Large-Grained Cylindrical Block Copolymer Morphologies by One-Step Room-Temperature Casting,Macromolecules

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Large-Grained Cylindrical Block Copolymer Morphologies by One-Step Room-Temperature Casting
Macromolecules ( IF 5.1 ) Pub Date : 2020-12-01 , DOI: 10.1021/acs.macromol.0c02026
Arkadiusz A Leniart ₁ , Przemyslaw Pula ₁ , Esther H R Tsai ₂ , Pawel W Majewski ₁

Affiliation

We report a facile method of ordering block copolymer (BCP) morphologies in which the conventional two-step casting and annealing steps are replaced by a single-step process where microphase separation and grain coarsening are seamlessly integrated within the casting protocol. This is achieved by slowing down solvent evaporation during casting by introducing a nonvolatile solvent into the BCP casting solution that effectively prolongs the duration of the grain-growth phase. We demonstrate the utility of this solvent evaporation annealing (SEA) method by producing well-ordered large-molecular-weight BCP thin films in a total processing time shorter than 3 min without resorting to any extra laboratory equipment other than a basic casting device, i.e., spin- or blade-coater. By analyzing the morphologies of the quenched samples, we identify a relatively narrow range of polymer concentration in the wet film, just above the order–disorder concentration, to be critical for obtaining large-grained morphologies. This finding is corroborated by the analysis of the grain-growth kinetics of horizontally oriented cylindrical domains where relatively large growth exponents (1/2) are observed, indicative of a more rapid defect-annihilation mechanism in the concentrated BCP solution than in thermally annealed BCP melts. Furthermore, the analysis of temperature-resolved kinetics data allows us to calculate the Arrhenius activation energy of the grain coarsening in this one-step BCP ordering process.

中文翻译：

一步室温铸造法制备大晶粒圆柱形嵌段共聚物形态

我们报告了一种简便的嵌段共聚物（BCP）形态排序方法，其中传统的两步铸造和退火步骤被单步过程取代，其中微相分离和晶粒粗化无缝集成在铸造协议中。这是通过在 BCP 铸造溶液中引入非挥发性溶剂来减缓铸造过程中的溶剂蒸发来实现的，从而有效地延长晶粒生长阶段的持续时间。我们通过在不到 3 分钟的总处理时间内生产出有序的大分子量 BCP 薄膜来证明这种溶剂蒸发退火 (SEA) 方法的实用性，而无需借助基本铸造设备以外的任何额外实验室设备，即.、旋转或刮刀涂布机。通过分析淬火样品的形貌，我们确定了湿膜中相对较窄的聚合物浓度范围，略高于有序-无序浓度，这对于获得大颗粒形貌至关重要。这一发现得到了水平定向圆柱域晶粒生长动力学分析的证实，其中观察到相对较大的生长指数 (1/2)，表明浓缩 BCP 溶液中的缺陷消灭机制比热退火 BCP 中更快融化。此外，对温度分辨动力学数据的分析使我们能够计算这一一步 BCP 排序过程中晶粒粗化的阿伦尼乌斯活化能。

更新日期：2020-12-22

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