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TOYOTAMA Akiko

    Graduate School of Pharmaceutical Sciences Department of Physical Chemistry of Colloid and Polymer　Associate Professor
Contact： toyotamaphar.nagoya-cu.ac.jp
Last Updated :2025/04/29

Researcher Information

URL

J-Global ID

Research Interests

  • crystal growth   センサー   コロイド結晶   コロイド   微粒子   

Research Areas

  • Nanotechnology/Materials / Composite materials and interfaces

Education

  •        -   Nagoya City University  薬学研究科
  •        -   Nagoya Institute of technology

Association Memberships

  • 日本結晶成長学会   日本化学会   高分子学会   

Published Papers

Books etc

MISC

Industrial Property Rights

  • 特許7261415:ダイヤモンド格子構造を有するコロイド結晶及びその製造方法  
    山中淳平, 豊玉彰子, 奥薗透, 藤田みのり, 青山柚里奈, 南まどか
  • 特許7253169:SPR測定用基板及びその製造方法  
    山中淳平, 平嶋尚英, 豊玉彰子, 奥薗透, 青山柚里奈, 内田文生, 瀧口義浩
  • 特許6754963:コロイド共晶、コロイド共晶固化体、及びそれらの製造方法  
    豊玉彰子, 山中淳平, 奥薗透, 宇田聡, 野澤純
  • 特許5663752 (2014/12/19):コロイド結晶の製造方法及びコロイド結晶  
    公立大学法人名古屋市立大学
  • 特許5622327 (2014/10/03):アクリル樹脂組成物およびその製造方法、並びにそれを用いて形成した建築用材、身飾品および光学材料  
  • 特許5322298:樹脂組成物およびその製造方法、並びにそれを用いて形成した建築用材および身飾品  
  • 特許5256565:コロイド結晶ゲル、コロイド結晶ゲルを製造する方法、および、素子  

Research Grants & Projects

  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/04 -2024/03 
    Author : 山中 淳平; 奥薗 透; 豊玉 彰子
     
    サブミクロンからミクロンサイズの構造周期を持つ、ダイヤモンド型の結晶格子は、可視および赤外光を閉じ込める「完全フォトニック結晶」として働くことが知られ、実用化が待望されている。本研究では、最近開発した「2次元の負荷電コロイド結晶」を第1層とし、その上に正・負の荷電コロイド粒子を交互積層する新規手法を用い、数層以上の繰り返し単位を持つ、シート状ダイヤモンド格子を構築する。本研究では粒子間の相互作用と摩擦力を最適化することで、光学特性評価が可能な、一辺がmm以上の断面を持つ格子を作製するための方法論を確立する。 令和３年度は、粒子間静電相互作用と摩擦力の調節による２層目構造の大面積化を検討した。表面修飾が容易なシリカ粒子（市販）を一層目として用いた。また、カチオン性のシランカップリング剤を用い、正電荷を導入したシリカ粒子を２層目粒子に用いた。顕微鏡観察により１、２層目を識別するため、２層目粒子には赤色蛍光色素を導入した。各層の粒子サイズは500nmおよび1μmの２種類とした。 まず、基板の表面電荷数を最適化し、１層目粒子（負に荷電）のコロイド結晶を、mm オーダーの領域に渡って吸着させることに成功した。次に、２層目粒子の吸着位置に対する添加塩濃度依存性を検討し、２層目粒子の規則性（ボンド配向パラメーター）が完全に規則的な場合の９０％に達する積層構造を得た。現状ではおよそ100μm四方に渡って規則的に２層目が吸着した構造が得られている。 このほか、界面活性剤や高分子を添加して粒子表面を修飾し、粒子間の摩擦力を調整する手法を検討しているが、複数の粒子を橋渡しして凝集を生じる場合があり、濃度条件などを改善する必要がある。 また、当初は２年目以降に計画していたが、平面波展開法によるバンド構造の計算を開始した。単層ダイヤモンドのフォトニックバンドの周波数域と粒径、屈折率の関係について、予備的な結果を得た。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Okuzono Tohru
     
    A mechanism of diffusiophoresis with chemical reaction on a charged colloidal particle has been proposed. A theoretical model that describes the dynamics of a colloidal particle and surrounding weak electrolyte solutions has been constructed. It has been shown theoretically and numerically that the phoretic motion emerges as a response to the concentration gradient of the electrolyte. It has also been shown that the symmetry breaking of the surface charge distribution due to concentration gradients generates the force which leads to the directional motion of the particle. In a system with no electrolyte concentration gradient, a constant velocity applied to the particles results in an electrostatic force in the direction of that velocity, which reduces the apparent viscosity.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Toyotama akiko
     
    Colloidal systems have been widely studied as a crystallization model for atomic systems. However, the distinction between a universal phenomenon that can be modeled with colloids and a phenomenon peculiar to colloids that is not found in atomic systems is not always be clear. Here, we studied using a depletion-attracting colloidal system in which attractive force acts between colloidal particles with coexistence of polymer. In the system, the interaction is completely opposite (attractive or repulsive) on the presence or absence of depletant inside and outside the crystal structure. Then, we focused on an influence of the particle size on the crystal shape. The crystal shapes significantly varied depending on the particle size. For the smaller particles, the crystals were more significantly facetted, while larger particles formed less ordered aggregates. The observed change in the crystal phase was explainable in terms of decreases in attraction energy on increasing the particle size.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Yamanaka Junpei
     
    Assemblies of small numbers of colloidal particles (colloidal clusters) have attracted considerable attention as (i) models to study atomic and molecular clusters, and (ii) structural units for higher order structure. Particularly, regular tetrahedral clusters are of interest, because they are units of diamond lattices, which act as perfect photonic crystals. Thus far, we have studied the colloidal clustering via Coulomb attraction between oppositely charged colloidal particles. However, frictional forces acting between the particles prevented formation of regular tetrahedral clusters with a good symmetry. Here, we tuned the frictional force by tuning the magnitude of Coulomb force. The optimum conditions to form the regular clusters were examined. Base on the present results, the space experiment on colloidal clusters will be performed in the International Space Station in 2020.
  • コロイド結晶の構造制御と新規波長選択光学材料の創製
    JST：戦略的創造研究推進事業（さきがけ）
    Date (from‐to) : 2014/10 -2018/03 
    Author : 豊玉彰子
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2014/04 -2017/03 
    Author : Toyotama Akiko
     
    Crystal defects have significant influence on properties of various materials such as melting point and electric conductivity. Therefore control the defect is quite important technique. The defect often caused by contamination due to impurity. Though many models of exclusion of impurity are proposed, it is difficult to observe that exclusion process directly.And, the colloidal crystallization has extensively been studied as models to study phase transition in general1 over the past few decades. Here, we report the behavior of "impurity" particles, which were added to the charged colloidal crystals. In the case of the impurity particles are much smaller than the main component, they were present in the stable area around the particles which form the crystal structure. Despite impurities were excluded from the crystals during the homogeneous crystallization, crystal grain growth, and unidirectional crystallization processes when they have larger diameter.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2012/04 -2015/03 
    Author : YAMANAKA Junpei; OKUZONO Tohru; TOYOTAMA Akiko
     
    We examined clustering of oppositely charged binary colloidal particles. Optimum conditions were examined for the formations of tetrahedral clusters (particle size ratio, concentration ratio, charge number, etc). We also found that clustering of polystyrene (PS) and silica particles, both of which were negatively charged, could be controlled by additions of cationic surfactant cetylpyridinium chloride (CPC); Because of the absorption of the CPC molecules, the charge number of the PS and silica particles decreased with increasing CPC concentration (Csurf) and inverted to be positive after passing through the isoelectric point (Csurf = Ciep). The hydrophobic PS particles had much lower Ciep than that of hydrophilic silica particles. When Csurf was in the region between their Ciep’s, the PS and silica particles were charged oppositely, resulted in the clustering. Constructions of higher organizations of clusters are in progress.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2012/04 -2014/03 
    Author : TOYOTAMA Akiko
     
    In-situ observation of impurities diffusion in atomic/molecular crystal lattices is quite difficult. Therefore colloidal crystals have attracted considerable attention as models to study such diffusion behavior. Colloidal crystals have various advantages to study the crystallization as models. That is, (1) the individual particles can be easily observed by optical microscopy, (2) there are various experimental parameters which control the interparticle interaction, and (3) the characteristic time is long enough to observe non-equilibrium and dynamic processes. Here, we report the direct observation of the impurity particles of the colloidal crystals by optical microscopy. We could determine the trajectory of the particles, which shows hopping behavior between two lattice points. It is the elementary step of the diffusion.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2009 -2011 
    Author : TOYOTAMA Akiko
     
    In this study, we observed nucleation and crystal growth processes of the charged colloid by using an inverted microscope. The micrographs were taken at 60 fps. By using the obtained images, the crystallization degree of the colloid were visualized, and the particle motions of the lattice vibration were analyzed. Furthermore, we could observe the inclusion and the exclusion process of the impurity particle into/from the crystal lattice structure.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2008 -2010 
    Author : YAMANAKA Jumpei; YONESE Masakatsu; TOYOTAMA Akiko
     
    Colloidal crystals have attracted considerable attentions as photonic materials. In the present study, we applied thermal annealing and zone-melting methods, which have been used for fabrications of single crystals and removing crystal defects in crystalline materials, to the colloidal crystals. We found that both sizes and optical quality of the crystals are improved by the present methods. The resulted colloidal crystals could be immobilized in polymer gels.

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