Y形聚合物刷代表一类特殊的二元混合聚合物刷,其中不同均聚物的组合导致独特的相行为。虽然大多数理论和模拟研究使用单分散模型,实验系统总是多分散的。这种差异阻碍了理论和实验结果的联系。在这项理论研究中,我们采用耗散粒子动力学研究了在良好溶剂条件下多分散性对接枝到平坦表面的Y形刷的相行为的影响。多分散性保持在实验可实现的值内,并通过Schulz-Zimm分布进行建模。总的来说,考虑了10个系统,从而涵盖了单分散的相行为,部分多分散和完全多分散体系。使用真实聚合物的这种通用表示,我们在单分散系统中观察到波纹结构和聚集体。此外,多分散刷形成了一个稳定的穿孔层,以前在单分散研究中未观察到,并影响其余相的稳定性。尽管在良好的溶剂条件下和熔融状态下实验观察到了穿孔层,进一步确认其在良好溶剂条件下的系统中的存在需要将真实聚合物映射到反映的中尺度模型上,例如,不同的聚合物刚度,并排除体积效应或表面的直接影响,只提到几个参数。最后,在这项工作中,我们证明了中尺度建模成功地描述了多分散模型,这为快速探索复杂系统开辟了道路,例如在选择性或不良溶剂中或在非平衡条件下的多分散Y形刷。
Y-shaped polymer brushes represent a special class of binary mixed polymer brushes, in which a combination of different homopolymers leads to unique phase behavior. While most theoretical and simulation studies use monodisperse models, experimental systems are always polydisperse. This discrepancy hampers linking theoretical and experimental results. In this theoretical study, we employed dissipative particle dynamics to study the influence of polydispersity on the phase behavior of Y-shaped brushes grafted to flat surfaces under good solvent conditions. Polydispersity was kept within experimentally achievable values and was modeled via Schulz-Zimm distribution. In total, 10 systems were considered, thus covering the phase behavior of monodisperse, partially polydisperse and fully polydisperse systems. Using such generic representation of real polymers, we observed a rippled structure and aggregates in monodisperse systems. In addition, polydisperse brushes formed a stable perforated layer not observed previously in monodisperse studies, and influenced the stability of the remaining phases. Although the perforated layer was experimentally observed under good solvent conditions and in the melt state, further confirmation of its presence in systems under good solvent conditions required mapping real polymers onto mesoscale models that reflected, for example, different polymer rigidity, and excluded volume effects or direct influence of the surface, just to mention a few parameters. Finally, in this work, we show that mesoscale modeling successfully describes polydisperse models, which opens the way for rapid exploring of complex systems such as polydisperse Y-shaped brushes in selective or bad solvents or under non-equilibrium conditions.