Molecular dynamics simulations for interfacial structure and affinity between carboxylic acid-modified Al2O3 and polymer melts

Takamasa Saito; Masaki Kubo; Takao Tsukada; Eita Shoji; Gota Kikugawa; Donatas Surblys; Momoji Kubo

doi:10.1063/5.0169721

Molecular dynamics simulations for interfacial structure and affinity between carboxylic acid-modified Al2O3 and polymer melts

J Chem Phys. 2023 Oct 28;159(16):164708. doi: 10.1063/5.0169721.

Authors

Takamasa Saito¹, Masaki Kubo¹, Takao Tsukada², Eita Shoji³, Gota Kikugawa⁴, Donatas Surblys⁴, Momoji Kubo⁵

Affiliations

¹ Department of Chemical Engineering, Tohoku University, 6-6-07 Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
² New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
³ Department of Mechanical Systems Engineering, Tohoku University, 6-6-01 Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
⁴ Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.
⁵ Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan.

PMID: 37888762
DOI: 10.1063/5.0169721

Abstract

Controlling the dispersion state of nanoparticles in a polymer matrix is necessary to produce polymer nanocomposites. The surface modification of nanoparticles is used to enable their dispersion in polymers. Moreover, molecular dynamics (MD) simulations are useful for revealing the interfacial properties between nanoparticles and polymers to aid in the design of materials. In this study, the effect of surface coverage, modifier length, and polymer species on the interfacial structure and affinity between surface-modified Al2O3 and polymer melts were investigated using all-atom MD simulations. Hexanoic, decanoic, and tetradecanoic acids were used as surface modifiers, and polypropylene (PP), polystyrene (PS), and poly (methyl methacrylate) (PMMA) were used as polymers. The work of adhesion Wadh and the work of immersion Wimm were selected as quantitative measures of affinity. Wadh was calculated using the phantom-wall approach, and Wimm was calculated by simply subtracting the surface tension of polymers γL from Wadh. The results showed that Wadh and Wimm were improved by surface modification with low coverage, owing to a good penetration of the polymer. The effect of modifier length on Wadh and Wimm was small. Whereas Wadh increased in the following order: PP < PS < PMMA, Wimm increased as follows: PMMA < PS < PP. Finally, the trend of Wadh and Wimm was organized using the Flory-Huggins interaction parameter χ between the modifier and the polymer. This study demonstrates that the interfacial affinity can be improved by tuning the surface coverage and modifier species depending on the polymer matrix.