分子集合体における相分離現象の解明

金沢大学工学部研究課題/領域番号:02740229, 研究期間(年度):1990出典：研究課題「分子集合体における相分離現象の解明」課題番号02740229（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-02740229/）を加工して作

分子集合体系における分子のノンランダム分布

疎水性相互作用により組織化した分子集合体系を創成し、分子間相互作用によるノンランダム分布の解明と蛍光発光制御モデル系の構築を目的とした。撥水撥油性を兼ね備えたフルオロカーボン系の分子は、分子集合体中における局所的な分子凝集を実現し、蛍光発光効率に大きな影響を与えた。分布に対する分子間相互作用による影響を考慮した分子集合体中の組成分布を記述する理論を構築して、微視的環境の異なる2種類のミクロドメインが形成される現象を解明した。本研究から、希薄水溶液中でもミクロ的に相分離した反応場を提供し、反応の制御や新たな機能性発現への応用が期待される。ピレン誘導体にフルオロカーボン鎖を導入し、蛍光発光型界面活性剤を新規合成した。混合ミセル系で蛍光挙動を検討すると、希薄水溶液でも励起二量体蛍光が顕著で、ミセル中でミクロ的に凝集した状態になることが予想された。また、フルオロカーボン鎖を有する消光剤を合成し、ミセル系におけるピレンの蛍光消光挙動を検討した。その撥油性からミセルヘノンランダム分布すること、混合ミセル系では蛍光消光が顕著に抑制され、ミクロ的に相分離した状態にあることを害証した。さらに、蛍光物質としてキノリン類をミセル系に適用すると、蛍光消光挙動とミセル表面への対イオン分布の知見が得られることを見出した。以上のように、疎水性のピレン、界面活性剤型のピレン誘導体と消光剤、水溶性のキノリン類プローブを用いて、ミセル内部と外部の両面からミセル系へのプローブ分子のノンランダム分布について明らかにした。We aim to clarify the nonrandom distribution among self-organized systems and the luminescence control by intermolecular interactions. Introducing fluorocarbon chain which have various unique properties, the fluorescence intensity of probes can be significantly affected by the segregation in molecular assembly systems. The statistical distribution of probes between micelles is approached by the statistical mechanics. The theoretical model treating the interactions between probes predicts the two populations of micelles with largely different in compositions. The generation and control of various chemical reactions will be tested in the microphase separated micelle systems with a dilute aqueous solutions.We prepared the pyrene derivatives with a fluorocarbon chain. The excimer fluorescence significantly increased by the microscopic phase separation even in dilute aqueous solutions. We also found out that the pyrene fluorescence was quenched by the new quenchers with a fluorocarbon chain. The fluorescence quenching behavior can be explained by the nonrandom distribution among micelles. The observed no quenching can be explained by the existence of two kinds of mixed micelles. The counterion distribution at micelle surface was examined by the fluorescence quenching behavior of quinoline derivatives. The nonrandom distribution behavior was clarified by the hydrophobic pyrene probe, the surfactant-type pyrene and quenchers, and water-soluble quinoline probes from the viewpoint of both interior and exterior to micelle.研究課題/領域番号:10640557, 研究期間(年度):1998-2000出典：「分子集合体系における分子のノンランダム分布」研究成果報告書　課題番号10640557 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)　　　本文データは著者版報告書より作

Aqueous solution properties of pyridinium-type perfluorinated surfactants and simulation of mixture CMC

The critical micelle concentrations (CMCs) of 1,1,2,2-tetrahydroperfluoroalkylpyridinium chloride have been determined by measurements of surface tension and electrical conductivity, etc. The CMCs of perfluorinated surfactants were only about 0.02 times that of hydrocarbon one with the same carbon number. Aqueous solutions of fluorocarbon surfactants gave low surface tensions in comparison with those of hydrocarbon surfactants. The area per surfactant molecule at the airâwater interface decreased with increasing length of the fluorocarbon chain. Electromotive force measurements were made with chloride-responsive electrodes on surfactants solutions. The micelle ionization degrees decreased with increasing length of the alkyl chain. The group contribution method simulated the mixture CMCs of binary surfactants with various alkyl chain lengths. The group contribution method proved to be very useful to predict not only the mixture CMCs but also the demixing regions of binary mixtures having great differences in CMC

Convenient Estimation for Counterion Dissociation of Cationic Micelles Using Chloride-Sensitive Fluorescence Probe

Chloride-sensitive fluorescence probe provides a new approach to studying the degree of micellar counterion dissociation (α). The fluorescence of N-ethoxycarbonylmethyl-6-methoxyquinolinium bromide (MQAE) is quenched by chloride ion with linear Stern–Volmer plots. Thus the fluorescence intensity can be used to monitor the concentration of free chloride ion in micellar solutions. The Stern–Volmer plot gave a distinct break at critical micelle concentration (CMC) due to the counterion binding to micelles. The estimated α and CMCs of cationic surfactants including fluorocarbon ones were in fair agreement with the reported experimental values. The MQAE has greater sensitivity to bromide ion of CTAB than chloride ion of CTAC. The α of 0.16 for CTAB micelles was almost constant up to 0.2 M CTAB at 35°C. The α values of CTAB micelles decreased with increasing the concentrations of CTAB and NaBr along with micellar growth

What determines the size of liquid capillary condensates below the bulk melting point?

金沢大学理工研究域物質化学系Capillary condensation from vapor has been studied at temperatures below the bulk melting point Tm of the condensing substance using a surface force apparatus. Both mica and mica modified by self-assembly of a fluorinated surfactant (perfluoro-1H,1H,2H,2H-decylpyridinium chloride) have been used as substrate surfaces. The condensing liquids, cyclooctane and menthol, nearly wet (contact angle <15°) mica but show a high (∼60°) contact angle on the fluorinated surface. As in previous studies with unmodified mica, we find that both cyclooctane and menthol condense as liquids below Tm, and that the size of the condensates at solid-vapor coexistence is limited and inversely proportional to the temperature depression below Tm, or Ar. A comparison of the size of the condensates between the fluorocarbon surfaces and the mica surfaces and the quantitative dependence of the size of the condensate on ΔT for cyclooctane lead us to conclude that the maximum condensate size is determined by the equilibrium between condensed, "supercooled" liquid and vapor, and is hence proportional to the surface tension of the liquid-vapor interface. From a consideration of the equilibrium between a liquid and a hypothetical solid condensate, it is concluded that a solid condensate does not usually form for kinetic reasons although two exceptions were found in earlier work. © 2007 American Chemical Society

Effect of the side chain of N-acyl amino acid surfactants on micelle formation: An isothermal titration calorimetry study

金沢大学大学院自然科学研究科物質情報解析The enthalpy of micelle formation, critical micelle concentration (CMC), and aggregation number of micelles for seven amino acid type surfactants, sodium N-dodecanoyl-glycinate (C12Gly), -l-alaninate (C12Ala), -l-valinate (C12Val), -l-leucinate (C12Leu), -l-phenylalaninate (C12Phe), -l-glutaminate (C12Gln), and -l-threoninate (C12Thr), were obtained at three temperatures ranging from 288.15 to 308.15 K by isothermal titration calorimetry. The enthalpies of micelle formation for these surfactants were positive at 288.15 K and decreased with increasing temperature to ultimately become negative above 308.15 K. The CMC of the amino acid surfactants decreased monotonously with increasing hydrophobicity of the amino acid residue without exception, while with the exception of the C12Phe system, the enthalpy of micelle formation increased. The micellization behavior of C12Phe also deviated from that of other amino acid systems in terms of the heat capacity and the aggregation number. These results suggest the presence of a strong intra-micelle interaction between the side chains of phenylalanine. © 2007 Elsevier B.V. All rights reserved

Krafft temperature and enthalpy of solution of N-acyl amino acid surfactants and their racemic modifications: Effect of the counter ion

金沢大学工学部The Krafft temperatures and enthalpies of solution of N-hexadecanoyl alaninate and valinate, and N-tetradecanoyl phenylalaninate were obtained from differential scanning calorimetry. The Krafft temperature of N-acyl amino acid surfactant increased with decreasing size of the counter ion, with some exceptions. The enthalpy of solution was endothermic and increased with decreasing size of the counter ion except for the cases of lithium salt. The results showed that the L-L interaction in the solid state of N-hexadecanoyl amino acid surfactant salt was superior to the D-L interaction for both the alanine and valine systems when the counter ion size increased. However, the D-L interaction was still advantageous for the phenylalanine system with Cs+ as a counter ion. Both Fourier transform infrared spectroscopy studies and theoretical calculations suggested that the difference in magnitudes of the interactions between peptide and counter ion was a dominant factor for the chiral effect

Aggregation behavior of cationic fluorosurfactants in water and salt solutions. A CryoTEM survey

金沢大学理工研究域物質化学系The aggregation behavior of the cationic fluorocarbon surfactants 1,1,2,2-tetrahydroperfluoroalkylpyridinium chloride and 2-hydroxy-1,1,2,3,3-pentahydroperfluoroalkyldiethylammonium chloride in aqueous solution have been studied using cryo-transmission electron microscopy as the main technique. The effects on aggregate structure of factors such as surfactant and salt concentration, counterion type, and alkyl chain length were investigated. Similar to hydrocarbon surfactants the fluorocarbon surfactants self-assemble into various aggregates such as micelles, threadlike micelles, vesicles, and other lamellar aggregates. A distinctive property of the fluorocarbon surfactants is their tendency to form structures with little curvature, such as cylindrical micelles and bilayer structures. Even a very small reduction of the repulsion between the headgroups is sufficient to accomplish a sphere to rod transition, so that a solution of globular micelles in water is turned into a highly viscous, sometimes viscoelastic solution on the addition of low concentrations of a simple salt. The differences between the fluorocarbon and hydrocarbon surfactants are discussed. © 1999 American Chemical Society

Contrast variation SANS investigation of composition distributions in mixed surfactant micelles

金沢大学理工研究域物質化学系Small angle neutron scattering measurements have been performed on three systems (HFDeP-d5-C (N-1(1,1,2,2-tetrahydroperfluorodecanoyl)pyridinium-d5 chloride)/C16PC in 63 mM NaCl; HFDeP-d5-C/C12PC in 200 mM NaCl, and as an example of an ideally mixed system, SDS/SDS-d25 in 200 mM NaCl) containing micelles formed in a binary mixture of surfactants, in order to investigate the composition distribution of the mixed micelles. The experimental data were collected varying the contrast between the average scattering length density of micelles and aqueous solvent by changing the H2O/D 2O ratio. Analysis of data includes a model-independent approach - the indirect Fourier transformation method and direct modeling - simultaneous fit at all contrasts by the scattering from micelles of equal size and shape with composition distribution and an effective interaction. It has earlier been shown (Almgren, M.; Garamus, V. M. J. Phys. Chem. B 2005, 109, 11348) that for micelles of equal size, independent of the composition, and with negligible intermicellar interactions, the scattered intensity at zero angle varies quadratically with the contrast, with the minimum intensity at the nominal match point proportional to σ2, the variance of the micelle composition distribution. Within the regular solution framework, the composition distribution and its variance are uniquely defined by the value of the interaction parameter and the micelle aggregation number. At 25°C, the first system gave σ = 0.37, corresponding to a broad, bimodal composition distribution, the second σ = 0.22, a broad distribution with a shallow minimum at the midpoint. For SDS/SDS-d25, we found σ = 0.006 ± 0.030, which is a smaller value than that of the binominal composition distribution expected for an ideally mixed system. © 2007 American Chemical Society