JP2004089996A - Manufacturing method of colloidal crystal of cm size - Google Patents
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この発明は、表面電荷を有するコロイド粒子から成るｃｍサイズの３次元単結晶を製造する方法に関する。 {Circle around (1)} The present invention relates to a method for producing a cm-sized three-dimensional single crystal composed of colloid particles having a surface charge.
近年、コロイド粒子が液体中で形成する結晶構造（コロイド結晶）に着目した応用展開が検討されている。コロイド結晶は粒子が三次元的に規則正しく配列した集合体であり、１）表面に電荷を持つイオン性コロイド粒子（シリカ、イオン性高分子ラテックス等）が水等の極性液体中において、粒子間の強い静電的相互作用により安定化され形成する場合と、２）非イオン性コロイド粒子がパッキングして形成する場合があるが、本発明が対象とするのは、前者のイオン性コロイド粒子系である。
コロイド結晶の結晶面間隔は、原子・分子系結晶の場合よりはるかに大きく、しばしば用いられる実験条件（イオン性粒子系の場合、粒径０．１〜１μｍ、粒子の体積分率１０−３〜１０−１）において、可視光の波長のオーダーとなる。このため、コロイド結晶は可視光のBragg回折により、イリデセンスと呼ばれる虹色の光を発し、また、可視光に対する特異的な吸収帯（フォトニックバンドギャップ）を持つ。これらの特性に基づき、コロイド結晶を用いて新規な特性を持つ光学素子を作製する試みが近年盛んに行われている。
In recent years, application development focusing on a crystal structure (colloidal crystal) formed by colloid particles in a liquid has been studied. Colloidal crystals are aggregates in which particles are regularly arranged in a three-dimensional manner. 1) Ionic colloidal particles (silica, ionic polymer latex, etc.) having a charge on the surface are mixed in a polar liquid such as water. There are a case where it is formed by being stabilized by strong electrostatic interaction and a case where it is formed by packing 2) nonionic colloid particles. The present invention is directed to the former ionic colloid particle system. is there.
The crystal plane spacing of the colloidal crystal is much larger than that of the atom / molecule type crystal, and often used experimental conditions (in the case of the ionic particle type, the particle diameter is 0.1 to 1 μm, the volume fraction of the particle is 10 −3 to 10 −3 ). In 10 -1 ), it is on the order of the wavelength of visible light. For this reason, the colloidal crystal emits iridescent light called iridescence by Bragg diffraction of visible light, and has a specific absorption band (photonic band gap) for visible light. In recent years, attempts have been actively made to produce optical elements having novel characteristics using colloidal crystals based on these characteristics.
例えば、本発明者らは、シリカコロイドを用い、塩基（ＮａＯＨ）を添加したｐＨが均一の系で、粒子表面電荷数を増加させることにより、コロイドの結晶化が生じることを見出した（非特許文献１）。更に、本発明者らは、この実験を拡張し、ｐＨが均一の系で、ＮａＯＨ濃度、添加塩（ＮａＣｌ）濃度に加えて、粒子濃度も変数とした、結晶化の３次元相図を決定し、既存の理論と比較した（非特許文献２，３）。また、顕微鏡法によりこのコロイド結晶グレインを観察して、グレインの合体による成長過程や、粒子濃度によるグレインサイズの変化を検討した（Langmuir, vol.15, No.8, 1684-2702 (1999)）。しかし、これらの論文には、相図上で液体−結晶相境界に近いほど、結晶グレインサイズは大きいことは示されているが、系統的な調査にもかかわらず、数ｃｍの単結晶は常法では得られていなかった。
また、本発明者らは、このような課題を解決するために、既にイオン性コロイドの分散液に、温度変化と共に解離度が変化する弱電離物質を加えて温度を変化させることにより、このコロイドを結晶化することができることを見出している（特許文献１）。
For example, the present inventors have found that colloidal crystallization occurs by increasing the number of particle surface charges in a system in which a base (NaOH) is added to a uniform pH using silica colloid (non-patented). Reference 1). Furthermore, the present inventors extended this experiment and determined a three-dimensional phase diagram of crystallization in a system with a uniform pH, in which the particle concentration was also a variable in addition to the NaOH concentration and the added salt (NaCl) concentration. And compared with the existing theory (Non-Patent Documents 2 and 3). The colloidal crystal grains were observed by microscopy, and the growth process due to the coalescence of the grains and the change in the grain size due to the particle concentration were examined (Langmuir, vol.15, No.8, 1684-2702 (1999)). . However, these papers show that the closer to the liquid-crystalline phase boundary on the phase diagram, the larger the crystal grain size, but despite systematic investigations, single-cm single crystals of Was not obtained by law.
In order to solve such problems, the present inventors have already added a weakly ionized substance whose degree of dissociation changes with temperature to a dispersion of an ionic colloid to change the temperature of this colloid. Can be crystallized (Patent Document 1).
本発明は、イオン性コロイド分散液から、特殊な装置や複雑な工程を必要とせずに比較的簡単にコロイド結晶を製造することのできる技術を提供することを目的とする。 An object of the present invention is to provide a technique capable of relatively easily producing colloidal crystals from an ionic colloidal dispersion liquid without requiring special equipment or complicated steps.
本発明者らは、コロイド分散液のイオン濃度や粒子濃度を結晶化条件を満たすように選択し、初期のコロイド粒子の表面電荷数が結晶化条件を下回るようにしておいて、分散液中にｐＨ勾配又はイオン濃度勾配を設けると、ｐＨの増加又はイオン濃度の減少によりコロイド粒子の表面電荷数が増加するため、コロイドの表面電荷数が結晶化条件を満たした位置にあるコロイド粒子から順次結晶化し、更に、このような結晶化条件を満たす領域を空間的に移動させると、この移動に従って大きな単結晶が形成されることを見出し、本発明を完成させた。 The present inventors have selected the ion concentration and particle concentration of the colloidal dispersion so as to satisfy the crystallization conditions, and set the initial surface charge number of the colloidal particles to be lower than the crystallization conditions. When a pH gradient or an ion concentration gradient is provided, the surface charge number of the colloid particles increases due to an increase in the pH or a decrease in the ion concentration. The inventors have further found that when a region satisfying such crystallization conditions is spatially moved, a large single crystal is formed in accordance with the movement, thereby completing the present invention.
即ち、本発明は、表面電荷を有するコロイド粒子が極性溶媒に分散されたコロイド分散液にｐＨ勾配を設け、このｐＨを徐々に上げることにより、該分散液に該コロイド粒子から成る３次元結晶を製造する方法であって、該コロイド分散液中のコロイド濃度が０．０１〜７０体積％であり、該コロイド分散液の初期ｐＨを（等電点＋２）以下として、該ｐＨ勾配を（等電点＋２）から（等電点＋６）の範囲のｐＨを含んだものとする方法である。
ｐＨ勾配を設け、ｐＨを徐々に上げるために、このコロイド溶液中に塩基又は塩基の弱酸塩を含有させた高分子ゲルを静置してもよいし、このコロイド溶液に塩基若しくは塩基の弱酸塩又はこれらを含む溶液を添加してもよいし、このコロイド溶液を高分子ゲルを介して塩基又は塩基の弱酸塩の溶液に接触させてもよい。
このようにｐＨを徐々に上げることにより、その結果、結晶化領域が空間的に移動し、大きなコロイド単結晶の生成を促すこととなる。
That is, the present invention provides a pH gradient in a colloidal dispersion in which colloidal particles having a surface charge are dispersed in a polar solvent, and gradually raises the pH to form a three-dimensional crystal composed of the colloidal particles in the dispersion. A method for producing the colloidal dispersion, wherein the colloid concentration in the colloidal dispersion is 0.01 to 70% by volume, the initial pH of the colloidal dispersion is (isoelectric point +2) or less, and the pH gradient is (isoelectricity). This is a method that includes a pH in the range of (point +2) to (isoelectric point +6).
In order to provide a pH gradient and gradually raise the pH, a polymer gel containing a base or a weak acid salt of a base may be left in the colloid solution, or a base or a weak acid salt of the base may be added to the colloid solution. Alternatively, a solution containing these may be added, or this colloid solution may be brought into contact with a solution of a base or a weak acid salt of a base via a polymer gel.
By gradually increasing the pH in this manner, as a result, the crystallization region moves spatially, which promotes the formation of a large colloid single crystal.
また、本発明は、表面電荷を有するコロイド粒子が極性溶媒に分散されたコロイド分散液にイオン濃度勾配を設け、このイオン濃度を徐々に下げることにより、該分散液に該コロイド粒子から成る３次元結晶を製造する方法であって、該コロイド分散液中のコロイド濃度が０．０１〜７０体積％であり、該コロイド分散液の初期イオン濃度を１０μＭ以上とし、該イオン濃度勾配を１μＭ〜１０ｍＭ範囲のイオン濃度を含んだものとする方法である。このイオン濃度勾配は、ある範囲のイオン濃度から成るが、１μＭ〜１０ｍＭのいずれかのイオン濃度（即ち、結晶化の起こるイオン濃度）を含めばよい。
イオン濃度勾配を設け、イオン濃度を徐々に下げるために、このコロイド溶液中にイオン交換樹脂を静置してもよい。
このようにイオン濃度を徐々に下げることにより、その結果、結晶化領域が空間的に移動し、大きなコロイド単結晶の生成を促すこととなる。
Further, the present invention provides a colloidal dispersion in which colloidal particles having surface charges are dispersed in a polar solvent, and an ion concentration gradient is provided. A method for producing crystals, wherein the colloid concentration in the colloidal dispersion is 0.01 to 70% by volume, the initial ion concentration of the colloidal dispersion is 10 μM or more, and the ion concentration gradient is 1 μM to 10 mM. It is a method that includes the ion concentration of This ion concentration gradient consists of a certain range of ion concentrations, and may include any ion concentration of 1 μM to 10 mM (that is, the ion concentration at which crystallization occurs).
In order to provide an ion concentration gradient and gradually lower the ion concentration, the ion exchange resin may be left standing in the colloid solution.
By gradually lowering the ion concentration in this manner, as a result, the crystallization region moves spatially, which promotes the generation of a large colloid single crystal.
本発明においては系を密閉系に保つことができるため、イオン性不純物による汚染を防いで高性能のコロイド結晶を得ることができる。
本発明で得られる単結晶は、単結晶としたのち、結晶を高分子ゲルで固定し、媒体の蒸発を避けるために容器内に密閉して光学素子として使用できる。コロイド結晶には、回折波長を容易に制御できる（粒子濃度を変えることによる）こと、材料が安価であること、リソグラフィー法とくらべ、コロイドの自己組織化を利用しているため、周期構造が短時間で形成されること、などのメリットがあり、光フィルター、フォトニック素子として幅広く応用可能である。
In the present invention, since the system can be maintained in a closed system, contamination by ionic impurities can be prevented and a high-performance colloidal crystal can be obtained.
The single crystal obtained by the present invention can be used as an optical element after being made into a single crystal, the crystal fixed with a polymer gel, and sealed in a container to avoid evaporation of the medium. Colloidal crystals have a short periodic structure because the diffraction wavelength can be easily controlled (by changing the particle concentration), the material is inexpensive, and self-assembly of the colloid is used as compared to lithography. It has advantages such as being formed in time, and can be widely applied as an optical filter and a photonic element.
まず、本発明の結晶生成の原理を説明する。
イオン性コロイド系においては粒子間静電的相互作用の増加に伴って結晶化が起こり、ここで、静電的相互作用の大きさは、粒子の有効表面電荷密度（σｅ）の増加、粒子の体積分率（φ）の増加、または添加塩濃度（Ｃｓ）の減少により増加することが本発明者らにより見出されている（Phys. Rev. E. 53, R4314 (1996)、Phys.Rev.Lett.vol.80,no.26,5806-5809 (1998)）。
First, the principle of the crystal formation of the present invention will be described.
In ionic colloid systems, crystallization occurs with increasing electrostatic interactions between particles, where the magnitude of the electrostatic interaction is determined by an increase in the effective surface charge density (σ e ) of the particles, Have been found by the present inventors to increase with an increase in the volume fraction (φ) or a decrease in the added salt concentration (C s ) (Phys. Rev. E. 53, R4314 (1996), Phys. .Rev. Lett. Vol. 80, no. 26, 5806-5809 (1998)).
イオン性コロイド系の相図の一例として、直径１２０ｎｍのシリカ粒子の結晶化の相図を図１に示す。σｅ、φ、Ｃｓを、この相図の固相（結晶化）領域にすることによって、コロイドは結晶化する。例えば、初期状態を有効表面電荷密度（σｅ）が十分に低い状態にしておき、塩基の添加によりｐＨを上げると、有効表面電荷密度（σｅ）が増加し、これに伴って、コロイド粒子間の静電反発が強くなり、コロイドは結晶化する。また、初期状態を添加塩濃度（Ｃｓ）が十分に高い状態にしておき、イオン濃度を減少させると、添加塩濃度（Ｃｓ）が減少し、相図の固相（結晶化）領域に入ることにより、コロイドは結晶化する。 As an example of a phase diagram of an ionic colloid system, a phase diagram of crystallization of silica particles having a diameter of 120 nm is shown in FIG. The colloid is crystallized by setting σ e , φ, and C s in the solid phase (crystallization) region of this phase diagram. For example, if the initial state is such that the effective surface charge density (σ e ) is sufficiently low and the pH is increased by adding a base, the effective surface charge density (σ e ) increases, and accordingly, the colloid particles The electrostatic repulsion between them increases, and the colloid crystallizes. Also, when the initial state is such that the added salt concentration (C s ) is sufficiently high and the ion concentration is reduced, the added salt concentration (C s ) decreases, and the solid state (crystallization) region of the phase diagram is reduced. Upon entry, the colloid crystallizes.
これまでσｅ値の制御は、コロイド粒子の表面電荷密度を積極的に変化させるべきとの考えから、コロイド分散液に専ら強電離物質（強電解質）を添加することにより行われていた。例えば、本発明者らも、以前の実験では、シリカコロイド系に水酸化ナトリウムＮａＯＨを添加し、シリカ粒子表面の弱酸性シラノール基（Ｓｉ−ＯＨ）の解離度を変化させるように試みた（Phys. Rev. E. 53, R4314 (1996)）。ＮａＯＨは強塩基であり、その解離（ＮａＯＨ→Ｎａ＋ ＋ ＯＨ−）はほぼ完全であると見なせる。しかし、これまでの技術は、ｐＨやイオン濃度を一定とするような条件でのみ行われて来たため、大きな単結晶を形成させることは出来なかった。 Up to now, the control of the σ e value has been performed by adding a strong ionizing substance (strong electrolyte) exclusively to the colloidal dispersion liquid, based on the idea that the surface charge density of the colloid particles should be positively changed. For example, the present inventors have also tried in previous experiments to add sodium hydroxide NaOH to a silica colloid system to change the degree of dissociation of weakly acidic silanol groups (Si-OH) on the surface of silica particles (Phys Rev. E. 53, R4314 (1996)). NaOH is a strong base, its dissociation (NaOH → Na + + OH - ) can be regarded as being almost completely. However, the conventional techniques have been used only under the condition that the pH and the ion concentration are kept constant, so that a large single crystal cannot be formed.
しかし、本発明においては、初期のコロイド分散液を図１の結晶化領域外になるように設定し、図１の結晶化領域をもたらすようなｐＨ勾配又はイオン濃度勾配をコロイド分散液中に設け、これを空間的に移動させることにより、コロイド結晶を成長させる点に特徴がある。また、この液相と固相（結晶）間の移動は可逆的であるので、コロイド分散液を非結晶化（液相）と結晶化（固相）とを条件次第で随時繰り返すことが可能である。 However, in the present invention, the initial colloidal dispersion is set so as to be outside the crystallization region of FIG. 1, and a pH gradient or an ion concentration gradient that provides the crystallization region of FIG. 1 is provided in the colloidal dispersion. It is characterized in that a colloidal crystal is grown by spatially moving the colloidal crystal. In addition, since the movement between the liquid phase and the solid phase (crystal) is reversible, the colloidal dispersion liquid can be repeatedly non-crystallized (liquid phase) and crystallized (solid phase) depending on conditions. is there.
従って、例えば、図２に示すように、コロイド粒子（シリカ微粒子）が水に分散されたコロイド分散液においては、表面電荷を有するコロイド粒子は、ｐＨの増加によりその表面の電荷化数が増加する。即ち、その表面を覆っている弱酸性のシラノール基（Ｓｉ−ＯＨ）のＯＨが一部解離してマイナスの電荷（Ｏ−）を持つとともに、その周囲に対イオンと呼ばれるプラスイオン（Ｈ＋）が分布している。これに塩基添加（ｐＨ増加）すると、シラノール基が部分的に中和され、表面の電荷が増加し、これにともなって、粒子間の静電反発が強くなり、結晶化が起こる。
例えば、図３に示すように系の底部に塩基を含むゲルを置いたり、又は高濃度の塩基を含む溶液を分散しないようにそのままコロイド分散液に添加すると、ここから塩基が除放されることにより、ｐＨ勾配が形成され、結晶化条件を満たしたゲル近傍から結晶化が始まり、時間とともに塩基は拡散してゆき、結晶化条件を満たす点が空間的に移動するに従って、単結晶が柱状に成長する。
Therefore, for example, as shown in FIG. 2, in a colloidal dispersion liquid in which colloidal particles (silica fine particles) are dispersed in water, the number of charged particles on the surface of the colloidal particles having a surface charge increases due to an increase in pH. . That is, the OH of the weakly acidic silanol group (Si—OH) covering the surface partially dissociates to have a negative charge (O − ), and a positive ion (H + ) called a counter ion around the OH. Are distributed. When a base is added thereto (an increase in pH), the silanol groups are partially neutralized, and the surface charge increases. As a result, electrostatic repulsion between particles becomes stronger, and crystallization occurs.
For example, if a gel containing a base is placed at the bottom of the system as shown in FIG. 3, or if a solution containing a high concentration of a base is directly added to a colloidal dispersion so as not to be dispersed, the base is released from the colloidal dispersion. As a result, a pH gradient is formed, crystallization starts near the gel that satisfies the crystallization conditions, the base diffuses with time, and as the points satisfying the crystallization conditions move spatially, the single crystal becomes columnar. grow up.
また、コロイド粒子（シリカ微粒子）が水に分散されたコロイド分散液においては、表面電荷を有するコロイド粒子は、分散液中のイオン濃度の減少により、その表面の電荷化数が増加し、コロイド粒子は結晶化する。例えば、図４に示すように系にイオン交換樹脂を置いて、Ｃｓが高い状態から出発し、Ｃｓを減少させることで、非結晶状態から結晶状態へ変化させる。このような結晶化条件を満たす点が空間的に移動するに従って、単結晶が柱状に成長する。 In a colloidal dispersion in which colloidal particles (silica fine particles) are dispersed in water, the number of charged particles on the surface of the colloidal particles having a surface charge increases due to the decrease in the ion concentration in the dispersion, and the colloidal particles Crystallizes. For example, as shown in FIG. 4, an ion-exchange resin is placed in the system, starting from a state where Cs is high, and changing from an amorphous state to a crystalline state by decreasing Cs. As the points satisfying such crystallization conditions move spatially, the single crystal grows in a columnar shape.
本発明の方法において、コロイドは、ｐＨ又はイオン濃度によって電荷数が変化するコロイド表面電荷を有するコロイドであれば特に制限なく用いることができる。このようなコロイド粒子として、シリカ粒子（ＳｉＯ２）をはじめとする、金属酸化物粒子、または弱酸／弱塩基を表面に持つ、高分子微粒子（カルボキシ変性ポリスチレンラテックスなど）を用いることができる。また、これらの成分で表面をコートした他の成分の粒子も同様の効果を有すると考えられる。従って、コロイド粒子として、シリカ粒子又は表面をシリカで被覆したコロイド粒子が好ましい。
結晶を形成することのできるコロイド粒子の粒径は約５０ｎｍ〜数μｍであり、粒径分布は標準偏差で１０％以下である。コロイド粒子の粒径が大きすぎると、粒子の沈降が著しいため結晶が形成されず、また粒径分布が広い試料は結晶を生じにくく不適である。
In the method of the present invention, any colloid having a colloid surface charge whose charge number changes depending on pH or ion concentration can be used without particular limitation. As such colloid particles, metal oxide particles such as silica particles (SiO 2 ) or polymer fine particles (such as carboxy-modified polystyrene latex) having a weak acid / weak base on the surface can be used. It is also considered that particles of other components whose surfaces are coated with these components have the same effect. Therefore, as the colloid particles, silica particles or colloid particles whose surface is coated with silica are preferred.
The particle size of the colloidal particles capable of forming crystals is about 50 nm to several μm, and the particle size distribution has a standard deviation of 10% or less. If the particle size of the colloidal particles is too large, crystals will not be formed due to remarkable sedimentation of the particles, and a sample having a wide particle size distribution is unlikely to form crystals and is unsuitable.
媒体は、極性媒体であれば特に制限なく用いることができる。例えば、水、極性の有機媒体（アルコール、エチレングリコール、ジメチルホルムアミド）及びこれらの混合物などが挙げられ、これらを用いてコロイド結晶が形成され得ることが確認されている。
媒体に関しては、コロイド粒子表面の解離基（電荷付与基）、及び添加した弱電離物質（弱酸、弱塩基、塩）が解離できるような高い誘電率を呈することができれば、水以外の液体も使用可能である。例えば、フォルムアミド類（例えば、ジメチルフォルムアミド）やアルコール類（例えば、エチレングリコール類）を使用することができる。これらはそのまま使用することもできるが、一般的には水との混合物として使用するのが好ましい。
As the medium, any polar medium can be used without particular limitation. For example, water, a polar organic medium (alcohol, ethylene glycol, dimethylformamide) and a mixture thereof are mentioned, and it has been confirmed that a colloidal crystal can be formed using these.
As for the medium, a liquid other than water can be used as long as it can exhibit a dissociation group (charge-providing group) on the surface of the colloid particles and a high dielectric constant capable of dissociating the added weakly ionized substance (weak acid, weak base, salt). It is possible. For example, formamides (for example, dimethylformamide) and alcohols (for example, ethylene glycols) can be used. These can be used as they are, but generally, they are preferably used as a mixture with water.
コロイド分散液は、市販のコロイド用粒子を水などの適当な液体媒質に分散させたり、ゾル−ゲル法などにより合成したものを用いればよいが、一般に、コロイド結晶は微量の塩（イオン性不純物）の存在によってその生成が阻害されるため、コロイド分散液の調製にあたっては充分な脱塩が必要である。例えば、水を用いる場合には、まず精製水に対して、用いた水の電気伝導度が使用前の値と同程度になるまで透析を行い、次に充分に洗浄したイオン交換樹脂（陽イオン及び陰イオン交換樹脂の混床）を試料に共存して少なくとも１週間保つことにより、脱塩精製を行う。 The colloidal dispersion may be obtained by dispersing commercially available colloidal particles in an appropriate liquid medium such as water, or by synthesizing the particles by a sol-gel method. In general, a colloidal crystal contains a trace amount of salt (ionic impurities). The production of a colloidal dispersion requires sufficient desalting since the production is inhibited by the presence of ()). For example, when using water, first, dialysis is performed on the purified water until the electric conductivity of the used water becomes substantially the same as the value before use, and then a sufficiently washed ion exchange resin (cationic resin) is used. And a mixed bed of anion-exchange resin) and coexistence in the sample for at least one week to carry out desalination purification.
単結晶成長の最適ｐＨは、粒子の荷電状態のｐＨ変化に依存するが、ｐＨ勾配が（等電点＋２）から（等電点＋６）の範囲のｐＨを含んだｐＨ勾配であることが適当である。例えば、シリカの場合には等電点はｐＨ＝２であるので、ｐＨ勾配が４〜８の範囲のｐＨを含んだｐＨ勾配であればよい。このｐＨ勾配は、ある範囲のｐＨから成るが、この範囲のいずれかのｐＨ（即ち、結晶化の起こるｐＨ）を含めばよい。なお、等電点とはコロイド懸濁液中のコロイド粒子が電場の中で泳動しないコロイド粒子固有のｐＨであり、このとき粒子の表面電荷が０となる（北原文雄・渡辺昌著「界面電気現象」共立出版 p.204 (1972)、日本化学会編「コロイド科学 第一巻」東京化学同人 p.174 (1995)等）。
即ち、例えば、シリカではこのｐＨ範囲で結晶化が起こるため、このような結晶化の起こるｐＨを含んだｐＨ勾配を設ける必要がある。このようなｐＨ勾配は、ｐＨをに上げることにより、空間的に徐々に移動し、それと共に結晶化に適した領域も徐々に移動する。この移動に伴って単結晶が形成されるものと考えられる。
また、コロイド分散液の初期ｐＨを（等電点＋２）以下とするが、例えば、シリカの場合には等電点はｐＨ＝２であるので、コロイド分散液の初期ｐＨを４以下とすればよい。
The optimum pH for single crystal growth depends on the change in pH of the charged state of the particles, but it is appropriate that the pH gradient be a pH gradient including a pH in the range of (isoelectric point +2) to (isoelectric point +6). It is. For example, in the case of silica, since the isoelectric point is pH = 2, the pH gradient may be a pH gradient including a pH in the range of 4 to 8. The pH gradient consists of a range of pH, but may include any pH in this range (ie, the pH at which crystallization occurs). The isoelectric point is the pH of the colloidal particles in the colloidal suspension in which the colloidal particles do not migrate in an electric field. At this time, the surface charge of the particles becomes 0 (Fumio Kitahara, Masaru Watanabe, “Interfacial Electricity”). Phenomenon ”Kyoritsu Shuppan p.204 (1972), edited by The Chemical Society of Japan,“ Colloid Science Vol. 1 ”, Tokyo Kagaku Doujin p.174 (1995), etc.).
That is, for example, silica crystallizes in this pH range, so it is necessary to provide a pH gradient including the pH at which such crystallization occurs. Such a pH gradient gradually moves spatially by increasing the pH, and also a region suitable for crystallization gradually moves. It is considered that a single crystal is formed with this movement.
Further, the initial pH of the colloidal dispersion is set to (isoelectric point + 2) or less. For example, in the case of silica, the isoelectric point is pH = 2. Good.
コロイド分散液にｐＨ勾配を設ける手段に特に制限はなく、いかなる方法により分散液中にｐＨ勾配を形成させてもよいが、例えば、コロイド溶液中に塩基又は塩基の弱酸塩を含有させた高分子ゲルを静置したり、コロイド溶液に塩基若しくは塩基の弱酸塩又はこれらを含む溶液を添加したり、又はコロイド溶液を高分子ゲルを介して塩基又は塩基の弱酸塩の溶液に接触させて、塩基が高分子ゲルを浸透してコロイド分散液に移行するようにすること等により、分散液中にｐＨ勾配を設けることができる。
塩基は、アンモニア、ＮａＯＨをはじめとする無機塩基、有機アンモニウムなど、いかなる有機塩基を用いることができる。弱塩基、強塩基いずれでもよい。また、塩基の弱酸塩を用いることもできる。粒子としてシリカを用いたとき、シリカのpKaの最小値は約6.4であり（R.K.Iler, "The chemistry of silica", Weiley, N.Y.,1979）、これとpKaが同等若しくはこれより大きい酸からなる塩が対象となる。このような弱酸として、例えば、炭酸H2CO3（pKa = 6.35）が挙げられる。
高分子ゲルは適当な時間内で塩基を放出することのできるものであればよく、媒体中で溶解しない、すべての合成・天然ゲルが該当する。
上記塩基や塩基の弱酸塩を含有させた高分子ゲル中の塩基の含有量は０．１〜１０ｍＭが好ましく、上記塩基を含む溶液中の塩基濃度は同じく０．１〜１０ｍＭが好ましい。
There is no particular limitation on means for providing a pH gradient in the colloidal dispersion, and a pH gradient may be formed in the dispersion by any method. For example, a polymer in which a base or a weak acid salt of a base is contained in a colloidal solution The gel is allowed to stand, a base or a weak acid salt of a base or a solution containing these is added to the colloid solution, or the colloid solution is contacted with a solution of a base or a weak acid salt of a base via a polymer gel to form a base. For example, a pH gradient can be provided in the dispersion by permeating the polymer gel and transferring to the colloid dispersion.
As the base, any organic base such as ammonia, inorganic bases such as NaOH, and organic ammonium can be used. Either a weak base or a strong base may be used. Further, a weak acid salt of a base can also be used. When silica was used as the particles, the minimum value of the pKa of the silica was about 6.4 (RKIler, "The chemistry of silica", Weiley, NY, 1979), and a salt consisting of an acid having a pKa equal to or larger than this was found. Be eligible. Such weak acids include, for example, H 2 CO 3 carbonate (pKa = 6.35).
The polymer gel may be any as long as it can release a base within an appropriate time, and includes all synthetic and natural gels that do not dissolve in a medium.
The content of the base in the polymer gel containing the base or the weak acid salt of the base is preferably 0.1 to 10 mM, and the base concentration in the solution containing the base is also preferably 0.1 to 10 mM.
更に本発明においてコロイド分散液にイオン濃度勾配を設け、これを空間的に移動させることにより、コロイド結晶を調製することができる。
イオン濃度勾配を設けるために用いるイオン交換樹脂としては、陽イオン交換樹脂、陰イオン交換樹脂及びこれらの混合物(mixbed)のいずれを用いてもよく、コロイド分散液に共存することによって、系のイオン濃度を減少させ得るものならいかなるものを用いてもよい。
イオンは価数、符号（プラスまたはマイナス）によらず、系のイオン強度をとおして、コロイド粒子間の静電相互作用を減少させうるものならいかなるイオンを用いてもよい。
単結晶成長の最適イオン濃度として、上限はコロイドが凝集しない１０ｍＭ、下限は常法で媒体を精製しうる限界の１μＭが好ましい。
Further, in the present invention, a colloid crystal can be prepared by providing an ion concentration gradient in the colloidal dispersion liquid and moving it spatially.
As the ion exchange resin used for providing the ion concentration gradient, any of a cation exchange resin, an anion exchange resin and a mixture thereof (mixbed) may be used. Any substance that can reduce the concentration may be used.
Regardless of the valence and sign (plus or minus), any ion may be used as long as it can reduce the electrostatic interaction between the colloid particles through the ionic strength of the system.
As the optimum ion concentration for single crystal growth, the upper limit is preferably 10 mM at which the colloid does not aggregate, and the lower limit is preferably 1 μM, which is a limit at which the medium can be purified by a conventional method.
コロイド単結晶を形成するためのコロイド分散液におけるコロイド粒子の濃度範囲は広く、例えば、０．０１〜７０体積％のコロイド濃度域で、通常のコロイド単結晶を生成することができる。
この場合、コロイド粒子として、特にシリカ粒子や高分子ラテックス粒子が好ましい。
結晶が形成するための時間は、後述の実施例では、１ｃｍのものが約３０時間で形成しているが、ｐＨ、塩濃度、コロイド濃度により大きく変化し、これ以上を要することもあると考えられる。
コロイド分散液の温度は、コロイド結晶化についてあまり大きな影響を与えない。溶媒の凝固点から、沸点近くまで可能である。粘性の温度変化を通して、結晶化速度に影響するものと考えられる。
The concentration range of the colloidal particles in the colloidal dispersion liquid for forming the colloidal single crystal is wide, and for example, an ordinary colloidal single crystal can be formed in the colloid concentration range of 0.01 to 70% by volume.
In this case, silica particles and polymer latex particles are particularly preferable as the colloid particles.
The time required for crystal formation is about 30 hours for a 1 cm crystal in the examples described below, but it is considered that the time greatly varies depending on the pH, salt concentration, and colloid concentration, and may take longer. Can be
The temperature of the colloidal dispersion has no significant effect on colloidal crystallization. It is possible from the freezing point of the solvent to near the boiling point. It is thought that the crystallization rate is affected through the viscosity temperature change.
なお、本発明の単結晶を形成させるためのコロイド分散液の調整にあたっては、イオン性不純物による汚染を可能な限り避ける必要がある。この点、ガラスからは塩基性不純物が水中に溶出し、粒子のσｅ値を増加させるため、ガラス製の容器及び器具の使用は避ける。また空気中の二酸化炭素は水に溶解して炭酸を生じるため、窒素等の雰囲気下で調製を行うことが望ましい。さらに、容器、器具類は精製水（電気伝導度 0.6μＳ／cm以下）で充分洗浄したのち使用する。
以下、実施例にて本発明を例証するが、本発明を限定することを意図するものではない。
In preparing the colloidal dispersion for forming the single crystal of the present invention, it is necessary to avoid contamination by ionic impurities as much as possible. In this regard, the glass basic impurities are eluted into the water, to increase the sigma e value of the particles, the use of glass container and instrument are avoided. In addition, since carbon dioxide in the air is dissolved in water to generate carbonic acid, it is desirable to perform the preparation under an atmosphere such as nitrogen. Further, containers and instruments should be thoroughly washed with purified water (electrical conductivity: 0.6 μS / cm or less) before use.
Hereinafter, the present invention is illustrated by examples, but is not intended to limit the present invention.
まず、アクリルアミドゲルを次のようにラジカル重合法により合成した。
モノマーとして、アクリルアミド１．３３Ｍ、架橋剤として、Ｎ，Ｎ’−メチレンビスアクリルアミド１０ｍＭ、光重合開始剤（和光純薬社製ＶＡ−０８６）０．４ｍｇ／ｍｌを含む水溶液５ｍｌを調製しアルゴンを１０分間バブリングして脱酸素して反応液とした。本反応液を、石英窓を備えた分解型反応セルに入れ、厚さ１ｍｍ、断面９×９ｍｍの正方形のゲルを得た。
なお、ゲル合成の際、厚さ１ｍｍ、断面９×９ｍｍの正方形で、表面にビニル基を導入した石英板を共存させることにより、石英板と強く付着したゲルとした。これにより、その後のゲルの体積変化を軽減することができ、また石英板が重しとなって、ゲルを結晶成長セル（後述）の底部に保つことができた。石英板へのビニル基の導入は次のようにした。まず、エタノール３０ｍｌ、アンモニア水２ｍｌ、メタクリロキシプロピルトリエトキシシラン（ＴＰＭ）１ｍｌを１時間混合した。次に石英板をこの溶液中に入れて、数時間保った。これにより、シランカップリング剤であるＴＰＭが石英と反応し、表面にビニル基（メタクリル酸残基）が導入された。
First, an acrylamide gel was synthesized by a radical polymerization method as follows.
5 ml of an aqueous solution containing 1.33 M of acrylamide as a monomer, 10 mM of N, N'-methylenebisacrylamide as a crosslinking agent, and 0.4 mg / ml of a photopolymerization initiator (VA-086, manufactured by Wako Pure Chemical Industries, Ltd.) was prepared. The mixture was deoxygenated by bubbling for 10 minutes to obtain a reaction solution. This reaction solution was placed in a decomposition type reaction cell equipped with a quartz window to obtain a square gel having a thickness of 1 mm and a cross section of 9 × 9 mm.
At the time of gel synthesis, a gel having a thickness of 1 mm, a cross section of 9 × 9 mm, and a quartz plate having a vinyl group introduced on the surface was coexisted to form a gel strongly adhered to the quartz plate. As a result, the subsequent change in the volume of the gel could be reduced, and the quartz plate weighed, thereby keeping the gel at the bottom of the crystal growth cell (described later). The vinyl group was introduced into the quartz plate as follows. First, 30 ml of ethanol, 2 ml of aqueous ammonia, and 1 ml of methacryloxypropyltriethoxysilane (TPM) were mixed for 1 hour. The quartz plate was then placed in this solution and kept for several hours. As a result, TPM as a silane coupling agent reacted with the quartz, and a vinyl group (methacrylic acid residue) was introduced on the surface.
このようにして得られた石英板に付着したゲルを、１ｍＭ ＮａＯＨ水溶液３ｍｌ中に１日保ち、ゲル中にＮａＯＨを含ませたのち、１×１×４ｃｍのポリスチレンセルの底部に置いた。１日後に水のｐＨは約８となり、ＮａＯＨの放出が確認された。
１×１×４ｃｍのポリスチレンセルに透析法及びイオン交換法により十分精製した３ｖｏｌ％のシリカコロイド分散液（日本触媒社ＫＥ−Ｐ１０Ｗ、粒子直径１２０ｎｍ）３ｍｌを加えた。この時点の条件は、ＣＳ＝２μＭ、φ＝０．０３（３ｖｏｌ％）、σｅ＝０．０７μＣ／ｃｍ２）（ＮａＯＨ未添加）、ｐＨは約５であった。
次に、上記石英板に付着したゲルを１ｍＭ ＮａＯＨ水溶液中に１日保つことによりゲル中にＮａＯＨを含ませたものを、この容器の底部に置き、セル上部をフィルムで密閉した後、室温にて約３０時間静置したところ、サイズが約１ｃｍの柱状の結晶成長が観察された。柱状結晶の成長のようすを図５に示す。
The gel thus attached to the quartz plate was kept in 3 ml of a 1 mM NaOH aqueous solution for 1 day, and NaOH was contained in the gel, and then placed on the bottom of a 1 × 1 × 4 cm polystyrene cell. One day later, the pH of the water was about 8, and the release of NaOH was confirmed.
To a 1 × 1 × 4 cm polystyrene cell, 3 ml of a 3 vol% silica colloid dispersion (KE-P10W, Nippon Shokubai Co., particle diameter 120 nm) sufficiently purified by a dialysis method and an ion exchange method was added. The conditions at this time were CS = 2 μM, φ = 0.03 (3 vol%), σe = 0.07 μC / cm 2 ) (without addition of NaOH), and pH was about 5.
Next, the gel adhering to the quartz plate was kept in a 1 mM NaOH aqueous solution for 1 day, and the gel containing NaOH was placed at the bottom of the container, and the cell upper portion was sealed with a film, and then cooled to room temperature. After standing for about 30 hours, columnar crystal growth of about 1 cm in size was observed. FIG. 5 shows how the columnar crystals grow.
透析法及びイオン交換法により十分精製したシリカコロイド（直径１１２ｎｍ、電荷密度０．１μＣ／ｃｍ２を水で希釈し濃度３ｖｏｌ％の分散液とした。この分散液３ｍｌを、幅１ｃｍ、奥行き１ｃｍ、高さ４ｃｍのポリスチレンセルに入れ、上部より０．０１Ｍ ＮａＯＨ１０μＬを静かに滴下したのち、セル上部を密封し、室温にて静置した。試料上部のＮａＯＨを滴下した箇所に、ただちに微結晶が生じた。結晶は重力により、１０分程度でセル底部に落下した。このとき、分散液のうち高濃度のＮａＯＨを含む部分も、結晶領域の粒子と粒子の間に閉じ込められた形でともに落下し、微結晶が試料底部に達した後、ＮａＯＨが微結晶から放出された。これにより、最初に形成された微結晶の周囲に、最大で高さ約５ｍｍ〜１ｃｍ、幅数ｍｍ〜５ｍｍの柱状結晶が生成した。 A silica colloid sufficiently purified by a dialysis method and an ion exchange method (diameter: 112 nm, charge density: 0.1 μC / cm 2 was diluted with water to obtain a dispersion having a concentration of 3 vol%. 3 ml of this dispersion was 1 cm wide, 1 cm deep, After placing in a 4 cm-high polystyrene cell, 10 μL of 0.01 M NaOH was gently added dropwise from the upper part, the upper part of the cell was sealed, and allowed to stand at room temperature. The crystal dropped to the bottom of the cell in about 10 minutes due to gravity, and at this time, the portion of the dispersion containing high-concentration NaOH also fell down in a form trapped between the particles in the crystal region. After the crystallites reached the bottom of the sample, NaOH was released from the crystallites, so that around the initially formed crystallites, a maximum height of about 5 mm to 1 cm and a width of about 5 mm to 1 cm. Columnar crystals of mm~5mm was generated.
得られた結晶の反射スペクトル測定結果を図６に示す。コロイド結晶に由来する回折ピークが明瞭に認められる。測定には、瞬間マルチチャンネル分光器（大塚電子製）を用い、光ファイバーを介して直径約３ｍｍの円形の領域のスペクトルを測定している。図６のスペクトル（ａ）、（ｂ）は、最初に形成された微結晶集合体のスペクトル、（ｃ）は柱状結晶のスペクトルである。微結晶部分には、１次ピーク（６４０ｎｍ）に加え、多結晶構造の特徴である１／√２のピーク（４５３ｎｍ）が存在するが、柱状結晶においては１次ピークのみが観察される。これは、柱状結晶グレイン部分が、配向の揃った結晶グレインであることを意味する。なお、スペクトル（ａ）〜（ｃ）で１次ピーク位置が異なるのは、重力によりシリカ粒子（比重〜２．２）が若干沈降し、濃度勾配を生じた結果である。
柱状結晶のサイズは、最初に滴下するＮａＯＨ濃度により大きく異なった。たとえば、１）５μＬ及び２）１５μＬを滴下した場合は、それぞれ最大で、１）幅約１ｍｍ、高さ３ｍｍ、及び２）幅３ｍｍ、長さ５ｍｍの柱状グレインが得られた。
FIG. 6 shows the measurement result of the reflection spectrum of the obtained crystal. A diffraction peak derived from the colloidal crystal is clearly observed. For the measurement, an instantaneous multi-channel spectrometer (manufactured by Otsuka Electronics Co., Ltd.) is used to measure the spectrum of a circular region having a diameter of about 3 mm via an optical fiber. The spectra (a) and (b) in FIG. 6 are the spectra of the microcrystal aggregates formed first, and (c) is the spectrum of the columnar crystals. In the microcrystalline portion, in addition to the primary peak (640 nm), a peak of 1 / √2 (453 nm) which is a characteristic of the polycrystalline structure exists, but only the primary peak is observed in the columnar crystal. This means that the columnar crystal grains are crystal grains with uniform orientation. The difference in the primary peak position between the spectra (a) to (c) is the result of the silica particles (specific gravity to 2.2) slightly settling due to gravity, resulting in a concentration gradient.
The size of the columnar crystals varied greatly depending on the NaOH concentration dropped first. For example, when 1) 5 μL and 2) 15 μL were dropped, a maximum of 1) about 1 mm wide and 3 mm high, and 2) 3 mm wide and 5 mm long columnar grains were obtained, respectively.
ポリスチレンラテックス（粒子直径１００ｎｍ、電荷数４．４μＣ／ｃｍ２）の２．０ｖｏｌ％水分散液にＮａＣｌ水溶液を添加して濃度０．１ｍＭとした後、０．３ｍｌのイオン交換樹脂（Ｂｉｏ−Ｒａｄ社、ＡＧ５０１Ｇ−Ｘ８（Ｄ）、２０−５０ｍｅｓｈ）を添加し、室温で静置した。幅１．３ｍｍ、の柱状結晶が樹脂近傍より成長し、その高さは、２４時間後には０．７５ｃｍ、７５時間後には１．５ｃｍ、であった。
また、同上のポリスチレンラテックス２．０ｖｏｌ％水分散液にＮａＣｌを添加して０．１ｍＭとした後、カチオン交換樹脂（Ｂｉｏ−Ｒａｄ社 ＡＧ５０Ｗ−Ｘ８、２０〜５０ｍｅｓｈ）１個を添加し、室温で静置した。幅１．１ｍｍの柱状結晶が樹脂近傍より成長し、その１２０時間後には０．６ｃｍであった。
A 2.0 vol% aqueous dispersion of polystyrene latex (particle diameter 100 nm, charge number 4.4 μC / cm 2 ) was added with an aqueous NaCl solution to a concentration of 0.1 mM, and then 0.3 ml of ion exchange resin (Bio-Rad). AG501G-X8 (D), 20-50 mesh) was added and left at room temperature. A columnar crystal having a width of 1.3 mm grew from the vicinity of the resin, and its height was 0.75 cm after 24 hours and 1.5 cm after 75 hours.
Further, after adding NaCl to a 2.0 vol% aqueous dispersion of the same polystyrene latex to make 0.1 mM, one cation exchange resin (AG50W-X8, Bio-Rad AG, 20 to 50 mesh) was added, and the mixture was added at room temperature. It was left still. Columnar crystals having a width of 1.1 mm grew from the vicinity of the resin, and after 120 hours, were 0.6 cm.
シリカコロイド粒子KE-W10（日本触媒社、粒径：113nm、有効表面電荷密度: 0.07μC/cm2、比重: 2.17）はイオン交換法及び透析法により精製を行って用いた。水はMilli-Qシステム（Millipore, MA, U.S.A.）により得た超純水（電気伝導度0.4〜0.6μS/cm）を用いた。結晶の成長は、実体顕微鏡及び顕微鏡用デジタルカメラDXM1200（1200万画素、ニコン製）と、デジタルカメラCOOLPI×950（211万画素、ニコン製）を用いて行った。
1×1×4 cmのPMMA製セルにKE-W10シリカコロイド分散液を3〜4 ml入れた。この時点の分散液のpHは約４であった。次に、表１に示す量の0.01 M水酸化ナトリウム水溶液（和光純薬工業製）を静かに滴下し、室温で静置した。
Silica colloid particles KE-W10 (Nippon Shokubai Co., Ltd., particle size: 113 nm, effective surface charge density: 0.07 μC / cm 2 , specific gravity: 2.17) were purified and used by an ion exchange method and a dialysis method. The water used was ultrapure water (electric conductivity: 0.4 to 0.6 μS / cm) obtained by a Milli-Q system (Millipore, MA, USA). Crystal growth was performed using a stereo microscope and a digital camera for microscope DXM1200 (12 million pixels, manufactured by Nikon) and a digital camera COOLPI × 950 (2.11 million pixels, manufactured by Nikon).
3 to 4 ml of the KE-W10 silica colloid dispersion was placed in a 1 × 1 × 4 cm cell made of PMMA. The pH of the dispersion at this point was about 4. Next, a 0.01 M aqueous sodium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) in the amount shown in Table 1 was gently dropped, and allowed to stand at room temperature.
このサンプルにおいては、NaOH溶液を滴下すると微結晶が直ちに上部に生成した。NaOH分散時のpHは約６であった。この微結晶の集合体はまず徐々に底部に沈降し堆積し、やがて、この微結晶の集合体から柱状にグレインが成長した。次の段階では、大きなグレインがレンガ状に生成し、最後の成長段階では、最大サイズのグレインが徐々に生成し1×1×1cmまでに達した。さらに時間が経過すると小さなグレインがcmサイズ単結晶の内部に現れた。
In this sample, when the NaOH solution was dropped, microcrystals were immediately formed at the top. The pH at the time of NaOH dispersion was about 6. The aggregate of the microcrystals first settled and deposited gradually at the bottom, and then the grains grew in a columnar shape from the aggregate of the microcrystals. In the next stage, large grains grew in the form of bricks, and in the last growth stage, grains of the largest size gradually formed, reaching 1 × 1 × 1 cm. Over time, small grains appeared inside the cm-sized single crystal.
市販の分光用セル（10×10×45mm、PSt製）の底板に穴を開けた後、高さ約5mmの高分子ゲル（アクリルアミドゲル）を設置したセルを作製し、混床型イオン交換樹脂を用いて充分に精製したシリカコロイド分散液（日本触媒社製、KE-W10、体積分率4.0%）をセルに入れた。精製直後の分散液のpHは約4であった。大気と接触した状態で1時間以上静置した初期pH9.4、9.5、9.8のNaOH水溶液にセルを浸漬した。用いた装置の模式図を図８に示す。
また、ｐH時間変化を図９に示す。空気中の炭酸ガスが溶け込むためPHが時間とともに下がる。炭酸ナトリウムの拡散によっても結晶は出来るので、このような状況でも問題は無い。
約1時間経過後、数ミリメートル幅の柱状コロイド単結晶がゲル上面から上方に向かって成長を開始した。複数個のコロイド単結晶が高さ1.0センチメートルほど成長した（約21時間経過）後、その上部にセル内全体を占有するセンチメートル角のコロイド単結晶が形成された。このコロイド単結晶は分散液上面（気液界面）まで成長し、高さ約1.5cmとなった。
After making a hole in the bottom plate of a commercially available spectroscopic cell (10 x 10 x 45 mm, made of PSt), a cell with a polymer gel (acrylamide gel) about 5 mm high was prepared, and a mixed-bed ion exchange resin was prepared. A silica colloid dispersion liquid (KE-W10, manufactured by Nippon Shokubai Co., Ltd., volume fraction 4.0%) sufficiently purified using was placed in the cell. The pH of the dispersion immediately after purification was about 4. The cell was immersed in an aqueous solution of NaOH having an initial pH of 9.4, 9.5, and 9.8 which was allowed to stand for at least one hour in contact with the atmosphere. FIG. 8 shows a schematic diagram of the apparatus used.
FIG. 9 shows the change with time in pH. PH decreases with time due to the dissolution of carbon dioxide in the air. Since crystals can be formed by diffusion of sodium carbonate, there is no problem in such a situation.
After about one hour, a columnar colloid single crystal having a width of several millimeters began to grow upward from the upper surface of the gel. After a plurality of colloid single crystals grew to a height of about 1.0 cm (about 21 hours), a centimeter-square colloid single crystal occupying the whole inside of the cell was formed thereon. This colloidal single crystal grew to the upper surface of the dispersion liquid (gas-liquid interface) and became about 1.5 cm in height.
１ コロイド分散液
２ 高分子ゲル
３ 穴
４ NaOH溶液
1 Colloid dispersion 2 Polymer gel 3 Hole 4 NaOH solution
Claims (8)
The method according to claim 6, wherein an ion exchange resin is allowed to stand in the colloid solution to form an ion concentration gradient, and the ion concentration is gradually reduced.
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| JP2006208453A (en) * | 2005-01-25 | 2006-08-10 | Toyota Central Res & Dev Lab Inc | Thin film of particulate-arrayed body, its manufacturing method and manufacturing apparatus for the thin film of particulate arrayed body |
| JP2008093654A (en) * | 2006-09-11 | 2008-04-24 | Nagoya City Univ | Colloidal crystal making method, and colloidal crystal |
| WO2009145031A1 (en) | 2008-05-28 | 2009-12-03 | 公立大学法人名古屋市立大学 | Process for producing colloidal crystal and colloidal crystal |
| US9976228B2 (en) | 2011-03-08 | 2018-05-22 | Public University Corporation Nagoya City University | Method for producing colloidal crystal and colloidal crystal |
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| JP2000044225A (en) * | 1998-07-21 | 2000-02-15 | Lucent Technol Inc | Method for forming article using sol-gel method |
| JP2002060626A (en) * | 2000-08-23 | 2002-02-26 | Fuji Photo Film Co Ltd | Water soluble polymer dispersion liquid, halogenated silver picture emulsion using the dispersion liquid and halogenated silver picture photosensitive material using the emulsion |
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| JP2000044225A (en) * | 1998-07-21 | 2000-02-15 | Lucent Technol Inc | Method for forming article using sol-gel method |
| JP2002060626A (en) * | 2000-08-23 | 2002-02-26 | Fuji Photo Film Co Ltd | Water soluble polymer dispersion liquid, halogenated silver picture emulsion using the dispersion liquid and halogenated silver picture photosensitive material using the emulsion |
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| JP2006208453A (en) * | 2005-01-25 | 2006-08-10 | Toyota Central Res & Dev Lab Inc | Thin film of particulate-arrayed body, its manufacturing method and manufacturing apparatus for the thin film of particulate arrayed body |
| JP2008093654A (en) * | 2006-09-11 | 2008-04-24 | Nagoya City Univ | Colloidal crystal making method, and colloidal crystal |
| WO2009145031A1 (en) | 2008-05-28 | 2009-12-03 | 公立大学法人名古屋市立大学 | Process for producing colloidal crystal and colloidal crystal |
| JP5663752B2 (en) * | 2008-05-28 | 2015-02-04 | 公立大学法人名古屋市立大学 | Method for producing colloidal crystal and colloidal crystal |
| US9017477B2 (en) | 2008-05-28 | 2015-04-28 | Nagoya City University | Process for producing colloidal crystal and colloidal crystal |
| US9976228B2 (en) | 2011-03-08 | 2018-05-22 | Public University Corporation Nagoya City University | Method for producing colloidal crystal and colloidal crystal |
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