Molecular dynamics simulations of single siloxane dendrimers: Molecular structure and intramolecular mobility of terminal groups

A O Kurbatov; N K Balabaev; M A Mazo; E Yu Kramarenko

doi:10.1063/1.5009988

Molecular dynamics simulations of single siloxane dendrimers: Molecular structure and intramolecular mobility of terminal groups

J Chem Phys. 2018 Jan 7;148(1):014902. doi: 10.1063/1.5009988.

Authors

A O Kurbatov¹, N K Balabaev², M A Mazo³, E Yu Kramarenko¹

Affiliations

¹ Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
² Institute of Mathematical Problems of Biology, Keldysh Institute of Applied Mathematics RAS, Pushchino, Moscow Region 142290, Russia.
³ Semenov Institute of Chemical Physics RAS, Moscow 119991, Russia.

PMID: 29306281
DOI: 10.1063/1.5009988

Abstract

Molecular dynamics simulations of two types of isolated siloxane dendrimers of various generations (from the 2nd to the 8th) have been performed for temperatures ranging from 150 K to 600 K. The first type of dendrimer molecules has short spacers consisting of a single oxygen atom. In the dendrimers of the second type, spacers are longer and comprised of two oxygen atoms separated by a single silicon atom. A comparative analysis of molecular macroscopic parameters such as the gyration radius and the shape factor as well as atom distributions within dendrimer interior has been performed for varying generation number, temperature, and spacer length. It has been found that the short-spacer dendrimers of the 7th and 8th generations have a stressed central part with elongated bonds and deformed valence angles. Investigation of the time evolution of radial displacements of the terminal Si atoms has shown that a fraction of the Si groups have a reduced mobility. Therefore, rather long time trajectories (of the order of tens of nanoseconds) are required to study dendrimer intramolecular dynamics.