Emanuela Zaccarelli

Emanuela Zaccarelli
Italian National Research Council | CNR · Institute for Complex Systems ISC

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208
Publications
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10,223
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Publications

Publications (208)
Article
Full-text available
The structural characterization of microgels at interfaces is fundamental to understand both their 2D phase behavior and their role as stabilizers that enable emulsions to be broken on demand. However, this characterization is usually limited by available experimental techniques, which do not allow a direct investigation at interfaces. To overcome...
Preprint
Full-text available
Poly(N-isopropylacrylamide)-based microgels are soft colloids undergoing a Volume Phase Transition (VPT) close to ambient temperature. Although widely employed for fundamental research and application purposes, the modifications of the microgel internal structure occurring at the VPT are not yet completely understood, especially concerning the role...
Article
Full-text available
Water is known to play a fundamental role in determining the structure and functionality of macromolecules. The same crucial contribution is also found in the in silico description of polymer aqueous solutions. In this work, we exploit the widely investigated synthetic polymer poly(N-isopropylacrylamide) (PNIPAM) to understand the effect of the ado...
Article
Full-text available
Active matter may sometimes behave almost indistinguishably from equilibrium matter. This is particularly evident for some particle-based models and active field-theories close to a critical point which falls in the Ising universality class. Here we show however that, even when critical, active particles strongly violate the equilibrium fluctuation...
Preprint
Full-text available
Poly(N-isopropylacrylamide) (PNIPAM) is a synthetic polymer that is widely studied for its thermoresponsive character. However, recent works also reported evidence of a low temperature (protein-like) dynamical transition around 225 K in concentrated PNIPAM suspensions, independently of the polymer architecture, i.e., both for linear chains and for...
Article
Poly(N-isopropylacrylamide) (PNIPAM) is a synthetic polymer that is widely studied for its thermoresponsive character. However, recent works also reported evidence of a low temperature (protein-like) dynamical transition around 225 K in concentrated PNIPAM suspensions, independently of the polymer architecture, i.e., both for linear chains and for...
Article
Full-text available
This paper is a guest editorial for a special issue 'Depletion Forces and Asakura-Oosawa Theory' of The Journal of Chemical Physics dedicated to depletion effects in soft materials. The issue contains papers exploring experimental and theoretical developments as well as diverse applications of depletion forces in a variety of fields including (bio)...
Preprint
Full-text available
Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of polyacrylic acid. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affec...
Preprint
Full-text available
The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(Nisopropylacrylamide) (PNIPAM) and polyacrylic acid (PAAc) at fixe...
Preprint
The design of complex materials and the formation of specific patterns often arise from the properties of the individual building blocks. In this respect, colloidal systems offer a unique opportunity because nowadays they can be synthesized in the laboratory with many different shapes and features. Hence, an appropriate choice of the particle chara...
Article
Full-text available
We combine small-angle scattering experiments and simulations to investigate the internal structure and interactions of composite poly(N-isopropylacrylamide)-poly(ethylene glycol) (PNIPAM-PEG) microgels. At low temperatures the experimentally determined form factors and the simulated density profiles indicate a loose internal particle structure wit...
Preprint
We combine small angle scattering experiments and simulations to investigate the internal structure and interactions of composite Poly(N-isopropylacrylamide)-Poly(ethylene glycol) (PNIPAM-PEG) microgels. At low temperatures the experimentally determined form factors and the simulated density profiles indicate a loose internal particle structure wit...
Article
Full-text available
Thermoresponsive microgels are one of the most investigated types of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling proc...
Preprint
We numerically investigate the correlation function, the response and the breakdown of the Fluctuation-Dissipation Theorem (FDT) in active particles close to the motility-induced critical point. We find a strong FDT violation in the short time and wavelength regime, where the response function has a larger amplitude than the fluctuation spectrum. C...
Article
The addition of co-solutes to colloidal suspensions is often employed to induce tunable depletion interactions. In this work, we investigate effective colloidal interactions arising from binary co-solute mixtures of hard spheres and patchy particles. By changing the relative concentration of the two species, we show that the resulting effective pot...
Preprint
Against common sense, auxetic materials expand when stretched or contract when compressed by uniaxial strain, being characterized by a negative Poisson's ratio $\nu$. The amount of perpendicular deformation in response to the applied force can be at most equal to the imposed one, so that $\nu=-1$ is the lowest bound for the mechanical stability of...
Article
Full-text available
Monolayers of soft colloidal particles confined at fluid interfaces are at the core of a broad range of technological processes, from the stabilization of responsive foams and emulsions to advanced lithographic techniques. However, establishing a fundamental relation between their internal architecture, which is controlled during synthesis, and the...
Article
Full-text available
By means of Langevin dynamics simulations, we investigate the gel formation of randomly functionalized polymers in solution, with the ability to form both intra- and intermolecular reversible bonds. Under highly dilute conditions, these polymers form soft nano-objects (so-called single-chain nanoparticles, SCNPs), resulting from the purely intramol...
Article
Hypotheses Additives are commonly used to tune macromolecular conformational transitions. Among additives, trehalose is an excellent bioprotectant and among responsive polymers, PNIPAM is the most studied material. Nevertheless, their interaction mechanism so far has only been hinted without direct investigation, and, crucially, never elucidated in...
Preprint
The addition of co-solutes to colloidal suspensions is often employed to induce tunable depletion interactions. In this work we investigate effective colloidal interactions arising from binary co-solute mixtures of hard spheres and patchy particles. By changing the relative concentration of the two species, we show that the resulting effective pote...
Preprint
We report extensive numerical simulations of different models of 2D polymer rings with internal elasticity. We monitor the dynamical behavior of the rings as a function of the packing fraction, to address the effects of particle deformation on the collective response of the system. In particular, we compare three different models: (i) a recently in...
Article
We report extensive numerical simulations of different models of 2D polymer rings with internal elasticity. We monitor the dynamical behavior of the rings as a function of the packing fraction to address the effects of particle deformation on the collective response of the system. In particular, we compare three different models: (i) a recently inv...
Preprint
Thermoresponsive microgels are one of the most investigated class of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling proc...
Article
Full-text available
Due to their unique structural and mechanical properties, randomly cross-linked polymer networks play an important role in many different fields, ranging from cellular biology to industrial processes. In order to elucidate how these properties are controlled by the physical details of the network (e.g., chain-length and end-to-end distributions), w...
Article
Full-text available
The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylic acid (PAAc) at fix...
Preprint
Full-text available
Monolayers of soft colloidal particles confined at fluid interfaces have been attracting increasing interest for fundamental studies and applications alike. However, establishing the relation between their internal architecture, which is controlled during synthesis, and their structural and mechanical properties upon interfacial confinement, which...
Article
In this review, we discuss recent advances in the investigation of colloidal systems interacting via a combination of short-range attraction and long-range repulsion. The prototypical examples of this phenomenology are charged colloids with depletion interactions, but the results apply, to a large extent, also to suspensions of globular proteins, c...
Article
Full-text available
Combining elastic incoherent neutron scattering experiments at different resolutions with molecular dynamics simulations, we report the observation of a proteinlike dynamical transition in linear chains of poly(N-isopropylacrylamide). We identify the onset of the transition at a temperature Td of about 225 K. Due to a global fit procedure, we find...
Preprint
In this work we use a multi-technique approach to gain new insights into the effects of trehalose on the volume phase transition of poly(N-isopropylacrylamide) (PNIPAM) microgels, a model synthetic biomimetic system. By dynamic light scattering the temperature-dependent microgel hydrodynamic volume is monitored, while Raman spectroscopy and molecul...
Article
Full-text available
By using extensive all-atom molecular dynamics simulations of an atactic linear polymer chain, we provide microscopic insights into Poly(N-isopropylacrylamide) (PNIPAM) coil-to-globule transition addressing the roles played by both temperature and pressure. We detect a coil-to-globule transition up to large pressures, showing an intriguing reentran...
Article
We perform large-scale computer simulations of an off-lattice two-dimensional model of active particles undergoing a motility-induced phase separation (MIPS) to investigate the systems critical behaviour close to the critical point of the MIPS curve. By sampling steady-state configurations for large system sizes and performing finite size scaling a...
Article
Full-text available
Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and Polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of Polyacrylic acid. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affec...
Preprint
Full-text available
Ionic microgel particles are intriguing systems in which the properties of thermo-responsive polymeric colloids are enriched by the presence of charged groups. In order to rationalize their properties and predict the behaviour of microgel suspensions, it is necessary to develop a coarse-graining strategy that starts from the accurate modelling of s...
Preprint
Full-text available
Due to their unique structural and mechanical properties, randomly-crosslinked polymer networks play an important role in many different fields, ranging from cellular biology to industrial processes. In order to elucidate how these properties are controlled by the physical details of the network (\textit{e.g.} chain-length and end-to-end distributi...
Preprint
Full-text available
By means of Langevin dynamics simulations, we investigate the gel formation of randomly functionalized polymers in solution, with the ability to form both intra-and intermolecular reversible bonds. Under highly dilute conditions, these polymers form soft nano-objects (so-called single-chain nanoparticles, SCNPs), resulting from the purely intramole...
Article
We present a systematic investigation of static and dynamic properties of block copolymer micelles with cross-linked cores, representing model polymer-grafted nanoparticles, over a wide concentration range from a dilute regime to an arrested (crystalline) state, by means of light and neutron scattering, complemented by linear viscoelasticity. We ha...
Article
Full-text available
We present a multiscale characterization of aqueous solutions of the bovine eye lens protein βH crystallin from dilute conditions up to dynamical arrest, combining dynamic light scattering, small-angle x-ray scattering, tracer-based microrheology, and neutron spin echo spectroscopy. We obtain a comprehensive explanation of the observed experimental...
Preprint
Full-text available
We present a systematic investigation of static and dynamic properties of block copolymer micelles with crosslinked cores, representing model polymer-grafted nanoparticles, over a wide concentration range from dilute regime to an arrested (crystalline) state, by means of light and neutron scattering, complemented by linear viscoelasticity. We have...
Article
Full-text available
Ionic microgel particles are intriguing systems in which the properties of thermo-responsive polymeric colloids are enriched by the presence of charged groups. In order to rationalize their properties and predict the behaviour of microgel suspensions, it is necessary to develop a coarse-graining strategy that starts from the accurate modelling of s...
Preprint
Poly-N-isopropylacrylamide (PNIPAM) phase diagram is explored in a wide range of temperature and pressure using extensive all-atom molecular dynamics simulations. By exploiting a simple model of an atactic linear polymer chain, we provide novel insights into PNIPAM coil-to-globule transition addressing the roles played by both temperature and press...
Preprint
Combining elastic incoherent neutron scattering and differential scanning calorimetry, we investigate the occurrence of the volume phase transition (VPT) in very concentrated PNIPAM microgel suspensions, from a polymer weight fraction of 30~wt\% up to dry conditions. Although samples are arrested at the macroscopic scale, atomic degrees of freedom...
Preprint
We perform large-scale computer simulations of an off-lattice two-dimensional model of active particles undergoing a motility-induced phase separation (MIPS) to investigate the systems critical behaviour close to the critical point of the MIPS curve. By sampling steady-state configurations for large system sizes and performing finite size scaling a...
Preprint
Combining elastic incoherent neutron scattering experiments at different resolutions and molecular dynamics simulations, we report the observation of a protein-like dynamical transition in Poly(N-isopropylacrylamide) chains. We identify the onset of the transition at a temperature Td of about 225~K. Thanks to a novel global fit procedure, we find q...
Article
Full-text available
Soft colloids are increasingly used as model systems to address fundamental issues such as crystallization and the glass and jamming transitions. Among the available classes of soft colloids, microgels are emerging as the gold standard. Since their great internal complexity makes their theoretical characterization very hard, microgels are commonly...
Article
Combining elastic incoherent neutron scattering and differential scanning calorimetry, we investigate the occurrence of the volume phase transition (VPT) in very concentrated poly-(N-isopropyl-acrylamide) (PNIPAM) microgel suspensions, from a polymer weight fraction of 30 wt. % up to dry conditions. Although samples are arrested at the macroscopic...
Article
Microgel particles have emerged in the last few years as a favourite model system for fundamental science and for innovative applications ranging from industrial to biomedical fields. Despite their potentialities, no works so far have focused on the application of microgels for cultural heritage preservation. Here we show their first use for this p...
Article
We study colloidal gels formed by competing electrostatic repulsion and short-range attraction by means of extensive numerical simulations under external shear. We show that, upon varying the repulsion strength, the gel structure and its viscoelastic properties can be largely tuned. In particular, the gel fractal dimension can be either increased o...
Preprint
We study colloidal gels formed by competing electrostatic repulsion and short-range attraction by means of extensive numerical simulations under external shear. We show that, upon varying the repulsion strength, the gel structure and its viscoelastic properties can be largely tuned. In particular, the gel fractal dimension can be either increased o...
Preprint
Soft colloids are increasingly used as model systems to address fundamental issues such as crystallisation and the glass and jamming transitions. Among the available classes of soft colloids, microgels are emerging as the gold standard. Since their great internal complexity makes their theoretical characterization very hard, microgels are commonly...
Preprint
Full-text available
Poly(N-isopropylacrylamide), PNIPAM, is a widely studied polymer, which serves as a key constituent of nanostructured soft materials with responsive properties. Upon increasing temperature the PNIPAM polymer chain undergoes a reversible coil-to-globule transition at ~305K, which is reflected by a volume phase transition in cross-linked architecture...
Article
Full-text available
Recent progress has been made in the numerical modelling of neutral microgel particles with a realistic, disordered structure. In this work we extend this approach to the case of co-polymerised microgels where a thermoresponsive polymer is mixed with acidic groups. We compare the cases where counterions directly interact with microgel charges or ar...
Article
Thermoresponsive microgels are soft colloids that find widespread use as model systems for soft matter physics. Their complex internal architecture, made of a disordered and heterogeneous polymer network, has been so far a major challenge for computer simulations. In this work, we put forward a coarse-grained model of microgels whose structural pro...
Article
Poly (N-isopropylacrylamide), PNIPAM, is a widely studied polymer, which serves as a key constituent of nanostructured soft materials with responsive properties. Upon increasing temperature the PNIPAM polymer chain undergoes a reversible coil-to-globule transition at T~305 K, which is reflected by a volume phase transition in cross-linked architect...
Article
In this article, we examine the collective particle dynamics, as expressed by the time correlation function of the longitudinal particle current density, of several different fluids in the vicinity of their freezing points/lines. We consider and compare results obtained by dynamic light scattering for a suspension of hard spheres and by molecular d...
Article
The growing interest in the dynamical properties of colloidal suspensions, both in equilibrium and under an external drive such as shear or pressure flow, requires the development of accurate methods to correctly include hydrodynamic effects due to the suspension in a solvent. In the present work, we generalize Multiparticle Collision Dynamics (MPC...
Chapter
In this chapter we describe numerical procedures to evaluate the phase behavior of coarse-grained models for globular proteins. Specifically we focus on models based on hard spheres complemented with “patchy-like” anisotropic interactions that mimic the attractive regions on the surface of the proteins. We introduce the basic elements of grand cano...
Article
Full-text available
Soft colloids enable the exploration of states with densities exceeding that of random close packing, but it remains unclear whether softness controls the dynamics under these dense conditions. Experimental studies have reported conflicting results, and numerical studies have so far focused primarily on simple models that allow particles to overlap...
Preprint
The growing interest in the dynamical properties of colloidal suspensions, both in equilibrium and under an external drive such as shear or pressure flow, requires the development of accurate methods to correctly include hydrodynamic effects due to the suspension in a solvent. In the present work, we generalize Multi-Particle Collision Dynamics (MP...
Article
Full-text available
An important open problem in materials science is whether a direct connection exists between single-particle elastic properties and macroscopic bulk behavior. Here, we address this question by focusing on the archetype of soft colloids: thermoresponsive microgels. These colloidal-sized polymer networks are often assumed to interact through a simple...
Preprint
Full-text available
Recent progress has been made in the numerical modelling of neutral microgel particles with a realistic, disordered structure. In this work we extend this approach to the case of co-polymerised microgels where a thermoresponsive polymer is mixed with acidic groups. We compare the cases where counterions directly interact with microgel charges or ar...
Article
Concentrated solutions of monoclonal antibodies have attracted considerable attention due to their importance in pharmaceutical formulations, yet their tendency to aggregate and the resulting high viscosity pose considerable problems. Here we present a systematic study of their structural and dynamic properties using a combination of scattering met...
Article
Full-text available
Soft particles display highly versatile properties with respect to hard colloids, even more so at fluid-fluid interfaces. In particular, microgels, consisting of a crosslinked polymer network, are able to deform and flatten upon adsorption at the interface due to the balance between surface tension and internal elasticity. Despite the existence of...
Article
The long debated protein dynamical transition was recently found also in non-biological macromolecules, such as poly-N-isopropylacrylamide (PNIPAM) microgels. Here, by using atomistic molecular dynamics simulations, we report a description of the molecular origin of the dynamical transition in these systems. We show that PNIPAM and water dynamics b...