# Impact of Particle Arrays on Phase Separation Composition Patterns

**Authors:** Supriyo Ghosh, Arnab Mukherjee, Raymundo Arroyave, Jack F. Douglas  
**arXiv:** [2006.08362](https://arxiv.org/abs/2006.08362)  
**Date:** 2020-06-10  
**Summary page:** https://www.summarizepaper.com/en/paper/2006.08362v1/

## Key points

- The study investigates the effect of fixed constellations of particles on surface-directed spinodal decomposition of binary blends
- Particles with preferential affinity for one component influence phase separation morphology
- Phase-field simulations show that phase separation morphology can be controlled and tuned depending on factors such as interparticle spacing, blend composition, and time
- Transient target patterns emerge at early times when interparticle spacing is large compared to the spinodal wavelength
- Target patterns stabilize for characteristic length, time, and composition scales specific to pure phase separating mixtures
- Various configurations including single-particle, multi-particle, and cluster-particle systems are simulated to mimic pattern substrates in phase separation processes
- Tailoring particle configuration or substrate pattern configuration along with relative fluid-particle composition allows for control over phase separation morphology similar to block copolymer materials but at larger scales
- Limited experiments confirm trends observed in simulations and provide guidance for engineering patterned blends and mixtures with technological applications.

## Summary

In this study, the authors investigate the effect of fixed constellations of particles on the surface-directed spinodal decomposition of binary blends. They focus on particles whose surfaces have a preferential affinity for one of the components in order to examine how their presence influences phase separation morphology. Using phase-field simulations, the researchers find that the morphology of phase separation in the presence of particle arrays can be controlled and tuned. Depending on factors such as interparticle spacing, blend composition, and time, the phase separation morphology can exhibit continuous, droplet, lamellar or hybrid patterns. One interesting finding is that when the interparticle spacing is large compared to the spinodal wavelength, a transient target pattern emerges at early times. This pattern consists of alternate rings of preferred and non-preferred phases and tends to adopt the symmetry of the particle configuration. The authors observe that these target patterns stabilize for certain characteristic length, time and composition scales specific to pure phase separating mixtures. To illustrate a range of phenomena exhibited by mixture-particle systems, various configurations are simulated including single-particle, multi-particle and cluster-particle systems with different geometrical arrangements which mimic pattern substrates in phase separation processes. The simulations demonstrate that by tailoring either the particle configuration or substrate pattern configuration along with relative fluid-particle composition it is possible to achieve desirable control over phase separation morphology similar to block copolymer materials but at significantly larger scales than those accessible using block copolymers alone. Limited experiments are conducted to confirm trends observed in simulations providing valuable guidance for engineering patterned blends and other mixtures with technological applications. Overall this study sheds light on how fixed constellations of particles can influence phase separation behavior in binary blends offering insights into controlling and manipulating phase separation morphology through particle arrangement and composition adjustments.