A5020232591- Pickering emulsions and particle stabilization
- Hydrogels: synthesis, properties, applications
- Surfactants and Colloidal Systems
- Polymer Surface Interaction Studies
- Proteins in Food Systems
- Rheology and Fluid Dynamics Studies
- Phase Equilibria and Thermodynamics
- Advanced Materials and Mechanics
- Advanced Polymer Synthesis and Characterization
- Supramolecular Self-Assembly in Materials
- Block Copolymer Self-Assembly
- Material Dynamics and Properties
- Heat and Mass Transfer in Porous Media
- Lipid Membrane Structure and Behavior
- Polysaccharides Composition and Applications
- Fluid Dynamics and Mixing
- Advanced Sensor and Energy Harvesting Materials
- Carbon dioxide utilization in catalysis
- Radical Photochemical Reactions
- Innovative Microfluidic and Catalytic Techniques Innovation
- Liquid Crystal Research Advancements
- Characterization and Applications of Magnetic Nanoparticles
- Nanopore and Nanochannel Transport Studies
- Molecular Sensors and Ion Detection
- Electrostatics and Colloid Interactions
RWTH Aachen University
2016-2024
Sapienza University of Rome
2023
Ikerbasque
2023
Institute for Complex Systems
2023
National Academies of Sciences, Engineering, and Medicine
2023
Lund University
2023
Institut Laue-Langevin
2023
Material Physics Center
2023
FH Aachen
2019-2021
Abstract Microgels are solvent-swollen nano- and microparticles that show prevalent colloidal-like behavior despite their polymeric nature. Here we study ultra-low crosslinked poly( N -isopropylacrylamide) microgels (ULC), which can behave like colloids or flexible polymers depending on dimensionality, compression other external stimuli. Small-angle neutron scattering shows the structure of ULC in bulk aqueous solution is characterized by a density profile decays smoothly from center to...
We investigate soft, temperature-sensitive microgels at fluid interfaces. Though having an isotropic, spherical shape in bulk solution, the become anisotropic upon adsorption. The structure of interfaces is described by a core–corona morphology. Here, we how changing temperature across microgel volume phase transition temperature, which leads to swelling/deswelling aqueous phase, affects behavior within monolayer. combine compression isotherms, atomic force microscopy imaging,...
The structural characterization of microgels at interfaces is fundamental to understand both their 2D phase behavior and role as stabilizers that enable emulsions be broken on demand. However, this usually limited by available experimental techniques, which do not allow a direct investigation interfaces. To overcome difficulty, here we employ neutron reflectometry, allows us probe the structure responsiveness in-situ air-water interface. We investigate two types with different cross-link...
The softness of nanohydrogels results in unique properties and recently attracted tremendous interest due to the multi-functionalization interfaces. Herein, we study extremely soft temperature-sensitive ultra-low cross-linked (ULC) nanogels adsorbed solid/water interface by atomic force microscopy (AFM). ultra-soft seem disappear classical imaging modes since a sharp tip fully penetrates these porous networks with very low forces range steric interactions (ca. 100 pN). However, detailed...
Solutions of ultra-low crosslinked microgels show viscoelastic properties in between rigid particles and flexible polymers. The dominance particle-like polymer-like behavior depends on the concentration microgel solution.
As lateral compression is applied, microgel particles with different softness exhibit distinct behaviours. Hard microgels (green particles) are pushed away from the air–water interface, whereas soft ones (orange less deformed.
Soft pair potentials predict a reentrant liquid phase for high concentrations, behavior not observed experimentally. Here, very soft microgels confined at an oil-water interface are used as model system of particles interacting via potential in two dimensions (2D). Interfacial rheology measurements demonstrate the existence different flow regimes that depend on compression monolayer. Such also leads to non-monotonic variation elastic moduli and yield stress These results, together with...
The formation of smart emulsions or foams whose stability can be controlled on-demand by switching external parameters is great interest for basic research and applications. An emerging group stabilizers are microgels, which nano- micro-sized, three-dimensional polymer networks that swollen a good solvent. In the last decades, influence various stimuli on two-dimensional phase behavior microgels at air- oil-water interfaces has been studied. However, impact top-phase itself barely...
The role of electrostatics on the interfacial properties polyelectrolyte microgels has been discussed controversially in literature. It is not yet clear if, or how, Coulomb interactions affect their behavior under confinement. In this work, we combine compression isotherms, atomic force microscopy imaging, and computer simulations to further investigate pH-responsive at oil–water interfaces. At low compression, charged can be compressed more than uncharged microgels. in-plane effective area...
The structure of poly(N-isopropylacrylamide) (PNIPAM) microgels adsorbed onto a solid substrate is investigated in the dry and hydrated states by means atomic force microscopy (AFM). We compare two different systems: regularly cross-linked microgel containing 5 mol % cross-linker ultra-low (ULC) prepared without dedicated cross-linker. Furthermore, we three adsorption processes: (i) situ from solution, (ii) spin-coating, (iii) Langmuir–Blodgett deposition an oil–water interface. results...
The phase behavior of supersoft spheres is explored using solutions ultralow cross-linked poly(N-isopropylacrylamide)-based microgels as a model system. For these microgels, the effects electric charges on their surfaces can be neglected and therefore only role softness investigated. samples show liquid-to-crystal transition at higher volume fraction with respect to both hard stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition expected face...
Surface-active polymers have important applications as effective and responsive emulsifiers, foaming agents, coatings. In this contribution, we explore the impact of polymer architecture on behavior at oil-water interfaces by comparing different poly(N-isopropylacrylamide) (pNIPAM)-based systems, namely, monolayers linear star-shaped macromolecules, ultralow cross-linked, regular hollow microgels. Compression isotherms were determined experimentally well computer simulations. The latter...
Abstract Near‐equilibrium stimulus‐responsive polymers have been used extensively to introduce morphological variations in dependence of adaptable conditions. Far‐less‐well studied are triggered transformations at constant These require the involvement metastable states, which either able approach equilibrium state after deviation from metastability or can be frozen on returning nonequilibrium equilibrium. Such functional macromolecular systems hold great promise for on‐demand...
Monolayers of polymer microgels adsorbed at the liquid interfaces were studied by dissipative particle dynamics simulations. The results demonstrated that compressibility monolayers can be widely tuned varying cross-linking density and their (in)compatibility with immiscible liquids. In particular, compression (increase 2D concentration microgels) leads to decrease lateral size. Herewith, shape individual soft particles gradually changes from oblate (diluted system) nearly spherical...
Anisotropic, submicrometer-sized particles are versatile systems providing interesting features in creating ordering two-dimensional systems. Combining hard ellipsoids with a soft shell further enhances the opportunities to trigger and control order alignment. In this work, we report rich 2D phase behavior show how softness affects of anisotropic at fluid oil-water interfaces. Three different core-shell were synthesized such that they have same elliptical hematite-silica core but differ...
In situ interfacial rheology and numerical simulations are used to investigate microgel monolayers in a wide range of packing fractions, ${\ensuremath{\zeta}}_{2D}$. The heterogeneous particle compressibility determines two flow regimes characterized by distinct master curves. To mimic the architecture reproduce experiments, an interaction potential combining soft shoulder with Hertzian model is introduced. contrast bulk conditions, elastic moduli vary nonmonotonically...
Micro- and nanogels are widely used to stabilise emulsions simultaneously implement their responsiveness the external stimuli. One of factors that improves emulsion stability is nanogel softness. Here, we study how softest can be synthesised with precipitation polymerisation N-isopropylacrylamide (NIPAM), ultra-low crosslinked (ULC) nanogels, oil-in-water emulsions. We show ULC efficiently already at low mass concentrations. These resistant droplet flocculation, stable against coalescence,...
We report the effect of short OEG chains on adsorption behaviour thermoresponsive PNIPAM-based functional microgels at oil–water interface temperatures below and above volume phase transition temperature microgels.
We investigated the interaction between microgel monolayers at air–water interface and a hard colloid in water. Our results show that change from soft to repulsive interfaces when VPTT is exceeded.
Abstract The europium(III) complex 1 -Cl 3 ( S,S -2,2′-(((1,10-phenanthroline-2,9-diyl)bis(methanylylidene))bis(azanylylidene))bis(3-methylbutanamide)europiumtrichloride) undergoes, only in the presence of amino acid tryptophan, a change emission at 615 nm. In few equivalents europium is enhanced while it disappears upon addition large amounts. This behavior can be assigned to displacement sensitizing phenanthroline ligand 2 •Trp latter case.
Abstract The softness of nanohydrogels results in unique properties and recently attracted tremendous interest due to the multi‐functionalization interfaces. Herein, we study extremely soft temperature‐sensitive ultra‐low cross‐linked (ULC) nanogels adsorbed solid/water interface by atomic force microscopy (AFM). ultra‐soft seem disappear classical imaging modes since a sharp tip fully penetrates these porous networks with very low forces range steric interactions (ca. 100 pN). However,...
Microgels are confined to fluid interfaces in numerous applications, yet many aspects of the microgel-covered interface remain unclear. In this work, we use interfacial shear and dilatational rheology study effects electrostatics on mechanical characteristics polyelectrolyte microgel monolayers at oil-water as a function concentration. We find clear correlation between influence charges properties their two-dimensional phase behavior. At lower concentrations, moduli uncharged larger than...
Studying the properties of soft nanoparticles exposes students to emerging trends in materials science, fosters interdisciplinary knowledge, and prepares them for their own contributions both academic industrial settings. We developed a laboratory atomic force microscopy (AFM) experiment using poly-N -isopropylacrylamide (PNI- PAM) microgels investigated single nanogels as well monolayers by AFM quantitative image analysis. The experiments show how are deformed at interfaces learn quantify...
The adsorption of ellipsoidal colloidal particles on liquid interfaces induces interfacial deformation, resulting in anisotropic interface-mediated interactions and the formation superstructures. Soft prolate-shaped microgels at air-water interface offer an ideal model for studying spontaneous capillary-driven self-assembly due to their tunable aspect ratio, controlled functionality, softness. These consist a polystyrene core surrounded by cross-linked, fluorescently labeled poly( <mml:math...