Rapid, interface-driven domain orientation in bottlebrush diblock copolymer films during thermal annealing
Rapid, interface-driven domain orientation in bottlebrush diblock copolymer films during thermal annealing
复制标题
热退火过程中瓶刷二嵌段共聚物薄膜中快速、界面驱动的畴取向
DOI：
10.1039/d1sm01634b
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发表时间：
2022
期刊：
影响因子：
3.4
通讯作者：
Diao, Ying
中科院分区：
文献类型：
--
作者：
Patel, Bijal B.;Walsh, Dylan J.;Patel, Kush;Kim, Do Hoon;Kwok, Justin J.;Guironnet, Damien;Diao, Ying
有利的聚合物-基底相互作用在嵌段共聚物（BCP）熔体中诱导表面取向场。在接近平衡处理的线性BCP中，在畴取向随机化之前，畴的排列通常持续少量的周期（0.4 -6 D 0）。Bottlebrush BCP是一类新兴材料，具有源自实质性分子刚性的独特链动力学，能够以超高（>100 nm）畴周期快速组装，具有强光子性质（结构色）。本工作评估界面诱导有序PS-b-PLA瓶刷二嵌段共聚物薄膜在热退火过程中的平面表面之间。为了清楚地观察从表面到体的取向顺序的衰减，我们选择研究微米级的薄膜跨越大于200片层周期。原位光学显微镜和透射紫外-可见光谱用于监测退火过程中的光子特性，并与非原位紫外-可见反射测量，横截面扫描电子显微镜（SEM）和小角X射线散射（SAXS）配对，以探测域微结构的演变。观察到光子特性在150 °C下退火的几分钟内饱和，透射响应随膜厚度的变化而明显变化。高度对准的表面区域的深度被发现在30-100片层周期的范围内随机变化，取向梯度的锐度随着膜厚度的增加而显著降低。这一观察结果表明，在表面的对齐，异质成核，晶粒和取向各向同性，均匀成核，晶粒在整个散装之间的增长的竞争。这项工作证明了瓶刷嵌段共聚物在快速制造工作流程中的高潜力，并为定向自组装到BBCP订购的未来应用提供了一个比较点。
Favorable polymer-substrate interactions induce surface orientation fields in block copolymer (BCP) melts. In linear BCP processed near equilibrium, alignment of domains generally persists for a small number of periods (∼4–6 D0) before randomization of domain orientation. Bottlebrush BCP are an emerging class of materials with distinct chain dynamics stemming from substantial molecular rigidity, enabling rapid assembly at ultrahigh (>100 nm) domain periodicities with strong photonic properties (structural color). This work assesses interface-induced ordering in PS-b-PLA bottlebrush diblock copolymer films during thermal annealing between planar surfaces. To clearly observe the decay in orientational order from surface to bulk, we choose to study micron-scale films spanning greater than 200 lamellar periods. In situ optical microscopy and transmission UV-Vis spectroscopy are used to monitor photonic properties during annealing and paired with ex situ UV-Vis reflection measurement, cross-sectional scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) to probe the evolution of domain microstructure. Photonic properties were observed to saturate within minutes of annealing at 150 °C, with distinct variation in transmission response as a function of film thickness. The depth of the highly aligned surface region was found to vary stochastically in the range of 30–100 lamellar periods, with the sharpness of the orientation gradient decreasing substantially with increasing film thickness. This observation suggests a competition between growth of aligned, heterogeneously nucleated, grains at the surface and orientationally isotropic, homogeneously nucleated, grains throughout the bulk. This work demonstrates the high potential of bottlebrush block copolymers in rapid fabrication workflows and provides a point of comparison for future application of directed self-assembly to BBCP ordering.