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Corrales T.P.,Max Planck Institute for Polymer Research | Corrales T.P.,University of Tarapaca | Friedemann K.,Max Planck Institute for Polymer Research | Fuchs R.,Max Planck Institute for Polymer Research | And 5 more authors.
Langmuir | Year: 2016

Nanofibers composed of silica nanoparticles, used as structural building blocks, and polystyrene nanoparticles introduced as sacrificial material are fabricated by bicolloidal electrospinning. During fiber calcination, sacrificial particles are combusted leaving voids with controlled average sizes. The mechanical properties of the sintered silica fibers with voids are investigated by suspending the nanofiber over a gap and performing three-point bending experiments with atomic force microscopy. We investigate three different cases: fibers without voids and with 60 or 260 nm voids. For each case, we study how the introduction of the voids can be used to control the mechanical stiffness and fracture properties of the fibers. Fibers with no voids break in their majority at a single fracture point (70% of cases), segmenting the fiber into two pieces, while the remaining cases (30%) fracture at multiple points, leaving a gap in the suspended fiber. On the other hand, fibers with 60 nm voids fracture in only 25% of the cases at a single point, breaking predominantly at multiple points (75%). Finally, fibers with 260 nm voids fracture roughly in equal proportions leaving two and multiple pieces (46% vs 54%, respectively). The present study is a prerequisite for processes involving the controlled sectioning of nanofibers to yield anisometric particles. © 2016 American Chemical Society. Source


Fickert J.,Max Planck Institute for Polymer Research | Landfester K.,Max Planck Institute for Polymer Research | Crespy D.,Max Planck Institute for Polymer Research | Crespy D.,Vidyasirimedhi Institute of Science and Technology VISTEC
Polymer Chemistry | Year: 2016

We introduce here a concept allowing the synthesis of smart nanocapsules without a surfactant. Copolymers with masked carboxylic acid groups are desilylated during the nanocapsule preparation and this leads to pH-responsive and self-stabilized nanocontainers encapsulating a large amount of hydrophobic substances. The nanocapsules can be either disrupted for release applications or reversibly aggregated by lowering the pH of the dispersion. The concentration of the nanocapsules in water can be increased by more than 6 times by isolating the nanocontainers at low pH and re-dispersing them at high pH values. © 2016 The Royal Society of Chemistry. Source


Marchand G.,University of Nantes | Soetens J.-C.,CNRS Institute of Molecular Sciences | Jacquemin D.,University of Nantes | Jacquemin D.,Institut Universitaire de France | Bopp P.A.,Vidyasirimedhi Institute of Science and Technology VISTEC
Journal of Chemical Physics | Year: 2015

We demonstrate that different sets of Lennard-Jones parameters proposed for the Na+ ion, in conjunction with the empirical combining rules routinely used in simulation packages, can lead to essentially different equilibrium structures for a deprotonated poly-L-glutamic acid molecule (poly-L-glutamate) dissolved in a 0.3M aqueous NaCl solution. It is, however, difficult to discriminate a priori between these model potentials; when investigating the structure of the Na+-solvation shell in bulk NaCl solution, all parameter sets lead to radial distribution functions and solvation numbers in broad agreement with the available experimental data. We do not find any such dependency of the equilibrium structure on the parameters associated with the Cl- ion. This work does not aim at recommending a particular set of parameters for any particular purpose. Instead, it stresses the model dependence of simulation results for complex systems such as biomolecules in solution and thus the difficulties if simulations are to be used for unbiased predictions, or to discriminate between contradictory experiments. However, this opens the possibility of validating a model specifically in view of analyzing experimental data believed to be reliable. © 2015 AIP Publishing LLC. Source


Malzahn K.,Max Planck Institute for Polymer Research | Ebert S.,Max Planck Institute for Polymer Research | Schlegel I.,Max Planck Institute for Polymer Research | Neudert O.,Max Planck Institute for Polymer Research | And 8 more authors.
Advanced Healthcare Materials | Year: 2016

The enhanced relaxation of hydrogen atoms of surrounding water from suitable contrast agent promotes magnetic resonance imaging as one of the most important medical diagnosis technique. The key challenge for the preparation of performant contrast agents for magnetic resonance imaging with high relaxivity is to ensure a high local concentration of contrast agent while allowing a contact between water and the contrast agent. Both requirements are answered by tailoring a semipermeable confinement for a gadolinium complex used as contrast agent. A locally high concentration is achieved by successfully encapsulating the complex in polymer nanocontainers that serves to protect and retain the complex inside a limited space. The access of water to the complex is achieved by carefully controlling the chemistry of the shell and the core of the nanocontainers. The confinement of the nanocontainers enables an increased relaxivity compared to an aqueous solution of the contrast agent. The nanocontainers are successfully applied in vivo to yield enhanced contrast in magnetic resonance imaging. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Jiang S.,Max Planck Institute for Polymer Research | Jiang S.,Shanxi Institute of Coal CAS Chemistry | Jiang S.,University of Chinese Academy of Sciences | Lv L.-P.,Max Planck Institute for Polymer Research | And 4 more authors.
RSC Advances | Year: 2016

Materials capable of controlling the release of functional agents are promising for drug delivery and corrosion protection. A dual-responsive multicompartment nanostructure is designed by embedding redox-responsive nanocapsules in pH-responsive nanofibers by colloid-electrospinning. This combination allows an enhanced control over the release of payloads directed by properties of nanocontainers and nanofibers. © The Royal Society of Chemistry 2016. Source

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