ИСТИНА

In recent years, several interesting properties of polymeric nanocomposite material have been experimentally observed. In particular, supramolecular aggregates can be formed in so-called "smart" nanomaterials resulting in self-assembly initiated by functional groups, which in turn can be arranged into various spatial nanostructures. This is accomplished through the mechanism of molecular recognition and subsequent ordering of the resulting aggregates. These systems include thermoplastic silicone-urethane (TPSU) block copolymers containing two blocks based on nonpolar polydimethylsiloxane (PDMS) and polar urethane groups. Due to the chemical nature of these blocks, TPSU possess a number of unique properties, including very low glass transition temperature, high oxidation resistance, thermal stability, hydrophobicity, physiological inertness and increased permeability. Although these polymers are studied for a long time, their internal structure still is not reliably known. We discuss the results of large-scale molecular dynamics simulations of the TPSU-SiO2 nanocomposite. The copolymer contains PDMS and bis(4-socyanatocyclohexyl)methane (HMDI) blocks. Our results indicate that the HMDI blocks tend to parallel alignment due to the hydrogen bonds between them. As a result, the microphase separation occurs in the simulation cell, and the PDMS and HMDI blocks form bicontinuous phase. Thus, the polymer matrix itself can be considered as a self-organizing polymer-polymer nanocomposite, because it is reinforced by the continuous phase of HMDI blocks crosslinked by hydrogen bonds. It explains the significant tensile strength inherent in such copolymers. The effect of silica nanoparticles on the thermal and mechanical properties of TPSU is also discussed. Acknowledgment This work was carried out using high-performance computing resources of federal center for collective usage at NRC “Kurchatov Institute” (http://computing.kiae.ru/) and a software package for multi-level predictive modeling morphology, thermal and mechanical properties of nanocomposites with polymer matrix, developed in the framework of the project ERA-RUS-14891 (0021028) by Kintech Lab Ltd (http://www.kintechlab.com/). The Russian Foundation for Basic Research (RFBR) (project 16-03-00223) is also appreciated.