersed liquid crystals, grafted nanorod-dispersed liquid crystal alignments It becomes possible to provide a film, a polarizing optical element, and a cap agent-modified nanorod.

  Furthermore, according to the present invention, it is possible to accurately determine and control the coating amount of the initiator that is the starting point of polymerization, and to highly control the amount of polymer chains grafted on the surface, The orientation of the nanorods can be highly controlled by adjusting the interaction between the grafted nanorods in the grafted nanorod-dispersed liquid crystal of the present invention and the low-molecular liquid crystals in the liquid crystal matrix.

It is a schematic diagram which shows suitable one Embodiment of the grafted nanorod obtained when the initiator coating amount in the initiator modification nanorod of this invention is 0.4 nm- ² . It is a schematic diagram which shows suitable one Embodiment of the grafted nanorod obtained when the initiator coating amount in the initiator modification nanorod of this invention is 0.6 nm- ² . It is a schematic diagram which shows suitable one Embodiment of the grafted nanorod obtained when the initiator coating amount in the initiator modification nanorod of this invention is 2.0 nm- ² . It is a conceptual diagram which shows suitable one Embodiment of the manufacturing method of the initiator modification nanorod of this invention. 6 is a conceptual diagram illustrating a method for producing an initiator-modified nanorod of Comparative Example 1. FIG. It is a graph which shows angle distribution in the orientation evaluation of the grafted nanorod dispersion | distribution liquid crystal aligning film obtained in Example 2, 4. 4 is a FE-SEM photograph of the grafted nanorod-dispersed liquid crystal alignment film obtained in Example 1. FIG. 4 is an FE-SEM photograph of the liquid crystal alignment film obtained in Reference Example 1. FIG.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

[Initiator-modified nanorods and production method thereof]
First, the initiator-modified nanorod of the present invention and the production method thereof will be described. The production method of the initiator-modified nanorods of the present invention is as follows:
Obtaining a cap agent-modified nanorod in which the cap agent is bonded to a part of the surface of the nanorod by binding the cap agent to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more;
After the step of obtaining the capping agent-modified nanorod, the capping agent and the initiator are bound to the surface of the nanorod by binding an initiator having a polymerization initiator group to the surface of the nanorod that is not bound to the capping agent. Obtaining a modified initiator-modified nanorod;
The initiator-modified nanorod of the present invention is obtained by the method for producing an initiator-modified nanorod of the present invention.

<Nanorod>
The nanorod according to the present invention is a rod-shaped nanoparticle having an average aspect ratio of 1.2 or more, and the rod-shaped refers to an anisotropic shape having a major axis and a minor axis. Examples of the shape include a rod shape, a linear shape, a plate shape, a cylindrical shape, an elliptical shape, and a spindle shape. When the shape of the nanorod is such a rod shape, the wavelength characteristics and the like of the liquid crystal can be controlled using the grafted nanorod obtained by using the obtained initiator-modified nanorod.

  In the present invention, the average aspect ratio needs to be 1.2 or more, and is preferably 1.2 to 15. When the average aspect ratio is less than the lower limit, when the obtained grafted nanorod is used in a polarizing optical element, the function of the alignment film as the polarizing optical element cannot be sufficiently exhibited. On the other hand, when the aspect ratio exceeds the upper limit, the orientation of the obtained grafted nanorods tends to be lowered.

  In the present invention, the average aspect ratio means an average value of the ratio of the length in the major axis direction to the diameter in the minor axis direction (length in the major axis direction / diameter in the minor axis direction). The length in the major axis direction is the maximum length, the diameter in the minor axis direction is the maximum diameter, and the average aspect ratio, the average length in the major axis direction, and the average diameter in the minor axis direction are arbitrary. These 20 or more nanorods can be measured with a transmission electron microscope or a scanning electron microscope, and the values can be averaged.

  Moreover, as a nanorod which concerns on this invention, it is preferable that the average diameter of a short axis direction is 1-100 nm, It is more preferable that it is 1-50 nm, It is more preferable that it is 5-20 nm, It is 7-15 nm It is particularly preferred. When the average diameter is less than the lower limit value, the obtained initiator-modified nanorods and grafted nanorods tend to aggregate, and when the upper limit value is exceeded, the liquid crystal alignment film or the like is included. It tends to reduce its transparency.

  Examples of the base material of the nanorod according to the present invention include metals such as gold, silver, copper, aluminum, zinc, tin, nickel, cobalt, platinum, titanium, tungsten, and zirconium; silica, zinc oxide, alumina, titania, and zirconia. And metal oxides such as iron oxide and tin oxide; high molecular compounds such as polystyrene, polymethyl methacrylate, and polycarbonate, which can be appropriately selected according to the purpose. Among these, metals and metal oxides are preferable from the viewpoint that the range in which the effect of orientation of the obtained grafted nanorods can be utilized is remarkably widened. As the nanorod according to the present invention, one of these nanorods may be used alone, or two or more nanorods made of different base materials may be used in combination. Furthermore, as such nanorods, commercially available ones may be used, and those prepared by a known method may be used as appropriate.

<Coupling agent>
As a method for producing the initiator-modified nanorod of the present invention, before the step of obtaining the cap agent-modified nanorod, the coupling agent is bonded to the surface of the nanorod by bonding the coupling agent to the surface of the nanorod. Preferably, the method further includes a step of obtaining a coupling agent-modified nanorod, and the cap agent and the initiator are each bonded to the nanorod via the coupling agent.

  Such a coupling agent has a functional group A capable of binding to the surface of the nanorod and a functional group B not bound to any of the surface of the nanorod and the functional group A. preferable. The functional group A and the functional group B may be one kind or two or more kinds in the coupling agent, respectively, or may be one or two or more. In the present invention, the surface of the nanorod can be covered with the functional group B by using such a coupling agent.

  The functional group A is a functional group capable of binding to the surface of the nanorod, and refers to a group having a strong interaction with the surface of the nanorod or capable of forming a chemical bond, A group capable of covalently bonding to the nanorod surface is preferred. Examples of such a functional group A include a thiol group, a sulfide group, an amino group, a thioisocyanide group, an isocyanide group, and a hydroxyl group when the nanorod surface is a metal. When the nanorod surface is a metal oxide, a monoalkoxysilyl group, a dialkoxysilyl group, a trialkoxysilyl group, a monoisocyanate silyl group, a diisocyanate silyl group, a triisocyanate silyl group, a monochlorosilyl group, Examples thereof include a dichlorosilyl group, a trichlorosilyl group, a dimethylsilylamino group, a hydroxyl group, a carboxyl group, and a phosphonylic acid group. Among these, an alkoxysilyl group such as a methoxysilyl group, an ethoxysilyl group, and an isopropyloxysilyl group is preferable. Moreover, when the nanorod surface is a polymer compound, examples thereof include a monoalkoxysilyl group, a dialkoxysilyl group, and a trialkoxysilyl group.

  The functional group B is a group that does not bind to the surface of the nanorod, that is, a group that does not have a strong interaction with the surface of the nanorod, does not chemically bond, and does not bind to the functional group A. . Further, it is a group capable of binding to the functional group C1 of the cap agent and the functional group C2 of the initiator used in the subsequent steps. Such a functional group B is not particularly limited, and depends on the nanorod, the functional group A, the functional group C1, and the functional group C2, but from the viewpoint that a bond can be generated under mild conditions in the subsequent steps. Examples thereof include an amino group, a hydroxyl group, a carboxyl group, a halogenated acyl group, a halogenated sulfonyl group, a thiol group, and an isocyanate group.

  Examples of coupling agents having such a functional group A and functional group B include thiol-based couplings such as 3-mercapto-1-propanol, 4-mercapto-1-butanol, and 5-mercapto-1-pentanol. Agents: 3-aminopropylmethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane (trimethoxy [3- (phenylamino) propyl] silane), 3-mercaptopropyltrimethoxysilane, Examples include silane coupling agents such as 3-isocyanatopropyltriethoxysilane, and one of these may be used alone, or two or more may be used in combination. A preferred coupling agent in the present invention depends on the nanorod, the functional group A, the functional group C1, and the functional group C2, and thus cannot be generally described. For example, the nanorod is made of zinc oxide. In the case where the initiator is a living radical polymerization initiator, a compound having a trialkoxysilyl group and an amino group is preferable. Specific examples of such a compound include 3-aminopropyltrimethoxysilane, 3- Examples include aminopropyltriethoxysilane and trimethoxy [3- (phenylamino) propyl] silane.

<Cap agent>
The cap agent according to the present invention is a compound capable of binding to the surface of the nanorod, and the binding may be direct binding to the nanorod surface or indirect binding to the surface-modified nanorod. May be. Examples of the surface modification method include modification with a surfactant and modification with the coupling agent. In the present invention, the cap agent tends to be bonded to the surface of the nanorod more firmly and easily. In view of the above, it is preferable that the surface of the nanorod is bonded with the coupling agent by modifying the surface of the nanorod.

  When directly binding to the nanorod, the cap agent preferably has a strong interaction with the surface of the nanorod or a group capable of forming a chemical bond. As such a group, the functional group mentioned as the functional group A in the said coupling agent is mentioned, for example.

  In the case of binding via the coupling agent, the cap agent preferably has a functional group C1 capable of binding to the functional group B. Moreover, it is preferable that it does not have any of the group which can couple | bond with the functional group C2 of the initiator used in a subsequent process, and the polymerization initiating group which has a polymerization initiating ability. The functional group C1 may be one kind or two or more kinds in the cap agent, or may be one or two or more. However, from the viewpoint of easy reaction control. , One per cap agent molecule. In the present invention, by using such a capping agent, it is possible to cover a part of the surface of the nanorod with a capping agent that does not react with the initiator (more preferably with a group that does not react with the functional group C2). Thus, the initiator coating amount can be controlled.

  The functional group C1 is not particularly limited. For example, when the functional group B is an amino group, examples thereof include a halogenated alkyl group, a carboxyl group, a halogenated acyl group, and a halogenated sulfonyl group. When the functional group B is a hydroxyl group, examples include a halogenated acyl group and a halogenated sulfonyl group. When the functional group B is a carboxyl group, examples include a hydroxyl group and an amino group. When the functional group B is a chlorocarbonyl group or a chlorosulfonyl group, examples thereof include a hydroxyl group, an amino group, and a phenyl group. When the functional group B is a thiol group, a vinyl group, (meta ) Acrylate group and the like, and when the functional group B is an isocyanate group, examples thereof include a hydroxyl group and an amino group.

  Examples of the capping agent having such a functional group C1 include 1-bromopropane, 1-bromobutane, 1-bromopentane, 1-bromohexane, benzyl bromide, acetic acid, propionic acid, acetyl chloride, 1,3-dibromo. Examples include propane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 4-bromobenzyl bromide, etc. Even if one of these is used alone, two or more are combined. May be used. Among these, from the viewpoint that nondestructive quantification by X-ray fluorescence analysis (XRF) can be performed, the capping agent according to the present invention is preferably a compound containing bromine. -Dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane, 1,6-dibromohexane, 4-bromobenzyl bromide are preferred.

<Initiator>
The initiator according to the present invention is a compound that has a polymerization initiating group having a polymerization initiating ability, can bind to the surface of the nanorod, and does not bind to the cap agent. The bond to the nanorod surface may be a direct bond to the nanorod surface or an indirect bond to the surface-modified nanorod. Examples of the surface modification method include modification with a surfactant and modification with the coupling agent. In the present invention, the initiator tends to be bonded to the surface of the nanorods more firmly and easily. In view of the above, it is preferable that the surface of the nanorod is bonded with the coupling agent by modifying the surface of the nanorod.

  In the case of directly bonding to the nanorod, the initiator preferably has a strong interaction with the surface of the nanorod or a group capable of forming a chemical bond. As such a group, the functional group mentioned as the functional group A in the said coupling agent is mentioned, for example.

  In the case of binding via the coupling agent, the initiator preferably has a functional group C2 capable of binding to the functional group B and the polymerization initiating group. The functional group C2 and the polymerization initiating group may be one kind or two or more kinds in the initiator, respectively, and each may be one or two or more. From the viewpoint that it is easy to control, it is preferable that there is one for each molecule of the initiator.

  The functional group C2 is not particularly limited, and examples thereof include the functional groups listed as the functional group C1 in the cap agent. Examples of the polymerization initiating group include a radical polymerization initiating group, an anionic polymerization initiating group, and a cationic polymerization initiating group. Among these, living radical polymerization is possible from the viewpoint that polymer polymerization with a narrow molecular weight distribution is possible. An initiating group is preferred. In addition, the living radical polymerization initiating group is not accompanied by generation of acid or base, and therefore has a tendency not to affect the shape of the nanorods. From the viewpoint of RAFT polymerization initiating group, NMP polymerization initiating group, ATRP polymerization initiating group. From the viewpoint that there are few restrictions on the type of monomer to be polymerized, an ATRP polymerization initiating group is more preferable. Examples of such an ATRP polymerization initiating group include an α-halogenocarboxyl group in the case of ATRP using an alkyl halide as a catalyst, and among these, from the viewpoint of reactivity, a bromoisobutyrate group Is preferred.

  Examples of the initiator having such a functional group C2 and a polymerization initiating group include, for example, 3-bromopropyl 2-bromoisobutyrate, 4-bromobutyl 2-bromoisobutyrate, etc. 2-bromoisobutyric acid esters having a linear alkyl group of -8 in the ester moiety; o- (bromomethyl) benzyl 2-bromoisobutyrate, m- (bromomethyl) benzyl 2-bromoisobutyrate, p- (bromomethyl) A benzene ring having a bromomethyl group, such as benzyl 2-bromoisobutyrate, (4- (bromomethyl) naphthalen-1-yl) methyl 2-bromoisobutyrate, and / or a naphthalene ring as a substituent. And 2-bromoisobutyric acid esters having 8 linear alkyl groups at the ester site. Be used one of al alone may be used in combination of two or more. Among these, as the initiator according to the present invention, the same element as the cap agent according to the present invention (more preferably bromine) is used from the viewpoint that nondestructive quantification can be performed by X-ray fluorescence analysis (XRF). Preferably, for example, p- (bromomethyl) benzyl 2-bromoisobutyrate is preferable.

  A preferred embodiment of each step of the method for producing an initiator-modified nanorod of the present invention will be described below with reference to the drawing (FIG. 2). In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

<Coupling agent modified nanorods>
In the initiator-modified nanorod manufacturing method of the present invention, first, it is preferable to obtain a coupling agent-modified nanorod in which the coupling agent is bonded to the surface of the nanorod by bonding a coupling agent to the surface of the nanorod. By reacting the coupling agent (coupling agent 2) having the functional group A and the functional group B on the surface of the nanorod (nanorod 1), the coupling agent is coupled to the surface of the nanorod via the functional group A. It is more preferable to obtain a coupling agent-modified nanorod (coupling agent-modified nanorod 5) to which is bonded. Such a reaction method depends on the coupling agent and cannot be generally described. For example, when the coupling agent is a silane coupling agent, the nanorods are dispersed in a solvent. Examples include a method in which the coupling agent is added to the prepared solution and reacted for 1 to 48 hours (preferably 2 to 12 hours) while performing ultrasonic treatment. Examples of the solvent include organic solvents such as ethanol, acetonitrile, methanol, and toluene, and mixed solvents of the organic solvent and water.

In the step of obtaining the coupling agent-modified nanorod, the mixing ratio of the nanorod and the coupling agent is preferably an amount that allows the coupling agent to cover the entire surface of the nanorod. The mixing ratio is more preferably 5 or more molecules per 1 nm ^{2 of} surface area, and more preferably 20 to 40 molecules. When the amount of the coupling agent is less than the lower limit value, the obtained initiator-modified nanorods and grafted nanorods tend to aggregate, and on the other hand, even if a coupling agent is used exceeding the upper limit value, Since the nanorod surface is not coated, it is economically disadvantageous.

  Moreover, in the coupling agent modification nanorod surface obtained, it is preferable that the ratio of the coupling agent coating amount (mass in terms of organic matter) to the total weight of the coupling agent modification nanorod is 0.01 to 0.1. More preferably, it is -0.06. When the ratio of the coupling agent coating amount is less than the lower limit value, the initiator cannot be sufficiently coated in the subsequent step, and the density of polymer chains grafted to the obtained initiator-modified nanorods is sufficiently controlled. On the other hand, when the above upper limit is exceeded, the initiator coating amount in the resulting initiator-modified nanorods decreases, and the density of polymer chains to be grafted decreases, and the dispersion of the grafted nanorods Tend to decrease the property and orientation.

In the present invention, the ratio (W2) of the coupling agent coating amount (the mass in terms of organic matter) to the total weight of the coupling agent-modified nanorod can be determined by thermogravimetric analysis (TG). Then, 20 mg of the obtained coupling agent-modified nanorod was placed in a platinum measuring pan and heated to 900 ° C. at a temperature rising rate of 10 ° C./min in a mixed atmosphere where the flow rates of air and nitrogen were both 200 mL / min. To do. Next, the mass (mass of ash) when reaching 900 ° C. is measured to determine the ratio (w2) of the mass of ash to the total mass before heating, and the following formula:
W2 = 1-w2- {w2 × (1-w1) ÷ w1}
(W1 represents the proportion of ash in the nanorods.)
Can be calculated.

<Cap agent modified nanorods>
In the initiator-modified nanorod manufacturing method of the present invention, a cap agent-modified nanorod in which the cap agent is bonded to a part of the surface of the nanorod is obtained by binding a cap agent to a part of the surface of the nanorod. In the step of obtaining the cap agent-modified nanorod, the coupling agent-modified nanorod (coupling agent-modified nanorod 5) is reacted with the cap agent (cap agent 3) having the functional group C1 on the surface thereof. It is preferable to obtain a cap agent-modified nanorod (cap agent-modified nanorod 6) in which the cap agent is bonded to a partial functional group B of the agent via the functional group C1. In FIG. 2, D represents a group that is not bonded to any one of the functional group B, the functional group C2, and the polymerization initiating group. Such a reaction method depends on the functional group B and the functional group C1, and thus cannot be generally described. For example, the cap is added to a solution in which the coupling agent-modified nanorod is dispersed in a solvent. The method of making it react for 1 to 48 hours (preferably 2 to 12 hours), adding an agent and performing ultrasonic treatment is mentioned. In addition, as said solvent, the thing similar to what was mentioned in preparation of the above-mentioned coupling agent modification nanorod is mentioned.

  In the present invention, by adjusting the mixing ratio of the nanorod or the coupling agent-modified nanorod and the cap agent in the step of obtaining the cap agent-modified nanorod, an initiator-modified nanorod having a target initiator coating amount is obtained. be able to. The mixing ratio depends on the target initiator coating amount, but when the coupling agent-modified nanorod is used, the grafted nanorod obtained by grafting the polymer chain to the obtained initiator-modified nanorod is liquid crystal. From the viewpoint that the grafted nanorods can be more uniformly oriented when dispersed in a matrix, the molar ratio of the functional group B in the coupling agent-modified nanorod and the functional group C1 in the cap agent. The number of moles of functional group B / number of moles of functional group C1 is preferably 0.5 to 2.0, more preferably 0.7 to 1.5. When the molar ratio is less than the lower limit value, the initiator coating amount is excessively increased, and the density of the polymer chain is increased to cause steric hindrance, so that it is difficult to control the orientation of the grafted nanorods. On the other hand, when the upper limit is exceeded, the density of the polymer chain decreases and the grafted nanorods tend to aggregate. In this case, since the molar ratio is smaller than the theoretical ratio, the unreacted functional group B that can react with the functional group C2 remains even if the molar ratio is 1 or less. To do.

Further, in the obtained cap agent-modified nanorod, the ratio of the coating amount of the cap agent and the coupling agent (the mass in terms of organic matter) to the total weight of the coupling agent-modified nanorod is preferably 0.05 to 0.13, It is more preferable that it is 0.07-0.1. When the ratio is within such a range, the amount of capping agent coating on the capping agent-modified nanorod is 1.0 to 3.0 nm ⁻² in terms of surface modification density (number of molecules of capping agent per 1 nm ^{2 of} surface area). Preferably 1.5-2. nm ^-2 . If the cap coating amount is less than the lower limit, the initiator coating amount to be coated in the subsequent step becomes too large, and the density of polymer chains to be grafted increases, resulting in steric hindrance. On the other hand, when the upper limit is exceeded, the density of the polymer chains decreases and the grafted nanorods tend to aggregate.

In the present invention, the ratio (W3) of the cap agent and coupling agent coating amount (mass in terms of organic matter) to the total weight of the cap agent-modified nanorod can be determined by thermogravimetric analysis (TG), specifically First, 20 mg of the obtained cap agent-modified nanorod was put in a platinum measuring pan, and the mixed gas atmosphere and air flow rates were both 200 mL / min up to 900 ° C. at a heating rate of 10 ° C./min. Heat. Next, the mass (mass of ash) of the sample when it reached 900 ° C. was measured to determine the ratio (w3) of the mass of the ash to the total mass before heating.
W3 = 1-w3- {w3 × (1-w1) ÷ w1}
(W1 represents the proportion of ash in the nanorods.)
Can be calculated.

Further, in the present invention, the cap agent coating amount refers to the number of molecules of the cap agent per 1 nm ² of the cap agent-modified nanorod surface (surface modification density of the cap agent), and the amount of organic substance by the thermogravimetric analysis (TG). Can be determined based on Specifically, the ratio of organic matter to inorganic matter in each sample is expressed by the following formula:
Ratio of organic substance to inorganic substance in coupling agent-modified nanorod (R2):
R2 = W2 × w1 ÷ w2
Ratio of organic substance to inorganic substance in cap agent-modified nanorod (R3):
R3 = W3 × w1 ÷ w3
From these, the cap agent coating amount (surface modification density) per 1 nm ² of the surface of the cap agent-modified nanorod is calculated from the following formula:
Cap agent coating amount [nm ⁻² ] = (R ₃ −R 2) × X _c ÷ (1−Y × R 2)
{Wherein X _c is the following formula:
_{X c = {N A × D} × r × l × 10 -21} ÷ (M c × 2 × (1 + r))
(N _A represents Avogadro's constant, D is shows the density of the nanorods [g / cm ^3], r represents the average radius of the nanorods, l denotes the average length of the nanorods, the molecular weight of M _c is capping agent Show.)
Y is represented by the following formula:
Y = Expression amount of inorganic substance in coupling agent / molecular weight of coupling agent. }
Can be calculated and obtained.

  By the step of obtaining such a cap agent-modified nanorod, the cap agent is modified so that the cap agent is bonded to a part of the surface of the nanorod and the surface of the nanorod is not bonded to the cap agent. A coupling agent is bonded to the surface of the nanorod, preferably the nanorod, the cap agent is bonded to the nanorod through the coupling agent, and the cap agent is not bonded to the region. Cap agent-modified nanorods in which the coupling agent is exposed can be obtained.

<Initiator-modified nanorods>
In the initiator-modified nanorod manufacturing method of the present invention, the cap agent and the initiator are then attached to the surface of the nanorod by binding an initiator having a polymerization initiator group to the surface of the nanorod that is not bound to the cap agent. An initiator-modified nanorod with an agent attached is obtained. In the step of obtaining the initiator-modified nanorod, an initiator (initiator 4) having the functional group C2 and the polymerization initiator group (polymerization initiator group E) on the surface of the cap agent-modified nanorod (cap agent-modified nanorod 6). It is preferable to obtain an initiator-modified nanorod (initiator-modified nanorod 7) in which the initiator is bonded to the unreacted functional group B remaining in the coupling agent via the functional group C2. Such a reaction method depends on the functional group B and the functional group C2, and thus cannot be generally described. For example, the initiator is dissolved in a solution in which the cap agent-modified nanorod is dispersed in a solvent. And reacting for 1 to 48 hours (preferably 2 to 12 hours) with sonication. Examples of the solvent include the same solvents as those mentioned in the preparation of the coupling agent-modified nanorod.

  In the step of obtaining the initiator-modified nanorod, the mixing ratio of the capping agent-modified nanorod and the initiator is set so that a part of the surface of the nanorod is covered with the cap agent in the previous step. A mixing ratio that allows the initiator to cover the surface to which the cap agent is not bonded (preferably, because the number of the functional groups B that can react with the functional group C2 in the previous step is adjusted by the cap agent. Any unreacted functional group B remaining in the coupling agent can be reacted (more preferably, a mixing ratio at which all can react).

Further, in the initiator-modified nanorods obtained, when the grafted nanorods obtained by grafting polymer chains are dispersed in a liquid crystal matrix, the grafted nanorods can be more uniformly oriented. from the viewpoint, the initiator coverages, the surface-modified density (number of molecules of the surface area of 1 nm ² per initiator) is preferably 0.3～1.0Nm ^-2, in 0.3～0.8Nm ^-2 More preferably. When the initiator coating amount is less than the lower limit value, the grafted nanorods obtained by decreasing the density of the polymer chain tend to aggregate. On the other hand, when the upper limit value is exceeded, the polymer chain has a tendency to aggregate. Since the density increases and steric hindrance occurs, it tends to be difficult to control the orientation of the grafted nanorods.

In the present invention, the initiator coating amount in the initiator-modified nanorod means the number of initiator molecules per 1 nm ^{2 of the} initiator-modified nanorod surface (surface modification density of the initiator), and thermogravimetric analysis (TG). Can be obtained based on the amount of organic substance. Specifically, first, 20 mg of the obtained initiator-modified nanorod was placed in a platinum measurement pan, and the temperature increase rate was 10 ° C./min in a mixed atmosphere where the flow rates of air and nitrogen were both 200 mL / min. To 900 ° C., and the mass (mass ash) when the temperature reaches 900 ° C. is measured to determine the ratio (w4) of the ash mass to the total mass before heating. Then the following formula:
W4 = 1-w4- {w4 × (1-w1) ÷ w1}
(W1 represents the proportion of ash in the nanorods.)
The ratio (W4) of the cap agent, the coupling agent, and the initiator coating amount (mass in terms of organic matter) to the total weight of the initiator-modified nanorod is obtained. Next, the ratio of organic matter to inorganic matter (R4) in the initiator-modified nanorods is represented by the following formula:
R4 = W4 × w1 ÷ w4
Calculated, which from the above-described R2 and R3, the following initiator coverage at the surface 1nm per ^second initiator modified nanorods (surface modification density) formula by:
Initiator coverage (TG) [nm ⁻² ] = (R 4 −R 3) × X _s ÷ (1−Y × R 2)
{Wherein X _s is the following formula:
_{X s = {N A × D} × r × l × 10 -21} ÷ (M s × 2 × (1 + r))
_(N A, D, r and l are as described above, respectively, _{M s} represents the molecular weight of the initiator.)
Y is as described above. )
It is represented by }
Can be calculated and obtained.

In addition, the method for producing an initiator-modified nanorod of the present invention coats the cap agent and the initiator stepwise, and the cap agent and the initiator can be freely selected. It is possible to design in accordance with the analysis method, and it is possible to quantify the initiator coating amount in the obtained initiator-modified nanorods with high accuracy in a non-destructive manner. As such a non-destructive quantification method, for example, a method of performing fluorescent X-ray analysis (XRF) using a compound containing a common element (Z) such as bromine as the cap agent and the initiator may be mentioned. It is done. Specifically, fluorescent X-ray analysis (XRF) (trade name: ZSX Primus II, manufactured by Rigaku Corporation) is performed on the obtained cap agent-modified nanorods and initiator-modified nanorods, and the start in terms of organic matter in the initiator-modified nanorods The coating amount (XRF) of the agent is expressed by the following formula:
Initiator coverage ^{(XRF) [nm -2] =} {m (s) -m (c)} × {N A × D × r × l × 10 -21 ÷ (M s × 2 × (1 + r))}
(In the above formula, m (s) is an initiator-modified nanorod, and m (c) is a cap-agent-modified nanorod, respectively:
m = analyzed value of Z ÷ analyzed value of nanorod × molecular weight of nanorod ÷ molecular weight of Z. N _A , D, r, l and M _s are as described above. )
Calculated by

Thus, in the method for producing initiator-modified nanorods of the present invention, the amount of initiator coating that is the starting point of polymerization can be directly quantified nondestructively, so that the amount can be highly controlled, It becomes possible to control the amount of polymer chains grafted on the surface. For example, FIG. 1A to FIG. 1C show the preferred grafted nanorods obtained when the initiator coating amounts in the initiator-modified nanorods of the present invention are 0.4, 0.6, and 2.0 nm ⁻² , respectively. Although the schematic diagram showing one embodiment is shown, it is possible to control the density of polymer chains to be grafted by adjusting the initiator coating amount.

[Grafted nanorods and production method thereof]
Next, the grafted nanorod of the present invention and the production method thereof will be described. The method for producing the grafted nanorod of the present invention comprises:
By polymerizing a polymerizable monomer starting from the polymerization initiation group of the initiator-modified nanorod of the present invention, a grafted nanorod having a polymer chain grafted thereon is obtained. It is obtained by the method for producing grafted nanorods of the present invention. In the method for producing grafted nanorods of the present invention, the initiator-modified nanorods of the present invention, which can control the initiator coating amount to a high degree, are used, so that the density of polymer chains to be grafted can be controlled to a high degree. it can.

<Polymerizable monomer, polymer chain>
The polymerizable monomer according to the present invention is not particularly limited as long as it has a group capable of being polymerized starting from the polymerization initiation group. Examples of such groups include methacrylate groups, acrylate groups, styryl groups, α-methylstyryl groups, acrylamide groups, methacrylamide groups, and vinylamide groups. In addition, as the polymerizable monomer according to the present invention, when the obtained grafted nanorods are aligned in the liquid crystal, a polymer chain having better interaction with the low-molecular liquid crystal compound can be obtained. A compound having a liquid crystalline mesogenic structure is preferable from the viewpoint that it can be more uniformly aligned in a wide region.

Examples of the liquid crystalline mesogenic structure include the following formula:
_{^{- [S 1] a - [}} M 1 - [S 2] b] b '- [M 2 - [S 3] c] c' - [M 3 - [S 4] d] d '-S 5 -
A mesogenic structure represented by In the above formula, M ¹ , M ² and M ³ are each independently an unsubstituted or substituted aromatic group, an unsubstituted or substituted alicyclic group, an unsubstituted or substituted heterocyclic group, and mixtures thereof. Indicates the divalent group selected. Examples of the substituent group, thiol, amide, hydroxy _(C 1 ~C ₁₈₎ alkyl, isocyanato _(C 1 ~C ₁₈₎ alkyl, acryloyloxy, acryloyloxy _(C 1 ~C ₁₈₎ alkyl, _halogen, C 1 -C ₁₈ alkoxy, poly (C ₁ -C ₁₈ alkoxy), amino, amino (C ₁ -C ₁₈ ) alkylene, C ₁ -C ₁₈ alkylamino, di- (C ₁ -C ₁₈ ) alkylamino, C ₁ -C _{18 alkyl,} C 2 _{-C 18 alkenes,} C 2 _{-C 18 alkyne,} C 1 _{-C 18} alkyl _(C 1 ~C _{18) alkoxy,} C 1 _{-C 18 alkoxycarbonyl,} C 1 _{-C 18 alkylcarbonyl, C} 1 ~ C ₁₈ alkyl carbonate, aryl carbonate, perfluoro (C ₁ -C ₁₈ ) alkylamino, Di- (perfluoro (C ₁ -C ₁₈ ) alkyl) amino, C ₁ -C ₁₈ acetyl, C ₃ -C ₁₀ cycloalkyl, C ₃ -C ₁₀ cycloalkoxy, isocyanato, amide, cyano, nitro; cyano, halo, or C ₁ -C ₁₈ are polysubstituted with mono-substituted with are or halo alkoxy include C ₁ -C ₁₈ alkyl group linear or branched.

  Further, in the above formula, a, b, c and d each independently represent an integer of 0 to 20, and b ', c' and d 'each independently represent an integer of 0 to 4. However, the sum (b ′ + c ′ + d ′) of b ′, c ′ and d ′ is 1 or more.

In the above formula, S ¹ , S ² , S ³ _, S ⁴ and S ⁵ are each independently
_{[A] - (CH 2)} e -, - (CF 2) f -, - Si (CH 2) e -, and _{- (Si (CH 3) 2} O) h - in either formula selected from Groups represented by the above (e is independently an integer of 1-20, and f is independently an integer of 1-16),
[B] -N (Z)-, -C (Z) = C (Z)-, -C (Z) = N-, -C (Z ') _2- C (Z') _2- A group represented by any formula (Z is independently selected from hydrogen, C ₁ -C ₆ alkyl, cycloalkyl and aryl, and Z ′ is independently C ₁ -C ₆ alkyl, one selected from cycloalkyl and aryl.), and,
[C] —O—, —C (O) —, —O—C (O) —, —C≡C—, —N═N—, —S—, —S (O) —, —S (O ) (O) -, - ( O) S (O) O -, - from O (O) S (O) groups and linear or branched represented by _O-C 1 _{-C 24} alkylene residue one selected (the C ₁ -C ₂₄ alkylene residue is unsubstituted or is monosubstituted by cyano or halo, are polysubstituted by halo.)
A spacer group selected from However, when two or more spacer groups containing heteroatoms are linked, the spacer groups are linked so that the heteroatoms are not directly linked to each other. Also, when S ¹ and S ⁵ are linked to another group, they are linked so that the heteroatoms are not directly linked to each other.

  The polymer chain according to the present invention is a chain formed by polymerizing the polymerizable monomer, and is bonded to the initiator via the polymerization initiating group. As such a polymer chain, when the obtained grafted nanorods are aligned in the liquid crystal, the interaction with the low-molecular liquid crystal compound becomes better, and the grafted nanorods can be aligned more uniformly in a wide region. From the viewpoint of tending, it is preferable to exhibit a nematic liquid crystal. Examples of monomers capable of forming such a polymer chain include 2- (4-methoxybiphenyl-4′-yloxy) ethyl methacrylate, 4- (4-methoxybiphenyl-4′-yloxy) butyl methacrylate, 4- Methoxyphenyl 4- (4-methacryloyl) butoxybenzoate, 4-methoxyphenyl 4- (6-methacryloyl) hexyloxybenzoate, 4- (6-methacryloyl) hexyloxycinnamic acid, 4 '-(4-methoxycinnamoyl ) -4-phenylphenoxyethyl methacrylate, 4 ′-(4-methoxycinnamoyl) -4-phenylphenoxyhexyl methacrylate, and the like. One of these may be used alone, or two or more may be used in combination. May be.

  As the amount of the monomer and the polymerization conditions in such a method for producing a grafted nanorod, a known method can be adopted as appropriate, and a known catalyst and / or solvent can be appropriately used according to the polymerization initiating group. . Further, the amount of polymer chain in the grafted nanorods obtained by such a production method is not particularly limited and can be appropriately adjusted according to the purpose. However, the mass ratio of carbon to the whole grafted nanorods (degree of grafting) ) Is preferably 15 to 90% by mass in terms of carbon mass, more preferably 20 to 60% by mass, and even more preferably 40 to 60% by mass. . When the degree of grafting is less than the lower limit value, the grafted nanorods tend to aggregate. On the other hand, when the degree of grafting exceeds the upper limit value, a low molecular liquid crystal is obtained when the grafted nanorods are dispersed in a liquid crystal matrix. The orientation due to the interaction with the compound tends to be inhibited.

The degree of grafting (C _TG ) can be determined by thermogravimetric analysis (TG). Specifically, first, 20 mg of the obtained grafted nanorods was put in a platinum measurement pan, and in a mixed atmosphere in which the flow rates of air and nitrogen were both 200 mL / min, the heating rate was 10 ° C./min. It heats to 900 degreeC, measures the mass (mass mass of ash) when it reaches 900 degreeC, and calculates | requires the ratio (w5) of the mass of the said ash content with respect to the total mass before a heating. Then the following formula:
W5 = 1-w5- {w5 × (1-w1) ÷ w1}
(W1 represents the proportion of ash in the nanorods.)
The ratio (W5) of the organic substance to the total weight of the grafted nanorods is obtained by the following formula, and the ratio (R5) of the organic substance to the inorganic substance in the grafted nanorods is expressed by the following formula:
R5 = W5 × w1 ÷ w5
Calculated by Next, the mass ratio of carbon in the coupling agent, cap agent, initiator, and polymerizable monomer is C2, C3, C4, and C5, respectively. From R5 and R2, R3, and R4, the following formula:
_CTG [mass%] = {{C2 * R2 + C3 * (R3-R2) + C4 * (R4-R3) + C5 * (R5-R4)} * W5} / R5
Can be calculated.

[Grafted nanorod-dispersed liquid crystal]
Next, the grafted nanorod-dispersed liquid crystal of the present invention will be described. The grafted nanorod-dispersed liquid crystal of the present invention is one in which the grafted nanorod of the present invention is dispersed in a matrix containing a low-molecular liquid crystal compound.

  Examples of the low-molecular liquid crystal compound according to the present invention include compounds exhibiting liquid crystallinity having a molecular weight of 250 or less, preferably in a liquid or liquid crystal state at room temperature, and preferably a compound having the mesogenic structure. . Furthermore, the low-molecular liquid crystal compound has the same liquid crystal phase as the polymer chain grafted to the grafted nanorods in the liquid crystal state from the viewpoint that the compatibility between the matrix and the grafted nanorods tends to be high. It is preferable that the low molecular liquid crystal compound and the polymer chain grafted to the grafted nanorod are both nematic.

  Specific examples of such a low-molecular liquid crystal compound include 4-cyano-4′-pentyloxybiphenyl (5OCB), 4-cyano-4′-hexyloxybiphenyl (6OCB), and 4-cyano-4′-. Heptyloxybiphenyl (7OCB), 4-cyano-4'-pentylbiphenyl (5CB), 4-cyano-4'-hexylbiphenyl (6CB), 4-cyano-4'-heptylbiphenyl (7CB), 4- (trans -4-pentylcyclohexyl) benzonitrile (5CHBN), 4- (trans-4-heptylcyclohexyl) benzonitrile (7CHBN), 5-hexyl-2- (4-hexylphenyl) pyrimidine, 4-pentylphenyl 4- (benzyl Oxy) benzoate, 4-butoxyphenyl 4-propylcyclohex Examples include sun carboxylate, 4-pentyloxyphenyl 4-propylcyclohexanecarboxylate, 4-ethoxyphenyl 4-butylcyclohexanecarboxylate, etc., and one of these may be used alone or in combination of two or more. May be. Among these, 5OCB, 6OCB, 7OCB, 5CB, 6CB, 7CB, and the like are preferable from the viewpoint of easy orientation at a viscosity of 200 mPa · s or less and the availability of materials.

  The matrix according to the present invention preferably contains the low-molecular liquid crystal compound and a solvent. Examples of the solvent include anisole, toluene, xylene, mesitylene, chlorobenzene, 1-methoxy-2-propanol, propylene glycol 1-monomethyl ether 2-acetate, and the like. Further, the matrix according to the present invention may further contain a surfactant or the like for the purpose of improving applicability when applied to a substrate within a range not impairing the effects of the present invention. Good.

  In the grafted nanorod-dispersed liquid crystal of the present invention, the content of the low-molecular liquid crystal compound is preferably 2% by mass or more, more preferably 3 to 20% by mass with respect to the entire grafted nanorod-dispersed liquid crystal. preferable. If the content of the low-molecular liquid crystal compound is less than the lower limit value, the uniformity of the degree of orientation of the grafted nanorods tends to deteriorate. On the other hand, if the content exceeds the upper limit value, the nanorod content decreases. When the grafted nanorod-dispersed liquid crystal obtained in the above is used for a polarizing optical element, the function of the polarizing optical element as an alignment body tends to be lowered.

  In the grafted nanorod-dispersed liquid crystal of the present invention, the content of the grafted nanorod is preferably 0.1 to 10% by mass with respect to the entire grafted nanorod-dispersed liquid crystal, and 0.5 to 5. More preferably, it is 0% by mass. When the content of the grafted nanorod is less than the lower limit, the function of the polarizing optical element as an alignment body when the grafted nanorod-dispersed liquid crystal obtained for reducing the nanorod content is used in the polarizing optical element. On the other hand, when the upper limit is exceeded, the fluidity is lowered and the orientation tends to be deteriorated.

  The method for dispersing the grafted nanorods in the matrix containing the low-molecular liquid crystal compound is not particularly limited. For example, the grafted nanorods are added to the solvent for 1 to 48 hours (preferably 2 to 12 hours) A method of dissolving the low-molecular liquid crystal compound in the solvent after dispersing by applying ultrasonic treatment is mentioned.

[Grafted nanorod-dispersed liquid crystal alignment film]
Next, the grafted nanorod-dispersed liquid crystal alignment film of the present invention will be described. The grafted nanorod-dispersed liquid crystal alignment film of the present invention is obtained by aligning the grafted nanorod-dispersed liquid crystal. In the present invention, the grafted nanorods can be aligned extremely uniformly by the interaction between the polymer chain of the grafted nanorods and the low-molecular liquid crystal compound.

  As a method for aligning the grafted nanorod-dispersed liquid crystal, a conventionally known method can be appropriately employed. For example, a method of applying the grafted nanorod-dispersed liquid crystal on a rubbing-treated substrate can be mentioned. In the present invention, from the viewpoint that the low-molecular liquid crystal compound is uniaxially aligned, the grafted nanorod-dispersed liquid crystal is applied onto an alignment film obtained by rubbing a polyimide resin film formed by applying on a substrate. Is preferred.

  In the grafted nanorod-dispersed liquid crystal alignment film obtained by such a method, the grafted nanorods are aligned with a very uniform degree of alignment, and the standard deviation of the alignment angle can be 25 or less, more preferably 17 or less. Further, when a metal or a metal oxide is used as the nanorod, it is possible to leave only the nanorod while maintaining the degree of orientation by removing the organic substance from such an orientation film.

  Further, such a grafted nanorod-dispersed liquid crystal alignment film can be suitably used for a polarizing optical element. In such a polarizing optical element, the grafted nanorods are aligned with a very uniform degree of alignment, and thus are wide. A viewing angle, an excellent contrast ratio, a high-speed electro-optical response, and the like can be achieved.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In addition, the coating amount measurement of each modifier, the grafting degree measurement, and the dispersion evaluation of the grafted nanorod-dispersed liquid crystal in each Example and each Comparative Example were performed according to the following methods.

<Measurement of coating amount of modifier>
(I) Measurement by thermogravimetric analysis (TG) The ratio of ash in the nanorods, coupling agent-modified nanorods, cap agent-modified nanorods, and initiator-modified nanorods obtained in each of the examples and comparative examples was measured by thermogravimetric analysis (TG). ) (Trade name: TG / DTA7200, manufactured by Hitachi High-Tech Science Co., Ltd.), and the initiator coating amount in the initiator-modified nanorod was calculated as the number of molecules per 1 nm ² . That is, using the nanorods, coupling agent-modified nanorods, cap-agent-modified nanorods, and initiator-modified nanorods obtained in each Example and Comparative Example as samples, first, 20 mg of each dried powder sample was measured for platinum. In a mixed atmosphere where the flow rates of air and nitrogen are both 200 mL / min, the sample is heated to 900 ° C. at a heating rate of 10 ° C./min. Mass, corresponding to an inorganic substance). Next, the ratio of the mass of the ash to the total mass before heating the sample is obtained, respectively, w1 (the ratio of the ash in the nanorod), w2 (the ratio of the ash in the coupling agent-modified nanorod), w3 (in the cap agent-modified nanorod) Ratio of ash), w4 (the ratio of ash in the initiator-modified nanorods).

Next, the ratio of the coating amount of the modifier (the mass of the organic substance) to the total mass of each sample is expressed by the following formula:
Ratio of the coating amount of the coupling agent in the coupling agent-modified nanorod (W2):
W2 = 1-w2- {w2 × (1-w1) ÷ w1}
Ratio of coating amount of cap agent and coupling agent in the total weight of the cap agent-modified nanorod (W3):
W3 = 1-w3- {w3 × (1-w1) ÷ w1}
Ratio of the coating amount of the cap agent, the coupling agent and the initiator in the total weight of the initiator-modified nanorod (W4):
W4 = 1-w4- {w4 × (1-w1) ÷ w1}
Calculated by

Moreover, the ratio of the organic substance with respect to the inorganic substance in each sample is represented by the following formula:
Ratio of organic substance to inorganic substance in coupling agent-modified nanorod (R2):
R2 = W2 × w1 ÷ w2
Ratio of organic substance to inorganic substance in cap agent-modified nanorod (R3):
R3 = W3 × w1 ÷ w3
Ratio of organic substance to inorganic substance in initiator-modified nanorod (R4):
R4 = W4 × w1 ÷ w4
Calculated by Next, from the above formula, the initiator coating amount (surface modification density) per 1 nm ² of the surface of the initiator-modified nanorod is expressed by the following formula:
Initiator coating amount (TG) [nm ⁻² ] = (R 4 −R 3) × (R 4 −R 3) × X _s ÷ (1−Y × R 2)
{Wherein X _s is the following formula:
_{X s = {N A × D} × r × l × 10 -21} ÷ (M s × 2 × (1 + r))
(N _A represents Avogadro's constant, D is shows the density of the nanorods [g / cm ^3], r represents the average radius of the nanorods, l denotes the average length of the nanorods, the molecular weight of M _s is the initiator Show.)
(In the case of Examples 1 to 4: X _s = 28.4), Y represents the following formula:
Y = formula weight of the inorganic substance in the coupling agent ÷ molecular weight of the coupling agent (in the case of Examples 1 to 4: Y = 0.448). }
Calculated by

(Ii) Measurement by X-ray fluorescence analysis (XRF) The cap-agent-modified nanorods and initiator-modified nanorods obtained in the respective Examples and Comparative Examples were respectively subjected to X-ray fluorescence analysis (XRF) (trade name: ZSX Primus II, Rigaku). The initiator coating amount (XRF) in terms of organic matter in the initiator-modified nanorods is expressed by the following formula:
Initiator coverage ^{(XRF) [nm -2] =} {m (s) -m (c)} × {N A × D × r × l × 10 -21 ÷ (M s × 2 × (1 + r))}
(In the above formula, m (s) is an initiator-modified nanorod, and m (c) is a cap-agent-modified nanorod, respectively:
m = analyzed value of bromine ÷ analyzed value of nanorod × molecular weight of nanorod ÷ 79.9
A value obtained by, N _A represents Avogadro's constant, D is shows the density of the nanorods [g / cm ^3], r represents the average radius of the nanorods, l denotes the average length of the nanorods, M _s Indicates the molecular weight of the initiator (in the case of Example 1: N _A × D × r × l × 10 ⁻²¹ ÷ (M _s × 2 × (1 + r)) = 94). )
Calculated by

<Grafting degree measurement>
The thermogravimetric analysis (TG) (product name: TG / DTA7200 (manufactured by Hitachi High-Tech Science Co., Ltd.), and the mass ratio of carbon to the whole grafted nanorod (degree of grafting (C _TG )) was calculated. That is, first, the ratio (w5) of the mass of ash to the total mass before heating the grafted nanorods was determined in the same manner as in the measurement by (i) thermogravimetric analysis (TG). Then the following formula:
W5 = 1-w5- {w5 × (1-w1) ÷ w1}
(W1 represents the proportion of ash in the nanorods.)
The ratio (W5) of the organic substance to the total weight of the grafted nanorods is obtained by the following formula, and the ratio (R5) of the organic substance to the inorganic substance in the grafted nanorods is expressed by the following formula:
R5 = W5 × w1 ÷ w5
Calculated by Next, the mass ratio of carbon in the coupling agent, cap agent, initiator, and polymerizable monomer is C2, C3, C4, and C5, respectively. From R5 and R2, R3, and R4, the following formula:
_CTG [mass%] = {{C2 * R2 + C3 * (R3-R2) + C4 * (R4-R3) + C5 * (R5-R4)} * W5} / R5
Calculated by

<Evaluation of orientation of grafted nanorod-dispersed liquid crystal alignment film>
The grafted nanorod-dispersed liquid crystal alignment film obtained in each example and comparative example was observed and obtained with a field emission scanning electron microscope (FE-SEM: trade name: S-4800, manufactured by Hitachi High-Technologies Corporation). For the FE-SEM photograph, the orientation angle of the nanorods was calculated using image analysis software (Winroof, manufactured by Mitani Corporation). The orientation angle was an angle with respect to the long axis (horizontal axis) of the FE-SEM photograph, and the standard deviation was calculated by performing Gaussian fitting on the plot of the angle distribution. When the standard deviation was calculated and the standard deviation value was 25 or less, the orientation was evaluated as “good”, and the others were evaluated as “bad”.

Example 1
[Synthesis of Nanorod I]
First, 4.4 g (20 mmol) of zinc acetate dihydrate was dissolved in 500 mL of ethanol (solution a). Next, 67.5 g (1.25 mol) of sodium methoxide was gradually added and dissolved in 375 mL of ethanol with stirring, and 25 mL of ultrapure water was added 10 minutes after complete dissolution, and the solution a was further mixed. The resulting mixed solution was reacted for 24 hours while gently shaking at 43 ° C. The dispersion obtained after the reaction was centrifuged (rotation radius: 168 mm) under the condition of 9,200 × g / 20 min, and the recovered precipitate was redispersed in ethanol. After the centrifugation and redispersion operations were performed twice with ultrapure water, it was confirmed that the supernatant was neutral. The obtained precipitate was redispersed in ethanol and centrifuged (rotation radius: 168 mm) under the condition of 9,200 × g / 20 min to obtain 104 mL of ethanol dispersion. Of the obtained ethanol dispersion, 2 mL was centrifuged under a condition of 14,100 × g / 10 min (rotation radius 60 mm), and the collected precipitate was vacuum-dried at 80 ° C. for 2 hours to obtain white powder Nanorod I (ZnO nanorods). ) The obtained nanorod I had a mass of 0.29 g, and the overall yield was estimated to be 1.5 g. The obtained nanorod I had an average length in the major axis direction of 50 nm, an average diameter in the minor axis direction of 10 nm (aspect ratio: 5.0), and a density of 5.606 g / cm ³ .

[Synthesis of Coupling Agent Modified Nanorod II]
First, 100 mL of ethanol was added to 1.0 g of nanorod I, and sonicated for 6 hours. Next, 1 mL of ultrapure water was added to the obtained dispersion, 1.0 g of trimethoxy [3- (phenylamino) propyl] silane and 0.30 g of hexylamine were added, and the mixture was reacted for 6 hours under ultrasonic waves. The dispersion after the reaction was centrifuged (rotation radius: 107 mm) under the condition of 43,200 × g / 30 min, and the recovered precipitate was redispersed in ethanol. The centrifugation and redispersion operations were performed three times in total, and then the solvent was changed from ethanol to acetonitrile, and the same operation was performed three times in total to obtain 29 mL of an acetonitrile dispersion. Of the obtained acetonitrile dispersion, 6 mL was centrifuged under a condition of 14,100 × g / 10 min (rotation radius 60 mm), and the collected precipitate was vacuum-dried at 80 ° C. for 2 hours to produce a white powder coupling agent-modified nanorod II was obtained. The mass of the obtained coupling agent-modified nanorod II was 0.25 g, and the overall yield was estimated to be 1.2 g. Moreover, the ratio (W2) of the coupling agent coating amount (mass of organic substance) in the total mass of the obtained coupling agent-modified nanorods II was 0.036.

[Synthesis of Cap Agent Modified Nanorod III]
First, 0.22 g of the coupling agent-modified nanorod II was dispersed in 40 mL of acetonitrile and sonicated for 1 hour. Next, 19 mg of 4-bromobenzyl bromide, 4.9 mg of proton sponge and 10 mL of acetonitrile were added to the obtained dispersion, and the mixture was reacted for 6 hours under ultrasound (molarity corresponding to the phenylamine group in the coupling agent-modified nanorod II). Number / 4 moles of bromobenzyl bromide: 1.2). The dispersion after the reaction was centrifuged (rotation radius: 107 mm) under the condition of 43,200 × g / 30 min, and the recovered precipitate was redispersed in acetonitrile. The centrifugation and redispersion operations were performed three times in total to obtain 32.60 g of acetonitrile dispersion. 4.70 g of the obtained acetonitrile dispersion was centrifuged under a condition of 14,100 × g / 10 min (rotation radius 60 mm), and the recovered precipitate was vacuum-dried at 80 ° C. for 2 hours to obtain a light brown powder cap agent Modified nanorod III was obtained. The mass of the obtained cap agent-modified nanorod III was 25 mg, and the overall yield was estimated to be 0.17 g. Moreover, the ratio (W3) of the coating amount (mass of organic substance) of the cap agent and the coupling agent in the total mass of the obtained cap agent-modified nanorod III was 0.082.

[Synthesis of initiator-modified nanorods IV]
First, 0.15 g of the cap agent-modified nanorod III was dispersed in 40 mL of acetonitrile and sonicated for 1 hour. Next, 27 mg of p- (bromomethyl) benzyl 2-bromoisobutyrate, 4.9 mg of proton sponge and 10 mL of acetonitrile were added to the obtained dispersion, and reacted for 6 hours under ultrasonic waves. The dispersion after the reaction was centrifuged (rotation radius: 107 mm) under the condition of 43,200 × g / 30 min, and the recovered precipitate was redispersed in acetonitrile. After performing the centrifugation and redispersion operations three times in total, the recovered precipitate was vacuum dried at 80 ° C. for 2 hours to obtain 151 mg of light-brown powder initiator-modified nanorods IV.

The ratio (W4) of the cap agent, the coupling agent and the initiator coating amount (mass of organic matter) in the total mass of the obtained initiator-modified nanorod IV was 0.087, and the initiator coating amount (TG) was 1 nm. ^The ratio in terms of the amount of organic substance per ² (the mass in terms of carbon of the initiator / the mass of all compounds on the surface of the initiator-modified nanorods) was 0.42 nm ⁻² . Moreover, when the measurement by a fluorescent X ray analysis (XRF) was performed, the initiator coating amount (XRF) in the obtained initiator modification nanorod IV was also 0.42 nm- ² .

[Synthesis of grafted nanorod V]
First, 1 mL of anisole was added to 73 mg of initiator-modified nanorods IV (initiator conversion: 5.4 μmol) and dispersed by sonication. Subsequently, 9.4 mg (60 μmol) of 2,2′-bipyridine, 192 mg (0.5 mmol) of 4- (4- (4-methoxyphenoxycarbonyl) phenyloxy) butyl methacrylate and 0.75 mL of anisole were added to the obtained dispersion. Was added. This solution was subjected to vacuum degassing and Ar purge cycles three times in total, and then mixed with 3.0 mg (30 μmol) of Cu (I) Cl under vacuum. The resulting mixed solution was stirred at room temperature (25 ° C.) for 5 minutes and then stirred at 80 ° C. for 24 hours, and then the reaction solution was exposed to the atmosphere to stop the reaction. Next, the graft body was reprecipitated by gently dropping methanol into the reaction solution while irradiating ultrasonic waves, and the precipitate was recovered by centrifugation (rotation radius: 87 mm) under the condition of 880 × g / 20 min. This re-precipitation and centrifugation were performed three times in total, and then the recovered precipitate was vacuum-maintained at 95 ° C. for 2 hours to obtain 110 mg of brown powder grafted nanorods V. The degree of grafting (C _TG ) of the obtained grafted nanorod V was 49% by mass.

[Preparation of Grafted Nanorod Dispersed Liquid Crystal VI]
First, 1 mL of anisole was added to 10 mg of the grafted nanorods V and sonicated for 6 hours. Next, 2.5 mg of 4-cyano-4′-pentyloxybiphenyl (5OCB) was dissolved in 60 μL of the obtained dispersion to obtain grafted nanorod-dispersed liquid crystal VI.

[Preparation of Grafted Nanorod-Dispersed Liquid Crystal Alignment Film VII]
First, a 2-inch silicon substrate was irradiated with UV / O ₃ for 15 minutes. Next, 500 μL of AL-1254 (polyimide diluted solution manufactured by JSR) was dropped on this silicon substrate through a hydrophilic disk filter having a pore diameter of 0.2 μm, and spin coating was performed under the condition of 2,000 rpm / 30 sec after the condition of 300 rpm / 5 sec. did. Subsequently, the film was baked under conditions of 60 ° C./1 min and then 220 ° C./1 hr to obtain a thin film having a thickness of about 60 nm. The obtained thin film was subjected to a five-reciprocating rubbing process by a rubbing machine under the conditions of a stage-substrate distance of 2.75 mm, a stage moving speed of 500 rpm, and a rubbing cloth rotating speed of 500 rpm, thereby producing a rubbing substrate.

  Next, the manufactured rubbing substrate was divided into 1 to 1.5 cm squares, and dust on the substrate was removed with compressed nitrogen, and then grafted nanorod-dispersed liquid crystal VI was passed through the hydrophilic disc filter with a pore size of 0.2 μm on this rubbing substrate. The solution was dropped and spin-coated under the condition of 3,000 rpm / 30 sec. Next, annealing was performed under the condition of 63 ° C./12 hours in the atmosphere to obtain a grafted nanorod-dispersed liquid crystal alignment film VII having a thickness of about 20 nm.

(Example 2)
The molar ratio of the functional group in the coupling agent-modified nanorod II to 4-bromobenzyl bromide (the number of moles corresponding to the phenylamine group in the coupling agent-modified nanorod II / 4 the number of moles of 4-bromobenzyl bromide) is 1.5. Except for the above, a cap agent-modified nanorod III was obtained in the same manner as in Example 1. In addition, an initiator-modified nanorod IV, a grafted nanorod V, a grafted nanorod dispersed liquid crystal VI, and a grafted nanorod dispersed liquid crystal alignment film VII were obtained in the same manner as in Example 1 except that this was used. The initiator coating amount (TG) in the obtained initiator-modified nanorod IV was 0.30 nm ⁻² , and the degree of grafting (C _TG ) of the obtained grafted nanorod V was 42% by mass.

(Example 3)
The molar ratio of the functional group in coupling agent-modified nanorod II to 4-bromobenzyl bromide (number of moles corresponding to phenylamine group in coupling agent-modified nanorod II / number of moles of 4-bromobenzyl bromide) is 1.0. Except for the above, a cap agent-modified nanorod III was obtained in the same manner as in Example 1. In addition, an initiator-modified nanorod IV, a grafted nanorod V, a grafted nanorod dispersed liquid crystal VI, and a grafted nanorod dispersed liquid crystal alignment film VII were obtained in the same manner as in Example 1 except that this was used. The initiator coating amount (TG) in the obtained initiator-modified nanorod IV was 0.60 nm ⁻² , and the degree of grafting (C _TG ) of the obtained grafted nanorod V was 42% by mass.

Example 4
First, 1 mL of anisole was added to 10 mg of the grafted nanorod V obtained in the same manner as in Example 2 and subjected to ultrasonic treatment for 6 hours, followed by centrifugation under conditions of 14,500 rpm / 10 min. Example 2 except that 4-cyano-4′-pentyloxybiphenyl (5OCB) was dissolved to 2.5 mg with respect to 60 μL of the obtained supernatant and used as grafted nanorod-dispersed liquid crystal VI. Similarly, a grafted nanorod-dispersed liquid crystal alignment film VII was obtained.

(Comparative Example 1)
First, 0.27 g of the coupling agent-modified nanorod II obtained in Example 1 was dispersed in 40 mL of acetonitrile and sonicated for 1 hour. Next, 0.9 g of p- (bromomethyl) benzyl 2-bromoisobutyrate, 168 mg of proton sponge and 10 mL of acetonitrile were added to the obtained dispersion, and reacted for 6 hours under ultrasonic waves. The dispersion after the reaction was centrifuged (rotation radius: 107 mm) under the condition of 43,200 × g / 30 min, and the recovered precipitate was redispersed in acetonitrile. After performing the centrifugation and redispersion operations three times in total, the collected precipitate was vacuum-dried at 80 ° C. for 2 hours to obtain 117 mg of brown powder of initiator-modified nanorods VIII. The ratio (W4) of the mass of the organic substance to the total mass of the obtained initiator-modified nanorod VIII was 0.10.

  Next, 21 mg of brown powder grafted nanorods IX was obtained in the same manner as in Example 1 except that 21.9 mg of initiator-modified nanorods VIII (5.4 μmol in terms of initiator) was used. Further, a grafted nanorod-dispersed liquid crystal X and a grafted nanorod-dispersed liquid crystal alignment film XI were obtained in the same manner as in Example 1 except that this grafted nanorod IX was used. For reference, FIG. 3 shows a conceptual diagram illustrating a method for producing the initiator-modified nanorod VIII of Comparative Example 1.

(Reference Example 1)
A liquid crystal alignment film was obtained in the same manner as in Example 1 except that the initiator-modified nanorod IV was used in place of the grafted nanorod V.

Table 1 shows the amount of initiator coating per 1 nm ² (TG), the degree of grafting of grafted nanorods (C _TG ), and grafting in the initiator-modified nanorods obtained in Examples 1 to 3 and Comparative Example 1. The result of the orientation evaluation of a nanorod dispersion | distribution liquid crystal aligning film is shown. FIG. 4 shows the angular distribution in the evaluation of the orientation of the grafted nanorod-dispersed liquid crystal alignment films obtained in Examples 2 and 4, and FIG. 5 shows the grafted nanorod-dispersed liquid crystal orientation obtained in Example 1. FIG. 6 shows an FE-SEM photograph of the liquid crystal alignment film obtained in Reference Example 1, respectively. FIG. 4 also shows the angular distribution (Example 2 *) obtained for the grafted nanorods obtained in Example 2 in the same manner as in the evaluation of the orientation of the grafted nanorod-dispersed liquid crystal alignment film.

  As is clear from the above results, in the production method of the present invention, even if the amount of the initiator to be coated is determined non-destructively (XRF), the result is the same as the measurement by TG (Example 1). It was confirmed that the amount of initiator can be accurately quantified nondestructively. Furthermore, as is clear from the results shown in Table 1 and FIGS. 4 to 5, in the grafted nanorod-dispersed liquid crystal alignment film obtained by using the grafted nanorod obtained by the present invention, the nanorods are uniformly improved. It has been confirmed that the polymer chains can be oriented and the density of the polymer chains grafted according to the present invention can be highly controlled. On the other hand, the orientation in the grafted nanorod-dispersed liquid crystal alignment film obtained in Comparative Example 1 was poor, and it was confirmed that it was difficult to control the orientation of the nanorods. This is because the surface of the nanorods was entirely covered with the initiator as shown in FIG. 3, and the amount of initiator coating increased so that the degree of grafting increased, resulting in steric hindrance with the low-molecular liquid crystal compound. The inventors speculate.

  As described above, according to the present invention, the initiator coating amount can be controlled to a high degree, and the initiator coating amount can be directly quantified in a non-destructive manner. Initiator-modified nanorods that can be obtained by the above-described method, and the density of polymer chains to be grafted can be controlled to a high degree, grafted nanorods obtained using the initiator-modified nanorods, and production methods thereof, grafted nanorods dispersed liquid crystal alignment It becomes possible to provide a film, a polarizing optical element, and a cap agent-modified nanorod.

  1 ... Nanorod, 2 ... Coupling agent, 3 ... Cap agent, 4 ... Initiator, 5 ... Coupling agent modified nanorod, 6 ... Cap agent modified nanorod, 7 ... Initiator modified nanorod, 8 ... Initiator modified nanorod (Comparison Example).

Claims (15)

Obtaining a cap agent-modified nanorod in which the cap agent is bonded to a part of the surface of the nanorod by binding the cap agent to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more;
After the step of obtaining the capping agent-modified nanorod, the capping agent and the initiator are bound to the surface of the nanorod by binding an initiator having a polymerization initiator group to the surface of the nanorod that is not bound to the capping agent. Obtaining a modified initiator-modified nanorod;
Including
The capping agent and the initiator contain bromine atoms ,
A method for producing an initiator-modified nanorod characterized by the above. Before the step of obtaining the cap agent-modified nanorod, the method further comprises the step of obtaining a coupling agent-modified nanorod in which the coupling agent is bound to the surface of the nanorod by binding a coupling agent to the surface of the nanorod. ,
Binding the capping agent and the initiator to the surface of the nanorods via the coupling agent,
The manufacturing method of the initiator modification nanorod of Claim 1 characterized by these. The coupling agent has a functional group A capable of binding to the surface of the nanorod, and a functional group B not binding to either the surface of the nanorod or the functional group A,
The cap agent has a functional group C1 capable of binding to the functional group B;
The initiator further has a functional group C2 capable of binding to the functional group B;
In the step of obtaining the coupling agent-modified nanorod, the coupling agent is bonded to the surface of the nanorod via the functional group A;
In the step of obtaining the cap agent-modified nanorod, the cap agent is bonded to the functional group B of a part of the coupling agent on the surface of the coupling agent-modified nanorod via the functional group C1;
Bonding the initiator via the functional group C2 to the unreacted functional group B remaining in the coupling agent on the surface of the cap agent-modified nanorod in the step of obtaining the initiator-modified nanorod;
The manufacturing method of the initiator modification nanorod of Claim 2 characterized by these.   The method for producing an initiator-modified nanorod according to any one of claims 1 to 3, wherein an average diameter in a minor axis direction of the nanorod is 1 to 100 nm.   The method for producing an initiator-modified nanorod according to any one of claims 1 to 4, wherein the polymerization initiating group is a living radical polymerization initiating group. A cap agent is bonded to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more, and an initiator having a polymerization initiating group is bonded to a surface of the nanorod where the cap agent is not bonded,
The capping agent and the initiator contain bromine atoms,
Initiator qualified nanorods, wherein a call. The initiator-modified nanorod according to claim 6, wherein the coating amount of the initiator is 0.3 to 1.0 nm ^-2 in terms of the number of molecules per 1 nm ² .   A grafted nanorod obtained by polymerizing a polymerizable monomer starting from the polymerization initiation group of the initiator-modified nanorod according to claim 6 or 7 to obtain a grafted nanorod having a polymer chain grafted thereon Production method. A cap agent is bonded to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more, and an initiator having a polymerization initiating group is bonded to a surface of the nanorod where the cap agent is not bonded,
The capping agent and the initiator contain a bromine atom;
Grafted nanorods characterized that you the polymerization initiation group polymer chain to the initiator through the are attached.   A grafted nanorod-dispersed liquid crystal, wherein the grafted nanorod according to claim 9 is dispersed in a matrix containing a low-molecular liquid crystal compound.   11. The grafted nanorod-dispersed liquid crystal according to claim 10, wherein in the liquid crystal state, the low molecular liquid crystal compound and the polymer chain grafted to the grafted nanorod are both nematic or smectic. . Grafted nanorods dispersed liquid crystal alignment film grafted nanorods dispersion crystal according to claim 10 or 11, characterized in that it is oriented.   A polarizing optical element using the grafted nanorod-dispersed liquid crystal alignment film according to claim 12. A cap agent is bonded to a part of the surface of the nanorod having an average aspect ratio of 1.2 or more, and the nanorod has a region where the cap agent is not bonded to the surface of the nanorod .
The capping agent contains a bromine atom,
Capping agent qualified nanorods, wherein a call.   A coupling agent is bonded to the surface of the nanorod, the cap agent is bonded to the nanorod via the coupling agent, and the coupling agent is bonded to a region where the cap agent is not bonded. The cap agent-modified nanorod according to claim 14, wherein the nanorod is exposed.