It is commonly realized that polydispersity may significantly affect the surface modification properties of polymer brush systems. In light of this, we systematically study morphologies of bidisperse polyelectrolyte brush grafted onto a spherical nanocolloid in the presence of trivalent counterions using molecular dynamics simulations. Via varying polydispersity, grafting density, and solvent selectivity, the effects of electrostatic correlation and excluded volume are focused, and rich phase behaviors of binary mixed polyelectrolyte brush are predicted, including a variety of pinned-patch morphologies at low grafting density and micelle-like structures at high grafting density. To pinpoint the mechanism of surface structure formation, the shape factor of two species of polyelectrolyte chains and the pair correlation function between monomers from different polyelectrolyte ligands are analyzed carefully. Also, electrostatic correlations, manifested as the bridging through trivalent counterions, are examined by identifying four states of trivalent counterions. Our simulation results may be useful for designing smart stimuli-responsive materials based on mixed polyelectrolyte coated surfaces.

人们普遍认识到，多分散性可能会显着影响聚合物刷系统的表面改性性能。鉴于此，我们使用分子动力学模拟系统地研究了在三价反离子存在下接枝到球形纳米胶体上的双分散聚电解质刷的形态。通过改变多分散性、接枝密度和溶剂选择性，重点关注静电相关性和排除体积的影响，预测二元混合聚电解质刷的丰富相行为，包括低接枝密度和胶束状的各种钉扎形貌接枝密度高的结构。为了查明表面结构形成的机制，仔细分析了两种聚电解质链的形状因子和来自不同聚电解质配体的单体之间的对相关函数。此外，通过识别三价抗衡离子的四种状态来检查静电相关性，表现为通过三价抗衡离子的桥接。我们的模拟结果可能有助于设计基于混合聚电解质涂层表面的智能刺激响应材料。