In recent years many studies into green solvents have been undertaken and deep eutectic solvents (DES) have emerged as sustainable and green alternatives to conventional solvents since they may be formed from cheap non-toxic organic precursors. In this study we examine amphiphile behaviour in these novel media to test our understanding of amphiphile self-assembly within environments that have an intermediate polarity between polar and non-polar extremes. We have built on our recently published results to present a more detailed structural characterisation of micelles of sodium dodecylsulfate (SDS) within the eutectic mixture of choline chloride and urea. Here we show that SDS adopts an unusual cylindrical aggregate morphology, unlike that seen in water and other polar solvents. A new morphology transition to shorter aggregates was found with increasing concentration. The self-assembly of SDS was also investigated in the presence of water; which promotes the formation of shorter aggregates.

Deep eutectic solvents (DES) resemble ionic liquids but are formed from an ionic mixture instead of being a single ionic compound. Here we present some results that demonstrate that surfactant sodium dodecyl sulfate (SDS) remains surface-active and shows self-assembly phenomena in the most commonly studied DES, choline chloride/urea. X-ray reflectivity (XRR) and small angle neutron scattering (SANS) suggest that the behavior is significantly different from that in water. Our SANS data supports our determination of the critical micelle concentration using surface-tension measurements and suggests that the micelles formed in DES do not have the same shape and size as those seen in water. Reflectivity measurements have also demonstrated that the surfactants remain surface-active below this concentration.

The Loq small angle neutron scattering (SANS) instrument at ISIS target station one (TS1) has proved an extremely popular and immensely productive SANS facility over the last 20 years. Loq is routinely operated with a 25 Hz disc chopper removing alternate neutron pulses from the 50 Hz source to provide a usable wavelength range of 2.2 to 10 Å. Scattered neutrons are recorded on a 0.64 m square 3He multiwire proportional counter (Ordela 2661N) fixed at ∼ 4 m from the sample, with a total flight path of 15 m from the decoupled liquid hydrogen moderator [1 http://www.isis.stfc.ac.uk/instruments/loq (http://www.isis.stfc.ac.uk/instruments/loq) [Google Scholar]].

Small-angle neutron scattering (SANS) and neutron reflection (NR) have become invaluable to many scientists in the soft matter community as methods of obtaining system information such as size, structure and particle interactions on the nanometer scale which cannot be achieved using other techniques. Neutron scattering is employed to study a wide range of soft matter science at ISIS, but this review will focus on three areas of interest: green solvents, polymer stability and drug delivery which have been chosen to illustrate how SANS and NR can be used to advance the understanding of the complex systems under investigation.

Natural silk is an important biopolymer with huge potential as it combines superb mechanical properties with environmentally sensitive production methods. Native silk dope taken straight from the gland can easily and without chemical assistance be drawn into strong fibres. Artificial silk fibres, on the other hand, rely on spinning dopes typically ‘reconstituted’ from natural silk fibres by strong chaotropic agents. Such fibres do not form readily, and often require chemical post-spin treatment for stabilisation. In addition these fibres tend to be brittle, and so far have been unable to match native fibres. Here we present novel rheometric data to argue that native and reconstituted silkworm silk dope differ in kind, not just in degree. While native silks behave like typical molten polymers, reconstituted silks do not. We conclude that rheology provides a powerful tool in the quest to learn from the Nature's polymer fibre technology.

The crystallization behaviour of an oligomer of hydroxybutyrate containing 24 repeat units has been studied over a wide range of temperature using optical microscopy to measure growth rates and observe morphologies and small angle X-ray scattering to measure crystal thicknesses. Crystals grew with a wide range of thicknesses between E/2 and E, where E is the extended chain length. Preferred crystal thicknesses corresponded to simple fractions of E, which result in a relatively higher proportion of chain folds in the surface. Growth rates peaked at 75°C and were unusually scattered at temperatures corresponding to a change in preferred chain conformation. Spherulites grown at the lower temperatures were banded: as the crystallization temperature was increased the banding disappeared, the shapes of the spherulites became less regular, and a coarser texture associated with reduced branching developed.

Silk production has evolved to be energetically efficient and functionally optimized1, yielding a material that can outperform most industrial fibres2,3, particularly in toughness. Spider silk has hitherto defied all attempts at reproduction4,5,6, despite advances in our understanding of the molecular mechanisms behind its superb mechanical properties7,8,9. Spun fibres, natural and man-made, rely on the extrusion process to facilitate molecular orientation and bonding2,10,11,12. Hence a full understanding of the flow characteristics of native spinning feedstock (dope) will be essential to translate natural spinning to artificial silk production. Here we show remarkable similarity between the rheologies for native spider-dragline and silkworm-cocoon silk, despite their independent evolution and substantial differences in protein structure. Surprisingly, both dopes behave like typical polymer melts. This observation opens the door to using polymer theory13,14 to clarify our general understanding of natural silks, despite the many specializations found in different animal species1,12,15,16,17,18.

Combustion synthesis techniques have been applied to an equiatomic mixture of Aluminium, Nickel, Titanium and Carbon powders in order to obtain NiAl/TiC composites. Both combustion modes have been used: the Self-propagating High-temperature mode (SHS), in which the reaction propagates through the sample under the form of a heat wave and the Thermal Explosion mode (TES), in which the reaction occurs simultaneously in the complete sample. The reactions have been followed in-situ by time-resolved diffraction, using synchrotron X-rays for the SHS mode and neutrons for the TES mode. Scanning Electron Micrographs and X-ray diffraction patterns of the final product have shown that the same final products were obtained when the mixture was synthesised under both combustion modes: a composite made of small and round TiC particles (~1 micron) embedded into a matrix of larger NiAl grains (5 microns). However, the Time-Resolved Diffraction studies have shown that, even with the same final products, the two combustion modes follow two completely different routes. Thus, for the SHS mode, the reaction is triggered by the formation of Nickel Aluminide and 3 intermediate phases are observed, and for the TES mode, the self-sustained reaction starts with the formation of Titanium Carbide and no intermediate phases have been seen.

Copolyarnides, based on 1,12-dodecanedicarboxylic acid and different ratios of 1,2-ethylenediamine and piperazine, i.e., PA2,14-co-pip,14 as well as the homopolymers PA2,14 and PApip,14 are Studied. Incorporation of the piperazine component in the homopolymer PA2.14 reduces the number of hydrogen bonds. This provides a unique opportunity to investigate the influence of hydrogen bonding on the origin of the Brill transition and chain mobility within polymer crystals. Time-resolved conformational. structural, and morphological changes during heating are followed by FTIR spectroscopy, WAXD, and SAXS. The findings are that from 0 to 62 mol % of piperazine the Brill transition occurs in the same temperature region. The transformation is triggered by the conformational changes in the methylene sequences of the main chain, followed by twisting in the methylene sequences next to the amide group. This results in enhanced chain mobility along the c-axis, causing lamellar thickening. For 80 mol % of piperazine and higher, no Brill transition is observed. However, conformational changes in the methylene sequences of the main chain occurs, triggering lamellar thickening.

MICROSIMPOSIA C72The second part of this talk concerns a new type of X-ray source, betatron, based on the relativistic laser-plasma interaction in gas.This source produces a polychromatic and highly collimated X-ray beam with duration about 25 fs.Its applications in time-resolved EXAFS and Laue diffraction, together with its comparison with other existing pulsed X-ray sources, will be presented.

High resolution X-ray scanning diffractometry is used to study the residual stress in binary metal/ceramic (Ni/Si3N4) diffusion bonds fabricated by simultaneous high temperature heating and uniaxial pressing. In order to diminish the experimental error on the stress determination, the method consists of three steps: (i) to measure the axial and radial strains following some selected lines at the inner volume of the ceramic; (ii) to fit the strain data using finite element method (FEM) analysis and (iii) to determinate stresses by using the results obtained from the FEM method in the strain calculation.

Thin films of cadmium sulfide (CdS) and cadmium carbonate (CdCO 3 ) were grown onto glass substrates by means of the chemical bath (CB) method.The temperature of grown was selected between 23-80 °C.At low temperatures, CdCO 3 is the compound predominant in the layers, whereas at high temperatures CdS is the compound deposited on the substrate.The gradual transition from an insulator CdCO 3 to a semiconductor CdS growth occurs when values a mixture increases.Physical properties of films they are studied by means of Xray diffraction, and optical absorption.

In semi-crystalline polymers a range of morphologies can be obtained in which a chain may traverse the amorphous region between the crystals or fold back into the crystals leading to adjacent or nonadjacent reentry, depending on the molecular architecture and crystallization conditions. This causes topological variations on the crystal surface and the occurrence of an interphase between the crystalline and amorphous domains, thus affecting the mechanical properties. In this chapter, we will discuss how the morphology within the interphase plays a prominent role in drawability, lamellar thickening and melting of thus crystallized samples. Normally, for linear polymers it is anticipated that extended chain crystals are thermodynamically most favorable, and ultimately, taking the example of linear polyethylene, it has been shown that such chains would form extended chain crystals. However, this condition will not be realized in a range of polymers upon crystallization from the melt, such as those which do not show lamellar thickening or in branched polymers where the side branches cannot be incorporated within the crystal and hence fully extended chains are not possible. From a series of experiments, it is shown that with sufficient time and chain mobility, although extended chain crystals are not achievable, the chains still disentangle and a thermodynamically stable morphology is formed with a disentangled crystallizable interphase.

The paper addresses the crystallization behavior of homogeneous branched polyethylenes, where the branches cannot be incorporated within the lattice. The polymer was chosen to investigate the morphology achievable by polymers where the chains cannot extend, which is considered to be a requisite to minimize the surface free energy. Pressure-temperature conditions similar to those necessary to form extended chain crystals in linear polyethylenes are applied. In-situ wide-angle X-ray diffraction and Raman spectroscopy are used to follow the structural and conformational changes during crystallization. The hexagonal phase is not observed in these polymers unlike in linear polyethylene. However, crystallization at elevated pressures results in a structural organization of the interphase and the fold surface; this provides adjacent reentry, where the branches will also possess structural order. Crystallization of these components leads to the formation of an incompressible open-orthorhombic phase (alpha = 7.56 angstrom, b = 5.03 angstrom, c = 2.55 angstrom, density = 960 kg/m(3)) in addition to the existing orthorhombic crystalline domain. With the crystallization of the chains at the interphase and on the fold surface, a contraction in the parent orthorhombic phase or its transformation into the monoclinic phase is observed. Our experimental data suggest that in such a class of polymers the thermodynamically stable state will be crystals with an ordered interphase that can be achieved ultimately by disentanglement of the chains in the amorphous region. The disentangled nature of the amorphous component is further supported by solid-state mechanical deformation of samples.

The rheological properties of fibroin silk solutions extracted from the middle division of Bombyx mori silkworms were examined. Acidification of the solutions with acetic acid vapor gelled the material, a process which at short time scales could be reversed by exposure to ammonia vapor. The solution could also be converted to sol from the gel state by the addition of EDTA. The possible mechanisms for gel formation in fibroin solutions is discussed as are the implications for the process of spinning silk fibers.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDissolution of Hydrogen-Bonded Polymers in Water: A Study of Nylon-4,6Sanjay Rastogi, Ann E. Terry, and Esther VinkenView Author Information Department of Chemical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands, and Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany Cite this: Macromolecules 2004, 37, 24, 8825–8828Publication Date (Web):October 29, 2004Publication History Received11 August 2004Revised8 October 2004Published online29 October 2004Published inissue 1 November 2004https://pubs.acs.org/doi/10.1021/ma0483423https://doi.org/10.1021/ma0483423rapid-communicationACS PublicationsCopyright © 2004 American Chemical SocietyRequest reuse permissionsArticle Views577Altmetric-Citations41LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Amides,Crystal structure,Phase transitions,Physical and chemical processes,Water Get e-Alerts

High resolution wide angle X-ray scattering has been used to follow changes in crystallinity and lattice parameter which occur on heating hydroxybutyrate oligomers. These effects can be correlated with changes in crystal thickness detected by small angle X-ray scattering. Melt-grown crystals from oligomers with 24 and 32 repeat units that initially contain once folded chains transform during slow heating to produce extended chain crystals. This chain unfolding occurs via a process of partial melting and recrystallization and is accompanied by an expansion in the crystal lattice of approximately 0.2% in the (110) fold direction. The presence of a benzyl protecting group on one end of the chain does not affect the transformation temperature but reduces the (020) and (110) lattice spacings very slightly, as well as increasing the rate of transformation. In all cases the stable crystal forms display specific crystal thicknesses simply related to the extended chain length, but the intermediate stages of thickening vary between samples.

Exact length hydroxybutyrate oligomers containing 24 and 32 repeat units have been prepared and their crystallization behaviour and crystal morphology observed.The oligomers form crystals from dilute solution and from the melt that have similar overall morphologies to crystals of the polymer, poly(hydroxybutyrate). Electron diffraction indicates that the chains are closely perpendicular to the basal planes of the crystals.Wide angle X-ray diffraction suggests that all crystals, no matter what their thickness, have a high degree of crystallinity and the same crystal structure.The crystals have a range of thicknesses, as measured by small angle X-ray diffraction. The most common thicknesses correspond to the extended stem length and to one half or, surprisingly, two thirds of that value. A model is proposed for the non-integer fraction crystals in which half of the chain ends are incorporated in the crystals themselves. (C) 2004 Elsevier Ltd. All rights reserved.

Synchrotron X-ray radiation has been used in situ to follow the crystallization of a hydroxybutyrate oligomer containing 32 repeat units from dilute solution in propylene carbonate, and to study chain unfolding during heating in oligomers with 24 and 32 repeat units. A discontinuity in growth rate occurs at 36–37°C for the 32-mer: crystals grown below this temperature contain folded chains, which transform during heating through a process of partial dissolution and re-crystallization to form extended chain crystals. Crystals grown above the transition temperature contain extended chains that do not rearrange during heating. A similar change happens in the 24-mer between 35 and 40°C. Thermal expansion in the (110) lattice direction (the fold direction) was in the range 5.3+/−0.3×10−5nm°C−1, with an additional discontinuous increase in 0.001nm accompanying chain unfolding.

“Single component” polymer composites, in which both the reinforcement and the matrix are made of the same polymer, are currently fabricated by subjecting oriented fibers to moderate pressure and temperature in a processing scheme termed “reversed pressure compaction”. In order to elucidate the nature of the transformations that lead from fibers to a monolithic composite, an X-ray diffraction study with a pressure cell was performed using synchrotron X-ray radiation (Beamline ID-11, ESRF). We observed a transition from the orthorhombic crystal to the meso-morphic hexagonal phase upon heating even at a low pressure (100 bar). The hexagonal phase also reappears even upon cooling from the melt. These indicate that the path to high-performance composites from the oriented PE fibers occurs via sintering of the hexagonal phase. This phase allows enough chain mobility for the compaction process yet maintains the chain orientation to a large extent.