Unravelling structural rearrangement of polymer colloidal crystals under dry sintering conditions

TL;DR

This study uses in situ X-ray scattering and DWBA analysis to reveal how polystyrene colloidal crystals structurally rearrange during dry sintering, including particle shape change and amorphisation, advancing nano-material design.

Contribution

It provides detailed nanoscale insights into the structural evolution of colloidal crystals during dry sintering, a novel application of DWBA analysis in this context.

Findings

Particles change shape from spheres to polyhedra during sintering

Crystalline domains undergo thermal expansion and amorphisation

Structural parameters vary with temperature and particle size

Abstract

Structural rearrangement of polystyrene colloidal crystals under dry sintering conditions has been revealed by in situ grazing incidence X-ray scattering. Measured diffraction patterns were analysed using distorted wave Born approximation (DWBA) theory and the structural parameters of as-grown colloidal crystals of three different particle sizes were determined for in-plane and out-of-plane directions in a film. By analysing the temperature evolution of diffraction peak positions, integrated intensities, and widths the detailed scenario of structural rearrangement of crystalline domains at a nanoscale has been revealed, including thermal expansion, particle shape transformation and crystal amorphisation. Based on DWBA analysis we demonstrate that in the process of dry sintering the shape of colloidal particles in a crystal transforms from a sphere to a polyhedron. Our results deepen the understanding of thermal annealing of polymer colloidal crystals as an efficient route to the design of new nano-materials.