Herein, we leveraged lithium salt doping of linear and cyclic block polymers (BPs) in thin film geometries to demonstrate how BP architecture influences self-assembled nanofeature sizes and interfacial widths in nanostructured thin films as a function of segregation strength. To mitigate potential issues with sample-to-sample variability and time-consuming synthesis, we used a single linear BP specimen that was ring-closed to generate an analogous cyclic BP, and we mixed the cyclic and/or parent linear BP with a lithium salt to modulate effective segregation strength (χ_effN). Based on X-ray reflectivity analyses, cyclic polystyrene-block-poly[oligo(ethylene glycol) methacrylate] BP thin film specimens had ∼20% smaller domain spacings than their linear counterparts at all χ_effNs and lower absolute sensitivities to changes in χ_eff at identical molecular weights. We also report the first direct measurements of interfacial widths in cyclic BP assemblies, which quantitatively demonstrated that interfacial mixing in cyclic BPs was greater relative to linear BPs. Furthermore, the trends in domain characteristics with increasing salt concentration qualitatively agreed with results from molecular dynamics (MD) simulations with increasing χ, despite the fact that salt species were not explicitly included in the MD simulations. Our results underscore the utility of lithium salt doping to explore the BP phase behavior of synthetically challenging macromolecules and demonstrate key architecture/segregation strength relationships in cyclic BP thin films, which provides useful information to further evaluate cyclic BP suitability for nanoscale patterning and templating applications.

中文翻译：

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盐掺杂的环状与线性嵌段聚合物薄膜的畴间距和组成轮廓行为：联合实验和仿真研究

在这里，我们利用线性几何结构和环状嵌段聚合物（BPs）在薄膜几何形状中的锂盐掺杂来证明BP结构如何影响纳米结构薄膜的自组装纳米特征尺寸和界面宽度，作为分离强度的函数。为了减轻样品间差异和耗时的合成过程中的潜在问题，我们使用了一个线性BP样品，将其闭环以生成类似的循环BP，然后将循环和/或母体线性BP与锂混合盐来调节有效的偏析强度（_χeff N）。基于X射线反射率分析，环状聚苯乙烯嵌段-聚[低聚（乙二醇）甲基丙烯酸酯] BP薄膜样品具有约20％更小的域间隔比在所有χ它们的线性对应物_EFF Ñ S和较低的绝对敏感性变化χ _EFF以相同的分子量。我们还报告了循环BP组件中界面宽度的首次直接测量结果，定量地证明了循环BP中的界面混合相对于线性BP更大。此外，尽管盐类并未明确包含在MD模拟中，但盐浓度增加的域特征趋势与χ增​​大的分子动力学（MD）模拟的结果在质量上一致。我们的结果强调了锂盐掺杂的实用性，以探索合成挑战性大分子的BP相行为并证明环状BP薄膜中的关键体系结构/偏析强度关系，这为进一步评估环状BP在纳米级图案和模板应用中的适用性提供了有用的信息。