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http://www.complexfluids.ethz.ch/snf19 This project is supported by the Swiss National Supercomputing Centre
Two homologous series of dendronized polymers (DPs) of the second and third generations, with different degrees of polymerization of the backbone, were synthesized combining two previously reported approaches. First, methacrylate-based DPs of the first generation were prepared via radical polymerization of the corresponding methacrylate macromonomers. As the side branches of such first-generation DPs can form hydrogen bonds and pi-pi stacks, they are referred to as "classic" (intermolecularly interacting) DPs. Second, the first-generation DPs so prepared were grafted with branched oligoethylene glycol groups to increase the size of the dendrons up to the second and third generations. Because of the different chemical structures of the outermost generations with respect to the inner one, these DPs are termed "hybrid" DPs. The glycol-based generations do not form intermolecular supramolecular associations, which so strongly control the aging dynamics and viscoelastic properties of the interacting DPs. Therefore, the series of hybrid DPs allow for investigating the dynamics of DPs for which synergistic effects because of supramolecular interactions and topology are reduced or absent. We find, at first glance surprisingly, that the loss of intermolecular peripheral interactions increases the equilibration time dramatically. Concerning the viscoelastic behavior of the hybrids of the second generation, the onset of global relaxation is observed at low frequencies. This is in contrast with supramolecular DPs having the same generation and the same backbone degree of polymerization, for which a clear plateau region was previously demonstrated. In addition, the low-frequency plateau of the elastic modulus increases upon increase of the degree of polymerization of the backbone, suggesting that one oligoethylene generation does not suffice to completely shield supramolecular interactions between the branches. Such a scenario is also supported by atomistic simulations. The hybrid DPs of the third generation display two distinct plateau regions of the storage modulus. The first one (at higher frequencies) is of the order of 10(6) Pa, and attributed to the interpenetration of the side branches, the second is of the order of 10(3) Pa. In contrast with the behavior of second-generation hybrid DPs, the degree of polymerization of the backbone has no effect on the low-frequency plateau of third-generation hybrid DPs. This suggests that supramolecular interactions do not contribute to the elastic plateau. Hence, we ascribe it to the entanglements of the entire hybrid DPs. The reported results are summarized in a table, which compares the properties of different DPs and provides the needed ingredients for tailoring the rheology of such hyperbranched polymers. [Costanzo, Salvatore; Vlassopoulos, Dimitris] Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 70013, Crete, Greece. [Costanzo, Salvatore; Vlassopoulos, Dimitris] Univ Crete, Dept Mat Sci & Technol, Iraklion 71003, Crete, Greece. [Costanzo, Salvatore; Pasquino, Rossana] Univ Naples Federico II, DICMAPI, Ple Tecchio 80, I-80125 Naples, Italy. [Scherz, Leon; Kroger, Martin; Schluter, A. Dieter] Swiss Fed Inst Technol, Dept Mat, Polymer Chem & Polymer Phys, CH-8093 Zurich, Switzerland. [Floudas, George] Univ Ioannina, Dept Phys, POB 1186, GR-45110 Ioannina, Greece. [Floudas, George] Max Planck Inst Polymer Res, D-55128 Mainz, Germany. Vlassopoulos, D (corresponding author), Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 70013, Crete, Greece.; Vlassopoulos, D (corresponding author), Univ Crete, Dept Mat Sci & Technol, Iraklion 71003, Crete, Greece.; Schluter, AD (corresponding author), Swiss Fed Inst Technol, Dept Mat, Polymer Chem & Polymer Phys, CH-8093 Zurich, Switzerland. dieter.schlueter@mat.ethz.ch; dvlasso@iesl.forth.gr [hide]
Principal Investigators
Argyrios Karatrantos (PI)
Institute of Science and Technology, Luxembourg ►
Martin Kröger (PI)
Polymer Physics, ETH Zurich, Switzerland ►
Project Partners
Clement Mugemana
Institute of Science and Technology, Luxembourg ►
Jeremy Odent
Laboratory of polymeric and composite materials, Mons University, Belgium ►
Scientific Staff
Ahmad Moghimikheirabadi
Polymer Physics, ETH Zurich, Switzerland ►
Secretary
Patricia Horn
Polymer Physics, ETH Zurich, Switzerland ►
Enjoy your reading
M Kroger,
Developments in Polymer Theory and Simulation
POLYMERS English 12 (2020) 30 ►Selected conferences (co-)organized by project members
3rd Global Summit Nanotechnology & Nanomedicine
Sep 2019, 3rd Global Summit Nanotechnology & Nanomedicine, Barcelona, Spain ►
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About this project
Fundamentally important to the processability and the material properties of polymer nanocomposites is the underlying interaction between polymer and nanoparticles, the resulting structure and dynamics. A high degree of nanoparticle dispersion is necessary for an effective reinforcement in a polymer matrix. A recent experimental approach to distributing nanoparticles into a polymer matrix is to let the interaction between nanoparticles and polymer chains to be of ionic nature.Ionic nanoparticles can impart charged polymers with unique mechanical and functional properties such as self-healing and shape memory. Upon studying a single model nanocomposite via molecular simulation, we found that nanoparticle dispersion can indeed be achieved due to the insertion of electrostatic charge, that nanoparticle diffusion slows down due to this electrostatic charge, and that the ionic nanoparticles move according to a hopping mechanism.
These recent findings have the potential to spur new studies in modelling ionic polymer nanocomposites containing ionic functionalized silica nanoparticles.
We hereby propose to focus in a more detailed and conclusive fashion on four combined experimental/theoretical research objectives:
Investigate the role of ionic interactions and calculate viscoelastic properties (viscosity, storage modulus, loss modulus) with nanoparticle loading, for differently charged and sequenced polymers.
Quantify the lifetime of dynamic crosslinks between nanoparticles and polymers, formed in ionic nanocomposites, during deformation processes.
Calculate the dynamics and structure of polymers and their entanglements for differently charged and filled polymer ionic nanocomposite models,
Resolve the role of nanosilica surface confinement on polymer entanglements and dynamics. The novelty of the proposed work stems from the combination of experiments, simulation and theoretical models to capture the interactions and polymer structural/dynamical, as well as rheological phenomena present in these ionic nanocomposites, who seem to offer qualitatively new properties worth being quantified and supplemented with an informed microscopic picture.
Lay-Summary (German only, as required by SNF)Hintergrund: Polymer-Nanokomposite (PNCs) stellen eine zunehmend wichtige Hybrid-Materialklasse dar. Das fehlende Verständnis der chemischen und physikalischen Mechanismen stellt seit Jahrzehnten ein Hindernis bei der weiteren Entwicklung dar. Für die Verarbeitung und die Eigenschaften von PNCs ist die Wechselwirkung zwischen Polymer und Nanoteilchen, sowie die resultierende Struktur und Dynamik von fundamentalem Interesse. Eine gute Dispersion der Nanoteilchen wird für die effiziente Verst&aauml;rkung von Polymer-Muttergewebe benötigt. Einer der neueren Ansätze, die diese Eigenschaft bewerkstelligen soll, ist die Verwendung von ionischen PNCs. Ionische Nanoteilchen können den ionischen Polymeren zudem neuartige mechanische und funktionelle Eigenschaften verleihen. Inhalt und Ziel des Forschungsprojekts ist ein besseres Verstädnis der ionischen PNCs. Dazu untersuchen wir die (i) Rolle von ionischen Wechselwirkungen und berechnen viskoelastische/mechanische Eigenschaften und ihre Abhäigkeit von System-Parametern (Konzentration, Ladungen, Ladungs-Sequenzen); (ii) Lebensdauer von Vernetzungspunkten in PNCs, isbesondere während Deformationsprozessen; (iii) Dynamik und Struktur der Polymere und deren Verschlaufungs-Netzwerke in Abhängigkeit der Ladungs-Sequenz; (iv) Rolle der Oberflächen-Beschaffenheit von Nano-Silikaten. Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts. Wir möchten neuen Technologien für PNCs den Weg bereiten, die benötigt werden, um leichte, hoch-qualitative, und multifunktionelle Materialien weiter zu entwickeln. Ionische PNCs verprechen nicht nur die genannten mechanischen Eigenschaften, sondern auch ein Potential für Selstheilung, ionische Leitfähigkeit, und selektive Permeabilitä Simulationsmodelle erlauben uns, die genannten Abhäigkeiten im Detail zu untersuchen, und öffnen eue Horizonte für das Design ionischer PNCs für Anwendungen etwa in der Biomedizin, Biotechnologie, Energiespeicherung, Gastrennung.
04 May 2025
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