Phase behaviour of two-component bottle-brush polymers with flexible backbones under poor solvent conditions

摘要

The phase behaviour of two-component bottle-brush polymers with fullyflexible backbones under poor solvent conditions is studied viamolecular-dynamics simulations, using a coarse-grained bead-spring model andside chains of up to $N=40$ effective monomers. We consider a symmetric modelwhere side chains of type A and B are grafted alternately onto a flexiblebackbone. The aim of this study to explore the phase behaviour of two-componentbottle-brushes depending on parameters, such as as the grafting density$\sigma$, the backbone length $N_b$, the side-chain length $N$, and thetemperature $T$. Based on a cluster analysis, we identify for our range ofparameters the regimes of fully phase separated systems, i.e., A-type sidechains form one cluster and B-type chains another, while the interface thatseparates these two clusters contains the backbone monomers. We find thatpearl-necklace or Janus-like structures, which normally occur for bottle-brushpolymers with rigid backbones under poor solvent conditions, are fullyattributed to the backbone rigidity, and, therefore, such structures areunlikely in the case of bottle brushes with fully flexible backbones. Also, acomparative discussion with earlier work on the phase behaviour ofsingle-component bottle-brush polymers with flexible backbones is performed.