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  • 1
    Language: English
    In: Science (New York, N.Y.), 30 March 2018, Vol.359(6383), pp.1509-1513
    Description: Active camouflage is widely recognized as a soft-tissue feature, and yet the ability to integrate adaptive coloration and tissuelike mechanical properties into synthetic materials remains elusive. We provide a solution to this problem by uniting these functions in moldable elastomers through the self-assembly of linear-bottlebrush-linear triblock copolymers. Microphase separation of the architecturally distinct blocks results in physically cross-linked networks that display vibrant color, extreme softness, and intense strain stiffening on par with that of skin tissue. Each of these functional properties is regulated by the structure of one macromolecule, without the need for chemical cross-linking or additives. These materials remain stable under conditions characteristic of internal bodily environments and under ambient conditions, neither swelling in bodily fluids nor drying when exposed to air.
    Keywords: Additives ; Skin Injuries ; Synthetic Products ; Injury Prevention ; Self Assembly ; Softness ; Body Fluids ; Skin ; Copolymers ; Mechanical Properties ; Elastomers ; Additives ; Color ; Skin ; Crosslinking ; Camouflage ; Drying ; Coding ; Feature Recognition ; Color ; Camouflage ; Stiffening ; Drying ; Deformation ; Polymers ; Coloration ; Fluid Dynamics ; Block Copolymers ; Elastomers ; Color ; Self-Assembly ; Strain ; Mechanical Properties ; Elastomers;
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    Language: English
    In: Advanced Materials, 12 July 2013, Vol.25(26), pp.3543-3548
    Description: displays humidity‐induced phase transitions from a hexagonal columnar structure to a bicontinuous cubic phase. The mesophases can be frozen by photopolymerization of acrylic end‐groups resulting in free‐standing membranes with different topology of ionic nanochannels. The obtained membranes with a well‐ordered ionic channel structure hold promise for applications in separation and catalysis.
    Keywords: Ionic Channels ; Bicontinuous Cubic Phase ; Columnar Mesophase ; Self‐Assembly ; Ion‐Conducting Membranes
    ISSN: 0935-9648
    E-ISSN: 1521-4095
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  • 3
    Language: English
    In: Angewandte Chemie International Edition, 12 September 2011, Vol.50(38), pp.8881-8885
    Description: : Upon crystallization, achiral polymers can form chiral crystalline lamellae, such as right‐ and left‐handed helicoids. The chiral parameter imparted by crystallization is the chain tilt with respect to the lamellar normal. Thus, lamella having crystalline stems tilted to the right from the normal to the basal plane will form right‐handed helicoids, and vice versa.
    Keywords: Chirality ; Crystallization ; Lamellar Twisting ; Polyethylene ; Polymers
    ISSN: 1433-7851
    E-ISSN: 1521-3773
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  • 4
    Language: English
    In: The journal of physical chemistry. B, 20 March 2014, Vol.118(11), pp.3207-17
    Description: Supramolecular assembly allows for enhanced control of bulk material properties through the fine modulation of intermolecular interactions. We present a comprehensive study of a cross-linkable amphiphilic wedge molecule based on a sulfonated trialkoxybenzene with a sodium counterion that forms liquid crystalline (LC) phases with ionic nanochannel structures. This compound exhibits drastic structural changes as a function of relative humidity (RH). Our combined structural, dynamical, and transport studies reveal deep and novel information on the coupling of water and wedge molecule transport to structural motifs, including the significant influence of domain boundaries within the material. Over a range of RH values, we employ (23)Na solid-state NMR on the counterions to complement detailed structural studies by grazing-incidence small-angle X-ray scattering. RH-dependent pulsed-field-gradient (PFG) NMR diffusion studies on both water and the wedge amphiphiles show multiple components, corresponding to species diffusing within LC domains as well as in the domain boundaries that compose 10% of the material. The rich transport and dynamical behaviors described here represent an important window into the world of supramolecular soft materials, carrying implications for optimization of these materials in many venues. Cubic phases present at high RH show fast transport of water (2 × 10(-10) m(2)/s), competitive with that observed in benchmark polymeric ion conductors. Understanding the self-assembly of these supramolecular building blocks shows promise for generating cross-linked membranes with fast ion conduction for applications such as next-generation batteries.
    Keywords: Strukturumwandlung ; Röntgenstrahl ; Diffusion ; Natrium ; Ionenkanal ; Relative Feuchtigkeit ; Dynamisches Verhalten ; Ionenleitung ; Baugruppe ; Selbstassemblierung ; Membran ; Chemistry;
    ISSN: 15206106
    E-ISSN: 1520-5207
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  • 5
    In: Journal of Applied Crystallography, 01 August 2011, Vol.44(4), pp.805-811
    Description: Small‐angle X‐ray scattering interface distribution function (IDF) analysis is successfully applied to evaluate the two‐ and three‐phase inter‐platelet gallery structure in synthetic montmorillonite (MMT) modified with a mixture of chemically grafted and physically adsorbed chains of a typical organic modifier, octadecyl trimethyl ammonium bromide. Two distinctly different states of adsorbed chains in the inter‐platelet galleries are identified. The first one corresponds to a fully cation‐exchanged structure with an inter‐platelet distance of about 21 Å. In this case the organic modifier is in a liquid‐like state, and the system does not exhibit any structural or thermal transitions between ambient temperature and 433 K. When the number of adsorbed chains exceeds the cation‐exchange capacity of the MMT platelets the inter‐platelet spacing is increased to 43 Å. In this case, the variable‐temperature IDFs reveal partially crystalline order in the inter‐platelet galleries, which vanishes at the melting point of the alkyl tails confined in the galleries.
    Keywords: Small‐Angle X‐Ray Scattering ; Interface Distribution Functions ; Paracrystalline Models ; Thermal Transitions ; Organoclays ; Octadecyl Trimethyl Ammonium Bromide
    ISSN: 0021-8898
    E-ISSN: 1600-5767
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  • 6
    Language: English
    In: Chemistry - A European Journal, 03/25/2013, Vol.19(13), pp.4300-4307
    Description: Keywords: alkynes; photochemistry; polymerization; topochemistry; X-ray diffraction Abstract A novel wedge-shaped compound containing two diacetylene tails, namely, methyl 3,5-bis(trideca-2,4-diyn-1yloxyl)benzoate (DDABM), was synthesized. As shown by UV/Vis spectroscopy this compound can be polymerized under UV irradiation. The crystalline structure of DDABM was investigated by grazing-incidence wide-angle X-ray diffraction on oriented crystalline films deposited on PTFE-rubbed silicon wafer substrates. Furthermore, the spherulites formed in thicker films were analyzed by wide-angle X-ray diffraction. A molecular packing model of DDABM based on the X-ray diffraction data is proposed. The diacetylene units are oriented along a defined lattice direction with a reticular distance of 4.85aA, which fulfills the requirements for topochemical polymerization. It was observed that UV polymerization does not affect the phase behavior of the compound, but mainly alters its optical properties. Author Affiliation: Interactive Materials Research - DWI an der RWTH Aachen e.V. and Institute for Technical and Macromolecular Chemistry of RWTH Aachen University, Forckenbeckstrasse 50, 52056 Aachen (Germany), Fax: (+49)241-80-233-01 Institut de Sciences des Materiaux de Mulhouse (IS2M-CNRS), 15 rue Jean Starcky, 68057 Mulhouse (France), Fax: (+33)389-60-87-99 Moscow State University, Faculty of Fundamental Physical and Chemical Engineering, GSP-1, 1-51 Leninskie Gory, Moscow, 119991 (Russian Federation) Interactive Materials Research - DWI an der RWTH Aachen e.V. and Institute for Technical and Macromolecular Chemistry of RWTH Aachen University, Forckenbeckstrasse 50, 52056 Aachen (Germany), Fax: (+49)241-80-233-01 Institut de Sciences des Materiaux de Mulhouse (IS2M-CNRS), 15 rue Jean Starcky, 68057 Mulhouse (France), Fax: (+33)389-60-87-99 Article Note: These authors contributed equally.
    Keywords: Crystal Structure -- Optical Properties ; Crystal Structure -- Analysis ; Polymerization -- Optical Properties ; Polymerization -- Analysis ; Polytetrafluoroethylene -- Optical Properties ; Polytetrafluoroethylene -- Analysis ; Alkynes -- Optical Properties ; Alkynes -- Analysis;
    ISSN: Chemistry - A European Journal
    E-ISSN: 09476539
    E-ISSN: 15213765
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  • 7
    Language: English
    In: Chemistry – A European Journal, 25 March 2013, Vol.19(13), pp.4300-4307
    Description: A novel wedge‐shaped compound containing two diacetylene tails, namely, methyl 3,5‐bis(trideca‐2,4‐diyn‐1yloxyl)benzoate (DDABM), was synthesized. As shown by UV/Vis spectroscopy this compound can be polymerized under UV irradiation. The crystalline structure of DDABM was investigated by grazing‐incidence wide‐angle X‐ray diffraction on oriented crystalline films deposited on PTFE‐rubbed silicon wafer substrates. Furthermore, the spherulites formed in thicker films were analyzed by wide‐angle X‐ray diffraction. A molecular packing model of DDABM based on the X‐ray diffraction data is proposed. The diacetylene units are oriented along a defined lattice direction with a reticular distance of 4.85 Å, which fulfills the requirements for topochemical polymerization. It was observed that UV polymerization does not affect the phase behavior of the compound, but mainly alters its optical properties. : A wedge‐shaped compound containing two diacetylene tails can be polymerized under UV irradiation. Detailed analysis of the crystalline structure of this compound revealed that the diacetylene units are oriented along a defined lattice direction (see picture) with a packing period of 4.85 Å, which fulfills the requirements for topochemical polymerization. Importantly, UV polymerization does not affect the phase behavior of the compound, but mainly alters its optical properties.
    Keywords: Alkynes ; Photochemistry ; Polymerization ; Topochemistry ; X‐Ray Diffraction
    ISSN: 0947-6539
    E-ISSN: 1521-3765
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  • 8
    Language: English
    In: Langmuir : the ACS journal of surfaces and colloids, 13 January 2015, Vol.31(1), pp.529-34
    Description: Noble metal nanoparticles with ligand shells are of interest for applications in catalysis, thermo-plasmonics, and others, involving heating processes. To gain insight into the structure-formation processes in such systems, self-assembly of carbohydrate-functionalized gold nanoparticles during precipitation from solution and during further heating to ca. 340 °C was explored by in situ combination of nanobeam SAXS/WAXS and nanocalorimetry. Upon precipitation from solution, X-ray scattering reveals the appearance of small 2D domains of close-packed nanoparticles. During heating, increasing interpenetration of the nanoparticle soft shells in the domains is observed up to ca. 81 °C, followed by cluster formation at ca. 125 °C, which transform into crystalline gold nuclei at around 160 °C. Above ca. 200 °C, one observes the onset of coalescence and grain growth resulting in gold crystallites of average size of about 100 nm. The observed microstructural changes are in agreement with the in situ heat capacity measurements with nanocalorimetry.
    ISSN: 07437463
    E-ISSN: 1520-5827
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  • 9
    Language: English
    In: Polymer, 2011, Vol.52(24), pp.5630-5643
    Description: The microstructure and mechanical properties of melt-spun isotactic polypropylene (iPP) fibers were studied for different take-up velocities and throughputs with a combination of small- and wide-angle X-ray scattering, calorimetry and tensile tests. With the increase of take-up velocity the mesomorphic fraction of the fibers steadily decreases while the crystalline fraction increases. The addition of an alpha-nucleating agent led to an increase of crystallinity and a slight decrease of the orientation factor. By contrast, a beta-nucleator resulted in a complete suppression of the fiber crystallinity. The orientation factor of the mesophase and/or crystalline phase is found to have a one-to-one correlation with the fiber tenacity and deformation at break. At the same time, the absolute values of crystallinity and/or mesomorphicity are fully uncorrelated with these mechanical characteristics. The observed correlations can be used for example to design and control the fiber mechanical properties by tuning the processing conditions such as take-up velocity, throughput and addition of nucleating agents.
    Keywords: Isotactic Polypropylene ; Fiber ; Herman Orientation Factor ; Engineering ; Chemistry
    ISSN: 0032-3861
    E-ISSN: 1873-2291
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  • 10
    In: The Journal of Nutrition, 2016, Vol. 146(12), pp.2594S-2600S
    Description: Arginine supplementation has the potential to improve the health of patients. Its use in hospitalized patients has been a controversial topic in the nutrition literature, especially concerning supplementation of septic patients. In this article, we review the relevant literature both for and against the use of arginine in critically ill, surgical, and hospitalized patients. The effect of critical illness on arginine metabolism is reviewed, as is its use in septic and critically ill patients. Although mounting evidence supports immunonutrition, there are only a few studies that suggest that this is safe in patients with severe sepsis. The use of arginine has been shown to benefit a variety of critically ill patients. It should be considered for inclusion in combinations of immunonutrients or commercial formulations for groups in whom its benefit has been reported consistently, such as those who have suffered trauma and those in acute surgical settings. The aims of this review are to discuss the role of arginine in health, the controversy surrounding arginine supplementation of septic patients, and the use of arginine in critically ill patients.
    Keywords: Arginine Supplementation ; Critical Care ; Surgery ; Immunonutrition ; Sepsis
    ISSN: 0022-3166
    E-ISSN: 1541-6100
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