Molecular origin of the two-step mechanism of gellan aggregation in Science Advances

ISC researchers in collaboration with the University of Ferrara and University of Rome Tor Vergata recently published a beautiful research work, Molecular origin of the two-step mechanism of gellan aggregation,  on Science Advances. The work provides the first microscopic overview of gellan aggregation detecting the coil to single-helix transition at dilute conditions and the formation of higher-order aggregates at high concentration.… Read the rest

News and Views on “Thermally reconfigurable random lasers”

Light can control microparticles and microstructures can shape light, leading to a wide range of practical applications as well as interesting physics.

By combining optically controlled micro-heaters with thermophilic particles attracted by them researchers form University College London obtained microlasers with programmable and reversible patterns. This achievement is a nice demonstration of what happens when colloidal science meets photonics and is now published in Nature Physics and highlighted by Neda Ghofraniha in News and Views .… Read the rest

A Random Walk in Physics – Book

A Random Walk in Physics: Beyond Black Holes and Time-Travels is a book by
Massimo Cencini, Andrea Puglisi, Davide Vergni and Angelo Vulpiani.

Read a review in italian at GalileoRead the rest

“Hyper-auxetic” polymer networks published in Nature Communications

Andrea Ninarello, José Ruiz-Franco & Emanuela Zaccarelli have published Onset of criticality in hyper-auxetic polymer networks in Nature Communications volume 13, Article number: 527 (2022)

Against common sense, auxetic materials expand or contract perpendicularly when stretched or compressed, respectively, by uniaxial strain, being characterized by a negative Poisson’s ratio ν. The amount of deformation in response to the applied force can be at most equal to the imposed one, so that ν = − 1 is the lowest bound for the mechanical stability of solids, a condition here defined as “hyper-auxeticity”.… Read the rest

PNAS: Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

ISC researchers  working on soft matter coauthored a interesting work on the Proceedings of the National Academy of Science (PNAS)
Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels
PNAS September 14, 2021 118 (37) e2109560118

Soft particles often combine colloidal and polymeric aspects, making them very valuable for both fundamental and applied science. Microgels, which are colloidal-scale polymer networks, are one of the most important examples in class of systems.… Read the rest

Roberta Angelini is guest Editor of Polymers

Our staff researcher Roberta Angelini is Guest Editor of a Special Issue  of Polymers on “Polymer Microgels: Synthesis and Application

Polymer microgels have attracted great attention in fundamental studies as good model systems for understanding the intriguing behaviors of soft colloids thanks to their elastic and deformable particles that provide a very rich phenomenology. These cross-linked particles with nanometric to micrometric dimensions are characterized by many fascinating properties such as swelling, softness, and responsivity that depend on their macromolecular architecture and can be triggered during the synthesis process.… Read the rest

Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy – Phys. Lett. A.

A. De Ninno, E. Nikollari, M. Missori and F. Frezza have published Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy in Physics Letters A.
• The permittivity of water is described in terms of two independent Debye functions.
• The model is also applied to chloride solutions.
• The excess high frequency response is explained without ad hoc corrective terms.… Read the rest

Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics – PRX

Fabrizio Camerin, Nicoletta Gnan, José Ruiz-Franco, Andrea Ninarello, Lorenzo Rovigatti, and Emanuela Zaccarelli have published Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics

The properties and the structure of colloids—in which particles of one substance are dispersed in another—are determined by the way those particles interact with each other. An easy guess might lead one to say that complex particles possess an equally complex interaction potential.… Read the rest

The microscopic role of deformation in the dynamics of soft colloids published in Nature

Nicoletta Gnan and Emanuela Zaccarelli have published The microscopic role of deformation in the dynamics of soft colloids in Nature Physics.

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, but neglect particle deformations.… Read the rest

Mauro Missori awarded a CNR/CACH Bilateral Agreement

Mauro Missori awarded a CNR Bilateral Agreement with the Chinese Academy of Cultural Heritage (CACH) with the project “Nanoscale degradation indexes of ancient Chinese and Italian papers for conservation & restoration applications”.

The aim of this joint research project is to develop degradation indexes of ancient Chinese and Italian papers for restoration applications. These activities require the use of specific physical and chemical diagnostics technique at the nanoscale suitable for the cellulose-based materials and, in general, for natural polymeric fibers.… Read the rest

A new look at effective interactions between microgel particles – Nature Communications

Maxime J. Bergman, Nicoletta Gnan, Marc Obiols-Rabasa, Janne-Mieke Meijer, Lorenzo Rovigatti, Emanuela Zaccarelli & Peter Schurtenberger
Nature Communications volume 9, Article number: 5039 (2018)

Thermoresponsive microgels find widespread use as colloidal model systems, because their temperature-dependent size allows facile tuning of their volume fraction in situ.
However, an interaction potential unifying their behavior across the entire phase diagram is sorely lacking.… Read the rest

Protein-like dynamical transition in concentrated microgels

Letizia Tavagnacco, Emanuela Zaccarelli and others published Evidence of a low-temperature dynamical transition in concentrated microgels in Science Advances.

A low-temperature dynamical transition has been reported in several proteins. We provide the first observation of a “protein-like” dynamical transition in nonbiological aqueous environments. To this aim, we exploit the popular colloidal system of poly-N-isopropylacrylamide (PNIPAM) microgels, extending their investigation to unprecedentedly high concentrations.… Read the rest

Emanuela Zaccarelli awarded a MIUR FARE grant

Emanuela Zaccarelli awarded a MIUR FARE grant with the project SOFTART: Enhancing microgels potentialities: ultrasoftness and cultural heritage applications.

The project builds on the ERC Consolidator project MIMIC and combines theoretical/numerical expertise of the MIMIC team led by Emanuela Zaccarelli with experimental work at CNR ISC carried out by the groups of Barbara Ruzicka, Roberta Angelini, Simona Sennato and Mauro Missori.… Read the rest

Flexible and Wearable Metamaterials: new frontiers in biomedical and safety&security applications

Metamaterials are engineered material having periodic structures that exhibit unique properties when they interact with electromagnetic waves in comparison with natural materials. They offer interesting applications throughout the electromagnetic spectrum and are crucial in the Terahertz (THz) frequency band which lies between microwave and infrared and thus invisible to the human eye. This band is a new frontier both for research and technological applications in sectors ranging from astronomy to cultural heritage.… Read the rest

When is a lubricant effective?

A plate shearing an interstitial granular medium and driven by an always ongoing spring feels less fricion when only few layers are present. Adding more layers results in an increase of friction,
nevertheless the plate slides more often. The ease of slipping is not determined by friction alone?


M A Annunziata, A Baldassarri, F Dalton, A Petri and G Pontuale, Increasing ‘ease of sliding’ also increases friction: when is a lubricant effective?Read the rest

Macromolecules Editors’ Choice: In Silico Synthesis of Microgel Particles

Congratulations to Nicoletta Gnan, Lorenzo Rovigatti, Maxime Bergman and Emanuela Zaccarelli whose article In Silico Synthesis of Microgel Particles has been selected as editor’s choice in Macromolecules.… Read the rest

Gaussian, non Gaussian and Anomalous diffusion to improve medical diagnosis

In the biomedical field, Diffusion Magnetic Resonance (DMR) images provide a measure of water proton displacements by probing motion on the mesoscopic length scale (around 10-20 µm), which is orders of magnitude smaller than the macroscopic MR resolution (typically 1-2 millimetres for clinical MR scanners).

Therefore, independently of image resolution (which is linked to the hardware of the NMR scanner) we can obtain microstructural information of human tissue at the mesoscopic length scale.… Read the rest

Molecole magnetiche su grafene per la spintronica

Una ricerca, svolta in collaborazione fra fisici e chimici italiani, tedeschi e spagnoli, mostra che è possibile realizzare nano-sistemi ibridi depositando magneti molecolari su grafene. L’interazione fra gli spin dei magneti molecolari e il gas bidimensionale di elettroni del grafene modifica profondamente la dinamica quantistica degli spin molecolari. Ciò apre la strada al controllo dello spin mediante campi elettrici nei nano-dispositivi per la spintronica (elettronica di spin) basati sul grafene.… Read the rest

New porous water ice metastable at atmospheric pressure obtained by emptying a hydrogen-filled ice

Leonardo del Rosso 1,2, Milva Celli 1 & Lorenzo Ulivi

The properties of some forms of water ice reserve still intriguing surprises. Besides the several stable or metastable phases of pure ice, solid mixtures of water with gases are precursors of other ices, as in some cases they may be emptied, leaving a metastable hydrogen-bound water structure. We present here the first characterization of a new form of ice, obtained from the crystalline solid compound of water and molecular hydrogen called C0-structure filled ice.… Read the rest

Biomimetic antimicrobial cloak by graphene-oxide agar hydrogel

Massimiliano Papi and others published a scientific report on an antibacterial cloak produced by laser printing graphene oxide hydrogels mimicking the Cancer Pagurus carapace.… Read the rest

The soft side of hard matter

Soft condensed matter is characterized by gigantic responses to  external perturbations which is the reason why these systems are extremely useful for applications, like liquid crystals in our cell phones displays. In contrast, hard condensed matter a.k.a. solids respond more weakly to external perturbations but present an enormous richness of interesting phases like metallic, insulating,  magnetic, superconducting, ferroelectric,  charge order, etc.  … Read the rest

Differential and absolute negative mobility in steady laminar flows

  Nonlinear response in out-of-equilibrium systems can show counter-intuitive behaviors, for instance cases where the force increases but the response decreases (negative differential mobility). Sometimes the response crosses zero and changes sign with respect to the force (absolute negative mobility). In classical physics this is usually observed within complicate models with obstacles and traps. We have demonstrated such complex non-linear phenomena in a much simpler and realistic system, ie.… Read the rest

Thermal convection in granular gases with dissipative lateral walls

Convection in molecular fluids is provided by the competition between gravity and an adverse temperature gradient (two thermostats, the hotter below, the colder above). In a granular gas it can be achieved by a single thermostat at the base, for instance a vibrating piston. Energy dissipation provides the “second thermostat” which spontaneously forms gradient and may stabilize a convective state. Here we have demonstrated that even the simple dissipation in the collision between grains and lateral walls is sufficient to trigger convection, without any critical threshold.… Read the rest

Heat, temperature and Clausius inequality in a model for active brownian particles

Living matter at the microscale, many kinds of cells, bacteria and other organisms, self-propel through a viscous fluid which acts as a thermal bath, dissipating the energy provided by the internal motor (pseudopoda, flagella, etc.). This energetic balance is ruled by non-equilibrium thermodynamics, as for heat engines. In this theoretical work we have given a mesoscopic description of this process, which allows to measure a local heat dissipation and a local non-equilibrium temperature (associated to self-propulsion and to the forces driving the active particle) which together provide a definition of active entropy production which satisfies the Clausius inequality.… Read the rest

Mechanism of self-propulsion in 3D-printed active granular particles



 We have reproduced the self propulsion of bacteria and animals with 3d-printed “active granular particles”. Those small artificial insects walk on a rough vibrated plate because of a subtle interplay between material elastic properties and solid-on-solid friction. The advantage of 3d-printed objects is in the possibility to tune certain features (here the inclination of “legs”) in order to verify theoretical predictions and establish an optimal shape for running.… Read the rest

Cages and anomalous diffusion in vibrated dense granular media

Caging is the typical microscopic phenomenon that “traps” molecules in a liquid at low temperature. The usual Brownian Motion of a tracer experiences a temporary “dynamical arrest” which eventually is broken restoring normal diffusion. In this work we have shown that at intermediate densities and temperature the same phenomenon occurs in granular liquids. At large densities and lower temperatures the late normal diffusion is replaced with superdiffusion.… Read the rest

Radio 3 Scienza on “Rappresentanza o governabilità”, A. Petri interviewed

Alberto Petri interviewed on “Rappresentanza o governabilità”, RAI ”Radio 3 Scienza”, February 3rd, 2014

Read the rest

Brownian Ratchet in a Thermal Bath Driven by Coulomb Friction

A Brownian Ratchet is a small engine which is conceived to extract work from molecular fluctuations. Examples of Brownian Ratchets occur in the cell, see for instance this nice movie about kinesin.

As well explained by Richard Feynmann, a Brownian Ratchet cannot perform its own task in an equilibrium environment, i.e. the fluctuations feeding energy to the ratchet cannot originate from a single thermal bath, in accordance with the second principle of thermodynamics.… Read the rest

Shaken Granular Lasers


A random laser is usually obtained pumping light through a disordered medium. The dynamics of light through a heterogeneous configuration of scatterers and cavities provides emitted spectra with random and fluctuating peaks which have a wide range of applications and are nowadays subject to an intense theoretical activity. In this work we have added a new flavour to the idea of random lasers, replacing the usually static disordered medium with a vibrofluidized granular material.… Read the rest

Quasi 2D granular dynamics

4000 spheres of steel (diameter 2mm) are deposited on a horizontal rough plate (200mm diameter, only a square 100mm X 100mm is shown) and are put in motion by vertical vibration of the plate (sinusoidal shaking, amplitude 0.7mm, frequency 200Hz). The resulting motion, on the plane, is a composition of random sliding on the plate and inelastic collisions among particles. This is a “non-equilibrium” Brownian motion.… Read the rest

Soft matter

The term “soft matter” refers to a very large class of materials, whose common characteristic is that they are composed of mesoscopic particles, i.e. particles with typical sizes ranging from 1 nm to a few microns. These particles are normally dispersed in a solvent, whose molecules are much smaller in size (typically of atomic dimensions). In addition, the solution may contain other small objects, such as polymeric chains, salt ions, etc.… Read the rest

Granular Dynamics Laboratory

Since July 2010, the Granular Dynamics Laboratory is operative – originally in room “010” and (from november 2012) –  in room “012” (ground floor of Fermi Building of the Physics Department) at the Sapienza unit of ISC. The laboratory includes two main experimental setups:


  1. Vertical vibration (2d and 3d granular experiments): an electrodynamic shaker LDS V455, which can reach a maximum acceleration of 105g, powered by a PA1000L power amplifier.
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Granular Phases

Steel spheres move on a plate. The “thermostat ” is a vibrating wall, following a sine law with frequency 20 Hz . Weak gravity (the plate has a small angle of inclination) draws the spheres toward the vibrating wall. In 5 minutes, slowly increasing the amplitude, the many “phases” of a granular material are explored, from an almost perfect crystal, through several liquid/turbulent/convective regimes, up to a gas-solid coexistence.… Read the rest


Granular fluids to explore non-equilibrium statistical mechanics

Founding Body: MIUR, Italy (reserved to selected ERC-Starting Grants 2007)
Total grant: € 1200k
Principal Investigator: Andrea Puglisi
Other participants:
Project duration: 2009-2014
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Granular Gases to explore Non-Equilibrium Statistical Mechanics

How do properties of molecular trajectories reflect on large scale transport and relaxation properties? Is it possible to directly and experimentally verify the Boltzmann’s program, connecting the microscopic level to the macroscopic description? Can we zoom into an out-of-equilibrium fluid and reveal, in the laboratory, its underlying microscopic reversibility? These are some of the questions addressed by the GRANULARCHAOS project, funded by an IDEAS grant (originally selected by ERC and then funded by italian FIRB) for five years.… Read the rest