Phase Separation and Aggregation in Multiblock Chains

TL;DR

This study investigates phase separation and aggregation behaviors in multiblock chains with hydrophilic and hydrophobic segments, revealing that both phenomena can occur depending on chain architecture and conditions, with implications for biomolecular condensates and polymer applications.

Contribution

It demonstrates that both phase separation and finite-size aggregation can occur in multiblock chains, depending on sequence pattern and conditions, expanding understanding of their complex behaviors.

Findings

Both phase separation and aggregation observed in specific chain architectures.

A bulk dense liquid forms from dilute phase containing finite-size aggregates.

Use of histogram-reweighting grand canonical Monte Carlo simulations to analyze behaviors.

Abstract

This article focuses on phase and aggregation behavior for linear chains composed of blocks of hydrophilic and hydrophobic segments. Phase and conformational transitions of patterned chains are relevant for understanding liquid-liquid separation of biomolecular condensates, which play a prominent role in cellular biophysics, but also for surfactant and polymer applications. Previous studies of simple models for multiblock chains have shown that, depending on the sequence pattern and chain length, such systems can fall into one of two categories: displaying either phase separation or aggregation into finite-size clusters. The key new result of the present study is that both formation of finite-size aggregates and phase separation can be observed for certain chain architectures at appropriate conditions of temperature and concentration. For such systems, a bulk dense liquid condenses from a dilute phase that already contains multi-chain finite-size aggregates. The computational approach involves several distinct steps using histogram-reweighting grand canonical Monte Carlo simulations, which are described here in some level of detail.