Structure of interacting aggregates of silica nanoparticles in a polymer matrix: Small-angle scattering and Reverse Monte-Carlo simulations

TL;DR

This study investigates the three-dimensional structure and interactions of silica nanoparticle aggregates in a polymer matrix using Small Angle Neutron Scattering and Reverse Monte Carlo simulations, revealing insights into aggregate shape and interactions.

Contribution

It introduces a combined analysis method using structure factors and Reverse Monte Carlo simulations to characterize nanoparticle aggregates in elastomers, providing new structural insights.

Findings

Identified the shape and interaction patterns of silica aggregates in elastomers.

Demonstrated the effectiveness of combining scattering data with Reverse Monte Carlo simulations.

Compared fractal models with experimental data for aggregate scattering.

Abstract

Reinforcement of elastomers by colloidal nanoparticles is an important application where microstructure needs to be understood - and if possible controlled - if one wishes to tune macroscopic mechanical properties. Here the three-dimensional structure of big aggregates of nanometric silica particles embedded in a soft polymeric matrix is determined by Small Angle Neutron Scattering. Experimentally, the crowded environment leading to strong reinforcement induces a strong interaction between aggregates, which generates a prominent interaction peak in the scattering. We propose to analyze the total signal by means of a decomposition in a classical colloidal structure factor describing aggregate interaction and an aggregate form factor determined by a Reverse Monte Carlo technique. The result gives new insights in the shape of aggregates and their complex interaction in elastomers. For comparison, fractal models for aggregate scattering are also discussed.