Stabilizing a Double Gyroid Network Phase with 2 nm Feature Size by Blending of Lamellar and Cylindrical Forming Block Oligomers.
Stabilizing a Double Gyroid Network Phase with 2 nm Feature Size by Blending of Lamellar and Cylindrical Forming Block Oligomers.
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DOI：
10.1021/jacsau.2c00101
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发表时间：
2022-06-27
期刊：
影响因子：
8
通讯作者：
Siepmann, J Ilja
中科院分区：
文献类型：
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作者：
Shen, Zhengyuan;Luo, Ke;Park, So Jung;Li, Daoyuan;Mahanthappa, Mahesh K;Bates, Frank S;Dorfman, Kevin D;Lodge, Timothy P;Siepmann, J Ilja
用分子动力学模拟研究了AB型二嵌段和AB 2型杂臂三嵌段两亲物（也称为高χ嵌段低聚物）的二元共混物，所述两亲物由糖基（A）和烃（B）嵌段组成。在它们的纯形式中，AB二嵌段和AB 2三嵌段两亲物分别自组装成有序的层状（LAM）和圆柱形（CYL）结构。然而，在中间组成下，富含AB 2的共混物（0.2 ≤ xAB ≤ 0.4）形成双螺旋（DG）网络，而在富含AB的共混物（0.5 ≤ xAB ≤ 0.8）中观察到穿孔层状结构（PL）。所有的有序的中间相目前域间距在3 nm以下，与1 nm的极性域的特征尺寸。结构分析表明，DG和PL结构的不均匀的界面曲率的LAM和CYL形成的两亲物的局部组成变化的支持。自洽平均场理论计算相关的AB和AB2嵌段聚合物的共混物也显示DG网络在中间组成，当A是少数嵌段，但PL是不稳定的。这项工作提供了分子水平的见解，如何混合形状填充分子架构，使网络相的形成与极小的特征尺寸在很宽的组成范围。
Molecular dynamics simulations are used to study binary blends of an AB-type diblock and an AB2-type miktoarm triblock amphiphiles (also known as high-χ block oligomers) consisting of sugar-based (A) and hydrocarbon (B) blocks. In their pure form, the AB diblock and AB2 triblock amphiphiles self-assemble into ordered lamellar (LAM) and cylindrical (CYL) structures, respectively. At intermediate compositions, however, the AB2-rich blend (0.2 ≤ xAB ≤ 0.4) forms a double gyroid (DG) network, whereas perforated lamellae (PL) are observed in the AB-rich blend (0.5 ≤ xAB ≤ 0.8). All of the ordered mesophases present domain pitches under 3 nm, with 1 nm feature sizes for the polar domains. Structural analyses reveal that the nonuniform interfacial curvatures of DG and PL structures are supported by local composition variations of the LAM- and CYL-forming amphiphiles. Self-consistent mean field theory calculations for blends of related AB and AB2 block polymers also show the DG network at intermediate compositions, when A is the minority block, but PL is not stable. This work provides molecular-level insights into how blending of shape-filling molecular architectures enables network phase formation with extremely small feature sizes over a wide composition range.