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ZQ Shen, HL Ye, C Zhou, M Kroger, Y Li,
Size of graphene sheets determines the structural and mechanical properties of 3D graphene foams
NANOTECHNOLOGY 29 (2018) 104001
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Graphene is recognized as an emerging 2D nanomaterial for many applications. Assembly of graphene sheets into 3D structures is an attractive way to enable their macroscopic applications and to preserve the exceptional mechanical and physical properties of their constituents. In this study, we develop a coarse-grained (CG) model for 3D graphene foams (GFs) based on the CG model for a 2D graphene sheet by Ruiz et al (2015 Carbon 82 103-15). We find that the size of graphene sheets plays an important role in both the structural and mechanical properties of 3D GFs. When their size is smaller than 10 nm, the graphene sheets can easily stack together under the influence of van der Waals interactions (vdW). These stacks behave like building blocks and are tightly packed together within 3D GFs, leading to high density, small pore radii, and a large Young's modulus. However, if the sheet sizes exceed 10 nm, they are staggered together with a significant amount of deformation (bending). Therefore, the density of 3D GFs has been dramatically reduced due to the loosely packed graphene sheets, accompanied by large pore radii and a small Young's modulus. Under uniaxial compression, rubber-like stress-strain curves are observed for all 3D GFs. This material characteristic is dominated by the vdW interactions between different graphene layers and slightly affected by the out-of-plane deformation of the graphene sheets. We find a simple scaling law E similar to rho(4.2) between the density rho and Young's modulus E for a model of 3D GFs. The simulation results reveal structure-property relations of 3D GFs, which can be applied to guide the design of 3D graphene assemblies with exceptional properties. Kroger, Martin/C-1946-2008; Shen, Zhiqiang/O-5073-2019; Li, Ying/B-9378-2008 Kroger, Martin/0000-0003-1402-6714; Shen, Zhiqiang/0000-0003-0804-2478; Li, Ying/0000-0002-1487-3350 Department of Mechanical Engineering at the University of Connecticut; GE Fellowship for Innovation; National Science Foundation [ACI-1053575]; Swiss National Science Foundation [200021_156106] Z S, H Y, and Y L are grateful for the support from the Department of Mechanical Engineering at the University of Connecticut. Z S and H Y would like to acknowledge the partial financial support from the GE Fellowship for Innovation. This research benefited in part from the computational resources and staff contributions provided by the Booth Engineering Center for Advanced Technology (BECAT) at the University of Connecticut. Part of this work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation under grant number ACI-1053575. M K was supported by the Swiss National Science Foundation through grant 200021_156106. [hide]
Principal Investigators
Leonard Sagis (PL)
Polymer Physics, ETH Zurich, Switzerland ►
Wageningen University, Netherlands ►
Patrick Ilg (PL)
Polymer Physics, ETH Zurich, Switzerland ►
University of Reading, United Kingdom ►
Peter Fischer (Co-PI)
Inst. Food, nutrition and health, ETH Zurich, Switzerland ►
Martin Kröger (PI)
Polymer Physics, ETH Zurich, Switzerland ►
Secretary
Patricia Horn
Polymer Physics, ETH Zurich, Switzerland ►
Involved Students
Ahmad Moghimikheirabadi
Polymer Physics, ETH Zurich, Switzerland ►
Enjoy your reading
LMC Sagis, BX Liu, Y Li, J Essers, J Yang, A Moghimikheirabadi, E Hinderink, C Berton-Carabin, K Schroen,
Dynamic heterogeneity in complex interfaces of soft interface-dominated materials
SCIENTIFIC REPORTS 9 (2019) 2938
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A Moghimikheirabadi, LMC Sagis, M Kroger, P Ilg,
Gas-liquid phase equilibrium of a model Langmuir monolayer captured by a multiscale approach
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 21 (2019) 2295
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PS Stephanou, M Kroger,
Assessment of the Tumbling-Snake Model against Linear and Nonlinear Rheological Data of Bidisperse Polymer Blends
POLYMERS 11 (2019) 376
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SA Vasudevan, A Rauh, M Kroger, M Karg, L Isa,
Dynamics and Wetting Behavior of Core-Shell Soft Particles at a Fluid-Fluid Interface
LANGMUIR 34 (2018) 15370
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YR Sliozberg, IC Yeh, M Kroger, KA Masser, JL Lenhart, JW Andzelm,
Ordering and Crystallization of Entangled Polyethylene Melts under Uniaxial Tension: A Molecular Dynamics Study
MACROMOLECULES 51 (2018) 9635
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J Kirk, M Kroger, P Ilg,
Surface Disentanglement and Slip in a Polymer Melt: A Molecular Dynamics Study
MACROMOLECULES 51 (2018) 8996
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A Moghimikheirabadi, LM Sagis, P Ilg,
Effective interaction potentials for model amphiphilic surfactants adsorbed at fluid-fluid interfaces
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 20 (2018) 16238
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A Ramirez-Hernandez, BL Peters, L Schneider, M Andreev, JD Schieber, M Muller, M Kroger, JJ de Pablo,
A Detailed Examination of the Topological Constraints of Lamellae-Forming Block Copolymers
MACROMOLECULES 51 (2018) 2110
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ZQ Shen, HL Ye, M Kroger, Y Li,
Aggregation of polyethylene glycol polymers suppresses receptor-mediated endocytosis of PEGylated liposomes
NANOSCALE 10 (2018) 4545
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ZQ Shen, HL Ye, M Kroger, Y Li,
Self-assembled core-polyethylene glycol-lipid shell nanoparticles demonstrate high stability in shear flow
PHYSICAL CHEMISTRY CHEMICAL PHYSICS 19 (2017) 13294
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Z Shen, M Roding, M Kroger, Y Li,
Carbon Nanotube Length Governs the Viscoelasticity and Permeability of Buckypaper
POLYMERS 9 (2017) 115
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CF Luo, M Kroger, JU Sommer,
Molecular dynamics simulations of polymer crystallization under confinement: Entanglement effect
POLYMER 109 (2017) 71
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CF Luo, M Kroger, JU Sommer,
Entanglements and Crystallization of Concentrated Polymer Solutions: Molecular Dynamics Simulations
MACROMOLECULES 49 (2016) 9017
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M Schuppler, FC Keber, M Kroger, AR Bausch,
Boundaries steer the contraction of active gels
NATURE COMMUNICATIONS 7 (2016) 13120
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MK Singh, P Ilg, RM Espinosa-Marzal, ND Spencer, M Kroger,
Influence of Chain Stiffness, Grafting Density and Normal Load on the Tribological and Structural Behavior of Polymer Brushes: A Nonequilibrium-Molecular-Dynamics Study
POLYMERS 8 (2016) 254
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YR Sliozberg, M Kroger, TL Chantawansri,
Fast equilibration protocol for million atom systems of highly entangled linear polyethylene chains
JOURNAL OF CHEMICAL PHYSICS 144 (2016) 154901
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PS Stephanou, M Kroger,
Solution of the complete Curtiss-Bird model for polymeric liquids subjected to simple shear flow
JOURNAL OF CHEMICAL PHYSICS 144 (2016) 124905
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Y Li, S Tang, M Kroger, WK Liu,
Molecular simulation guided constitutive modeling on finite strain viscoelasticity of elastomers
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS 88 (2016) 204
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ZQ Shen, DT Loe, JK Awino, M Kroger, JL Rouge, Y Li,
Self-assembly of core-polyethylene glycol-lipid shell (CPLS) nanoparticles and their potential as drug delivery vehicles
NANOSCALE 8 (2016) 14821
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A Halperin, M Kroger, FM Winnik,
Poly(N-isopropylacrylamide) Phase Diagrams: Fifty Years of Research
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 54 (2015) 15342
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MK Singh, P Ilg, RM Espinosa-Marzal, M Kroger, ND Spencer,
Polymer Brushes under Shear: Molecular Dynamics Simulations Compared to Experiments
LANGMUIR 31 (2015) 4798
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Selected conferences (co-)organized by project membersIWNET 2015
05 Jul - 10 Jul 2015, 7th International workshop on nonequilibrium thermodynamics (IWNET 2015), Hilvarenbeek, The Netherlands ►IWNET 2018
01 Jul - 06 Jul 2018, 8th International Workshop on Nonequilibrium Thermodynamics (IWNET 2018), Sint-Michielsgestel, The Netherlands ►
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About this project
Complex fluid-fluid interfaces are interfaces in which the adsorbed species self-assemble
into complex microstructures. Such interfaces are ubiquitous in nature, industrial processes,
and consumer products, and can be found in living cells, nano- and microcapsules, vesicles,
food emulsions, or foam. Compared to simple liquid-like interfaces (stabilized by
low molecular weight surfactants), complex interfaces display significant viscoelasticity,
with high values for their surface shear and dilatational moduli. Their stress-deformation
behavior dominates the macroscopic dynamics of multiphase materials that contain
such interfaces, and when this occurs those materials can be referred to as
Interface-Dominated Materials (IDMs).
Complex interfaces can be formed by a wide range of surface active components, such
as proteins, colloidal particles, polymers, lipids, or mixtures of these components.
In this proposal we will focus on complex interfaces stabilized by amphiphilic multi-block
copolymers. These polymers consist of alternating blocks of a hydrophilic repeating unit A,
and a hydrophobic repeating unit B. Amphiphilic copolymers can form interfaces with
exceptional mechanical properties. This makes them ideal candidates for application
in highly stable emulsions, or encapsulation systems with high mechanical stability, for application in food and pharmaceutical products.
Amphiphilic copolymers may form 2d gels, 2d (soft) glass phases, 2d (liquid) crystalline
phases, or even 2d metastable emulsions (phase-separated mixtures of immiscible copolymers)
after adsorption. The type of structure formed depends on surface concentration,
and length, distribution, rigidity, and hydrophobicity of the sub-blocks of the copolymer.
The response of polymer stabilized fluid-fluid interfaces to deformations or gradients in
temperature is often highly nonlinear. The nonlinearity in their response to perturbations
is a result of changes in this interfacial microstructure, induced by the applied
gradients. The effect of deformations on interfacial microstructure, and the effect
of these changes on macroscopic dynamics of interface-dominated materials is still
poorly understood. A more fundamental understanding of the nonlinear response of
polymer interfaces, is essential for a targeted design of high-end polymer stabilized
IDMs, such as encapsulation systems with environmental triggers, nanoparticles with
structured interfaces, or foam and emulsions with extreme stability. In view of the
widespread occurrence of IDMs, the study of dynamic mechanical properties of these
interfaces is highly relevant for many disciplines, such as colloid and interface
science, physical chemistry, polymer physics, pharmaceutical science, food science,
coating technology, or soft matter physics.
The aim of this project is to characterize the microstructure and mechanical properties
of interfaces stabilized by multi-block copolymers, using a multiscale multidisciplinary
approach, which integrates state of the art computational methods with surface rheological
experiments, and experimental interfacial structure evaluation. The computational
modeling will be done using Monte Carlo (MC) and Molecular Dynamics (MD) simulations.
We will measure both shear and dilatational surface properties, and the microstructure
will be evaluated using various forms of microscopy (AFM, TEM, SEM), and neutron
and X-ray reflectivity measurements. We will determine the mechanical properties
and interfacial structure as a function of surface polymer concentration, chemical
structure of the polymers (variation of number, size, and distribution of blocks),
and degree of hydrophobicity and rigidity of the sub-blocks. A detailed insight in
the dynamic behavior of copolymer interfaces will provide new insight in the macroscopic
dynamic behavior of polymer stabilized interface-dominated materials (emulsions,
foam, encapsulation systems, nanoparticles), and will allow a more targeted design
of these systems with tailor made properties, tuned for specific industrial applications.
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