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Conjugated polymer films play a decisive role in the construction of photoactive elements in organic electronic devices. Their morphology is mainly determined by self-assembly processes during crystallization initiated by π–π interactions between aromatic rings. However, currently there are only very limited methods to construct polymer matrix models taking into account their crystallization in the framework of computer simulations. In this paper, we propose an extension of a mesoscale modeling methodology based on the dissipative particle dynamics method. We use poly(3-hexylthiophene) (P3HT) as a prototype of the mesoscopic model of polymer chains. To take into account the π–π interactions, we implement the formation and breaking of additional dynamic non-covalent bonds between coarse particles mapped to thiophene rings. We show that the introduction of dynamic bonds makes it possible to simulate the self-assembly of the conjugated polymer chains into a hexagonally packed cylinder morphology and lamellar morphology with large thiophene stacks.

The influence of crosslinking process on the resulting structural properties of phthalonitrile matrices is studied through theoretical and experimental investigations. Multiscale procedure for generating fully atomistic phthalonitrile networks with simulation of radical polymerization reactions and specific reactions of triazine formation at the mesoscale level is presented and applied to the case of phthalonitrile resin based on low-melting monomer bis(3-(3,4-dicyanophenoxy)phenyl)phenyl phosphate. The structural properties of the generated networks of various conversions and with various amount of triazine are analyzed using the dissipative particle dynamics and atomistic molecular dynamics. Triazine-containing networks are much sparser in comparison with triazine-free ones in terms of simple cycle size. The values of density, coefficients of linear thermal expansion and glass transition temperatures (Tgs) agree with obtained experimental data, and are very similar for different crosslinking mechanisms. The dependence of Tg on conversion correlates well with the sol–gel transition in network structure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 362–374

Phthalonitrile compounds with siloxane bridges are recently suggested for producing thermosetting polymer composites with expanded processing range, excellent mechanical properties, and increased thermo-oxidative stability. Mesoscale chemistry concept is adopted to describe multipathway curing process in phthalonitriles by adding triple link (triazine) formation into chemical reactions scheme. Coarse-grained dissipative particle dynamics simulations have shown significant changes in matrix topology and mechanical properties with increase of the triazine reaction rate. In contrast to typical changes induced by high functionality crosslinkers, matrices with high content of triazine reach higher conversion degree, are less topologically interconnected, and are softer than ones without triazine.