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11 pages, 3736 KiB

Open AccessArticle

Removal Efficiency of Insoluble β-Cyclodextrin Polymer from Water–Soluble Carcinogenic Direct Azo Dyes

by Lamia Moulahcene, Mohamed Skiba, Nicolas Milon, Hammache Fadila, Frédéric Bounoure and Malika Lahiani-Skiba

Polymers 2023, 15(3), 732; https://doi.org/10.3390/polym15030732 - 31 Jan 2023

Cited by 2 | Viewed by 1493

Abstract

A batch system was applied to study the adsorption of three dyes (methyl violet, eriochrom black T and helianthin) from aqueous solution onto β-cyclodextrin polymer, synthesized by using citric acid as a cross linking agent. This polymer lets to adsorb only methyl violet [...] Read more.

A batch system was applied to study the adsorption of three dyes (methyl violet, eriochrom black T and helianthin) from aqueous solution onto β-cyclodextrin polymer, synthesized by using citric acid as a cross linking agent. This polymer lets to adsorb only methyl violet for this effect, several operator variables was checked only with this kind of dye, the removal efficiently increases with increase in adsorbent amount; elevation of temperature lets also to improve the dye adsorption; ionic strength has not effect on dye adsorption process, for the pH we have remarked a slight decrease in removal efficiently with increasing of pH values. Equilibrium study was investigated by applying three models (Langumir, Frendlich and Temkin), results show that Langumir isotherm is the appropriate model. FTIR spectra show the complex inclusion formation which dominates the adsorption mechanism, confirmed by the absence of characteristic peaks of methyl violet in ß-cyclodextrin after adsorption. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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16 pages, 6970 KiB

Open AccessArticle

Molecular Dynamics Simulations of Polydopamine Nanosphere’s Structure Based on Experimental Evidence

by Jesús Manzanares-Gómez, Salvador León, Esteban Climent-Pascual and María Pilar García-Armada

Polymers 2022, 14(24), 5486; https://doi.org/10.3390/polym14245486 - 15 Dec 2022

Viewed by 1509

Abstract

In this work, we show how to obtain internal monodispersed gold nanoparticles inside polydopamine (PDA) nanospheres that are also externally decorated with gold. The number of internal nanoparticles is affected by the size of the PDA nanosphere used, and the lower limit in [...] Read more.

In this work, we show how to obtain internal monodispersed gold nanoparticles inside polydopamine (PDA) nanospheres that are also externally decorated with gold. The number of internal nanoparticles is affected by the size of the PDA nanosphere used, and the lower limit in the number of gold nanoparticles in the center of decorated nanospheres, one single gold nanoparticle, has been reached. In addition, extensive molecular dynamics simulations of PDA nanospheres based on four different chemical motifs, in the presence of water and with different sizes, have been performed to gain insight into the arrangements capable of accommodating cavities. In particular, PDA nanospheres based on pyranoacridinotrione (PYR) units provide good agreement with the experimental attainment of internal metal nanoparticles. In these, the stacking of PYR units leads to a particular morphology, with large portions of space occupied by the solvent, that would explain the observed formation of gold nanoparticles inside the PDA nanosphere. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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18 pages, 3098 KiB

Open AccessArticle

Molecular Dynamics and Nuclear Magnetic Resonance Studies of Supercritical CO₂ Sorption in Poly(Methyl Methacrylate)

by Valentina V. Sobornova, Konstantin V. Belov, Alexey A. Dyshin, Darya L. Gurina, Ilya A. Khodov and Michael G. Kiselev

Polymers 2022, 14(23), 5332; https://doi.org/10.3390/polym14235332 - 06 Dec 2022

Cited by 5 | Viewed by 15570

Abstract

The study of supercritical carbon dioxide sorption processes is an important and urgent task in the field of “green” chemistry and for the selection of conditions for new polymer material formation. However, at the moment, the research of these processes is very limited, [...] Read more.

The study of supercritical carbon dioxide sorption processes is an important and urgent task in the field of “green” chemistry and for the selection of conditions for new polymer material formation. However, at the moment, the research of these processes is very limited, and it is necessary to select the methodology for each polymer material separately. In this paper, the principal possibility to study the powder sorption processes using ¹³C nuclear magnetic resonance spectroscopy, relaxation-relaxation correlation spectroscopy and molecular dynamic modeling methods will be demonstrated based on the example of polymethylmethacrylate and supercritical carbon dioxide. It was found that in the first nanoseconds and seconds during the sorption process, most of the carbon dioxide, about 75%, is sorbed into polymethylmethacrylate, while on the clock scale the remaining 25% is sorbed. The methodology presented in this paper makes it possible to select optimal conditions for technological processes associated with the production of new polymer materials based on supercritical fluids. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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14 pages, 1786 KiB

Open AccessArticle

Effective Tensile Strength Estimation of Natural Fibers through Micromechanical Models: The Case of Henequen Fiber Reinforced-PP Composites

by Francesc Xavier Espinach, Fernando Julian, Manel Alcalà, Fabiola Vilaseca, Félix Carrasco and Pere Mutjé

Polymers 2022, 14(22), 4890; https://doi.org/10.3390/polym14224890 - 12 Nov 2022

Cited by 2 | Viewed by 1401

Abstract

The performance of henequen fibers and polypropylene composites obtained by injection molding with and without coupling agent was evaluated. Henequen fibers are natural non-wood fibers mainly used in textile sector or in thermosetting matrix composites. In this work, henequen fibers have been used [...] Read more.

The performance of henequen fibers and polypropylene composites obtained by injection molding with and without coupling agent was evaluated. Henequen fibers are natural non-wood fibers mainly used in textile sector or in thermosetting matrix composites. In this work, henequen fibers have been used as a possible substitute reinforcement material for sized glass fibers. The surface charge density of the materials used was evaluated, as well as the morphology of the fibers inside the material. A significant reduction in the length of the fibers was observed as a consequence of the processing. The use of a 4% coupling agent based on fiber content was found to be effective in achieving significant improvements in the tensile strength of the composites in the reinforcement range studied. The influence of the aspect ratio on the coupling factor was determined, as well as the evaluation of the interface quality. The results obtained demonstrate the great potential of henequen fibers as reinforcement of composite materials, giving rise to strong interfaces with coupling. Finally, the comparison of henequen fiber composites with sized glass fiber composites showed that it is possible to substitute polypropylene composites with 20 wt.% glass fiber for 50 wt.% henequen fibers. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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23 pages, 5844 KiB

Open AccessArticle

Computational Foretelling and Experimental Implementation of the Performance of Polyacrylic Acid and Polyacrylamide Polymers as Eco-Friendly Corrosion Inhibitors for Copper in Nitric Acid

by Arafat Toghan, Ahmed Fawzy, Areej Al Bahir, Nada Alqarni, Moustafa M. S. Sanad, Mohamed Khairy, Abbas I. Alakhras and Ahmed A. Farag

Polymers 2022, 14(22), 4802; https://doi.org/10.3390/polym14224802 - 08 Nov 2022

Cited by 25 | Viewed by 1825

Abstract

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy [...] Read more.

Copper is primarily used in many industrial processes, but like many other metals, it suffers from corrosion damage. Polymers are not only one of the effective corrosion inhibitors but also are environmentally friendly agents in doing so. Hence, in this paper, the efficacy of two polyelectrolyte polymers, namely poly(acrylic acid) (PAA) and polyacrylamide (PAM), as corrosion inhibitors for copper in molar nitric acid medium was explored. Chemical, electrochemical, and microscopic tools were employed in this investigation. The weight-loss study revealed that the computed inhibition efficiencies (% IEs) of both PAA and PAM increased with their concentrations but diminished with increasing HNO₃ concentration and temperature. The results revealed that, at similar concentrations, the values of % IEs of PAM are slightly higher than those recorded for PAA, where these values at 298 K reached 88% and 84% in the presence of a 250 mg/L of PAM and PAA, respectively. The prominent IE% values for the tested polymers are due to their strong adsorption on the Cu surface and follow the Langmuir adsorption isoform. Thermodynamic and kinetic parameters were also calculated and discussed. The kinetics of corrosion inhibition by PAA and PAM showed a negative first-order process. The results showed also that the used polymers played as mixed-kind inhibitors with anodic priority. The mechanisms of copper corrosion in nitric acid medium and its inhibition by the tested polymers were discussed. DFT calculations and molecular dynamic (MD) modelling were used to investigate the effect of PAA and PAM molecular configuration on their anti-corrosion behavior. The results indicated that the experimental and computational study are highly consistent. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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18 pages, 8422 KiB

Open AccessArticle

Simulation of Motor Core Gluing Process with Fine Mesh Nets

by Yong-Jie Zeng, Chia-Wei Liang, Sheng-Jye Hwang, Yu-Da Liu and Chien-Sheng Huang

Polymers 2022, 14(21), 4596; https://doi.org/10.3390/polym14214596 - 29 Oct 2022

Cited by 1 | Viewed by 1019

Abstract

The actual process of using a resin to glue can optimize many shortcomings in the basic traditional process of welding a motor core. For example, the use of a resin for gluing can lead to a reduction in iron loss, improve rigidity, reduce [...] Read more.

The actual process of using a resin to glue can optimize many shortcomings in the basic traditional process of welding a motor core. For example, the use of a resin for gluing can lead to a reduction in iron loss, improve rigidity, reduce processing times, and improve product quality. When using a gluing method, the biggest challenge is the distribution of the resin; therefore, resin distribution is very much important. This experiment used fine mesh nets to eventually improve the unbalanced state of resin distribution. In this research, in order to predict real flow behavior during gluing, computer-aided engineering was used for computer simulation. The results of the simulation showed that the illustrated trend of the filling process was very much similar to the actual experimental results. The simulation results could mostly predict defects and make effective improvements, which can lead to a significant reduction in the money and time spent on experiments. The simulation results of the dipping process also showed that the distribution of resin with fine mesh nets was more even than without fine mesh nets. Fine mesh nets can eventually improve an over-flow problem, which, ultimately, causes bumps. In this research, a simulation analysis of the gluing process of a motor core with fine mesh nets was conducted, and the results show that the resin distribution and the flow front of the runner were more even than those without fine mesh nets. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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22 pages, 4531 KiB

Open AccessArticle

Knot Factories with Helical Geometry Enhance Knotting and Induce Handedness to Knots

by Renáta Rusková and Dušan Račko

Polymers 2022, 14(19), 4201; https://doi.org/10.3390/polym14194201 - 07 Oct 2022

Cited by 1 | Viewed by 83435

Abstract

We performed molecular dynamics simulations of DNA polymer chains confined in helical nano-channels under compression in order to explore the potential of knot-factories with helical geometry to produce knots with a preferred handedness. In our simulations, we explore mutual effect of the confinement [...] Read more.

We performed molecular dynamics simulations of DNA polymer chains confined in helical nano-channels under compression in order to explore the potential of knot-factories with helical geometry to produce knots with a preferred handedness. In our simulations, we explore mutual effect of the confinement strength and compressive forces in a range covering weak, intermediate and strong confinement together with weak and strong compressive forces. The results find that while the common metrics of polymer chain in cylindrical and helical channels are very similar, the DNA in helical channels exhibits greatly different topology in terms of chain knottedness, writhe and handedness of knots. The results show that knots with a preferred chirality in terms of average writhe can be produced by using channels with a chosen handedness. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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23 pages, 4561 KiB

Open AccessArticle

Silicic Acid Polymerization and SiO₂ Nanoparticle Growth in Hydrothermal Solution

by Vadim V. Potapov, Angel A. Cerdan and Denis S. Gorev

Polymers 2022, 14(19), 4044; https://doi.org/10.3390/polym14194044 - 27 Sep 2022

Cited by 5 | Viewed by 1597

Abstract

The approach of numerical simulation of orthosilicic acid OSA polymerization and SiO₂ nanoparticle formation in hydrothermal solution have been developed based on the model of the homogeneous stage of nucleation and the subsequent growth of particles. The influence of surface tension on [...] Read more.

The approach of numerical simulation of orthosilicic acid OSA polymerization and SiO₂ nanoparticle formation in hydrothermal solution have been developed based on the model of the homogeneous stage of nucleation and the subsequent growth of particles. The influence of surface tension on the interface of SiO₂–water, the rate of molecular deposition, and Zeldovich factor Z were evaluated. Temperature dependence on time, pH, initial OSA concentration, and ionic strength are the main parameters that determine the kinetics of colloid phase formation, the final average size of SiO₂ nanoparticles, and the particle size distribution and its polydispersity index. The results of the numerical simulation were verified with experimental data on OSA polymerization and measurement of nanoparticles sizes using the method of dynamic light scattering in a wide range of temperatures of 20–180 °C, pH = 3–9, SiO₂ content C_t of 300–1400 mg/kg, and ionic strength I_s of 0.0001–0.42 mol/kg. The results obtained can be used in the technology of hydrothermal synthesis of sols, gels, and nanopowders to regulate the kinetics of OSA polymerization and SiO₂ nanoparticle growth, particle size distribution, morphology, and structure of products. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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20 pages, 4396 KiB

Open AccessArticle

Molecular Insights into the Wall Slip Behavior of Pseudoplastic Polymer Melt in Nanochannels during Micro Injection Molding

by Wangqing Wu, Fengnan Duan, Baishun Zhao, Yuanbao Qiang, Mingyong Zhou and Bingyan Jiang

Polymers 2022, 14(15), 3218; https://doi.org/10.3390/polym14153218 - 08 Aug 2022

Cited by 2 | Viewed by 1646

Abstract

Wall slip directly affects the molding quality of plastic parts by influencing the stability of the filling flow field during micro injection molding. The accurate modeling of wall slip in nanochannels has been a great challenge for pseudoplastic polymer melts. Here, an effective [...] Read more.

Wall slip directly affects the molding quality of plastic parts by influencing the stability of the filling flow field during micro injection molding. The accurate modeling of wall slip in nanochannels has been a great challenge for pseudoplastic polymer melts. Here, an effective modeling method for polymer melt flow in nanochannels based on united-atom molecular dynamics simulations is presented. The effects of driving forces and wall–fluid interactions on the behavior of polyethylene melt under Poiseuille flow conditions were investigated by characterizing the slip velocity, dynamics information of the flow process, and spatial configuration parameters of molecular chains. The results indicated that the united-atom molecular dynamics model could better describe the pseudoplastic behavior in nanochannels than the commonly used finitely extensible nonlinear elastic (FENE) model. It was found that the slip velocity could be increased with increasing driving force and show completely opposite variation trends under different orders of magnitude of the wall–fluid interactions. The influence mechanism was interpreted by the density distribution and molecular chain structure parameters, including disentanglement and orientation, which also coincides with the change in the radius of gyration. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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14 pages, 1042 KiB

Open AccessFeature PaperArticle

Structure and Diffusion of Ionic PDMS Melts

by Argyrios V. Karatrantos, Jettawat Khantaveramongkol and Martin Kröger

Polymers 2022, 14(15), 3070; https://doi.org/10.3390/polym14153070 - 29 Jul 2022

Cited by 1 | Viewed by 2249

Abstract

Ionic polymers exhibit mechanical properties that can be widely tuned upon selectively charging them. However, the correlated structural and dynamical properties underlying the microscopic mechanism remain largely unexplored. Here, we investigate, for the first time, the structure and diffusion of randomly and end-functionalized [...] Read more.

Ionic polymers exhibit mechanical properties that can be widely tuned upon selectively charging them. However, the correlated structural and dynamical properties underlying the microscopic mechanism remain largely unexplored. Here, we investigate, for the first time, the structure and diffusion of randomly and end-functionalized ionic poly(dimethylsiloxane) (PDMS) melts with negatively charged bromide counterions, by means of atomistic molecular dynamics using a united atom model. In particular, we find that the density of the ionic PDMS melts exceeds the one of their neutral counterpart and increases as the charge density increases. The counterions are condensed to the cationic part of end-functionalized cationic PDMS chains, especially for the higher molecular weights, leading to a slow diffusion inside the melt; the counterions are also correlated more strongly to each other for the end-functionalized PDMS. Temperature has a weak effect on the counterion structure and leads to an Arrhenius type of behavior for the counterion diffusion coefficient. In addition, the charge density of PDMS chains enhances the diffusion of counterions especially at higher temperatures, but hinders PDMS chain dynamics. Neutral PDMS chains are shown to exhibit faster dynamics (diffusion) than ionic PDMS chains. These findings contribute to the theoretical description of the correlations between structure and dynamical properties of ion-containing polymers. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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25 pages, 6150 KiB

Open AccessArticle

Mesoscale Modeling of Agglomeration of Molecular Bottlebrushes: Focus on Conformations and Clustering Criteria

by Sidong Tu, Chandan K. Choudhury, Michaela Giltner, Igor Luzinov and Olga Kuksenok

Polymers 2022, 14(12), 2339; https://doi.org/10.3390/polym14122339 - 09 Jun 2022

Cited by 4 | Viewed by 1841

Abstract

Using dissipative particle dynamics, we characterize dynamics of aggregation of molecular bottlebrushes in solvents of various qualities by tracking the number of clusters, the size of the largest cluster, and an average aggregation number. We focus on a low volume fraction of bottlebrushes [...] Read more.

Using dissipative particle dynamics, we characterize dynamics of aggregation of molecular bottlebrushes in solvents of various qualities by tracking the number of clusters, the size of the largest cluster, and an average aggregation number. We focus on a low volume fraction of bottlebrushes in a range of solvents and probe three different cutoff criteria to identify bottlebrushes belonging to the same cluster. We demonstrate that the cutoff criteria which depend on both the coordination number and the length of the side chain allows one to correlate the agglomeration status with the structural characteristics of bottlebrushes in solvents of various qualities. We characterize conformational changes of the bottlebrush within the agglomerates with respect to those of an isolated bottlebrush in the same solvents. The characterization of bottlebrush conformations within the agglomerates is an important step in understanding the relationship between the bottlebrush architecture and material properties. An analysis of three distinct cutoff criteria to identify bottlebrushes belonging to the same cluster introduces a framework to identify both short-lived transient and long-lived agglomerates; the same approach could be further extended to characterize agglomerates of various macromolecules with complex architectures beyond the specific bottlebrush architecture considered herein. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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16 pages, 2056 KiB

Open AccessArticle

Kinetic, Isotherm, and Equilibrium Investigation of Cr(VI) Ion Adsorption on Amine-Functionalized Porous Silica Beads

by Anzu Nishino, Ayane Taki, Hiromichi Asamoto, Hiroaki Minamisawa and Kazunori Yamada

Polymers 2022, 14(10), 2104; https://doi.org/10.3390/polym14102104 - 21 May 2022

Cited by 3 | Viewed by 1928

Abstract

The hexavalent chromium (Cr(VI)) ion adsorption properties were conferred to porous silica beads by introducing alkylamine chains through functionalization with an aminosilane coupling agent, [3-(2-aminoethylamino)propyl]triethoxysilane (AEAPTES), or with an epoxysilane coupling agent, (3-glycidyloxypropyl)triethoxysilane (GOPTES), and polyfunctional amine compounds or poly-ethylenimines (PEIs). The presence [...] Read more.

The hexavalent chromium (Cr(VI)) ion adsorption properties were conferred to porous silica beads by introducing alkylamine chains through functionalization with an aminosilane coupling agent, [3-(2-aminoethylamino)propyl]triethoxysilane (AEAPTES), or with an epoxysilane coupling agent, (3-glycidyloxypropyl)triethoxysilane (GOPTES), and polyfunctional amine compounds or poly-ethylenimines (PEIs). The presence of amino groups on the silica beads was confirmed by XPS and the amount of amino groups increased to 0.270 mmol/g by increasing the AEAPTES concentration and/or reaction time. The adsorption capacity of the silica beads functionalized with AEAPTES was the maximum at the initial pH value of 3.0 and the initial adsorption rate increased with an increase in the temperature. The adsorption capacity increased with an increase in the amount of amino groups at pH 3.0 and 30 °C. The adsorption behavior obeyed the pseudo-second order kinetic model and was well expressed by the Langmuir isotherm. These results support that Cr(VI) ion adsorption is accomplished through the electrostatic interaction between protonated amino groups and HCrO₄⁻ ions. In addition, the adsorption capacity further increased to 0.192–0.320 mmol/g by treating the GOPTES-treated silica beads with triethylenetetramine, pentaethylenehexamine, or PEI. These empirical, equilibria, and kinetic aspects obtained in this study support that the porous silica-based adsorbents prepared in this study can be applied to the removal of Cr(VI) ions. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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10 pages, 9821 KiB

Open AccessArticle

Prediction of Thermal Conductivities of Rubbers by MD Simulations—New Insights

by Aleksandr Vasilev, Tommy Lorenz and Cornelia Breitkopf

Polymers 2022, 14(10), 2046; https://doi.org/10.3390/polym14102046 - 17 May 2022

Cited by 4 | Viewed by 1614

Abstract

In this article, two main approaches to the prediction of thermal conductivities by molecular dynamics (MD) simulations are discussed, namely non-equilibrium molecular dynamics simulations (NEMD) and the application of the Green–Kubo formula, i.e., EMD. NEMD methods are more affected by size effects than [...] Read more.

In this article, two main approaches to the prediction of thermal conductivities by molecular dynamics (MD) simulations are discussed, namely non-equilibrium molecular dynamics simulations (NEMD) and the application of the Green–Kubo formula, i.e., EMD. NEMD methods are more affected by size effects than EMD methods. The thermal conductivities of silicone rubbers in special were found as a function of the degree of crosslinking. Moreover, the thermal conductivities of thermoplastic polyurethane as function of the mass fraction of soft segments were obtained by those MD simulations. All results are in good agreement with data from the experimental literature. After the analysis of normalized heat flux autocorrelation functions, it has been revealed that heat in the polymers is mainly transferred by low-frequency phonons. Simulation details as well as advantages and disadvantages of the single methods are discussed in the article. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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9 pages, 2268 KiB

Open AccessCommunication

Mechanical Property of Long Glass Fiber Reinforced Polypropylene Composite: From Material to Car Seat Frame and Bumper Beam

by Bing Du, Zhengxuan Li, Huimin Bai, Qian Li, Changqi Zheng, Jingwei Liu, Feng Qiu, Zhenhua Fan, Hanjie Hu and Liming Chen

Polymers 2022, 14(9), 1814; https://doi.org/10.3390/polym14091814 - 29 Apr 2022

Cited by 11 | Viewed by 2740

Abstract

Long Fiber Reinforced Thermoplastic (LFT) is a lightweight, high-strength, and easy-to-recycle new vehicle composite material, and has good mechanical properties, heat resistance, and weather resistance, which has found increasing application in automobile industry. It is of importance to understand the relationship between micro [...] Read more.

Long Fiber Reinforced Thermoplastic (LFT) is a lightweight, high-strength, and easy-to-recycle new vehicle composite material, and has good mechanical properties, heat resistance, and weather resistance, which has found increasing application in automobile industry. It is of importance to understand the relationship between micro phase, macro-mechanical properties and the structural performance of automobile components. This article evaluates the performance of LFT from the level of material to automobile components. The mechanical properties of LFT were numerically and theoretically predicted to provide instruction for the next material choice. Two typical structural components, namely, car seat frame and bumper beam, were selected to evaluate the performance of LGF/PP compared with other competing materials in terms of mechanical properties and cost. In the case of the same volume, the seat frame of 40% LECT/PP composite material is lighter and cheaper, which is conducive to energy saving and emission reduction. It was shown that the 40% LECT/PA66 car bumper beam had a higher energy absorption ratio, lighter weight, higher specific energy absorption, and advantageous material cost. LFT is a promising candidate for existing automobile components with its performance fulfilling the requirements. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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25 pages, 3882 KiB

Open AccessArticle

Channels with Helical Modulation Display Stereospecific Sensitivity for Chiral Superstructures

by Renáta Rusková and Dušan Račko

Polymers 2021, 13(21), 3726; https://doi.org/10.3390/polym13213726 - 28 Oct 2021

Cited by 3 | Viewed by 26453

Abstract

By means of coarse-grained molecular dynamics simulations, we explore chiral sensitivity of confining spaces modelled as helical channels to chiral superstructures represented by polymer knots. The simulations show that helical channels exhibit stereosensitivity to chiral knots localized on linear chains by effect of [...] Read more.

By means of coarse-grained molecular dynamics simulations, we explore chiral sensitivity of confining spaces modelled as helical channels to chiral superstructures represented by polymer knots. The simulations show that helical channels exhibit stereosensitivity to chiral knots localized on linear chains by effect of external pulling force and also to knots embedded on circular chains. The magnitude of the stereoselective effect is stronger for torus knots, the effect is weaker in the case of twist knots, and amphichiral knots do exhibit no chiral effects. The magnitude of the effect can be tuned by the so-far investigated radius of the helix, the pitch of the helix and the strength of the pulling force. The model is aimed to simulate and address a range of practical situations that may occur in experimental settings such as designing of nanotechnological devices for the detection of topological state of molecules, preparation of new gels with tailor made stereoselective properties, or diffusion of knotted DNA in biological conditions. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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16 pages, 5672 KiB

Open AccessArticle

Multiscale Simulation of Semi-Crystalline Polymers to Predict Mechanical Properties

by Tobias Daniel Horn, Dario Heidrich, Hans Wulf, Michael Gehde and Jörn Ihlemann

Polymers 2021, 13(19), 3233; https://doi.org/10.3390/polym13193233 - 23 Sep 2021

Cited by 6 | Viewed by 2715

Abstract

A multiscale simulation method for the determination of mechanical properties of semi-crystalline polymers is presented. First, a four-phase model of crystallization of semi-crystalline polymers is introduced, which is based on the crystallization model of Strobl. From this, a simulation on the nanoscale is [...] Read more.

A multiscale simulation method for the determination of mechanical properties of semi-crystalline polymers is presented. First, a four-phase model of crystallization of semi-crystalline polymers is introduced, which is based on the crystallization model of Strobl. From this, a simulation on the nanoscale is derived, which models the formation of lamellae and spherulites during the cooling of the polymer by using a cellular automaton. In the solidified state, mechanical properties are assigned to the formed phases and thus the mechanical behavior of the nanoscale is determined by a finite element (FE) simulation. At this scale, simulations can only be performed up to a simulation range of a few square micrometers. Therefore, the dependence of the mechanical properties on the degree of crystallization is determined by means of homogenization. At the microscale, the cooling of the polymer is simulated by a cellular automaton according to evolution equations. In combination with the mechanical properties determined by homogenization, the mechanical behavior of a macroscopic component can be predicted. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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15 pages, 5823 KiB

Open AccessArticle

Elucidating the Aromatic Properties of Covalent Organic Frameworks Surface for Enhanced Polar Solvent Adsorption

by Mostafa Yousefzadeh Borzehandani, Emilia Abdulmalek, Mohd Basyaruddin Abdul Rahman and Muhammad Alif Mohammad Latif

Polymers 2021, 13(11), 1861; https://doi.org/10.3390/polym13111861 - 03 Jun 2021

Cited by 4 | Viewed by 2963

Abstract

Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 [...] Read more.

Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 and covalent triazine-based frameworks (CTF-1), are studied. In addition, a theoretical porous graphene (TPG) was included for comparison purposes. The three solid sheets were investigated for aromaticity and stability using quantum mechanics calculations and their ability for water and ethanol adsorption using molecular dynamics simulations. COF-1 demonstrated the poorest aromatic character due to the highest energy delocalization interaction between B–O bonding orbital of sigma type and unfilled valence-shell nonbonding of boron. CTF-1 was identified as the least kinetically stable and the most chemically reactive. Both COF-1 and CTF-1 showed good surface properties for selective adsorption of water via hydrogen bonding and electrostatic interactions. Among the three sheets, TPG’s surface was mostly affected by aromatic currents and localized π electrons on the phenyl rings which in turn made it the best platform for selective adsorption of ethanol via van der Waals interactions. These results can serve as guidelines for future studies on solvent adsorption for COFs materials. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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Review

Jump to: Research

44 pages, 6718 KiB

Open AccessReview

Modelling of Environmental Ageing of Polymers and Polymer Composites—Modular and Multiscale Methods

by Andrey E. Krauklis, Christian W. Karl, Iuri B. C. M. Rocha, Juris Burlakovs, Ruta Ozola-Davidane, Abedin I. Gagani and Olesja Starkova

Polymers 2022, 14(1), 216; https://doi.org/10.3390/polym14010216 - 05 Jan 2022

Cited by 33 | Viewed by 8070

Abstract

Service lifetimes of polymers and polymer composites are impacted by environmental ageing. The validation of new composites and their environmental durability involves costly testing programs, thus calling for more affordable and safe alternatives, and modelling is seen as such an alternative. The state-of-the-art [...] Read more.

Service lifetimes of polymers and polymer composites are impacted by environmental ageing. The validation of new composites and their environmental durability involves costly testing programs, thus calling for more affordable and safe alternatives, and modelling is seen as such an alternative. The state-of-the-art models are systematized in this work. The review offers a comprehensive overview of the modular and multiscale modelling approaches. These approaches provide means to predict the environmental ageing and degradation of polymers and polymer composites. Furthermore, the systematization of methods and models presented herein leads to a deeper and reliable understanding of the physical and chemical principles of environmental ageing. As a result, it provides better confidence in the modelling methods for predicting the environmental durability of polymeric materials and fibre-reinforced composites. Full article

(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)

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