WO2013176287A2

WO2013176287A2 - Deformation method for crosslinkable liquid-crystal polymer material, and optically driven compact

Info

Publication number: WO2013176287A2
Application number: PCT/JP2013/064629
Authority: WO
Inventors: 宍戸　厚; 圭司小川; アリプリィマギ; マッティビルキ; 純一間宮; 山田　雅之; 靖章桑田; 明香鶴丸
Original assignee: 大研医器株式会社; 国立大学法人東京工業大学
Priority date: 2012-05-25
Filing date: 2013-05-27
Publication date: 2013-11-28
Also published as: JP2013245296A; WO2013176287A3

Abstract

Provided is a technique for deforming a crosslinkable liquid-crystal polymer material containing photochromic molecules, without using the irradiation of ultraviolet-blue light. Ultra-short pulse light is irradiated on a crosslinkable liquid-crystal polymer material (12) containing photochromic molecules (101), and the crosslinkable liquid-crystal polymer material is deformed as a result of isomerisation being induced due to two-photon absorption by the photochromic molecules (101).

Description

Method for deforming cross-linked liquid crystal polymer material, light-driven molded body

The present invention relates to a method for deforming a cross-linked liquid crystal polymer material containing photochromic molecules. The present invention also relates to a light-driven molded body to which the above method can be applied, and more specifically to a light-driven medical instrument that is used by being inserted into a living body in surgery.

As a vasodilator, endovascular treatment is widely used in which a stenosis of a blood vessel is expanded from the inside using a stent or catheter introduced along the guide wire, or the guide wire itself.
A blood vessel having a stenosis that is a target of such endovascular treatment is mainly a coronary artery. Therefore, the guide wire is not inserted directly into the coronary artery in order to avoid bleeding, but is inserted from the blood vessel of the arm or leg and introduced to the stenosis of the coronary artery. This introduction is performed while viewing the position of the tip of the guide wire and the shape of the blood vessel under fluoroscopy.

Usually, the blood vessel is curved or branched along the path from the blood vessel of the arm or foot (insertion portion of the guide wire) to the stenosis portion of the coronary artery. In endovascular treatment, it is necessary to introduce a guide wire to the stenosis without damaging the blood vessel. Therefore, conventionally, it has been common to use different guide wires whose tips are shaped at various angles in accordance with the shape of the blood vessel.
Such a conventional guide wire can be inserted and removed using a catheter or the like introduced into the blood vessel along the guide wire, so that the guide wire and the catheter are inserted and removed each time. Etc. are introduced to the stenosis.

Patent Document 1 describes that the followability to a blood vessel is improved by changing the rigidity of the distal end portion of the guide wire by providing a coil at the distal end portion of the wire. *

In recent years, research has been conducted on liquid crystal materials that can be deformed and driven by irradiation with active light.
Patent Document 2 discloses a light-flexible liquid crystal molded body made of a polymer obtained from a polymerizable monomer having an azobenzene structure.
This light-flexible liquid crystal molded body can be bent by light irradiation using trans-cis photoisomerization of an azobenzene structure contained in a liquid crystal polymer material.

Non-Patent Documents 1 to 3 disclose crosslinked liquid crystal polymer thin films containing an azobenzene structure which is a photochromic molecule. *

Patent Document 3 discloses that a crosslinked liquid crystal polymer molded body into which photochromic molecules are introduced is irradiated with actinic light to induce a shape change of the crosslinked liquid crystal polymer molded body, and the crosslinked liquid crystal polymer molded body is rotated. A light induced rotation method is disclosed. *

Patent Document 4 includes a light-driven device including a cross-linked liquid crystal polymer thin film containing photochromic molecules, and inducing a shape change of the cross-linked liquid crystal polymer thin film in conjunction with on / off of actinic ray irradiation. A mold actuator is disclosed. *

Further, as described in each of the above-mentioned documents, the absorption wavelength of the trans form having an azobenzene structure is 300 to 400 nm, and the change in the shape of a molded body such as a cross-linked liquid crystal polymer thin film containing the azobenzene structure is It was known to be induced by irradiation with ultraviolet light to blue light.

JP 2011-206175 A JP 2005-255805 A JP 2008-115347 A JP 2010-68691 A

The guide wire described in Patent Document 1 is thought to change the rigidity of the tip and increase the followability to blood vessels in principle, but due to the structure of the coil, it is difficult to reduce the guide wire diameter. Not practical. *

Under such circumstances, there has been a demand for the development of a technique for deforming a guide wire or the like in a living body and a new medical instrument using such a technique.
Then, this invention makes it a subject to provide the technique which deform | transforms medical instruments, such as a guide wire, in vivo.

In order to solve the above problems, the present inventors have used a cross-linked liquid crystal polymer material that is deformed by irradiation with active light, as described in Patent Documents 2 to 4 and Non-Patent Documents 1 to 3, to guide wire. The guide wire could be deformed by irradiation with actinic light in vivo.
Here, since the absorption wavelength band of known photochromic molecules such as azobenzene is 300 to 400 nm as described above, in order to induce deformation of the crosslinked liquid crystal polymer material described in Patent Documents 1 to 3. Therefore, it is necessary to irradiate ultraviolet light to blue light.
However, since the absorption wavelength band of red blood cells in blood is also 300 to 400 nm, there is a risk that irradiation with ultraviolet light or blue light in the presence of blood causes an increase in the temperature of blood vessels. Therefore, it is difficult to adopt the method of deforming the guide wire formed of the crosslinked liquid crystal polymer material described in Patent Documents 1 to 3 with ultraviolet light to blue light.

Accordingly, it is a further object of the present invention to provide a technique for deforming a crosslinked liquid crystal polymer material containing a photochromic molecule irrespective of irradiation with ultraviolet light to blue light.

As a result of diligent research, the present inventors have made it possible to cause two-photon absorption in a conventionally known photochromic molecule such as azobenzene by using ultrashort pulsed light, which makes the photochromic molecule reversible. I found isomerization. And it discovered that the said bridge | crosslinking-type liquid crystal polymer material could be deformed by irradiating the bridge | crosslinking-type liquid crystal polymer material containing the said photochromic molecule | numerator with the ultrashort pulse light of a long wavelength, and this invention Was completed. *

The present invention that solves the above-described problems deforms the cross-linkable liquid crystal polymer material by irradiating the photochromic molecule-containing cross-linked liquid crystal polymer material with ultrashort pulse light and causing the photochromic molecule to absorb two-photons. This is a method for deforming a cross-linked liquid crystal polymer material.
According to such a method, it is possible to deform the cross-linked liquid crystal polymer material using light having a wavelength different from the wavelength conventionally used for the deformation of the cross-linked liquid crystal polymer material.

In a preferred embodiment of the present invention, the ultrashort pulse light is red light to infrared light. The photochromic molecule in the cross-linked liquid crystal polymer material preferably has an absorption wavelength band for ultraviolet light or blue light.
By using such a method, even when azobenzene or the like known as a typical photochromic molecule is used, the cross-linked liquid crystal polymer material can be deformed without using ultraviolet light.

In a preferred embodiment of the present invention, the pulse width of the ultrashort pulse light is 1 to 5000 femtoseconds. The intensity of the ultrashort pulse light is preferably 0.1 to 10 mW / cm ² .
By using such ultrashort pulse light, two-photon absorption of the photochromic molecule can be efficiently induced.

In a preferred form of the invention, the photochromic molecule is azobenzene.
Azobenzene is useful for increasing the deformation rate of the cross-linked liquid crystal polymer material because the intermolecular distance is greatly changed by isomerization.

In a preferred embodiment of the present invention, the crosslinked liquid crystal polymer material has a structure in which a polymer main chain is crosslinked by a crosslinking agent containing a photochromic molecule. *

In a preferred embodiment of the present invention, the crosslinked liquid crystal polymer material has uniaxial orientation.
Thereby, macroscopic deformation of the crosslinked liquid crystal polymer material can be induced by isomerization of the photochromic molecule.

The present invention that solves the above-described problems includes a main body having a deformable layer formed of a cross-linkable liquid crystal polymer material containing photochromic molecules, and ultrashort pulsed light irradiation for irradiating the deformable layer with ultrashort pulsed light. A light-driven molded body. *

Preferred examples of photochromic molecules and pulsed light in the light-driven molded body of the present invention are the same as those in the deformation method of the present invention. *

The light-driven molded article of the present invention is suitable for being driven and used in a living body, particularly in a blood vessel. *

A specific example of the light-driven molded body of the present invention is a light-driven guide wire. *

As one form of such a light-driven guide wire, a main body having a deformed layer made of a thin film formed of a core wire and a crosslinked liquid crystal polymer material containing a photochromic molecule covering the surface of the core wire; And an ultrashort pulse light irradiating unit including a light source that generates the ultrashort pulsed light and an optical fiber that transmits the ultrashort pulsed light to an irradiation position of the main body.

According to the present invention, it is possible to deform a crosslinkable liquid crystal polymer material using light having a wavelength different from the wavelength conventionally used for deformation of a crosslinkable liquid crystal polymer material containing photochromic molecules.
By utilizing this phenomenon, it is possible to transform a cross-linked liquid crystal polymer material containing photochromic molecules known to be isomerized by ultraviolet light to blue light using red light to infrared light. Become.

Thereby, the cross-linked liquid crystal polymer material can be applied to a medical instrument or the like used in a living body, particularly in a blood vessel. This makes it possible to deform the medical instrument in the living body, and is expected to improve safety and efficiency in diagnosis and treatment.
For example, by covering the surface of the guide wire introduced into the blood vessel with a film made of the above-mentioned cross-linked liquid crystal polymer material, the tip of the guide wire is bent into a required shape by irradiation with ultrashort pulse light, It is possible to introduce a guide wire along a blood vessel that is bent or branched. As a result, labor for inserting and removing a plurality of guide wires can be reduced, and the risk of blood vessel damage can be greatly reduced.

It is a figure explaining the deformation | transformation method of the bridge | crosslinking-type liquid crystal polymer material of this invention. It is a figure explaining the structure of the optical drive type guide wire of this invention. FIG. 3 is an enlarged sectional view taken along line AA in FIG. 2. It is a figure explaining the structure of the optical system used for the measurement of the 2nd harmonic light (SH) intensity | strength in an Example. It is a figure which shows the change of the 2nd harmonic light (SH) intensity with respect to the ultrashort pulse light irradiation time at the time of irradiating the ultrashort pulse light to the bridge | crosslinking-type liquid crystal polymer film produced in the Example. It is a photograph which shows the shape of a film at the time of irradiating active light to the bridge | crosslinking-type liquid crystal polymer film produced in the Example. (A) is a photograph in the case of irradiation with visible light after irradiation with ultraviolet light, and (B) is a photograph in the case of irradiation with visible light after irradiation with a near-infrared ultrashort pulse.

The method for deforming the cross-linked liquid crystal polymer material of the present invention will be described in detail below. The present invention is characterized in that the cross-linkable liquid crystal polymer material is deformed by irradiating the photochromic molecule-containing cross-linked liquid crystal polymer material with ultrashort pulse light and causing the photochromic molecule to absorb two-photons. .
That is, the present invention is based on the knowledge that photochromic molecules such as azobenzene can be two-photon absorbed using ultrashort pulsed light.

The crosslinked liquid crystal polymer material used in the method of the present invention contains photochromic molecules in its structure. As will be described in detail later, the photochromic molecule can be reversibly isomerized by irradiation with specific active light.
The crosslinked liquid crystal polymer material has a structure in which polymer main chains are loosely constrained by a crosslinking agent.

The introduction site of the photochromic molecule may be either a polymer main chain or a polymer side chain, but the photochromic molecule preferably constitutes at least a part of the mesogen. This is because the isomerization of the photochromic molecule efficiently induces the orientation change of the mesogen.

The introduction site of the photochromic molecule is preferably a polymer side chain. It is also preferable to use a polymer side chain containing this photochromic molecule as a crosslinking agent. By introducing a photochromic molecule into the cross-linking agent, it is possible to sufficiently cause a shape change of the cross-linked liquid crystal polymer material due to isomerization of the photochromic molecule. *

Known photochromic molecules can be used. Examples thereof include an azobenzene structure capable of trans-cis isomerization, a stilbenzene structure, a spiropyran structure capable of ring-opening-ring-closing isomerization, and a diaryl structure.
In particular, azobenzene represented by the following formula (1) is preferable because the intermolecular distance between the two benzenes greatly changes during isomerization.

Since the absorption wavelength band of the trans form of azobenzene is about 300 to 400 nm, it is isomerized to a cis form when irradiated with light (ultraviolet light) in the same range. This is a conventionally known phenomenon. The method of the present invention is characterized in that this isomerization is induced by two-photon absorption in azobenzene using ultrashort pulse light. This makes it possible to cause azobenzene to be cis-formed even with light having a wavelength longer than 300 to 400 nm, which is the absorption wavelength band of the trans form of azobenzene. That is, it is possible to cause azobenzene cis formation also by light having a wavelength of about 800 nm, which is twice or more the absorption wavelength band of the trans form of azobenzene. *

Further, since the absorption wavelength of the cis isomer of azobenzene is known to be about 500 to 650 nm, it returns to the trans isomer when irradiated with light in the same range (visible light). Azobenzene isomerized by two-photon absorption returns to the trans form upon irradiation with visible light.
When at least a part of the mesogen of the crosslinked liquid crystal polymer material is composed of, for example, azobenzene, the trans isomer acts to stabilize the liquid crystal phase and the cis isomer acts to destabilize the liquid crystal phase.

As described above, it is preferable that at least a part of the mesogen of the crosslinked liquid crystal polymer material is a photochromic molecule, but a part of the mesogen may be composed of other than the photochromic molecule. *

The cross-linked liquid crystal polymer material preferably has a smectic liquid crystal from the viewpoint of efficiently transmitting a mesogen orientation change to the polymer main chain. *

The cross-linked liquid crystal polymer material preferably has uniaxial orientation.
Thereby, macroscopic deformation of the crosslinked liquid crystal polymer material can be induced by isomerization of the photochromic molecule.

The crosslinked liquid crystal polymer material can be produced, for example, by polymerizing a polymerizable monomer having a photochromic molecule.
In the production of the crosslinked liquid crystal polymer material, a polymerizable monomer having a photochromic molecule and a liquid crystalline polymerizable monomer not having a photochromic molecule may be copolymerized. Further, a non-liquid crystalline polymerizable monomer may be further copolymerized.
Moreover, it is preferable that at least a part of the polymerizable monomer having a photochromic molecule is a crosslinked polymerizable monomer that functions as a crosslinking agent. As described above, by introducing a photochromic molecule into the crosslinking agent, it is possible to sufficiently cause a shape change of the crosslinked liquid crystal polymer material due to isomerization of the photochromic molecule.
These monomer ratios can be appropriately adjusted so as to have a degree of deformation according to the use of the material.

Examples of the polymerizable group of each polymerizable monomer include a (meth) acryloyloxy group, a (meth) acrylamide group, a vinyloxy group, a vinyl group, an epoxy group, and the like. ) Acroyloxy group and (meth) acrylamide group are preferred.
A well-known thing can be used for a polymerization initiator.

The above-mentioned crosslinked liquid crystal polymer material can be produced by a known method. That is, the polymerizable monomer may be polymerized under the condition where the mesogen is oriented. A well-known thing can also be used for a polymerization initiator.
For example, it is preferable to perform polymerization and molding simultaneously by photopolymerizing or thermally polymerizing a polymerizable monomer using a reaction vessel whose inner surface is oriented. Examples of the orientation treatment include a method of forming a polyimide layer on the inner surface of the reaction vessel and rubbing it in a specific direction, and applying an electric field / magnetic field.
In photopolymerization, it is preferable to irradiate a deflection perpendicular to the orientation direction of the photochromic molecule in order to suppress isomerization of the photochromic molecule.

The shape of the cross-linked liquid crystal polymer material is not particularly limited, and can be formed according to the application. For example, it can be a film or a fiber. *

The feature of the present invention is that the above-mentioned cross-linked liquid crystal polymer material is deformed by irradiating the photochromic molecule with two photons by irradiating the above-mentioned cross-linked liquid crystal polymer material with ultrashort pulse light.
The “ultrashort pulse light” in the present invention means very short pulse light having a pulse width of several picoseconds or less.
For example, the pulse width of the ultrashort pulse light is 5000 femtoseconds or less, preferably 1000 femtoseconds or less, more preferably 300 femtoseconds or less, and particularly preferably 100 femtoseconds or less. The lower limit of the pulse width is not particularly limited, but can be about 1 femtosecond. Thereby, the two-photon absorption of the photochromic molecule in the cross-linked liquid crystal polymer material can be efficiently induced. The intensity of the ultrashort pulse light used in the present invention is preferably 0.1 mW / cm ² or more, more preferably 0.1 to 10 mW / cm ² , more preferably 1 to 10 mW / cm ² . Thereby, the two-photon absorption of the photochromic molecule in the cross-linked liquid crystal polymer material can be efficiently induced.
Photochromic molecules are isomerized by two-photon absorption, thereby deforming the cross-linked liquid crystal polymer material.

Hereinafter, the deformation mechanism of the crosslinked liquid crystal polymer material of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram for explaining a change due to irradiation with active light of a cross-linked liquid crystal polymer film (cross-linked liquid crystal polymer material) 12 in which azobenzene (photochromic molecule) 101 is introduced into mesogen 11. The mesogen 11 in the crosslinked liquid crystal polymer film 12 has a high alignment order. A part of the mesogen 11 includes a trans isomer 101 of azobenzene.
When the trans isomer 101 of azobenzene is irradiated with an ultrashort pulse light having a wavelength of 800 nm, the trans isomer 101 is isomerized by two-photon absorption and the structure is changed to a cis isomer 102. Thereby, the alignment order of the mesogen 11 falls. Then, the decrease in the alignment order propagates to the liquid crystal polymer and the cross-linked liquid crystal polymer film 12 contracts (indicated by an arrow in FIG. 1).

The advantage of isomerization of photochromic molecules using two-photon absorption and the deformation of cross-linked liquid crystal polymer materials is the advantage of using light of a wavelength different from that used for conventional photochromic molecule isomerization. This is because the liquid crystal polymer material can be deformed.
For example, for isomerization of azobenzene, it has conventionally been necessary to irradiate ultraviolet light, but by using the method of the present invention, isomerization of azobenzene can also be caused by irradiation with red to infrared light. This means that deformation of the cross-linked liquid crystal polymer material can be caused by irradiation with red to infrared light.
According to such a method, it becomes possible to apply the deformation of the cross-linked liquid crystal polymer material even in a field where it has been difficult to use ultraviolet light.
For example, in a living body, particularly in a blood vessel, it is usually difficult to irradiate with ultraviolet light. This is because red blood cells absorb ultraviolet light and there is a risk that the temperature rises in the tissue. Therefore, conventionally, it has not been proposed to apply the deformation of the cross-linked liquid crystal polymer material by light irradiation to a medical device.

By using the method of the present invention, it becomes possible to cause deformation of the cross-linked liquid crystal polymer material by light having a long wavelength of red to infrared light. Accordingly, a medical instrument or the like for use in a living body, particularly in a blood vessel, can be formed of a light-driven cross-linked liquid crystal polymer material. And in a living body, it becomes possible to cause a deformation | transformation of a medical instrument by light irradiation. *

In this way, by applying the above-described method for deforming a cross-linked liquid crystal polymer material of the present invention, various light-driven molded articles including medical instruments can be manufactured.
The light-driven molded body of the present invention includes a main body portion having a deformable layer formed of a cross-linkable liquid crystal polymer material containing photochromic molecules, and a light irradiation portion for irradiating the deformable layer with ultrashort pulse light. Is provided.

Hereinafter, an embodiment of the light-driven molded body of the present invention will be described with reference to FIGS. 2 and 3.
A guide wire 1 shown in FIGS. 2 and 3 includes a wire main body 2 (main body portion) and a laser irradiation device 3 (very short pulse light irradiation portion). For the sake of convenience of explanation, this figure is an enlarged view of the distal end portion of the guide wire characteristic of the present invention, and does not show actual dimensions.
The wire body 2 includes a core wire 21 and a polymer jacket 22 (deformable layer) made of a cross-linked liquid crystal polymer material containing a photochromic molecule that covers the tip portion 211 of the core wire 21. The length of the core wire 21 is not particularly limited, but is about 200 mm to 5000 mm, and about 50 to 100 mm from the tip portion 211 is covered with the polymer jacket 22.
The core wire 21 is formed of a metal material such as stainless steel, similarly to the wire used in the conventional guide wire. Portions other than the tip end portion 211 of the core wire 21 are covered with a resin layer 21a such as polyolefin or fluorine resin.
As photochromic molecules in the cross-linked liquid crystal polymer material forming the polymer jacket 22, for example, azobenzene can be used.

The laser irradiation device 3 includes a laser light source 31 and an optical fiber 32 that transmits the ultrashort pulse laser light output from the laser light source 31 to the irradiation position of the polymer jacket 22 of the wire body 2. The laser light source 31 includes a light output control unit that turns on the output of the laser light by the operation of the operator. In the example shown in FIGS. 2 and 3, the optical fiber 32 is disposed along the core wire 21 and the tip portion 211, and is embedded in the resin layer 21 a and the polymer jacket 22.
The optical fiber 32 is preferably designed so that an ultrashort pulse laser beam can be irradiated to an arbitrary position of the polymer jacket 22. For example, by using an optical fiber 32 having a plurality of emitting portions 32a to 32d, it is possible to irradiate an extremely short pulse laser beam at an arbitrary position of the polymer jacket 22, and it is possible to adjust the degree of deformation and the like. . In this embodiment, the form which employ | adopted the bundle fiber which bundled the optical fiber from which length differs is shown.

Hereinafter, the deformation | transformation operation | movement of the guide wire 1 is demonstrated, referring FIG.
For example, the guide wire 1 is introduced toward a stenosis portion of a blood vessel. When the guide wire 1 is introduced to the point just before the branch point of the blood vessel, the output from the laser light source 31 is turned on so that the ultrashort pulse is emitted from the emitting portions 32a to 32d of the optical fiber 32 to the polymer jacket 22 of the wire body 2. Of near infrared laser light. The polymer jacket 22 irradiated with the ultrashort pulse laser beam is deformed at the irradiated portion, and as a result, the entire wire body 2 is bent (indicated by a virtual line). Further, when it is desired to undo the deformation, visible light may be irradiated by a laser irradiation device.
As described above, the guide wire can be introduced to the stenosis portion while deforming the distal end of the guide wire 1 in the direction along the blood vessel introduction direction in the blood vessel.

So far, the embodiment of the guide wire has been shown. However, the molded body of the present invention can be any medical device to be driven in vivo. For example, the molded article of the present invention can be configured as a catheter or a stent.

One example of the production of the cross-linked liquid crystal polymer film is shown, but the cross-linked liquid crystal polymer material used in the present invention is not limited to the example.
<Polymerizable monomer>
The polymerizable monomers used in the production of the cross-linked liquid crystal polymer film of this example are shown in chemical formulas (2) to (4).
The azobenzene cross-linking agent represented by the chemical formula (2) has a chiral moiety and develops an SmC _A ^* phase that is an antiferroelectric phase in both the temperature rising and temperature falling processes. Further, the NLO (nonlinear optics) cross-linking agent represented by the chemical formula (3) and the NLO monomer represented by the chemical formula (4) develop a ferroelectric SmC ^* phase only during the temperature lowering process. The monomers represented by chemical formula (3) and chemical formula (4) exhibited second harmonic generation activity (SHG).

As a result of measuring the UV-visible absorption spectrum in a dichloromethane solution for the polymerizable monomers of the above chemical formulas (2) to (4), the absorption wavelength band of each polymerizable monomer is around 400 nm, and the absorption wavelength is around 800 nm. It turns out that it has no belt. *

<Production of cross-linked liquid crystal polymer film>
Each polymerizable monomer was mixed at a ratio of 20 mol% of azobenzene crosslinking agent, 60 mol% of NLO crosslinking agent, and 20 mol% of NLO monomer to prepare a crosslinked liquid crystal polymer film (Azo-NLO film).
A sample for polymerization was prepared by adding 1 mol% of a photopolymerization initiator Lucirin TPO having absorption in the ultraviolet region to the mixed sample of each polymerizable monomer. The glass cell with an ITO electrode subjected to the planar alignment treatment was heated on a hot stage, and the sample for polymerization was sealed by capillary action at an isotropic phase temperature. While the AC voltage was applied, the temperature was lowered from the isotropic phase temperature to room temperature, and then photopolymerization was performed by irradiating visible light having a wavelength of 400 nm or more from a high-pressure mercury lamp for 5 hours with the DC voltage applied. Since azobenzene is isomerized by light having a wavelength of 400 nm, photoisomerization was suppressed as much as possible by irradiating polarized light perpendicular to the orientation direction of azobenzene. After the polymerization, a cross-linked liquid crystal polymer film was cut out with a cutter (5 mm × 10 mm).

<General characteristics of Azo-NLO film>
The thermal properties and orientation of the produced Azo-NLO film are shown below. As a result of DSC measurement, the phase transition peak observed before polymerization disappeared completely, and only the glass transition point appeared in the vicinity of −10 ° C.
In addition, as a result of observation with a polarizing microscope (POM), it was confirmed that periodic darkness and darkness could be confirmed every 45 ° with 35 ° as a dark field, and the produced film was uniformly uniaxially oriented.
Next, the polarization absorption spectrum was measured, and the orientation state of azobenzene in the Azo-NLO film was examined from the polarization plane dependency. As a result of measuring the absorbance at a wavelength of 456 nm by rotating the film by 5 °, the absorbance is maximized at an angle inclined by 35 °. Therefore, it is clear that azobenzene is tilted by 35 ° from the rubbing direction. became.

<Optical operation characteristics of Azo-NLO film> Ultra short pulse light having a wavelength of 800 nm (fundamental wave), a pulse width of 100 femtoseconds, and an intensity of 170 mW is incident on the Azo-NLO film (1 mW / cm ² ), and the secondary The temporal change of harmonic light (SH) intensity was examined. The incident angle of the ultrashort pulse light was set to 35 ° (indicated by symbol A in FIG. 4).
The optical system 4 used for the measurement of SH intensity is shown in FIG. That is, the femtosecond pulsed laser light from the light source 40 was passed through the polarizer 41, condensed by the lens 42, and incident on the sample (film) 44 through the ultraviolet light cut filter 43. The light passing through the analyzer 45 is passed through the infrared light cut filter 46 to remove the fundamental wave having a wavelength of 800 nm, and only the second harmonic SH light having a wavelength of 400 nm is amplified by the photomultiplier tube 47, and is sent to the oscilloscope 48. displayed. The fundamental wave was reflected by a glass plate (half mirror) 4a, passed through a neutral density filter 49, and detected by a photodetector 50. The light intensity of the fundamental wave was adjusted by rotating the half-wave plate 51.

Reference numerals

4b and 4c denote reflection mirrors. For the measurement of SH intensity, p-polarized and s-polarized SH light was detected using p-polarized incident light. Further, the incident angle was changed by rotating the sample around the direction perpendicular to the ground.

As a result, the SH intensity decreased with the lapse of time from the irradiation of the ultrashort pulse light of the fundamental wave, and reached a constant value in about 300 seconds (FIG. 5).
Then, when visible light was irradiated, it restored to the initial SH intensity in about 100 seconds (FIG. 5). Reproducibility was confirmed for these changes in SH intensity. Since the second harmonic generation activity is a second-order nonlinear optical effect, it is generated in a system in which polarization is aligned in one direction. Since the original SH intensity was restored by irradiation with visible light, the decrease in SH intensity was considered to be caused by a decrease in the degree of orientational order accompanying trans-cis photoisomerization of azobenzene (see FIG. 1).

Subsequently, POM observation was performed to confirm the molecular orientation change of the Azo-NLO film. In the POM image before the fundamental wave irradiation, the dark field was obtained when the angle between the polarizing plate and the molecular orientation direction was 0 °, and the bright field when 45 °. After the fundamental wave irradiation, the light intensity slightly changed at 0 °, and the amount of transmitted light decreased at the irradiation spot at 45 °. It was revealed that the molecular orientation change was reversibly induced by fundamental wave irradiation because it was restored to the original state by irradiation with visible light. *

Next, the photoisomerization behavior of Azo-NLO film during fundamental wave irradiation was examined by measuring UV-visible absorption spectrum. As a result of irradiation with the fundamental wave under the same conditions as described above, the absorption of the ππ ^* transition based on trans-azobenzene gradually decreased with the irradiation time, and the absorption based on the nπ ^* transition of the cis isomer increased. Subsequently, when visible light was irradiated for 1 minute, the absorption spectrum was restored to the initial state. From this result, it was revealed that the prepared Azo-NLO film exhibited trans-cis photoisomerization when irradiated with light of 800 nm.

Next, when the incident angle of the fundamental wave was changed to 0 ° and the SH intensity was measured in the same manner, the absorption of the ππ ^* transition derived from trans-azobenzene was gradually reduced as in the case of 35 °. The initial state was restored by visible light irradiation. Tests using NLO films made only from NLO crosslinkers have revealed that SHG is angle-dependent and that no SH light is generated at an incident angle of 0 °.
In this test, photoisomerization occurred even at an incident angle of 0 ° where no SH light was generated. Therefore, the isomerization behavior of azobenzene by fundamental wave irradiation is induced by two-photon absorption, which is a third-order nonlinear optical effect. I understood.
From this, it was found that isomerization of azobenzene can be caused by irradiating an ultrashort pulse with a wavelength near 800 nm.

<Deformation test of Azo-NLO film>
The optical motion behavior of Azo-NLO films when irradiated with light of different wavelengths was investigated.
The 2 mm × 2 mm × 20 μm Azo-NLO film prepared above was used as a sample, and the following light was irradiated at an incident angle of 0 °.
Ultraviolet light: wavelength 400 nm, 100 fs, intensity 20 μW / cm ²
Visible light: wavelength 530 nm, stationary light, intensity 10 mW / cm ²
Near infrared light: wavelength 800 nm, 100 fs, intensity 3.7 mW / cm ²

The results are shown in FIG.
When irradiated with light having a wavelength of 400 nm, it was bent toward the light source and restored to its original shape by irradiation with visible light having a wavelength of 530 nm. On the other hand, when a fundamental wave having a wavelength of 800 nm was irradiated, the film was bent to the opposite side of the light source and restored to its original shape by irradiation with visible light. Thus, it became clear that bending can also be induced by near-infrared light irradiation.

When irradiated with light having a wavelength of 400 nm, azobenzene has a relatively high molar extinction coefficient at a wavelength of 400 nm. Therefore, the shrinkage force can be inclined in the film thickness direction due to photoisomerization, and the conventional crosslinked azobenzene liquid crystal polymer It bends in the direction of the light source in the same way as light movement. On the other hand, when light with a wavelength of 800 nm is irradiated, although photoisomerization due to two-photon absorption occurs, the absorption cross section is relatively low due to the nonlinear optical effect, and the cis-body concentration gradient becomes small. As a result, shrinkage associated with orientation changes occurs throughout the film. That is, according to the irradiation with the ultrashort pulse light with a wavelength of 800 nm, it is possible to deform in the direction designed in advance regardless of the light source direction.
In addition, it is thought that the film produced in this test was bent to the opposite side to the light source due to the initial shape.

The present invention can be used for medical instruments such as a guide wire that can be optically driven in a living body.

10 azobenzene (photochromic molecule) 101 of the transformer 102 azobenzene azobenzene cis- 11 mesogenic 12 crosslinked liquid crystal polymer film (cross-linked liquid crystal polymer material) 1 guidewire 2 wire body 22 polymer jacket (modified layer) 3 laser irradiation device 31 Laser light source 32 optical fiber

Claims

The crosslinked liquid crystal polymer material is deformed by irradiating a cross-linked liquid crystal polymer material containing a photochromic molecule with ultrashort pulse light and inducing isomerization by two-photon absorption of the photochromic molecule. A method for deforming a cross-linked liquid crystal polymer material.
The cross-linked according to claim 1, wherein the photochromic molecule in the cross-linked liquid crystal polymer material has an absorption wavelength band for ultraviolet light or blue light, and the ultrashort pulsed light is red light to infrared light. Deformation method of liquid crystal polymer material.
3. The method for deforming a crosslinked liquid crystal polymer material according to claim 1, wherein the pulse width of the ultrashort pulsed light is 1 to 5000 femtoseconds.
4. The method for deforming a crosslinked liquid crystal polymer material according to claim 1, wherein the intensity of the ultrashort pulse light is 0.1 to 10 mW / cm 2 .
The method for deforming a crosslinked liquid crystal polymer material according to any one of claims 1 to 4, wherein the photochromic molecule is azobenzene.
6. The method for deforming a crosslinked liquid crystal polymer material according to claim 1, wherein the crosslinked liquid crystal polymer material has a structure in which a polymer main chain is crosslinked by a crosslinking agent containing a photochromic molecule.
The crosslinked liquid crystal polymer material according to any one of claims 1 to 6, wherein the crosslinked liquid crystal polymer material has uniaxial orientation, and the orientation is lowered by irradiation with the ultrashort pulsed light. Deformation method.
A main body having a deformable layer formed of a crosslinked liquid crystal polymer material containing a photochromic molecule, and an ultrashort pulsed light irradiation unit for irradiating the deformable layer with an ultrashort pulsed light A light-driven molded body.
9. The light according to claim 8, wherein the photochromic molecule in the crosslinked liquid crystal polymer material has an absorption wavelength band for ultraviolet light or blue light, and the ultrashort pulsed light is red light to infrared light. Drive molded body.
The light-driven molded article according to claim 8 or 9, wherein the photochromic molecule is azobenzene.
The light-driven molded article according to any one of claims 8 to 10, wherein the crosslinked liquid crystal polymer material has a structure in which a polymer main chain is crosslinked by a crosslinking agent containing a photochromic molecule.
The light-driven molded body according to any one of claims 9 to 11, which is used by being driven in a living body.
The light-driven molded body according to claim 12, which is used by being driven in a blood vessel.
An optically driven guide wire comprising the optically driven molded body according to claim 13.
The main body portion is composed of a core wire and the deformed layer formed of a thin film formed of a crosslinked liquid crystal polymer material containing a photochromic molecule covering the surface of the core wire, and the ultrashort pulsed light irradiation portion is The light-driven guide wire according to claim 14, further comprising: a light source that generates the ultrashort pulse light; and an optical fiber that transmits the ultrashort pulse light to an irradiation position of the main body.