Investigation of Thermal Expansion of Polyimide/SiO₂ Nanocomposites by Molecular Dynamics Simulations

Abstract

In this paper, an atomistic model for PI/SiO2 hybrid nanocomposites was designed for the investigation of physical properties of this material on the base of molecular dynamics simulations. The thermal properties of a reference pure PI matrix in the temperature range of 300–650 K were first investigated. The results for the CTE and the glass transition temperature showed good agreement with the experimental data. Then, the thermal expansion of the model of PI/silica composite material with different SiO2 fractions was investigated at normal conditions. The CTE of the composite model decreases with the increase in the SiO2 content in agreement with experimental studies. The results show a threshold for the SiO2 loading beyond which the material model exhibits ultra‐low thermal expansion.

Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates

“…Similar behavior was observed earlier in different polymer-filler composites. 41,[89][90][91] The middle-film density is obviously decreasing upon the temperature increase due to the film expansion in constant-pressure simulations.…”

Effect of nanosilica on the dielectric properties and thermal stability of polyimide/SiO2nanohybrid

“…Nowadays, polymer-inorganic hybrid materials become a popular topic in material science because they inherit the suitable properties from both inorganic component (heat resistance, retention of mechanical properties at high temperatures, and low thermal expansion) and those of organic polymer (toughness, ductility, and processability) [1][2][3][4][5]. Polyimides (PIs) as high-performance organic matrix are used in the preparation of hybrids due to having excellent thermal stability with respect to decomposition, good mechanical properties, chemical stability against oxidation, and low dielectric constant.…”

Simulating the ultrathin layer structure of dichloromethane on a solid substrate by means of density functional theory and molecular dynamics

“…These methods can be used to parameterize the mole cule-molecule and molecules-solid surface interac tion potentials apart from logically predicting a sub stance's properties (density, glass transition tempera ture, volume expansion coefficient, diffusion, free volume, heat conductivity, and so on [11][12][13][14][15][16][17][18]). Let us clarify this in detail.…”

“…For example, atomistic modeling uses force fields obtained from quantum mechanical calculations, followed by forcing the obtained param eters to fit the experimental data [21][22][23][24]. Hence MC and MD allow us not only to analyze the molecular structure of a system containing up to 10 7 atoms but also to calculate their physical properties with a high degree of accuracy [11][12][13][14][15][16][17][18]. Statistical analysis of the intermolecular distances and the mass centers of poly meric chain fragments in turn provide a way of deter mining the pair potentials of mesoscopic particle interaction (correlating with various total combina tions of atoms and molecules) needed to use the meso scopic methods.…”