Brownian cluster dynamics with short range patchy interactions. Its application to polymers and step-growth polymerization

We present a novel simulation technique derived from Brownian cluster dynamics used so far to study the isotropic colloidal aggregation. It now implements the classical Kern-Frenkel potential to describe patchy interactions between particles. This technique gives access to static properties, dynamics and kinetics of the system, even far from the equilibrium. Particle thermal motions are modeled using billions of independent small random translations and rotations, constrained by the excluded volume and the connectivity. This algorithm, applied to a single polymer chain leads to correct static and dynamic properties, in the framework where hydrodynamic interactions are ignored. By varying patch angles, various chain flexibilities can be obtained. We have used this new algorithm to model step-growth polymerization under various solvent qualities. The polymerization reaction is modeled by an irreversible aggregation between patches while an isotropic finite square-well potential is superimposed to mimic the solvent quality. In bad solvent conditions, a competition between a phase separation (due to the isotropic interaction) and polymerization (due to patches) occurs. Surprisingly, an arrested network with a very peculiar structure appears. It is made of strands and nodes. Strands gather few stretched chains that dip into entangled globular nodes. These nodes act as reticulation points between the strands. The system is kinetically driven and we observe a trapped arrested structure. That demonstrates one of the strengths of this new simulation technique. It can give valuable insights about mechanisms that could be involved in the formation of stranded gels.Comment: 55 pages, 32 figure

A patchy particle model for C-S-H formation

The composition and structure of Calcium-Silicate-Hydrate (C-S-H) phases depends on various reaction parameters leading to its formation. Molecular Dynamic simulation studies probing the formation and structure of C-S-H are generally computationally expensive and can reach only very short time scales. Herein, we propose a coarse graining approach to model the formation of C-S-H, using patchy particles and a modified Patchy Brownian Cluster Dynamics algorithm. The simulations show that patchy particle systems can recover the qualitative kinetic evolution of C-S-H formation, and the obtained final structures were comparable to previously reported molecular dynamics studies and experiments. The model was extended to study the effect of water in the polymerization of tetraethoxysilane oligomers, the principal component of an impregnation treatment for deteriorated concrete surfaces. The intermediate system properties predicted by the simulations, such as viscosity and gel time, and structure were found to be well in accordance with the tailored experiments.The work described in this manuscript has been performed under InnovaConcrete EC project, supported by funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement N◦760858. AP and JSD also acknowledge the support received from the BASKRETE initiative and the Joint Transborder Lab-oratory (LTC) “Aquitaine-Euskadi Network in Green Concrete and Cement-based Material

Wer ist heute 'Ehrenmann' und 'Ehrenfrau'? Ethische und jugendkulturelle Aspekte des deutschen Jugendworts des Jahres

Eine Jury des deutschen Langenscheidt-Verlags wählt jedes Jahr das sogenannte 'Jugendwort des Jahres'. 2018 fiel diese Wahl auf 'Ehrenmann' bzw. 'Ehrenfrau' im Sinne von 'jemand, der etwas (Besonderes) für einen tut'. In der Folge fand jedoch weder eine öffentliche Auseinandersetzung über die Herkunft des Begriffs statt noch darüber, was Ehre für Jugendliche heute bedeutet. Der Artikel möchte daher zunächst darstellen, was Ehre ist und welche soziale Funktion sie erfüllt, und anschließend die besondere Bedeutung von Ehre für Jugendliche in Migrationssituationen reflektieren. Schließlich folgen eine pop- und jugendkulturelle Analyse der Herkunft und Verwendung des Ausdrucks 'Ehrenmann' (und 'Ehrenfrau') sowie eine abschließende kritische Reflexion der Jurywahl.Every year, a jury of the German Langenscheidt-Verlag chooses the so-called 'youth expression of the year' (Jugendwort des Jahres). In 2018, this choice fell on 'man/woman of honour' (Ehrenmann/Ehrenfrau), in a sense of ‚someone doing something (special) for somebody‘. Interestingly, no public discourse followed to examine the origin of this unusual expression or the meaning of 'honour' for today's youth. The article, therefore, aims to outline what honour is and which social functions it fulfils, and then to reflect the particular significance of honour for adolescents with a migrant background. This is followed by a pop- and youth-cultural analysis of the origin and use of the expression 'man of honour' as well as a concluding critical reflection of the jury's choice

Irreversible aggregation of patchy colloidal particles : a computer simulation study

La variété des structures colloïdales auto assemblées est principalement due à la présence d'interactions anisotropes. Nous présentons ici une méthode numérique pour étudier l'agrégation irréversible par patches de particules sphériques. Il s'agit d'une amélioration de la dynamique d’amas browniens prenant en compte les interactions par patches et les mouvements de rotation. Nous limitons notre étude aux particules à deux patches opposés de taille variable. Une interaction isotrope, faible, est également ajoutée pour modéliser une polymérisation par étape dans diverses conditions de solvant. Cet algorithme a été testé sur des chaînes isolées et nous avons retrouvé les propriétés statiques et dynamiques attendues. En jouant sur la balance entre la qualité du solvant et la taille des patches diverses morphologies hors-équilibres sont obtenues. Même dans la limite diluée, les collisions corrélées jouent un rôle important et une description de type Smoluchowski échoue.The versatility of self assembling structures is mostly due to the presence of anisotropic interactions. We present a new simulation method to study irreversible patchy aggregation of spherical particles. It is a variation of the Brownian Cluster Dynamics method taking into account patchy interactions and rotational motions. We limit our case to particles with two oppositely located patches. The size of patches can vary and an isotropic interaction is superimposed around the particle to mimic step-polymerization with various solvent qualities. This new algorithm was successfully tested on single polymer chains and expected static and dynamic properties were recovered. Depending on the balance between solvent quality and patch size various out of equilibrium morphologies could be obtained. Even in the limit dilute solutions, correlated collisions play a key role and the Smoluchowski approach fails. We propose new directions for a better understanding of anisotropy effects on kinetics

Agrégation irréversible par patchs de particules colloïdales : une étude par simulation numérique

The versatility of self assembling structures is mostly due to the presence of anisotropic interactions. We present a new simulation method to study irreversible patchy aggregation of spherical particles. It is a variation of the Brownian Cluster Dynamics method taking into account patchy interactions and rotational motions. We limit our case to particles with two oppositely located patches. The size of patches can vary and an isotropic interaction is superimposed around the particle to mimic step-polymerization with various solvent qualities. This new algorithm was successfully tested on single polymer chains and expected static and dynamic properties were recovered. Depending on the balance between solvent quality and patch size various out of equilibrium morphologies could be obtained. Even in the limit dilute solutions, correlated collisions play a key role and the Smoluchowski approach fails. We propose new directions for a better understanding of anisotropy effects on kinetics.La variété des structures colloïdales auto assemblées est principalement due à la présence d'interactions anisotropes. Nous présentons ici une méthode numérique pour étudier l'agrégation irréversible par patches de particules sphériques. Il s'agit d'une amélioration de la dynamique d’amas browniens prenant en compte les interactions par patches et les mouvements de rotation. Nous limitons notre étude aux particules à deux patches opposés de taille variable. Une interaction isotrope, faible, est également ajoutée pour modéliser une polymérisation par étape dans diverses conditions de solvant. Cet algorithme a été testé sur des chaînes isolées et nous avons retrouvé les propriétés statiques et dynamiques attendues. En jouant sur la balance entre la qualité du solvant et la taille des patches diverses morphologies hors-équilibres sont obtenues. Même dans la limite diluée, les collisions corrélées jouent un rôle important et une description de type Smoluchowski échoue

Irreversible aggregation of patchy colloidal particles (a computer simulation study)

La variété des structures colloïdales auto assemblées est principalement due à la présence d'interactions anisotropes. Nous présentons ici une méthode numérique pour étudier l'agrégation irréversible par patches de particules sphériques. Il s'agit d'une amélioration de la dynamique d amas browniens prenant en compte les interactions par patches et les mouvements de rotation. Nous limitons notre étude aux particules à deux patches opposés de taille variable. Une interaction isotrope, faible, est également ajoutée pour modéliser une polymérisation par étape dans diverses conditions de solvant. Cet algorithme a été testé sur des chaînes isolées et nous avons retrouvé les propriétés statiques et dynamiques attendues. En jouant sur la balance entre la qualité du solvant et la taille des patches diverses morphologies hors-équilibres sont obtenues. Même dans la limite diluée, les collisions corrélées jouent un rôle important et une description de type Smoluchowski échoue.The versatility of self assembling structures is mostly due to the presence of anisotropic interactions. We present a new simulation method to study irreversible patchy aggregation of spherical particles. It is a variation of the Brownian Cluster Dynamics method taking into account patchy interactions and rotational motions. We limit our case to particles with two oppositely located patches. The size of patches can vary and an isotropic interaction is superimposed around the particle to mimic step-polymerization with various solvent qualities. This new algorithm was successfully tested on single polymer chains and expected static and dynamic properties were recovered. Depending on the balance between solvent quality and patch size various out of equilibrium morphologies could be obtained. Even in the limit dilute solutions, correlated collisions play a key role and the Smoluchowski approach fails. We propose new directions for a better understanding of anisotropy effects on kinetics.LE MANS-BU Sciences (721812109) / SudocSudocFranceF