Поиск способов управления структурой волокон прекурсоров на основе полиакрилонитрила является ключом к модификации свойств углеродных волокон. В публикации обсуждаются результаты мезомасштабного моделирования процессов структурообразования в смеси полиакрилонитрила, диметилсульфоксида и воды (хороший и плохой растворители для полимера). Выбор состава системы был сделан на основе представлений о составе волокон прекурсоров на поздних стадиях формирования в условиях коагуляционной ванны. Все расчеты выполнены с использованием динамической теории функционала плотности. Разработанная модель позволяет учитывать влияние изменения состава системы, влияния наполнителя в виде углеродных нанотрубок, температуры и сдвигового потока. Полученные результаты показывают, что посредством варьирования количества воды в системе (что определяется составом коагуляционной ванны) и введения углеродного наполнителя можно значительно изменять структуру полимера.

The key to the modification of the properties of carbon fibers is to understand how to control the structure of polyacrylonitrile-based precursors. Results of a mesoscale modeling of the structure formation processes in a mixture of polyacrylonitrile, dimethyl sulfoxide, and water (good and poor solvents for polymers) are reported. The system′s composition is chosen using the composition of precursor fibers at the later formation stages under coagulation bath conditions. All calculations are performed using the dynamic density functional theory. The proposed model considers effects caused by changes in the system composition, carbon nanotube filler, temperature, and shear flow. It is shown that the polymer structure can be significantly changed by varying the amount of water in the system (determined by the coagulation bath composition) and by introducing a carbon filler.

The dependence of the adhesion energy of the polyacrylonitrile oligomeric chain on the surfaces of carbon nanoparticles such as carbon nanotubes and graphene is studied in the framework of full atomistic molecular mechanics simulation using the polymer consistent force field and the open part of the condensed-phase optimized molecular potentials for atomistic simulation studies force field. The length of the polyacrylonitrile oligomer chain, the number of layers in the graphene nanoparticle, the diameter of the carbon nanotube, and the type and density of the modifier molecules on the surface of the graphene are the main parameters of the calculations. The graphene nanoparticle is taken as a limiting case corresponding to the large-diameter carbon nanotube. N-(2-aminoethyl) carbamoyl, nitrocyclohexane, benzamide, and dinitrobiphenyl are selected as surface modifiers. It is shown that with an increase in the number of layers and diameter of carbon nanotubes, the adhesion energy of the polyacrylonitrile oligomer chain increases, which allows us to consider multiwalled carbon nanotube with large diameters as a preferred filler for polyacrylonitrile. The estimates obtained also show that when surface modifiers are used, it is possible to increase the adhesion energy of polyacrylonitrile only in the case of low surface modifier densities.

Надмолекулярная организация сопряженных полимеров сильно влияет на подвижность носителей заряда и, следовательно, на свойства производимых электронных устройств на их основе. Поэтому является важным научится строить вычислительные модели способные воспроизводить структуру таких полимеров с максимально возможной точностью. Одной из главных движущих сил процесса самосборки надмолекулярных структур в сопряженных полимерах является п - п взаимодействие. Его учет является достаточно трудной задачей, особенно при построении мезомасштабных моделей. В данной работе мы используем теорию функционала электронной плотности для отработки методики расчета сопряженных полимеров с учетом п - п взаимодействия. Были изучены геометрические характеристики пачек из четырех молекул тетратиофена. Выполненные расчеты показывают, что использование функционала M06-2X-D3 позволяет корректно моделировать взаимодействия молекул олиготиофенов и структуру образующихся агрегатов, в то время как полуэмпирические расчёты методом PM7 сопряженных полимеров пригодны лишь для быстрой предварительной оптимизации моделей. Разработанная методика расчетов имеет важное значение для параметризации мезомасштабных схем моделирования. The properties of the supramolecular organization of conjugated polymers strongly affect the mobility of charge carriers and, consequently, the properties of produced electronic devices based on them. Therefore, it is important to learn how to build computational models capable of reproducing the structure of such polymers with the highest possible accuracy. One of the main driving forces of the self-assembly of supramolecular structures in conjugated polymers is п-п interaction. Taking it into account is a rather difficult task, especially when constructing mesoscale models. In this work, we use the electron density functional theory to develop a methodology for calculating conjugated polymers taking into account п-п interaction. The geometric characteristics of stacks of four tetra thiophene molecules were studied. The performed calculations show that the use of the M06-2X-D3 functional makes it possible to correctly model the interactions of oligothiophene molecules and the structure of the resulting aggregates, while semiempirical calculations by the PM7 method of conjugated polymers are suitable only for rapid preliminary optimization of models. The tested calculation technique is of great importance for the parametrization of mesoscale modeling schemes. Keywords: organic solar cells, organic polymers, thiophenes, quantum chemical calculations, п-п stacking interaction.

A concept of fabrication of well-organized conductive pathways in CP/NP blends in photovoltaic devices. It is assumed that to succeed in this task, one can use the property of AB diblock copolymers that, depending on the chemical structure of A and B blocks and the ratio between their lengths, these copolymers undergo microphase separation in bulk to form thermodynamically stable domains of cubic symmetry with 3D periodicity. Using a mesoscale simulation technique, we demonstrated that the morphology of the photoactive layer of photovoltaic devices can be controlled by selecting the surface NP modifier (responsible for the compatibility of NPs with the polymeric matrix), the chemical structure of the blocks of a conjugated copolymer, and their length.

A cysteine-silver solution (CSS) is a low-concentrated supramolecular system capable of gelation as a result of addition of initiating salts. The initial stage of CSS aging is studied in this work by a large-scale all-atom molecular dynamics simulation. From the calculations a possible structure of suprananomers based on silver mercaptide is determined along with their properties allowing them to form a gel network. The results obtained are consistent with the IR spectroscopic data and measurements of the ζ-potential.

Цистеин-серебряный раствор (ЦСР) — низкоконцентрированная супрамолекулярная система, способная к гелеобразованию в результате добавления солей-инициаторов. В работе изучена начальная стадия созревания ЦСР в рамках крупномасштабного полноатомного молекулярно-динамического моделирования. Благодаря расчетам установлена возможная структура супрамономеров на основе меркаптида серебра и их свойства, позволяющие им формировать гель-сетку. Полученные результаты согласуются с данными ИК-спектроскопии и измерениями ζ-потенциала.

The problem is considered of constructing coarse-grained models of matrices of conjugated polymers with regard to their crystallization. The performed simulation within the framework of the method of dissipative particle dynamics shows that to simulate the crystallization process, flexiblesemi-flexible chains with thermodynamically incompatible blocks can be used.

In this paper, the process of maturation of an aqueous solution of L-cysteine and silver nitrate using the method of atomistic molecular dynamics is investigated. To study the maturation process, an atomistic model of the solution was developed. The study allowed to obtain new data on the structure of silver mercaptide clusters and the role of their structural features in the process of further self-organization.

Structural transformations occurring in aqueous L-cysteine−silver-nitrate mixed solutions (CSSs) upon the addition of an initiating salt have been studied within the framework of mesoscopic simulation using the dissipative particle-dynamics method. Diffusion of silver mercaptide clusters is decelerated, and metastable chain aggregates thereof are formed in a narrow concentration range of the salt, probably due to the transition into a gel-like state. The results obtained are in qualitative agreement with the experimentally observed behavior of CSSs.

In this publication the results are presented of an analysis of statistical properties of the distribution of monomer units in copolymer chains synthesized in silico based on vinylcaprolactam and vinylimidazole. Such polymer chains demonstrate one of the basic properties of protein molecules, and exactly, they are able under conditions of a «bad» solvent (for vinylcaprolactam blocks) to take a dense globular structure with a hydrophobic core surrounded by a hydrophilic «corona». Despite the external similarity of the morphology of globules with protein-like copolymers, the distribution of comonomers attached to the first hydrophobic block has a random character.

A model based on the mesoscale simulation technique was developed for predicting the conditions for artificial enzyme formation from N-vinylcaprolactam (VCL) and N-vinylimidazole (NVI) by radical copolymerization of pre-synthesized poly-VCL blocks of different molecular weight with VCL and NVI comonomers. This synthetic procedure gives model copolymer chains. Upon a change in the solvent nature, these chains are able to form compact two-layer globular nanostructures with core–shell type morphology if the fraction of the first poly-VCL block is 25–38% of the total copolymer and the fraction of NVI monomers in the reaction mixture (in the concentration range considered) is maximum.

We present new results of computer simulations of synthesis of block A-AB copolymers. Our model shows that compact and water-soluble globules, which can be used as basis for sinzymes, can be obtained in narrow range of investigated parameters.

The results of simulating gelation in a cysteine–silver solution have been presented. All calculations have been carried out in terms of the dissipative particle dynamics method. In the developed model, the introduction of a salt, which initiates gelation, is taken into account implicitly by setting the parameters of the interaction between polar groups of cysteine and a solvent. It has been shown that fibers of gel network are formed in a narrow range of the initiating salt concentration due to weakened interaction of polar groups of cysteine with a solvent.

Представлены результаты моделирования гелеобразования в цистеин-серебряном растворе. Все расчеты выполнены в рамках метода диссипативной динамики частиц. В разработанной модели введение соли, инициирующей процесс гелеобразования, учитывается не явно, а посредством задания параметров взаимодействия между полярными группами цистеина и растворителя. Показано, что волокна сетки геля формируются в узком диапазоне концентрации соли-инициатора вследствие ослабления взаимодействия полярных групп цистеина с растворителем.

Results of coarse grained simulations of synthesis of amphiphilic AB copolymers with the aim to obtain compact and stable core-shell nanostructures are presented. It is shown that the target nanostructures are formed at an optimal monomer ratio in the reaction mixture. These results can be used as the reference point in a laboratory synthesis.