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Scattering Study (scattering + study)
Selected AbstractsUltra-Small-Angle X-Ray Scattering Study of PET/PC Nanolayers and Comparison to AFM ResultsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2008Fernando Ania Abstract The forced assembly of two immiscible polymers, produced by layer-multiplying co-extrusion, is analyzed by means of USAXS. Comparison of scattering and AFM results sheds light on many details of the nanolayered structure in PET/PC films. The role played by the volume concentration and cold crystallization of PET on the experimental scattering is discussed. The appearance of at least two scattering maxima in all cases, corresponding to higher orders of the same repeating distance, accounts for the high regularity of the developed nanostructure. It is finally shown that long spacing values, derived from a localized area in AFM, are in a good agreement with the USAXS values averaged over much larger areas. [source] Determination of Soot Particle Size in a Premixed Flame: a Static and Dynamic Light Scattering StudyPARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2003Gert Kroner Abstract In this contribution we report upon our static and dynamic light scattering experiments to characterize soot particles in flames. We studied sooting laminar premixed flame with acetylene as fuel mixed with air as oxidizer. The air equivalence ratio of the combustion was larger than one. We used a Kaskan type burner with circular geometry and a stabilizing flow of nitrogen around the flame. We focused on the determination of the size of the soot particles in the center of the flame as a function of height above burner. In addition we investigated the influence of the mixing ratio of the gases on the size of the particles. Our results show that static light scattering is better suited than dynamic light scattering for a fast and reliable characterization of soot particles in flames. The latter needs detailed a priori information about the flame to allow the unique determination of sizes from the diffusion measurements. The soot particles grow monotonously with height above burner and with decreasing air equivalence ratio. The aggregates have a fractal dimension lower than two. [source] Raman and Rayleigh scattering study of crystalline polyoxyethyleneglycolsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005M. Kozielski Abstract Results of the study of Raman and Rayleigh scattering in crystalline polyoxyethyleneglycols (PEG) and PEG 1500 aqueous solution are reported. The conformational changes of the polymer chain have been studied as a function of PEG water solution concentration and molecular weight. Intensity ratios of the gauche and trans conformation around C,C and C,O bonds have been estimated from the Raman spectra. Moreover, from the Raman band parameters the values of the order parameters versus aqueous solution concentration have been determined. The influence of an external electric field on these parameters has been analysed. Mutual orientation of polyoxyethyleneglycol chains in the crystalline and liquid state has been studied on the basis of the angular correlation parameters obtained from the Rayleigh band intensity as a function of aqueous solution concentration and molecular weight. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dynamic light scattering study of an amelogenin gel-like matrix in vitroEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2006Vassiliki Petta Amelogenin self-assembly is critical for the structural organization of apatite crystals during enamel mineralization. The aim of the present study was to investigate the influence of temperature and protein concentration on the aggregation of amelogenin nanospheres at high protein concentrations (> 4.4 mg ml,1) in order to obtain an insight into the mechanism of amelogenin self-assembly to form higher-order structures. Amelogenins were extracted from enamel scrapings of unerupted mandibular pig molars. The dynamics of protein solutions were measured using dynamic light scattering (DLS) as a function of temperature and at acidic pH. At pH 4,5.5, three kinds of particles were observed, ranging in size from 3 to 80 nm. At pH 6, heating the solution above ,,30°C resulted in a drastic change in the solution transparency, from clear to opaque. Low pH showed no aggregation effect, whilst solutions at a slightly acidic pH exhibited diffusion dynamics associated with the onset of aggregation. In addition, at the same temperature range, the hydrodynamic radii of the aggregates increased drastically, by almost one order of magnitude. These observations support the view that hydrophobic interactions are the primary driving force for the pH- and temperature-sensitive self-assembly of amelogenin particles in a ,gel-like' matrix. The trend of self-assembly in a ,gel-like matrix' is similar to that in solution. [source] In-situ small-angle neutron scattering study of pore filling and pore emptying in ordered mesoporous silicaJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2010M. Erko The capillary condensation and capillary emptying of water and perfluoropentane in ordered mesoporous SBA-15 silica is studied by in-situ small-angle neutron scattering (SANS). The SANS data can be perfectly described by a simple analytical model for spatially random pore filling (Laue scattering) for the entire range of pore-filling fractions. From this it is concluded that recently proposed pore correlations due to elastic interactions between neighbouring pores upon capillary condensation do not play a role in this system. The pores fill randomly according to their size distribution, in perfect agreement with the classical Kelvin equation. The relation between the overall pore-filling fraction as determined from the volumetric sorption isotherm, and the fraction of completely filled pores as obtained from the fit of the SANS data, allows conclusions to be drawn about the thermodynamic metastability of the adsorption process. [source] Small-angle neutron scattering study of the miscibility of metallocene-catalyzed octene linear low-density polyethylene and low-density polyethylene blendsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2009Tae Joo Shin Small-angle neutron scattering (SANS) analysis was performed to investigate the miscibility of blends of metallocene-catalyzed octene linear low-density polyethylene (octene-mLLDPE) and low-density polyethylene (LDPE). The quantitative SANS analysis found that the blends are miscible in both the melt and the quenched states. Moreover, this analysis confirmed that the radii of gyration of octene-mLLDPE(D) and LDPE(H) remain unchanged in the quenched state and that the two polymer components cocrystallize via fast crystallization from the melt state. [source] Small-angle X-ray scattering study of intramuscular fish bone: collagen fibril superstructure determined from equidistant meridional reflectionsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2008Christian Burger New insights into the bone collagen fibril superstructure have been obtained by novel small-angle X-ray scattering analysis. The analysis was carried out on the small-angle equidistant meridional reflections resulting from the periodic structure of collagen fibrils in their axial direction. Conventional two-dimensional analysis is difficult because of the large discrepancy of longitudinal and lateral length scales for individual fibrils, as well as their preferred orientation. The new approach represents an unapproximated analysis of the equidistant meridional reflections, which takes the exact separation of preferred orientation and fibril size effects into account. The analytical results (e.g. axial period, fibril diameter etc.) agree well with the parameters obtained from transmission electron microscopy. [source] Hierarchical structures formed by partially crystalline polymers in solution: from fundamentals to applications , a combined conventional, focusing and ultra-small-angle neutron scattering studyJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Dietmar Schwahn Multilevel aggregates with characteristic sizes covering four orders of magnitude, from 1,nm to 10,µm, are formed upon cooling decane solutions of poly(ethylene-butene) random copolymers (designated as PEB- n, where n is the number of ethyl side branches per 100 backbone C atoms) and wax-containing mixed solutions. The partially crystalline PEB-7.5 copolymers form two distinct morphologies that evolve on a range of length scales. When these polymers are mixed with wax molecules having a crystallization point lower than the polymer aggregation temperature, a hierarchy of morphologies evolves on decreasing the temperature. The multilevel structures were elucidated by combining conventional small-angle neutron scattering, focusing small-angle neutron scattering and ultra-small-angle neutron scattering investigations with microscopy. Contrast-matching analysis of the wax and copolymer components within the common morphologies revealed the wax-crystal modification capacity of the PEB-7.5 copolymers. Since the copolymers limit the growth of wax crystals, they are potential pour-point depressants for the fuel industry. [source] Vesicles as reactors of nanoparticles: an anomalous small-angle X-ray scattering study of the domains rich in copper ionsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Attila Bóta The formation of copper hydroxide and copper oxide particles in the gaps among the stacks of multilamellar vesicles is described, illustrating a new pathway in the preparation of nanometre-scale particles. The in situ structural characterization of both the solid particles and the vesicles as a reaction medium was performed in the initial and final states of the process by using anomalous small-angle X-ray scattering (ASAXS) and freeze-fracture methods. The ASAXS method provides a description of the particle-size distribution of the copper nanoparticles, in spite of the fact that they are present in low concentration. This method allows the particle formation and growth to be monitored throughout the whole time range of the synthesis. [source] Fracture of poly(vinylidene fluoride): a combined synchrotron and laboratory in-situ X-ray scattering studyJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Günther A. Maier Semi-crystalline polymers show a complex fracture mechanism, which is controlled by the micro-mechanisms associated with formation and breakdown of a plastic deformation region. Such regions develop at notches, cracks or other stress-raising defects. In the present paper, we use time-resolved synchrotron X-ray scattering techniques during the deformation process in poly(vinylidene fluoride) to study the plastic zone formation and fracture processes at different strain rates. This gives new insight into the micro-mechanisms of cavitation, lamellae separation and fibril formation in this particular material. [source] A small-angle neutron scattering study of fine-scale NbC precipitation kinetics in the ,-Fe,Nb,C systemJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2006F. Perrard The fine-scale precipitation of NbC in ferrite has been quantitatively characterized in the temperature range 873,1073,K for two alloy compositions, containing respectively 800,p.p.m. Nb and 400,p.p.m. Nb (by weight). Transmission electron microscopy (TEM) has revealed that the precipitates are located on dislocations, and have a plate-like morphology with an average aspect ratio between 2 and 3. Small-angle neutron scattering (SANS) has been systematically used to determine the precipitation kinetics. The validity of the quantitative SANS measurements of size and volume fraction has been assessed by TEM image analysis and chemical dissolution experiments. The precipitation kinetics is observed to depend strongly on temperature but to be similar for the two alloy compositions. From the measurements, it is inferred that precipitate nucleation is extremely rapid, in relation to the nature of the nucleation sites. A time,temperature transformation diagram is built from the kinetic data, showing a maximum reaction rate between 973 and 1073,K. [source] In-situ small-angle scattering study on the formation of a nanocrystalline soft-magnetic alloyJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000D. R. Dos Santos A detailed study is presented on the nanocrystallization of the amorphous alloy Fe86Zr7Cu 1B6 (indices indicate at. %). Melt-spun ribbons were rapidly annealed by Joule heating, and the electrical resistance showed strong variations during thermal treatment. X-ray diffraction patterns indicate that these variations are related to the nucleation and growth of ,-Fe nanocrystals, and from peak profile analysis we obtained the average grain size and crystalline volume fraction for different annealing currents. The disorder-order transition was studied by in-situ small-angle X-ray scattering during conventional furnace treatments. SAXS intensity evolution for different temperatures, both below and above the crystallization temperature of the alloy, showed that a fast atomic rearrangement leads to the formation of atomic clusters before crystallization. The evolution of the size distribution function of these clusters as a function of time and temperature was obtained assuming a polydisperse system of spherical particles. [source] Small-angle X-ray scattering study of the smart thermo-optical behavior of zirconyl aqueous colloidsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000L.A. Chiavacci The smart thermo-optical systems studied here are based on the unusual thermoreversible sol-gel transition of zirconyl chloride aqueous solution modified by sulfuric acid in the molar ratio Zr/SO4:3/1. The transparency to the visible light changes during heating due to light scattering. This feature is related to the aggregates growth that occurs during gelation. These reversible changes can be controlled by the amount of chloride ions in solution. The thermoreversible sol-gel transition temperature increases from 323 to 343 K by decreasing the molar ratio Cl/Zr from 7.0 to 1.3. In this work the effect of the concentration of chloride ions on the structural characteristics of the system has been analyzed by in situ SAXS measurements during the sol-gel transition carried out at 323 and 333 K. The experimental SAXS curves of sols exhibit three regions at small, medium and high scattering vectors characteristics of Guinier, fractal and Porod regimes, respectively. The radius of primary particles, obtained from the crossover between the fractal and Porod regimes, remains almost invariable with the chloride concentration, and the value (4 Å) is consistent with the size of the molecular precursor. During the sol-gel transition the aggregates grow with a fractal structure and the fractal dimensionality decreases from 2.4 to 1.8. This last value is characteristic of a cluster-cluster aggregation controlled by a diffusion process. Furthermore, the time exponent of aggregate growth presents values of 0.33 and 1, typical of diffusional and hydrodynamic motions. A crossover between these two regimes is observed. [source] Small and wide-angle X-ray scattering study of metallocene isotactic poly(propylene)JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000P.S. Dai We report a study of metallocene isotactic poly(propylene) (m-iPP) which crystallizes into , and , crystal modifications. Simultaneous in-situ small- and wide-angle X-ray scattering (SAXS and WAXS) were used to study kinetics during crystallization. Both techniques provide information about time development of crystallinity, while WAXS gives also kinetics of formation of , and , crystals. During the earliest stages of crystal formation, the SAXS Bragg peak occurs simultaneously, or slightly lags, the appearance of crystalline WAXS reflections. We conclude crystallization occurs by a nucleation and growth process in this m-iPP. [source] Nanoscale uniformity of pore architecture in diatomaceous silica: a combined small and wide angle x-ray scattering studyJOURNAL OF PHYCOLOGY, Issue 1 2000Engel G. Vrieling Combined small and wide angle X-ray scattering (SAXS and WAXS) analysis was applied to purified biogenic silica of cultured diatom frustules and of natural populations sampled on marine tidal flats. The overall WAXS patterns did not reveal crystalline phases (WAXS domain between 0.07 to 0.5 nm) in this biogenic silica, which is in line with previous reports on the amorphous character of the SiO2 matrix of diatom frustules. One exception was the silica of the pennate species Cylindrotheca fusiformis Reimann et Lewin, which revealed wide peaks in the WAXS spectra. These peaks either indicate the presence of a yet unknown crystalline phase with a repetitive distance (d -value ,0.06 nm) or are caused by the ordering of the fibrous silica fragments; numerous girdle bands. The SAXS spectra revealed the size range of pores (diameter d between 3.0 and 65 nm), the presence of distinct pores (slope transitions), and structure factors (oscillation of the spectra). All slopes varied in the range of ,4.0 to ,2.5, with two clear common regions among species: d < 10 nm (slopes ,4, denoted as region I and also called the Porod region), and 10.0 < d < 40.0 nm (slopes ,2.9 to ,3.8, denoted as region II). The existence of these common regions suggests the presence of comparable form (region I) and structure (region II) factors, respectively the shape of the primary building units of the silica and the geometry of the pores. Contrast variation experiments using dibromomethane to fill pores in the SiO2 matrix showed that scattering was caused by pores rather than silica particles. Electron microscopic analysis confirmed the presence of circular, elliptical, and rectangular pores ranging in size from 3 to 65 nm, determining the structure factor. The fine architecture (length/width ratio of pore diameters) and distribution of the pores, however, seemed to be influenced by environmental factors, such as the salinity of and additions of AlCl3 to the growth medium. The results indicate that diatoms deposit silica with pores <50 nm in size and are highly homologous with respect to geometry. Consequently, it is suggested that in diatoms, whether pennate or centric, the formation of silica at a nanoscale level is a uniform process. [source] Adsorption of 4,4,-thiobisbenzenethiol on silver surfaces: surface-enhanced Raman scattering studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2008Yuling Wang Abstract Adsorption of 4,4,-thiobisbenzenethiol (4,4,-TBBT) on a colloidal silver surface and a roughened silver electrode surface was investigated by means of surface-enhanced Raman scattering (SERS) for the first time, which indicates that 4,4,-TBBT is chemisorbed on the colloidal silver surface as dithiolates by losing two H-atoms of the SH bond, while as monothiolates on the roughened silver electrode. The different orientations of the molecules on both silver surfaces indicate the different adsorption behaviors of 4,4,-TBBT in the two systems. It is inferred from the SERS signal that the two aromatic rings in 4,4,-TBBT molecule are parallel to the colloidal silver surface as seen from the disappearance of ,CH band (3054 cm,1), which is a vibrational mode to be used to determine the orientation of a molecule on metals according to the surface selection rule, while on the roughened silver electrode surface they are tilted to the surface as seen from the enhanced signal of ,CH. The orientation of the C-S bond is tilted with respect to the silver surface in both cases as inferred from the strong enhancement of the ,CS. SERS spectra of 4,4,-TBBT on the roughened silver electrode with different applied potentials reveal that the enhancement of 4,4,-TBBT on the roughened silver electrode surface may be related to the chemical mechanism (CM). More importantly, the adsorption of 4,4,-TBBT on the silver electrode is expected to be useful to covalently adsorb metal nanoparticles through the free SH bond to form two- or three- dimensional nanostructures. Copyright © 2007 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman scattering study of the red dye laccaic acidJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2007M. V. Cañamares Abstract FT-Raman and surface-enhanced Raman scattering (SERS) spectroscopy were applied to the study of lac dye, a highly fluorescent anthraquinone red dye. The SERS spectra were obtained at different pH values, on Ag nanoparticles prepared by chemical reduction with citrate and hydroxylamine, and at several excitation wavelengths, in order to find the best experimental conditions for the detection of the lac dye. The lower detection limit was achieved using nanoparticles prepared by reduction with hydroxylamine, excitation at 514.5 nm, and slightly acidic pH conditions, thus exploiting a combination of factors including lower electrostatic repulsion between dye and nanoparticles and resonance Raman enhancement. A comparison between the adsorption of laccaic acid (LA) and carminic acid (CA), another anthraquinone red dye, was also done, based on the SERS spectra of both dyes. Copyright © 2007 John Wiley & Sons, Ltd. [source] Raman scattering study of molecules adsorbed on ZnS nanocrystalsJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2007Yanfei Wang Abstract The adsorption of 4-mercaptopyridine (4-Mpy) molecules on ZnS nanocrystals was investigated by means of Raman spectroscopy. We compared the Raman signals of 4-Mpy molecules adsorbed on ZnS nanocrystals and Ag substrate. The differences in the adsorption of 4-Mpy molecules on the semiconductor and the metal substrate were noted. The results demonstrated that adsorbed species on the semiconductor ZnS nanocrystals can be detected by Raman spectroscopy. Copyright © 2006 John Wiley & Sons, Ltd. [source] Raman scattering study of adsorption/desorption of water from single-walled carbon nanotubesJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2005Suresh C. Sharma Abstract We utilized Raman spectroscopy to investigate H2O adsorption in and desorption from single-walled carbon nanotubes (SWCNTs). SWCNT tips were opened by known chemical methods and H2O was inserted into the tubes via capillary action over periods up to 136 h. The wavenumbers in the OH bending region of H2O increase almost exponentially with H2O treatment time. Following H2O adsorption for 136 h, Raman spectra were also measured as a function of heat-treatment temperature. These data lead to 0.07 eV for the H2O desorption energy from SWCNTs. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adsorption of 3- and 4-benzoylpyridine on colloidal silver particles: a surface-enhanced Raman scattering studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2004Joydeep Chowdhury Abstract Surface-enhanced Raman scattering (SERS) spectra of 3- and 4-benzoylpyridine (BP) adsorbed on silver hydrosols were compared with the FTIR and normal Raman spectra in bulk and in solution. With a small fractional change in adsorbate concentration, the SER spectra of isomeric BPs show significant changes in their features, indicating different orientational changes of the different parts of the flexible molecule on the colloidal silver surface with adsorbate concentration. The appearance of a broad, long-wavelength band in the absorption spectra of the silver sol due to solute-induced coagulation of colloidal silver particles is found to be red shifted with increase in adsorbate concentration. The SER excitation profiles indicate that the resonance of the Raman excitation radiation with the new aggregation band contributes more to the SERS intensity than that with the original sol band. Copyright © 2004 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman scattering study of the adsorption of the anthraquinone pigment alizarin on Ag nanoparticlesJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2004M. V. Cañamares Abstract FT-Raman and surface-enhanced Raman scattering (SERS) spectroscopy were applied in the vibrational characterization and study of the adsorption and acidity behavior of the highly fluorescent anthraquinone dye alizarin on Ag colloids prepared by chemical reduction with hydroxylamine hydrochloride. The SERS spectra were obtained at different conditions of pH, excitation wavelength and pigment concentration in order to deduce the adsorption mechanism of this molecule. On the basis of the results found we propose an adsorption model for alizarin, which has a different acidic behavior on the metal surface to that in solution. On the metal the deprotonation order of the OH groups changes with respect to the aqueous solution, the OH in position 1 being the first to be ionized instead of that in position 2 as occurs in solution. The two main alizarin forms identified on the metal surface correspond to the mono- and dianionic alizarin species. Copyright © 2004 John Wiley & Sons, Ltd. [source] Raman scattering probe of anharmonic effects in NiSiJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2004S. K. Donthu Abstract We report a systematic temperature-dependent Raman scattering study of NiSi thin films. In agreement with the basic anharmonic theory, the strong Raman peak from NiSi at about 214 cm,1 shows phonon softening and broadening with an increase in the sample temperature. Comparative study of the temperature dependence of this first-order Raman peak from NiSi powder and the film show that NiSi layers of thickness 15,90 nm are under tensile thermal stress. The results also show that the total phonon shift observed in the temperature range 80,500 K is independent of the silicide film thickness. We have also shown that Raman spectroscopy is a faster and more sensitive technique than x-ray diffraction for phase identification in NiSi nanolayers, hence Raman scattering can be used as a valuable tool for in situ growth and process monitoring of nickel silicides. Copyright © 2004 John Wiley & Sons, Ltd. [source] Light scattering study on hybrid structures of Zn1,x,yCdxMnySe quantum wells with ferromagnetic Co wiresPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004M. Sakuma Abstract Sub-micron scale hybrid structures of Zn1,x,yCdxMnySe diluted magnetic semiconductor (DMS) quantum wells (QWs) with ferromagnetic Co wires have been fabricated for the purpose of applying local magnetic fields to the DMS-QW. The wire of DMS-QW with the width down to 100 nm was sandwiched between the Co wires. The magneto-optical properties are studied by spin-flip light scattering of paramagnetic Mn-ions in the DMS. The application of uniform magnetic fields higher than 0.25 T has been attained from the Co wires to the DMS-QWs. In addition, the field application from the Co to the DMS-QWs is switched on by weak magnetic fields of 0.03 T due to the magnetic shape anisotropy of the Co wires, which can realize the switching behavior of the spin alignment of Mn-ions in the DMS-QW. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photolysis of Br2 in CCl4 studied by time-resolved X-ray scatteringACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2010Qingyu Kong A time-resolved X-ray solution scattering study of bromine molecules in CCl4 is presented as an example of how to track atomic motions in a simple chemical reaction. The structures of the photoproducts are tracked during the recombination process, geminate and non-geminate, from 100,ps to 10,µs after dissociation. The relaxation of hot Br2* molecules heats the solvent. At early times, from 0.1 to 10,ns, an adiabatic temperature rise is observed, which leads to a pressure gradient that forces the sample to expand. The expansion starts after about 10,ns with the laser beam sizes used here. When thermal artefacts are removed by suitable scaling of the transient solvent response, the excited-state solute structures can be obtained with high fidelity. The analysis shows that 30% of Br2* molecules recombine directly along the X potential, 60% are trapped in the A/A, state with a lifetime of 5.5,ns, and 10% recombine non-geminately via diffusive motion in about 25,ns. The Br,Br distance distribution in the A/A, state peaks at 3.0,Å. [source] Small angle neutron scattering study of the structure and hydration of polyoxyethylene- block -polyoxybutylene in aqueous solutionPOLYMER INTERNATIONAL, Issue 7 2006J Patrick A Fairclough Abstract The micellar structure of a polyoxyethylene- block -polyoxybutylene diblock copolymer (E18B10; E = (OCH2CH2); B = OCH2CH(CH2CH3)) in water was studied by small angle neutron scattering. Results show a polydisperse spherical micelles at temperatures below 45 °C, a possible mixed phase at 45 °C and flexible worm-like micelles at 65 °C. The spherical micelles at 25 and 35 °C have radii of 39 and 40 Å and degrees of hydration of 28% and 26%, respectively. The worm-like micelles have a total length of approximately 1850 Å, with segment lengths of 123 Å, a core radius, Rax = 30 Å and hydration of 23%, at 65 °C. Copyright © 2006 Society of Chemical Industry [source] | |||||||||||||||||||