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Opposing polymer brush systems were investigated by computer simulations. In a coarse-grained model, chains were restricted to a face-centered cubic lattice with the excluded volume interactions only. The macromolecules were grafted onto two parallel impenetrable surfaces. The dynamic properties of these systems were studied by means of Monte Carlo simulations. The Dynamic Lattice Liquid model and a highly efficient parallel machine ARUZ were employed, which enabled studying large systems at long time scales. The influence of the surface grating density on the system dynamic was shown and discussed. It was demonstrated that the self-diffusion coefficient of solvent depended strongly on the grafting density. [ABSTRACT FROM AUTHOR]

The influence of obstacles in the form of polymer chains on the diffusion of a low-molecular-weight solvent was the subject of this research. Studies were performed by computer simulations. A Monte Carlo model-the Dynamic Lattice Liquid algorithm-based on the idea of cooperative movements was used. The tested materials were polymer networks with an ideal structure (with a uniform mesh size) and real, irregular networks (with a non-uniform mesh size) obtained numerically by copolymerization. The diffusion of the solvent was analyzed in systems with a polymer concentration that did not exceed 16%. The influence of the polymer concentration and macromolecular architecture structure on the mobility and character of the motion of the solvent was discussed. The influence of irregular network morphology on solvent dynamics appeared to be significantly stronger than that of regular networks and star-like polymers., Competing Interests: The authors declare no conflicts of interest.

A relationship between the electronic properties of metal ions in metallacarboranes and their ability to modulate mitochondrial oxidase activity and membrane hyperpolarization in cancer cells was demonstrated. Quantum chemistry methods, including DFT and molecular dynamics simulations, were used to understand the oxidized and reduced forms of metallacarboranes and their intramolecular rotatory behavior. According to the low-spin assumption for metal ions, the intramolecular oscillations of cluster ligands in metallacarboranes are significantly influenced by the type of metal and correspond to the cellular uptake of these complexes in vitro . In particular, the low-spin iron compound may be a new xenogeneic booster of redox homeostasis in cancer cells resistant to cisplatin, which induces metabolic 'exhaustion' of cancer cells and their death.

A generic model was developed for studies of the polymerization process of regular branched macromolecules. Monte Carlo simulations were performed employing the Dynamic Lattice Liquid algorithm to study this process. A core-first methodology was used in a living polymerization of stars with up to 32 arms, and dendrimers consisted of 4-functional segments. The kinetics of the synthesis process for stars with different numbers of branches and dendrimers was compared. The size and structure of star-branched polymers and dendrimers during the synthesis were studied. The influence of the functionality of well-defined cores on the structure and on the dispersity of the system was also examined. The differences in the kinetics in the formation of both architectures, as well as changes to their structures, were described and discussed.

Opposing polymer brush systems were synthesized and investigated by molecular modeling. Chains were restricted to a face-centered cubic lattice with the excluded volume interactions only. The system was confined between two parallel impenetrable walls, with the same number of chains grafted to each surface. The dynamic properties of such systems were studied by Monte Carlo simulations based on the dynamic lattice liquid model and using a highly efficient parallel machine ARUZ, which enabled the study of large systems and long timescales. The influence of the surface density and mean polymer length on the system dynamic was discussed. The self-diffusion coefficient of the solvent depended strongly on the degree of polymerization and on the polymer concentration. It was also shown that it is possible to capture changes in solvent mobility that can be attributed to the regions of different polymer densities.

The resonance Raman effect (RRE) is a phenomenon which results in a strong selective enhancement of Raman signals from the samples. Previous studies showed that the RRE in liquid water directly corresponds to its supramolecular structure. It was also reported that the electric-field-induced orientation of water molecules on the electrode surface results in the surface-enhanced Raman scattering (SERS) effect. In this work, we show the SERS effect for water molecules in the dispersion of silver nanoparticles (AgNPs) without any external electrical field. An enhancement factor was estimated to be (4.8 ± 0.8) × 10 6 for an excitation wavelength of 514.5 nm and for AgNPs with an average size of 34 ± 14 nm. The temperature experiment results showed a higher enhancement with temperature increase. Performed simulation studies revealed a slowdown of the mobility of the water molecules close to the surface of AgNPs., (Copyright © 2021, Filipczak et al.)