Chemical Engineering Department, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
Langmuir. 2013 Oct 15;29(41):12785-95. doi: 10.1021/la401775p. Epub 2013 Aug 2.
One of the challenges in creating high-performance polymer nanocomposites is establishing effective routes for tailoring the morphology of both the polymer mixture and the dispersed nanoparticles, which contribute desirable optical, electrical, and mechanical properties. Using computational modeling, we devise an effective method for simultaneously controlling the spatial regularity of the polymer phases and the distribution of the rods within this matrix. We focus on mixtures of photosensitive AB binary blends and A-coated nanorods; in the presence of light, the binary blends undergo a reversible chemical reaction and phase separation to yield a morphology resembling that of microphase-separated diblock copolymers. We simulate the effects of illuminating this sample with a uniform background light and a higher intensity, spatially localized light, which is rastered over the sample with a velocity v. The resulting material displays a periodically ordered, essentially defect-free morphology, with the A-like nanoparticles localized in lamellar A domains. The dynamic behavior of the rods within this system can be controlled by varying the velocity v and Γ2, the reaction rate coefficient produced by the higher intensity light. Specifically, the rastering light can drive the rods to be "pushed" along the lamellar domains or oriented perpendicular to these stripes. Given these attributes, we isolate scenarios where the system encompasses a complex hierarchical structure, with rods that are simultaneously ordered along two distinct directions within the periodic matrix. Namely, the rods form long nanowires that span the length of the sample and lie perpendicular to these wires in regularly spaced A lamellae. Hence, our approach points to new routes for producing self-organized rectangular grids, which can impart remarkable optoelectronic or mechanical properties to the materials.
在制备高性能聚合物纳米复合材料时，面临的挑战之一是建立有效途径来调控聚合物混合物和分散纳米颗粒的形态，这有助于获得理想的光学、电学和机械性能。我们使用计算建模，设计了一种有效方法来同时控制聚合物相的空间规则性和纳米棒在该基质中的分布。我们专注于光敏 AB 二元混合物和 A 包覆纳米棒的混合物；在光的存在下，二元混合物经历可逆化学反应和相分离，产生类似于微相分离嵌段共聚物的形态。我们模拟了用均匀背景光和强度更高、空间局部化的光照射该样品的效果，后者以速度 v 在样品上进行光栅扫描。所得材料显示出周期性有序、基本上无缺陷的形态，A 样纳米颗粒定位于层状 A 域中。通过改变速度 v 和 Γ2（高强度光产生的反应速率系数），可以控制该体系中棒的动态行为。具体来说，光栅光可以将棒“推动”沿着层状域，或使其垂直于这些条纹取向。鉴于这些属性，我们分离出系统具有复杂的层次结构的情况，其中棒在周期性基质内同时沿两个不同方向有序排列。即，棒形成长纳米线，横跨样品长度，并在规则间隔的 A 层片中垂直于这些纳米线。因此，我们的方法为制备自组织矩形网格指明了新途径，这可以为材料赋予显著的光电或机械性能。
