JP5120909B2 - Method for producing colloidal crystal gel, colloidal crystal gel, and optical element - Google Patents

Description

  The present invention relates to a method for producing a colloidal crystal gel, and more particularly, to a method for producing a colloidal crystal gel that makes light of a specific wavelength band having a relatively wide spread opaque or low-transmitted.

  In recent years, research on photonic crystals having a periodic refractive index distribution has been actively conducted. A photonic crystal has a light forbidden band (photonic band gap) that does not transmit light of a specific wavelength, and an optical functional device, an optical chip, an optical amplifier, a laser using such characteristics. Furthermore, development of new technologies such as quantum communication and computation is also expected.

  As such a photonic crystal, a colloidal crystal in which monodisperse fine particles form a self-organized three-dimensional structure by electrostatic interaction between particles in a colloidal dispersion is known. Recently, a colloidal crystal gel in which particles are immobilized by applying a polymer gel to the colloidal crystal has been developed. Such a colloidal crystal may have a wavelength band (stop band) in which light is not transmitted or is low-transmitted due to the formation of a photonic band gap from the visible light to the near-infrared light region due to its lattice constant. As is known, optical applications such as filters, switches, limiters, sensors, etc. are expected.

  When utilizing the optical characteristics of such colloidal crystals as photonic crystals, the use of stopbands that reflect visible light is central, so in addition to the technology that arbitrarily changes the center wavelength of the stopbands, A technique for arbitrarily changing the width is required.

  As a technique for arbitrarily changing the center wavelength of the stop band of the colloidal crystal, there is a technique for changing the interstitial distance of particles by swelling or shrinking the gel by applying stress or replacing the solvent (for example, Non-Patent Document 1). checking.). However, it is known that the stop band width is determined by the refractive index contrast between the particles and the solvent, but a technique for controlling these has not been developed yet.

Iwayama et al. Langmuir, Vol. 19, pages 977-980, 2003.

Accordingly, an object of the present invention is to provide a method for producing a colloidal crystal gel with a controlled stop band width (impermeable band). Here, the stop band width is a wavelength range that is caused by the formation of the photonic band gap and that is difficult to transmit light in a specific wavelength band having a spread. For example, the light transmittance is 40% or less. It is determined quantitatively by defining the wavelength range to be, but the transmittance value at this limit may be set to a range different from 40% depending on the application.
Here, “control of the stop band width” means to arbitrarily change the stop band width of the colloidal crystal gel.

The method for producing a colloidal crystal gel according to the present invention is a step of providing a colloidal crystal, wherein the colloidal crystal includes a solvent, a monomer, a crosslinking agent, a photopolymerization initiator, and particles that are periodically spatially arranged. a step, a step of irradiating light to the colloidal crystal, the irradiation conditions of the light does not satisfy the critical irradiation conditions, and the gel within the colloidal crystal uneven, a step, wherein Generating a plurality of regions having different interplanar spacing in the colloidal crystal and holding the colloidal crystal until there is no change in the opaque band of the transmission spectrum of the colloidal crystal, thereby achieving the above object .

  The particles may be selected from the group consisting of polystyrene particles, silica particles, and polymethyl methacrylate particles.

  The monomer may be N-methylol acrylamide or acrylamide.

  The providing step may include bubbling with an inert gas.

  The providing step may include the step of flowing the colloidal crystal using a capillary cell.

  In the step of irradiating the light, a light emitting diode can be used.

In the holding step , each of the interplanar spacings in the plurality of regions may be enlarged and reduced in a direction perpendicular to the wall surface of the cell provided with the colloidal crystal.

The method for producing a colloidal crystal gel according to the present invention is a step of providing a colloidal crystal, wherein the colloidal crystal includes a solvent, a monomer, a crosslinking agent, a photopolymerization initiator, and particles that are periodically spatially arranged. And a step of irradiating the colloidal crystal with light, wherein the irradiation condition of the light does not satisfy a critical irradiation condition, and the gelation in the colloidal crystal is made nonuniform. Holding the colloidal crystal, generating a plurality of regions having different interplanar spacing in the colloidal crystal, and stopping the holding before there is no change in the opaque band of the transmission spectrum of the colloidal crystal; and The step of irradiating the colloidal crystal with further light after the holding step, the light irradiation condition in the step of irradiating the light, and the light irradiation in the step of irradiating the further light. Total light irradiation conditions and conditions, include at least the critical irradiation condition is satisfied, and a step, thereby achieving the above object.

The colloidal crystal gel according to the present invention includes a step of providing a colloidal crystal comprising a solvent, a monomer, a crosslinking agent, a photopolymerization initiator, and particles periodically arranged in space, and a step of irradiating the colloidal crystal with light. The irradiation condition of the light does not satisfy the critical irradiation condition and makes the gelation in the colloidal crystal non-uniform, and generates a plurality of regions having different plane intervals in the colloidal crystal, The colloidal crystal is manufactured by a method including and including the step of holding the colloidal crystal until there is no change in the opaque band of the transmission spectrum of the colloidal crystal, and has a plurality of regions having different face spacings, thereby achieving the above object. .

  The colloidal crystal gel can be used for the optical element according to the present invention.

  The production method according to the present invention includes a step of providing a colloidal crystal, a step of irradiating the colloidal crystal with light that does not satisfy critical irradiation conditions, and a step of holding the colloidal crystal. Since light is irradiated so as not to satisfy the critical irradiation conditions for gelation, gelation becomes insufficient, and spatial unevenness (regions with different degrees of gelation) occurs in the degree of gelation. Thereafter, by holding the colloidal crystal irradiated with light, colloidal crystal gels having different degrees of swelling are generated depending on the location. As a result, a distribution occurs in the lattice spacing in the colloidal crystal gel, and a wide colloidal crystal gel with an impermeable band or a low transmission band can be produced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram showing a process for producing a colloidal crystal gel of the present invention.
Each process will be described.
Step S110: A colloidal crystal is provided. Any known method can be used to produce the colloidal crystal. For example, a desalting method (a method for removing impurity salts with an ion exchange resin or the like) and a concentrating method (a method for increasing the particle concentration by evaporation of a solvent, centrifugation, or the like) are not limited thereto. The colloidal crystal includes a solvent and periodically spatially arranged particles.
The particles are also called colloidal particles, and those having an average particle diameter of 50 nm to 1000 nm can be adopted. The particles can preferably be selected from the group consisting of, but not limited to, silica particles, polystyrene particles, and polymethylmethacrylate particles. The dispersion medium of the colloidal crystal is water or an aqueous solvent. An aqueous solvent is an aqueous solution of a water-soluble compound. Specifically, for example, it may be a water-soluble salt such as sodium chloride or potassium chloride, or an alcohol such as ethanol or ethylene glycol, but is not limited thereto.

  The colloidal crystal further includes a monomer, a crosslinking agent, and a photopolymerization initiator for later gelation. The monomer can be, for example, N-methylolacrylamide or acrylamide. The crosslinker can be, for example, bisacrylamide. The photopolymerization initiator can be, for example, camphorquinone. Here, the particles form a lattice plane that is parallel to a plane perpendicular to a specific direction (hereinafter referred to as a base plane) and has substantially the same plane spacing throughout the colloidal crystal. Are periodically arranged in space. Such a particle arrangement structure can Bragg reflect light.

  Step S120: irradiating the colloidal crystal with light. The light is arbitrary as long as it includes a wavelength component that activates the photopolymerization initiator, but is irradiated using, for example, a light emitting diode. Note that the light irradiation conditions do not satisfy the critical irradiation conditions for the gelation of colloidal crystals. By irradiating with light, the photopolymerization initiator is excited to initiate a polymerization reaction between the monomers and between the monomer and the crosslinking agent, thereby forming a polymer network.

  Here, the critical irradiation conditions for the gelation of the colloidal crystal will be described. As a result of intensive research by the present inventors, when the light irradiation is performed at a certain intensity or longer, the transmission spectrum of the colloidal crystal after the light irradiation has stopped is stable without changing over time. It was found that the transmission spectrum changes with time if the light irradiation time is below a certain level.

  However, in this specification, the “transmission spectrum of a colloidal crystal” means a transmission spectrum when light is transmitted along an optical axis perpendicular to the substrate surface. This light irradiation time depends on the intensity of the irradiated light.

  This phenomenon is that when the light irradiation time is below a certain level, the gelation of the colloidal crystals becomes non-uniform and incomplete, and spatial unevenness (regions with different degrees of gelation) occurs in the degree of gelation. Is presumed to be the cause. That is, since the degree of swelling may vary from region to region depending on the degree of gelation, regions having different interplanar spacing can be generated in each region in the equilibration process after light irradiation.

  It should be noted that such regions having different surface intervals are on a micro scale. As described above, in order to stabilize the transmission spectrum characteristic, there is a certain light irradiation time depending on the light irradiation intensity, which is expressed as “critical irradiation condition” in this specification.

  Note that the critical irradiation conditions vary depending on the combination of particles, solvent, monomer, and crosslinker used. Also, the light irradiation can be adjusted so as not to satisfy the critical irradiation conditions by controlling the irradiation intensity and / or the irradiation time. It is desirable to investigate the critical irradiation conditions depending on the combination of materials used in advance. If the obtained critical irradiation conditions are recorded in a memory or the like, the colloidal crystal gel of the present invention can be mechanically produced by program control.

  Step S130: Hold incomplete colloidal crystals with non-uniform gelation. As a result, the swelling equilibrium of the gel structure that was not uniform in step S120 proceeds, and regions having different surface intervals are generated for each region.

  On the other hand, when the holding is stopped before the swelling equilibrium of the gel structure is completely achieved, the particles in the respective regions having different degrees of progress of the gelation generated in step S120 are interplanar spacing satisfying the Bragg reflection condition in each region. However, it does not reach the maximum value of the surface spacing distribution.

  Note that the timing of stopping the holding varies depending on the desired non-transmission band (or low transmission band). Preferably, it is desirable to examine the change of the impermeable band until the gel tissue swelling equilibrium is completely achieved by the combination of materials used in advance. If the change of the obtained impermeable band is recorded in a memory or the like, the colloidal crystal gel of the present invention can be mechanically produced by program control.

  Step S140: If the holding is stopped before the swelling equilibrium of the gel structure is completely achieved in Step S130, the colloidal crystal is further irradiated with light. As a result, the expansion of the impermeable band stops. It is presumed that this is because the unpolymerized monomer and the crosslinking agent are polymerized and the gelation proceeds completely. Again, the light can be any light as long as it contains a wavelength component that activates the photopolymerization initiator, but the irradiation conditions of the light irradiated in step S120 and the irradiation conditions of the light irradiated in step S140 If the total light irradiation conditions of the above satisfy at least the critical irradiation conditions, the expansion of the impermeable band can be stopped.

  As described above, according to the method for producing a colloidal crystal gel of the present invention, since light is irradiated so as not to satisfy the critical irradiation condition, the gelation of the colloidal crystal becomes uneven and incomplete, There may be a plurality of regions (spatial unevenness) having different degrees of gelation. Thereafter, by holding such colloidal crystals, the swelling equilibrium of the gel structure is advanced, so that the degree of swelling varies from region to region, and regions having different interplanar spacing exist. As a result, a colloidal crystal gel having a wider impermeable band or a lower transmission band as compared with the prior art is obtained.

  Subsequent to step S140, the center of the stop band may be changed while maintaining a wide impermeable band by applying stress to the colloidal crystal gel or replacing the solvent. In this way, it is possible to provide a colloidal crystal gel that does not transmit or transmits a desired wavelength band in the visible light region.

  FIG. 2 is a diagram showing a mechanism for controlling the stop bandwidth in a colloidal crystal gel according to the production method of the present invention.

  FIG. 2 (A) shows an example of the interplanar spacing distribution of the colloidal crystal gel. Here, the interplanar spacing is intended to be the interplanar spacing of the lattice planes described in Step 110 of FIG. 1 when the particles form a lattice plane in a direction parallel to the base plane. FIG. 2B shows an example of a transmission spectrum of a colloidal crystal gel. 2A and 2B, the dotted line indicates the colloidal crystal gel in the prior art, and the solid line indicates the colloidal crystal gel according to the production method of the present invention.

As shown by the dotted line in FIG. 2 (A), the face spacing of the colloidal crystal gel according to the prior art is constant over the entire colloidal crystal gel, so it is concentrated on a predetermined face spacing value and spreads over the face spacing distribution. There is almost no W ₀ . The transmission spectrum of the colloidal crystal gel having such a spacing distribution is shown by the dotted line in FIG. Here, the spread W ₀ is scarcely, as shown by the dotted line in FIG. 2B, the wavelength range that does not transmit light (opaque band) is the center wavelength of the light of Bragg reflected light. It means less than 5%.

On the other hand, a colloidal crystal gel (not shown) produced by the production method of the present invention has regions having different degrees of swelling, that is, regions having different face spacings. Thereby, as indicated by a solid line in FIG. 2A, for example, a normal surface interval distribution having a constant spread W around a predetermined surface interval value is obtained. The spreads W ₀ and W satisfy the relationship W ₀ <W.

  The surface spacing distribution shown in FIG. 2A is merely an example, and there may be any distribution such as a uniform distribution, a t distribution, and an F distribution excluding the distribution shape shown in the prior art. The transmission spectrum of the colloidal crystal gel having such a spacing distribution is shown by a solid line in FIG. Compared to the colloidal crystal gel according to the prior art shown by the dotted line in FIG. The extent and shape of the impermeable band depends on the interplanar spacing distribution of the colloidal crystal gel.

  However, in the colloidal crystal gel obtained by the production method according to the present invention, preferably, the difference in the interplanar spacing over the entire colloidal crystal gel is such that the opaque band is 5% or more and 20% or less of the central wavelength of the wavelength of Bragg reflected light. If the above condition is satisfied, it is assumed that the apparent stop bandwidth is controlled.

  Thus, according to the present invention, by intentionally providing regions having different degrees of swelling inside the colloidal crystal gel, it is possible to create a state in which the distribution of the lattice spacing is enlarged and to control the apparent stop band width. Can do. In addition, by applying stress to the colloidal crystal gel obtained according to the present invention or substituting the solvent, a colloidal crystal gel in which the center wavelength of the impermeable band is further changed can be provided.

(Embodiment 2)
FIG. 3 is a schematic view of a filter system using a colloidal crystal gel according to the present invention.
The filter system 300 includes a light source unit 310 and a filter unit 340.

  The light source unit 310 includes a light source 320 and a light collecting unit 330. As the light source 320, for example, an arbitrary light generating device such as an optical fiber or a semiconductor laser emitting different wavelengths can be used. The condensing unit 330 may be an optical system (for example, a condensing lens, a collimating lens, or the like) provided for the light emitted from the light source 320 to enter the filter unit 340, but the beam shape and beam of the light emitted from the light source 320. It is not necessary depending on the diameter. The light source unit 310 may further include a movable unit (not shown), and the position of the light source 320 may be adjusted so that light is incident on a desired location of the filter unit 340.

The filter unit 340 includes at least one colloidal crystal gel 350. The colloidal crystal gel 350 is manufactured by the method described in the first embodiment. Each of the colloidal crystal gels 350 has a different impermeable zone. Various selections of the opacity band are made according to user requirements. When the light source unit 310 does not have a movable unit, the filter unit 340 may further include a movable unit (not shown).
In the example of FIG. 3, the colloidal crystal gels 350 are arranged in a direction perpendicular to the light incident direction, but the colloidal crystal gels 350 are aligned in a direction parallel to the light incident direction. They may be arranged as follows.

Next, the operation of the filter system 300 will be described.
The light emitted from the light source 320 is emitted from the light source unit 310 through the light collecting unit 330. Next, the light is incident on the colloidal crystal gel 350 that makes the desired wavelength band of the filter unit 320 opaque. A desired wavelength band is removed from the light that has passed through the filter unit 320, and the wavelength can be selected. According to the colloidal crystal gel 350 according to the present invention, it is possible to make a wavelength having a broader spread than in the past, so that the conventional filter system can be miniaturized. When colloidal crystal gel 350 of filter unit 320 is arranged in a line in a direction parallel to the incident direction of light, the user can also extract light having a desired narrowband wavelength.

  The filter system 300 is merely an example of applying the colloidal crystal gel 350 according to the manufacturing method of the present invention, and the colloidal crystal gel according to the manufacturing method of the present invention can be applied to switches, limiters, sensors, and the like.

  Although the filter system 300 that blocks light having a specific wavelength has been described in the second embodiment, the colloidal crystal gel 350 is not limited to a filter. It should be understood that the present invention is applicable to any application that utilizes the Bragg reflection of colloidal crystal gel 350.

  The present invention will now be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

  Colloidal crystals were prepared using a desalting method with an ion exchange resin. The produced colloidal crystal (particle volume concentration 10%) contains polystyrene particles (manufactured by Duke Scientific, particle size 198 nm, particle size standard deviation 3%) and water. Next, N-methylolacrylamide (1.2 M) as a monomer, bisacrylamide (10 mM) as a crosslinking agent, and camphorquinone (400 μM) as a photopolymerization initiator were added to the colloidal crystal and mixed.

  The mixture was bubbled with argon gas (Ar bubbling) for 10 minutes. Thereby, since the dissolved oxygen in a solvent is removed, it can prevent that a photoinitiator inactivates. The mixture was then placed in a capillary cell (0.1 × 9 × 70 mm) and allowed to flow. By flowing, a shearing force is generated inside the capillary cell, and a highly crystalline colloidal crystal can be obtained in a large area.

Gelation was performed by irradiating the colloidal crystal with light using a blue diode (MORITEX, current consumption 0.47A, operating voltage 5V). The light irradiation conditions were fixed at the irradiation intensity and the irradiation time was 1 hour. Thereafter, the sample irradiated with light was kept at room temperature from 0 to 50 hours in a state in the capillary cell. Ex _1-T (0
≦ T (time) ≦ 50, T: holding time).

  The transmission spectrum of the obtained sample was performed using ImSpector V10 (Kawasaki SteiTechno-Research Corp. Japan). The reference was air. The measurement wavelength range of the transmission spectrum was 400 nm to 1000 nm. The measurement results are shown in FIG.

In order to clarify the drawing, samples Ex _1-0 , Ex _1-2 , Ex _1-7 , Ex _1-20 , and
Only shown for Ex _1-50 . From the result of the transmission spectrum, the dependency of the dip width on the holding time is shown in FIG. 6, and the dependency of the dip width on the light irradiation time is shown in FIG.

  Here, the dip in the transmission spectrum means a portion where the transmittance is drastically decreased, and is the same as the above-described non-transmission band or low transmission band. Further, in this embodiment, the dip width is determined as the wavelength width at which the transmittance is 40%.

Ex _1-50 samples were irradiated with white light, and the transmission intensities for specific wavelengths of 750 nm, 800 nm, 850 nm, 900 nm and 950 nm were imaged as contrast of light and dark. The spatial resolution was 100 μm. The results are shown in FIG.

Comparative Example 1;
In Example 1, since it is the same except having set irradiation time to 3 hours, description is abbreviate | omitted. The sample obtained at each holding time is referred to as Pr _3-T (0 ≦ T (time) ≦ 50, T: holding time).
The transmission spectrum of the obtained sample was measured in the same manner as in Example 1. The results are shown in FIGS. 4, 6 and 7 and will be described in detail.
The Pr _3-50 sample was irradiated with white light in the same manner as in Example 1, and the transmission intensity for the specific wavelength was imaged. The results are shown in FIG.

In Example 1, after irradiating with light for 1 hour, held for 7 hours (sample Ex _1-7 ), and then
Further light irradiation was performed for 3 hours at the same irradiation intensity. Since other operations are the same as those in the first embodiment, description thereof is omitted. The sample was further held for a total of 50 hours. The obtained sample is referred to as Ex _{1-7-3-T ′} (0 ≦ T ′ (time) ≦ 43, T ′: total holding time). The transmission spectrum was measured in the same manner as in Example 1. From the result of the transmission spectrum, the dependency of the dip width on the retention time is shown in FIG. 6 and will be described in detail.

  In Example 1, since it is the same except that the light irradiation is performed for 0.5 hour and then held for 50 hours, the description is omitted. The transmission spectrum of the obtained sample was measured. The results are shown in FIG.

  In Example 1, since it is the same except having been irradiated for 2 hours and then held for 50 hours, the description is omitted. The transmission spectrum of the obtained sample was measured. The results are shown in FIG.

FIG. 4 is a diagram showing transmission spectra of Ex _1-T (A) and Pr _3-T (B). Each transmission spectrum indicated by a dotted line in the figure indicates a transmission spectrum of the colloidal crystal before irradiation with light.

The dip near 840 nm seen in both FIGS. 4A and 4B is caused by Bragg reflection by a lattice plane parallel to the wall surface of the capillary cell (here, corresponding to the (111) plane of the fcc structure). Is.
As shown in FIG. 4A, after the light irradiation for 1 hour, as the holding time T becomes longer, a clear dip width (impermeable band) is observed. Specifically, the dip width spreads to both the short wavelength side and the long wavelength side, centering on 840 nm seen before light irradiation. The dip width continued to expand to 0 <T (time) ≦ 30, and T> 30 was almost constant.

  Here, when the spread of the dip width is measured at a position where the transmittance is 40%, the spread of the dip width is approximately 2.6 times when the holding time is 30 hours or more, compared to when the holding time is zero. It was. The transmittance at the dip increased at 10 ≦ T ≦ 30, but did not change when T> 30. Moreover, although these transmission spectra showed changes in the dip, no changes were seen in other regions. For example, the transmittance in the transmissive region has a high value, and no change is observed in the position of the band edge on the short wavelength side.

The spread toward the long wavelength side indicates that the (111) plane spacing is increased. In order to compensate for such enlargement, a reduction in the spacing of the (111) plane occurs, which is considered to be the cause of the spread toward the short wavelength side. This suggests that the colloidal crystal gel has a plurality of regions having different face spacings. There was no change in the spectral shape other than the dip because the expansion and contraction of the (111) plane spacing was perpendicular to the cell wall, that is, [1
11] because it occurs in the direction, meaning that the swelling of the gel in the cell does not occur isotropically.

  It was confirmed that the increase in transmittance at the dip was of a level that would not cause any problems in practical use. However, this increase in transmittance can be solved by increasing the thickness of the colloidal crystal gel.

  From the above, in the material used in Example 1, it was found that the one-hour light irradiation under the above conditions satisfied Step S120 (FIG. 1). The reason why the dip width increases in relation to the holding time is due to the generation of regions having different face spacings, but it has been shown that the face spacing does not spread infinitely but saturates at a certain value. This saturation value may depend on the light irradiation conditions in step S120 (FIG. 1). Further, since no change was observed in the spectral shape other than dip regardless of the holding time, it was confirmed that the particles did not deteriorate crystallinity without being disturbed during the holding time.

  On the other hand, as shown in FIG. 4B, after 3 hours of light irradiation, the dip width and the spectral shape were constant regardless of the holding time. This indicates that the irradiation with light for 3 hours under the above conditions satisfies the critical irradiation condition, and once the critical irradiation condition is satisfied, the dip width is fixed.

FIG. 5 is a diagram showing transmission intensity images of Ex _1-50 (A) and Pr _3-50 (B) for various specific wavelengths.

  5A and 5B show images of transmission intensities for specific wavelengths of 750 nm, 800 nm, 850 nm, 900 nm, and 950 nm from the left. From FIG. 5 (A), it can be seen that holding for 50 hours after irradiation for 1 hour makes the entire sample opaque to the wavelength range of 800 nm to 900 nm. This result coincided with the transmission spectrum of FIG. 4A, indicating that the stop band was successfully controlled. On the other hand, FIG. 5B shows that when irradiated for 3 hours, only a narrow wavelength band in the vicinity of 850 nm is made opaque even if held for 50 hours thereafter.

FIG. 6 is a diagram showing the retention time dependence of the dip widths of Ex _1-T , Ex _{1-7-3-T ′} and Pr _3-T .

In the figure, ● represents Ex _1-T , ○ represents Ex _{1-7-3-T ′} , and ▲ represents Pr _3-T . In either case, the dip width immediately after light irradiation was between 40 and 50 nm. Ex _1-T is 0 <T (time) ≦
The dip width was broadened up to 30, but when T> 30, the dip width was saturated. The saturation dip width of Ex _1-T was 117 nm. On the other hand, the dip width of Pr _3-T was constant regardless of the holding time. The saturation dip width of Pr _3-T was 47 nm.

As shown in the graph of Ex _{1-7-3-T ′} , the spread of the dip width was stopped by further light irradiation at T ′ = 0 hours before the dip width was saturated. Thereafter, there was no change in the stopped dip width even after holding for a total of 50 hours. The stopped dip width was 72 nm. This indicates that the dip width can be appropriately stopped while the dip width is widening, which may be advantageous for controlling the dip width.

  Here, what is important is that the irradiation conditions for further light irradiation exceed the critical irradiation conditions together with the irradiation conditions for the first light irradiation. Preferably, the irradiation conditions for further light irradiation are critical irradiation conditions.

  FIG. 7 is a diagram showing the light irradiation time dependence of the dip width when the holding time after light irradiation is fixed to 50 hours.

  As shown in FIG. 7, it was found that the dip width depends on the light irradiation time if the light irradiation intensity is constant in step S120 of FIG. That is, a wider dip width is obtained as the light irradiation time is shorter. This indicates that in step S120 in FIG. 1, the dip width finally obtained is wider as the irradiation condition is farther from the critical irradiation condition.

  A person skilled in the art can easily conceive that when the light irradiation time is constant, a wider dip width is obtained as the light irradiation intensity is reduced. Thus, the dip width can also be controlled by appropriately controlling the light irradiation intensity and / or the light irradiation time.

  As described above, the production method according to the present invention can form regions having different degrees of swelling, that is, regions having different interplanar spacings, in the colloidal crystal gel. Thereby, the wavelength of Bragg reflection has a spread, and the dip (non-transmission band or low transmission band) in the light transmission spectrum can be extended. In addition, such regions with different interplanar spacing of particles can be easily manufactured by irradiating light so as not to satisfy the gelation critical irradiation condition.

  Such a colloidal crystal gel is not limited to the original lattice constant, and may have a wide opaque band in the visible light and near infrared light regions. Application to optical elements such as filters, switches, limiters, and sensors using such characteristics is possible.

The figure which shows the manufacturing process of the colloidal crystal gel of this invention The figure which shows the mechanism which controls the stop band width in the colloidal crystal gel by this invention Schematic diagram of filter system using colloidal crystal gel according to the present invention The figure which shows the transmission spectrum of Ex1 _-T (A) and Pr3 _-T (B) The figure which shows the transmission intensity image with respect to various specific wavelengths of _Ex1-50 (A) and _Pr3-50 (B) Ex _1-T, shows the ex _{1-7-3-T 'and} Pr _3-T retention time of each dip width dependence The figure which shows the light irradiation time dependence of the dip width when the holding time after light irradiation is fixed to 50 hours

Explanation of symbols

300 Filter System 310 Light Source Unit 320 Light Source 330 Optical System 340 Filter Unit 350 Colloidal Crystal Gel

Claims (17)

A method for producing a colloidal crystal gel comprising:
Providing a colloidal crystal, the colloidal crystal comprising a solvent, a monomer, a cross-linking agent, a photopolymerization initiator, and periodically spatially arranged particles;
A step of irradiating the colloidal crystal with light, wherein the irradiation condition of the light does not satisfy a critical irradiation condition, and makes the gelation in the colloidal crystal non-uniform, and
Generating a plurality of regions with different interplanar spacing in the colloidal crystal and holding the colloidal crystal until there is no change in the opaque band of the transmission spectrum of the colloidal crystal.   The method of claim 1, wherein the particles are selected from the group consisting of polystyrene particles, silica particles, and polymethylmethacrylate particles.   The method according to claim 1, wherein the monomer is N-methylolacrylamide or acrylamide.   The method of claim 1, wherein the providing step comprises bubbling with an inert gas.   The method of claim 1, wherein the providing step comprises flowing the colloidal crystal using a capillary cell.   The method according to claim 1, wherein the light irradiation step uses a light emitting diode.   2. The method according to claim 1, wherein, in the holding step, each of the interplanar spacings in the plurality of regions expands and contracts in a direction perpendicular to a wall surface of a cell provided with the colloidal crystal. A method for producing a colloidal crystal gel comprising:
Providing a colloidal crystal, the colloidal crystal comprising a solvent, a monomer, a cross-linking agent, a photopolymerization initiator, and periodically spatially arranged particles;
A step of irradiating the colloidal crystal with light, wherein the irradiation condition of the light does not satisfy a critical irradiation condition, and makes the gelation in the colloidal crystal non-uniform, and
Holding the colloidal crystal, generating a plurality of regions having different interplanar spacing in the colloidal crystal, and stopping the holding before the change in the opaque band of the transmission spectrum of the colloidal crystal disappears; and
The step of irradiating the colloidal crystal with further light after the holding step , the total light irradiation condition of the light irradiation condition in the step of irradiating the light and the light irradiation condition in the step of irradiating the further light, A process that satisfies at least the critical irradiation condition ; and
Including the method . A colloidal crystal gel that broadens the wavelength of Bragg reflection obtained by a method of producing a colloidal crystal gel, the method comprising:
Providing a colloidal crystal, the colloidal crystal comprising a solvent, a monomer, a cross-linking agent, a photopolymerization initiator, and periodically spatially arranged particles;
A step of irradiating the colloidal crystal with light, wherein the irradiation condition of the light does not satisfy a critical irradiation condition, and makes the gelation in the colloidal crystal non-uniform, and
Generating a plurality of regions with different interplanar spacing in the colloidal crystal, and holding the colloidal crystal until there is no change in the opacity band of the transmission spectrum of the colloidal crystal.
The colloidal crystal gel is a colloidal crystal gel having a plurality of regions having different spacings.   The colloidal crystal gel according to claim 9, wherein the particles are selected from the group consisting of polystyrene particles, silica particles, and polymethylmethacrylate particles.   The colloidal crystal gel according to claim 9, wherein the monomer is N-methylolacrylamide or acrylamide.   The colloidal crystal gel according to claim 9, wherein the providing step includes a step of bubbling with an inert gas.   The colloidal crystal gel according to claim 9, wherein the providing step includes a step of flowing the colloidal crystal using a capillary cell.   The colloidal crystal gel according to claim 9, wherein the light irradiation step uses a light emitting diode.   The colloidal crystal gel according to claim 9, wherein in the holding, each of the interplanar spacings in the plurality of regions expands and contracts in a direction perpendicular to a wall surface of the cell provided with the colloidal crystal. A colloidal crystal gel that broadens the wavelength of Bragg reflection obtained by a method of producing a colloidal crystal gel, the method comprising:
Providing a colloidal crystal, the colloidal crystal comprising a solvent, a monomer, a cross-linking agent, a photopolymerization initiator, and periodically spatially arranged particles;
A step of irradiating the colloidal crystal with light, wherein the irradiation condition of the light does not satisfy a critical irradiation condition, and makes the gelation in the colloidal crystal non-uniform, and
Holding the colloidal crystal, generating a plurality of regions having different interplanar spacing in the colloidal crystal, and stopping the holding before the change in the opaque band of the transmission spectrum of the colloidal crystal disappears; and
The step of irradiating the colloidal crystal with further light after the holding step , the total light irradiation condition of the light irradiation condition in the step of irradiating the light and the light irradiation condition in the step of irradiating the further light, A process that satisfies at least the critical irradiation condition ; and
A colloidal crystal gel. An optical element using the colloidal crystal gel according to claim 9-16.

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