Surface rheology of block-copolymer stabilized interfaces: a combined computational & experimental study. SNF project 200021_156106 at www.complexfluids.ethz.ch/snf15

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

Herein a new multifunctional formulation, referred to as a core-polyethylene glycol-lipid shell (CPLS) nanoparticle, has been proposed and studied in silico via large scale coarse-grained molecular dynamics simulations. A PEGylated core with surface tethered polyethylene glycol (PEG) chains is used as the starting configuration, where the free ends of the PEG chains are covalently bonded with lipid molecules (lipid heads). A complete lipid bilayer is formed at the surface of the PEGylated particle core upon addition of free lipids, driven by the hydrophobic properties of the lipid tails, leading to the formation of a CPLS nanoparticle. The self-assembly process is found to be sensitive to the grafting density and molecular weight of the tethered PEG chains, as well as the amount of free lipids added. At low grafting densities the assembly of CPLS nanoparticles cannot be accomplished. As demonstrated by simulations, a lipid bud/vesicle can be formed on the surface when an excess amount of free lipids is added at high grafting density. Therefore, the CPLS nanoparticles can only be formed under appropriate conditions of both PEG and free lipids. The CPLS nanoparticle has been recognized to be able to store a large quantity of water molecules, particularly with high molecular weight of PEG chains, indicating its capacity for carrying hydrophilic molecules such as therapeutic biomolecules or imaging agents. Under identical size and surface chemistry conditions of a liposome, it has been observed that the CPLS particle can be more efficiently wrapped by the lipid membrane, indicating its potential for a greater efficiency in delivering its hydrophilic cargo. As a proof-of-concept, the experimental realization of CPLS nanoparticles is explicitly demonstrated in this study. To test the capacity of the CPLS to store small molecule cargo a hydrophilic dye was successfully encapsulated in the particles' water soluble layer. The results of this study show the power and potential of simulation-driven approaches for guiding the design of more efficient nanomaterial delivery platforms. Shen, Zhiqiang/O-5073-2019; Kroger, Martin/C-1946-2008 Shen, Zhiqiang/0000-0003-0804-2478; Kroger, Martin/0000-0003-1402-6714; K. Awino, Joseph/0000-0003-3710-3014 Department of Mechanical Engineering at University of Connecticut; Department of Chemistry at University of Connecticut; Swiss National Science Foundation [200021_156106] Z. S. and Y. L. are grateful for the support from the Department of Mechanical Engineering at University of Connecticut. D. L., J. A. and J. R. would like to acknowledge the support from the Department of Chemistry at University of Connecticut. This research benefited in part from the computational resources and staff contributions provided for the Booth Engineering Center for Advanced Technology (BECAT) at the University of Connecticut. The contribution by M. K. was promoted by the Swiss National Science Foundation through grant no. 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

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

PS Stephanou, M Kroger,
Assessment of the Tumbling-Snake Model against Linear and Nonlinear Rheological Data of Bidisperse Polymer Blends
POLYMERS 11 (2019) 376

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

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

J Kirk, M Kroger, P Ilg,
Surface Disentanglement and Slip in a Polymer Melt: A Molecular Dynamics Study
MACROMOLECULES 51 (2018) 8996

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

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

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

ZQ Shen, HL Ye, M Kroger, Y Li,
Aggregation of polyethylene glycol polymers suppresses receptor-mediated endocytosis of PEGylated liposomes
NANOSCALE 10 (2018) 4545

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

Z Shen, M Roding, M Kroger, Y Li,
Carbon Nanotube Length Governs the Viscoelasticity and Permeability of Buckypaper
POLYMERS 9 (2017) 115

CF Luo, M Kroger, JU Sommer,
Molecular dynamics simulations of polymer crystallization under confinement: Entanglement effect
POLYMER 109 (2017) 71

CF Luo, M Kroger, JU Sommer,
Entanglements and Crystallization of Concentrated Polymer Solutions: Molecular Dynamics Simulations
MACROMOLECULES 49 (2016) 9017

M Schuppler, FC Keber, M Kroger, AR Bausch,
Boundaries steer the contraction of active gels
NATURE COMMUNICATIONS 7 (2016) 13120

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

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

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

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

A Halperin, M Kroger, FM Winnik,
Poly(N-isopropylacrylamide) Phase Diagrams: Fifty Years of Research
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 54 (2015) 15342

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


Selected conferences (co-)organized by project members

IWNET 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.

28 April 2024 mk