State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022, Jilin, China.
School of Physics, Northeast Normal University , Changchun 130024, Jilin, China.
Langmuir. 2016 Aug 23;32(33):8484-93. doi: 10.1021/acs.langmuir.6b01090. Epub 2016 Aug 8.
Degenerate behavior (i.e., forming different self-assembled structures for a given block copolymer (BCP) under the same confinement) commonly exists in various confined systems. Understanding degenerate behavior is crucial for precise control over the structures formed by self-assembly systems under confinement. In this study, the degenerate behavior of a self-assembled AB diblock copolymer/nanoparticle (NP) mixture in a cylindrical pore is studied using Monte Carlo simulation. We find that the degenerate behavior of such a mixture depends on the introduction of the NP. Under different pore sizes, four typical degenerate structures [i.e., single helices (S-helices), double helices (D-helices), parallel cylinders, and stacked toroids] can be obtained if the NP content is zero. However, when the NP content in the mixture is increased, it is found that the number of degenerate structures decreases, that is, only blocky structures can be obtained in the case of high NP content. Moreover, the probability of forming S-helices decreases, whereas the probability of forming D-helices increases with increase in the NP content. Analysis of the interactive enthalpy densities and the chain conformation of the systems indicates that entropy plays an important role in the degenerate structure formation. This study provides some new insights into the degenerate behavior of a BCP/NP mixture under confinement, which can offer a theoretical reference for further experiments.
在各种受限体系中，普遍存在退化行为（即在相同的受限条件下，给定嵌段共聚物（BCP）形成不同的自组装结构）。理解退化行为对于精确控制受限条件下自组装体系形成的结构至关重要。在这项研究中，我们使用蒙特卡罗模拟研究了圆柱形孔中 AB 两亲嵌段共聚物/纳米粒子（NP）混合物的退化行为。我们发现，这种混合物的退化行为取决于 NP 的引入。在不同的孔径下，如果 NP 含量为零，则可以得到四种典型的退化结构[即单螺旋（S-螺旋）、双螺旋（D-螺旋）、平行圆柱和堆积环体]。然而，当混合物中 NP 的含量增加时，我们发现退化结构的数量减少，也就是说，在高 NP 含量的情况下，只能得到块状结构。此外，形成 S-螺旋的概率降低，而形成 D-螺旋的概率随着 NP 含量的增加而增加。对体系的相互作用焓密度和链构象的分析表明，熵在退化结构形成中起着重要作用。这项研究为受限条件下 BCP/NP 混合物的退化行为提供了一些新的见解，可为进一步的实验提供理论参考。
