非离子型可聚合聚氨酯/苯乙烯的超浓乳液聚合

研究了以非离子型可聚合聚氨酯(PUAG)和苯乙烯(St)为混合单体的超浓乳液聚合, 并且考察了n(NCO)/n(OH)摩尔比、复合乳化剂体系质量浓度[E]、不同乳化剂的种类、引发剂质量浓度[I]、单体体积分数(或分散相体积分数, 也称内相比Φ)、聚合温度等因素对聚合稳定性、动力学的影响. 同时结合光相关光谱(PCS)测定了聚合物乳胶粒子大小和粒径分布, 用透射电子显微镜(TEM)观察了粒子形态, 结果表明: 当n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, [I]＝0.8% g/g (PUAG-St), [E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O时, 超浓乳液不仅有较好的聚合稳定性和较快的聚合速率, 而且粒径小分布均匀. 同时, 在此条件下的表观动力学表达式和表观活化能分别确定为R_p＝k[I]^0.50[E]^0.73[M]^0.54和 E_a＝29.7 kJ/mol. 热失重分析(TGA)进一步表明: 调节PUAG的含量可以达到对聚苯乙烯的改性, 提高聚苯乙烯的热稳定性.     

Soap-free synthesis of highly monodisperse magnetic polymer particles with amphoteric initiator

A method applying soap-free emulsion polymerization with an amphoteric initiator, 2,2′-azobis[N-(2-carboxyethyl)-2-2-methyl-propionamidine], is proposed for synthesis of highly monodisperse particles composed of magnetic nanoparticles (Fe₃O₄/γ–Fe₂O₃) and polystyrene. The magnetic nanoparticles were pretreated by surface modification for introducing double bonds onto the particles. In the polymerization, magnetic nanoparticles were continuously supplied to the system for a certain period after the initiation of polymerization at various pH. Dissociation degrees of ionizable groups in the initiator molecules were controlled through pH by changing NH₃ concentrations at a constant NH₄Cl concentration. Selection of suitable pH in the polymerization could produce polymer particles that perfectly incorporated the supplied magnetic nanoparticles. The magnetic polymer particles had a coefficient of variation of size distribution as low as 4.3% with an average diameter of 515 nm and a saturation magnetization of 7.3 emu/g-sample. Electrophoresis measurements indicated that the magnetic polymer particles had an isoelectric point of pH 4.1.     

Microemulsion polymerization of styrene using a polymerizable nonionic surfactant and a cationic surfactant

High polymer/surfactant weight ratios (up to about 15:1) of polystyrene microlatexes have been successfully produced by microemulsion polymerization using a small amount of polymerizable surfactant, ω-methoxypoly(ethylene oxide)₄₀ undecyl α-methacrylate macromonomer (PEO-R-MA-40), and cetyltrimethylammonium bromide (CTAB). After generating “seeding particles” in a ternary microemulsion containing only 0.2 wt% CTAB and 0.1 wt% styrene, the additional styrene containing less than 1 wt% PEO-R-MA-40 was added dropwise to the polymerized microemulsion for a period of about 4 h at room temperature. PEO-R-MA-40 copolymerized readily with styrene. The stable microlatexes were bluish-transparent at a lower polymer content and became bluish-opaque at a higher polymer content. Nearly monodisperse latex particles with diameters ranging from 50 to 80 nm and their molar masses ranging from 0.6 to 1.6 × 10⁶ g/mol could be obtained by varying the polymerization conditions. The dependence of the number of particles per milliliter of microlatex, the latex particle size and the copolymer molar mass on the polymerization time is discussed in conjunction with the effect of the macromonomer concentration. Received: 25 October/2000 Accepted: 2 February 2001     

Pathways for Water Loss from Doubly Protonated Peptides Containing Serine or Threonine

The doubly-protonated peptides Ala-Ala-Xaa-Ala-Ala-Ala-Arg show extensive loss of H₂O when Xaa = Ser or Thr. Using quasi-MS³ techniques the fragmentation reactions of the [M + 2H – H₂O]⁺² ions have been studied in detail. For both Ser and Thr, the [M + 2H – H₂O]⁺² ions show three primary fragmentation reactions, elimination of CH₃CH = NH, elimination of one Ala residue, and elimination of two Ala residues, in all cases forming doubly-charged products. From a study of the further fragmentation of these products, it is concluded that elimination of two Ala residues results in formation of a three-membered aziridine ring by interaction with the adjacent amide function as H₂O is lost. The elimination of one Ala residue results in formation of a five-membered oxazoline ring through interaction with the N-terminal adjacent carbonyl function as H₂O is lost. The elimination of CH₃CH = NH appears to involve formation of an eight-membered ring by interaction with the remote N-terminal carbonyl function as H₂O is lost. However, this initial structure undergoes rearrangement through interaction with the adjacent C-terminal carbonyl function prior to further fragmentation. The [MH – H₂O]⁺ ion of Ala-Ala-Ser-Ala-Ala-Ala also shows elimination of CH₃CH = NH, one Ala residue and two Ala residues.     

Two Novel Er-Cr Ion-Pair Complexeswith Hydrogen Bonding Network: Syntheses, Crystal Structures, and Magnetic Properties

Summary.  Two novel Er-Cr ion-pair complexes ([Er(DMA)₃(H₂O)₄][Cr(CN)₆] and [Er(MPL)₄(H₂O)₃][Cr(CN)₆]·2H₂O; DMA = dimethylacetamide, MPL = 1-methyl-2-pyrrolidinone) have been synthesized. [Er(DMA)₃(H₂O)₄][Cr(CN)₆] crystallizes in the monoclinic system (space group P _c ) with a = 9.789(2), b = 11.263(2), c = 13.997(3)?, β = 105.66(3)°, V = 1485.9(5)?³, Z = 2; [Er(MPL)₄(H₂O)₃][Cr(CN)₆]·2H₂O crystallizes in the monoclinic system (space group P2₁) with a = 9.447(2), b = 13.881(3), c = 14.673(3)?, β = 101.85(3), V = 1883.1(7)?³, Z = 2. X-Ray crystal diffraction analyses reveal that the two complexes form a hydrogen bonding network structure through the CN group and H₂O molecules. Variable temperature susceptibilities for the two complexes indicate that weak antiferromagnetic interactions exist between cation and anion pairs through this hydrogen bonding network.     

Kinetic study of the formation reaction of colloidal silica spheres by transmitted-light-intensity and dynamic light-scattering measurements

Kinetic analyses of the formation reaction of colloidal silica spheres which are synthesized from ethyl silicate (EtSi), ammonia and a trace of water in ethanol are made by the transmitted-light-intensity and dynamic light-scattering methods. Sphere size versus time profiles from the two methods agree well especially at the beginning of the reaction. The polymerization starts after a certain induction time (t _i) ranging from several tens of seconds to several minutes. t _i increases as the concentrations of NH₃, EtSi and/or H₂O decrease. The apparent rates of the reaction, v ^′ are estimated from the reciprocal periods between the intersections of the linear line with the initial and final horizontal lines in the cube root of the absorbance versus time plots. Log v ^′ increases linearly with slopes of 1, 2 and 0.5 as the logarithms of the concentrations of EtSi, NH₃ and/or H₂O increase, respectively. These results are consistent with the assumption proposed earlier that the polymerization mechanism of the formation of the small preliminary particles is followed by their coalescence to form large silica spheres. Received: 10 November 1998 Accepted in revised form: 12 January 1999     

Effect of synthesis parameters on the particle size, composition and colloid stability of polypyrrole–silica nanocomposite particles

 The effect of varying the oxidant, monomer and silica sol concentrations, silica sol diameter, polymerization temperature, stirring rate and oxidant type, on the particle size, polypyrrole content and conductivity of the resulting polypyrrole– silica colloidal nanocomposites has been studied. Surprisingly, nanocomposite formation appears to be relatively insensitive to most of the above synthesis parameters. One synthesis parameter which does have a significant and reproducible effect is the stirring rate: smaller, more monodisperse nanocomposite particles are obtained from rapidly stirred reaction solutions. However, this effect is only observed for the (NH₄)₂S₂O₈ oxidant. An alternative oxidant, H₂O₂/Fe³⁺, was found to give nanocomposites of similar particle size, polypyrrole content and conductivity to those obtained using the (NH₄)₂S₂O₈ oxidant. The colloid stability of these polypyrrole–silica nanocomposite particles depends on their silica content. The colloid stability of a silica-rich nanocomposite prepared using the (NH₄)₂S₂O₈ oxidant in the presence of electrolyte was comparable to that of a silica sol, whereas a polypyrrole-rich nanocomposite prepared using FeCl₃ had markedly poorer colloid stability under these conditions. These observations are consistent with a charge stabilization mechanism for these nanocomposite particles. Received: 5 March 1998 Accepted: 27 April 1998     

Preparation of monodisperse polystyrene microspheres: effect of reaction parameters on particle formation,and optical performances of its diffusive agent application

There are three monodisperse polystyrene (PSt) microspheres, 1.10, 3.13, and 5.21 um in diameter were prepared by dispersion polymerization in ethanol/iso-propanol media. 2,2′-azobis(isobutyronitrile) (AIBN) and poly(acrylic acid) (PAA) were utilized as initiator and steric stabilizer, respectively. The effects of the PAA stabilizer, AIBN initiator, St monomer, and EtOH solvent on particle size and size distribution were reviewed in this article. Besides, optical properties including total transmittance (T%) and transmittance haze (H%) were performed when these three monodisperse PSt microspheres were applied as diffusive agents. The results were examined in terms of total interface area in a system, and came up an optimal situation between transmittance haze (H _max% = 65%) and T% when total surface area of particles is around 45,000 cm².     

Comparative study of electrolessly deposited Pd/Ag films onto p-silicon (100)-activated seed layers of Ag and Pd

Pd/Ag films were electrolessly deposited onto p-silicon (100)-activated seed layers of Ag and Pd, respectively, in the solution of 0.005 mol l⁻¹ AgNO₃ + 0.005 mol l⁻¹ PdCl₂ + 4.5 mol l⁻¹ NH₃ + 0.16 mol l⁻¹ Na₂EDTA+0.1 mol l⁻¹ NH₂NH₂ (pH 10.5) at room temperature. The morphology and composition of the films were studied comparatively by using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Cathodic polarization curves for hydrogen evolution were recorded in 0.5-mol l⁻¹ H₂SO₄ without illumination, in which the obtained films served as working electrodes. The experimental results show that the film obtained on the Ag seed layer was rather a pure Ag film and not a Pd/Ag film, and the Ag deposition rate on Pd sites was much faster than that on Ag sites.     

Preparation, Thermal Behaviour, and Crystal Structure of MgAl2F8(H2O)2

 Single crystals of MgAl₂F₈(H₂O)₂ have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF₃ and MgAlF₅(H₂O)₂ in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F ² > 2σ (F ²)) = 0.0282, wR(F ² all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF₆ octahedra with an overall composition of AlF₄ ⁻ which are connected via common fluorine atoms of [MgF_4/2(H₂O)_2/1] octahedra. Group-subgroup relations of MgAl₂F₈(H₂O)₂ to WO₃(H₂O)_0.33 and to other M(II)M(III)₂ F₈(H₂O)₂ structures are briefly discussed. Above 570°C, MgAl₂F₈(H₂O)₂ decomposes under elimination of water into α-AlF₃, β-AlF₃, and MgF₂.     

Small-angle neutron-scattering study of bis(quaternaryammonium bromide) surfactant micelles in water. Effect of the long spacer chain on micellar structure

The microstructure of the normal micelles formed by dimeric surfactants with long spacers, [Br⁻(CH₃)₂N⁺(C _m H_{2 m +1})-(CH₂) _S  -(C _m H_{2 m +1})N⁺(CH₃)₂Br⁻, m = 10 and s = 8, 10 and 12], has been investigated by small-angle neutron scattering and compared with previously reported results for micelles of the same dimeric surfactants with shorter spacers (m = 10 and s = 2, 3, 4 and 6). It was found that for dimeric surfactants with long spacers (s = 8 and 10), both micellar growth and variation in shape occur to only a small extent, if at all, compared with dimeric surfactants with short spacers. However, for the dimeric surfactant with the longest spacer, s = 12, the extent of micellar growth and shape variation is also large. These results are due to the differences in conformation of dimeric surfactants with short spacers (s = 2–6) compared with that of the surfactants with long spacers (s = 8–12). Received: 15 June 1998 Accepted: 22 July 1998     

碳酸盐共沉淀法可控制备超高倍率锂离子电池正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

采用碳酸盐共沉淀法通过调节NH_3·H_2O用量来实现可控制备超高倍率纳米结构LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2正极材料。NH_3·H_2O用量会对颗粒的形貌、粒径、晶体结构以及材料电化学性能产生较大的影响。X射线衍射(XRD)分析和扫描电镜(SEM)结果表明,随着NH_3·H_2O用量的降低,一次颗粒形貌由纳米片状逐渐过渡到纳米球状,且nNH_3·H_2O∶(nNi+nCo+nMn)=1∶2样品晶体层状结构最完善、Li~+/Ni~(2+)阳离子混排程度最低。电化学性能测试结果也证实了nNH_3·H_2O∶(nNi+nCo+nMn)=1∶2样品具有最优异的循环稳定性和超高倍率性能。具体而言,在2.7~4.3 V,1C下循环300次后的放电比容量为119 m Ah·g~(-1),容量保持率为81%,中值电压基本无衰减(保持率为97%)。在100C(18 Ah·g~(-1))的超高倍率下,放电比容量还能达到56 m Ah·g~(-1),具有应用于高功率型锂离子电池的前景。此NH_3·H_2O比例值对于共沉淀法制备其他高倍率、高容量的正/负极氧化物材料具有一定的工艺参考价值。     

Formation of y + 10 and y + 11 Ions in the Collision-Induced Dissociation of Peptide Ions

Tandem mass spectra of peptide ions, acquired in shotgun proteomic studies of selected proteins, tissues, and organisms, commonly include prominent peaks that cannot be assigned to the known fragmentation product ions (y, b, a, neutral losses). In many cases these persist even when creating consensus spectra for inclusion in spectral libraries, where it is important to determine whether these peaks represent new fragmentation paths or arise from impurities. Using spectra from libraries and synthesized peptides, we investigate a class of fragment ions corresponding to y_n-1 + 10 and y_n-1 + 11, where n is the number of amino acid residues in the peptide. These 10 and 11 Da differences in mass of the y ion were ascribed before to the masses of [+ CO – H₂O] and [+ CO – NH₃], respectively. The mechanism is suggested to involve dissociation of the N-terminal residue at the CH-CO bond following loss of H₂O or NH₃. MS³ spectra of these ions show that the location of the additional 10 or 11 Da is at the N-terminal residue. The y_n-1 + 10 ion is most often found in peptides with N-terminal proline, asparagine, and histidine, and also with serine and threonine in the adjacent position. The y_n-1 + 11 ion is observed predominantly with histidine and asparagine at the N-terminus, but also occurs with asparagine in positions two through four. The intensities of the y_n-1 + 10 ions decrease with increasing peptide length. These data for y_n-1 + 10 and y_n-1 + 11 ion formation may be used to improve peptide identification from tandem mass spectra.     

Preparation,Thermal Behaviour,and Crystal Structure of MgAl<Subscript>2</Subscript>F<Subscript>8</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>

Summary.  Single crystals of MgAl₂F₈(H₂O)₂ have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF₃ and MgAlF₅(H₂O)₂ in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F ² > 2σ (F ²)) = 0.0282, wR(F ² all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF₆ octahedra with an overall composition of AlF₄ ⁻ which are connected via common fluorine atoms of [MgF_4/2(H₂O)_2/1] octahedra. Group-subgroup relations of MgAl₂F₈(H₂O)₂ to WO₃(H₂O)_0.33 and to other M(II)M(III)₂ F₈(H₂O)₂ structures are briefly discussed. Above 570°C, MgAl₂F₈(H₂O)₂ decomposes under elimination of water into α-AlF₃, β-AlF₃, and MgF₂. Received October 29, 2001. Accepted (revised) December 6, 2001     

The Thermal Dehydration of Magnesium Aluminum Pentafluoride Dihydrate: Crystal Structures of MgAlF5(H2O)2 and MgAlF5

Summary.  Small plate-like single crystals of MgAlF₅(H₂O)₂ have been obtained during hydrothermal treatment (270°C) of microcrystalline material prepared by precipitation of stoichiometric solutions of Al₂(SO₄)₃ ·  18H₂O and Mg(NO₃)₂ · 6H₂O with diluted hydrofluoric acid. The crystal structure of MgAlF₅(H₂O)₂ has been refined from single crystal data (Imma (# 74), Z = 4, a = 7.0637(7), b = 10.1308(10), c = 6.7745(7) ?, 398 structure factors, 33 parameters, R(F² > σ(F ²)) = 0.0245, wR(F² all) = 0.0525). Main features of the inverse weberite type structure are infinite chains of trans-bridged [AlF₆] octahedra which are connected via common fluorine atoms by isolated [MgF₄(H₂O)₂] octahedra. MgAlF₅(H₂O)₂ dehydrates at temperatures above 300°C to give MgAlF₅. XRPD analysis of this phase has revealed isotypism with FeAlF₅. The crystal structure of MgAlF₅ (Immm (# 71), Z = 2, a = 7.268(1), b = 6.123(2), c = 3.543(1) ?) is built of infinite chains of edge-sharing [MgF₆] octahedra and chains of corner-sharing [AlF₆] octahedra along [001]. Upon further heating to temperatures above 500°C, MgAlF₅ decomposes to MgF₂ and α − AlF₃. Received January 15, 2001. Accepted February 12, 2001     

The Thermal Dehydration of Magnesium Aluminum Pentafluoride Dihydrate: Crystal Structures of MgAlF5(H2O)2 and MgAlF5

 Small plate-like single crystals of MgAlF₅(H₂O)₂ have been obtained during hydrothermal treatment (270°C) of microcrystalline material prepared by precipitation of stoichiometric solutions of Al₂(SO₄)₃ ·  18H₂O and Mg(NO₃)₂ · 6H₂O with diluted hydrofluoric acid. The crystal structure of MgAlF₅(H₂O)₂ has been refined from single crystal data (Imma (# 74), Z = 4, a = 7.0637(7), b = 10.1308(10), c = 6.7745(7) ?, 398 structure factors, 33 parameters, R(F² > σ(F ²)) = 0.0245, wR(F² all) = 0.0525). Main features of the inverse weberite type structure are infinite chains of trans-bridged [AlF₆] octahedra which are connected via common fluorine atoms by isolated [MgF₄(H₂O)₂] octahedra. MgAlF₅(H₂O)₂ dehydrates at temperatures above 300°C to give MgAlF₅. XRPD analysis of this phase has revealed isotypism with FeAlF₅. The crystal structure of MgAlF₅ (Immm (# 71), Z = 2, a = 7.268(1), b = 6.123(2), c = 3.543(1) ?) is built of infinite chains of edge-sharing [MgF₆] octahedra and chains of corner-sharing [AlF₆] octahedra along [001]. Upon further heating to temperatures above 500°C, MgAlF₅ decomposes to MgF₂ and α − AlF₃.     

Crystal Structures of Na3PO2S2 · 11H2O and Na3POS3 · 11H2O

Summary.  Single crystals of sodium dithiophosphate undecahydrate (Na₃PO₂S₂ · 11H₂O) and sodium trithiophosphate undecahydrate (Na₃POS₃ · 11H₂O) were grown from aqueous solution. The crystal structures of Na₃PO₂S₂ · 11H₂O (P2₁2₁2₁; a = 1248.1(1), b = 945.2(1), c = 1383.1(1) pm; R ₁ = 0.0202, wR ₂ = 0.0502) and Na₃POS₃ · 11H₂O (Pna2₁; a = 1262.0(2), b = 947.6(2), c = 1431.5(2) pm; R ₁ = 0.0720, wR ₂ = 0.1371) are related to each other in a sense that all constituting units are arranged in similar positions and with similar orientations. The geometries of the anions were determined with high accuracy; thus, the structural parameters of the POS³⁻ ₃ anion were measured for the first time. Received September 25, 2001. Accepted January 21, 2002     

Thermodynamic Properties of Quaternary Aqueous Solutions of Chlorides Charge-type 1-1*1-1*2-1: NH4Cl + NaCl + YCl2 + H2O with Y ≡ Mg2+, Ca2+, and Ba2+

Thermodynamic properties of quaternary aqueous solutions of mixed chlorides of 1-1*1-1*2-1 charge type with the cations (Na⁺, NH₄ ⁺; Mg²⁺, Ca²⁺, Ba²⁺) were determined using the hygrometric method. The quaternary systems NH₄Cl + NaCl + MgCl₂ + H₂O, NH₄Cl + NaCl + CaCl₂+ H₂O, and NH₄Cl + NaCl + BaCl₂ + H₂O have been studied at 25 °C. The water activities were measured at total molalities from 0.44 mol⋅kg⁻¹ to saturation for different ionic-strength fractions y of NH₄Cl, y=(0.20,0.50,0.80), and different ionic strength ratios z for other solutes, z=(0.20,0.50 and 0.80) for each value of y. The obtained data allows the calculation of osmotic coefficients.     

Kinetics and thermodynamics of thermal decomposition of NH<Subscript>4</Subscript>NiPO<Subscript>4</Subscript>·6H<Subscript>2</Subscript>O

The single phase NH₄NiPO₄·6H₂O was synthesized by solid-state reaction at room temperature using NiSO₄·6H₂O and (NH₄)₃PO₄·3H₂O as raw materials. XRD analysis showed that NH₄NiPO₄·6H₂O was a compound with orthorhombic structure. The thermal process of NH₄NiPO₄·6H₂O experienced three steps, which involves the dehydration of the five crystal water molecules at first, and then deamination, dehydration of the one crystal water, intramolecular dehydration of the protonated phosphate groups together, at last crystallization of Ni₂P₂O₇. In the DTA curve, the two endothermic peaks and an exothermic peak, respectively, corresponding to the first two steps’ mass loss of NH₄NiPO₄·6H₂O and crystallization of Ni₂P₂O₇. Based on Flynn–Wall–Ozawa equation, and Kissinger equation, the average values of the activation energies associated with the thermal decomposition of NH₄NiPO₄·6H₂O, and crystallization of Ni₂P₂O₇ were determined to be 47.81, 90.18, and 640.09 kJ mol⁻¹, respectively. Dehydration of the five crystal water molecules of NH₄NiPO₄·6H₂O, and deamination, dehydration of the crystal water of NH₄NiPO₄·H₂O, intramolecular dehydration of the protonated phosphate group from NiHPO₄ together could be multi-step reaction mechanisms. Besides, the thermodynamic parameters (ΔH ^≠, ΔG ^≠, and ΔS ^≠) of the decomposition reaction of NH₄NiPO₄·6H₂O were determined.     

Raman scattering spectra and molecular conformations of bis(quaternaryammonium bromide)-water systems

The dimeric bis(quaternaryammonium bromide) surfactants, [Br⁻(CH₃)₂N⁺(C _m H_{2 m +1})—(CH₂) _s —(C _m H_{2 m +1})N⁺(CH₃)₂Br⁻, s = 2, 3 and m = 4, 6, 10 and 12, s = 6 and m = 8, 10, 12], have been synthesized and the phase maps of the sm6-8-water, sm6-10-water and sm6-12-water binary systems have been determined (sm6-8 implies s = 6, m = 8). In order to examine the molecular structures of these solid samples and of their dimeric surfactant-water binary systems, Raman spectra of the simple dimeric surfactants, sm2-4 and sm3-4, in which crystal structures of the trans- and cis-type conformations have been determined by single-crystal X-ray diffraction analysis, have been investigated, and Raman bands characteristic of these skeletal structures were found in the skeletal deformation region. On the basis of these characteristic Raman bands for the two conformations, it has been concluded that the dimeric surfactants, sm6-8, sm6-10 and sm6-12 also take up a cis-type conformation in the crystalline state. Furthermore, it has been found that the Raman bands in the C—H stretching, skeletal stretching and CH₂ scissoring regions are sensitive to phase structure. Received: 21 July 1998 Accepted in revised form: 9 November 1998