Topological Effects Near Order–Disorder Transitions in Symmetric Diblock Copolymer Melts
Topological Effects Near Order–Disorder Transitions in Symmetric Diblock Copolymer Melts
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DOI：
10.1021/acs.macromol.1c00780
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发表时间：
2021-08
期刊：
影响因子：
5.5
通讯作者：
Tom Herschberg;J. Carrillo;B. Sumpter;E. Panagiotou;Rajeev Kumar
中科院分区：
文献类型：
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作者：
Tom Herschberg;J. Carrillo;B. Sumpter;E. Panagiotou;Rajeev Kumar
用粗粒分子动力学模拟方法研究了高分子链拓扑结构对对称AB两嵌段共聚物熔体有序−无序转变的影响。具体地说，我们比较了对称(即50fi50)AB两嵌段共聚物熔体中相同链长的直链、环和三叶结在片层-无序转变附近的链构象。随着拓扑约束的引入，有序(片状)−无序转变温度和微区尺寸都向较低的值移动，导致以下顺序：线性链>；环>；三叶结。对聚合物链构象的研究，包括它们的旋转半径、它们的扭转值(衡量链围绕其自身的缠绕程度)和它们的琼斯多项式(一种测量曲线纠缠度的方法)表明，线性链和环保持拉伸，而在接近片层-无序转变的无序熔体中，结点被拉伸和收紧。这项工作强调了链拓扑结构在嵌段共聚物的ff检测微相分离中的重要作用。
: The e ff ects of polymer chain topology on the order − disorder transition of symmetric AB diblock copolymer melts are studied using coarse-grained molecular dynamics simulations. Speci fi cally, we compared chain conformations near the lamellar-disordered transition in melts of symmetric (i.e., 50 − 50) AB diblock copolymers of linear chains, rings, and trefoil knots at the same chain lengths. The order (lamellar) − disorder transition temperature and the domain sizes both shifted to lower values with the introduction of topological constraints, leading to the following sequence: linear chains > rings > trefoil knots. Investigation of the polymer chain conformations in terms of their radii of gyration, their writhe values (a measure for the degree of intertwining of a chain around itself), and their Jones polynomials (a method to measure entanglement of curves) showed that linear chains and rings remained stretched, while knots were stretched and tightened in disordered melts close to the lamellar-disorder transition. This work highlights chain topology as an important factor in a ff ecting microphase separation in block copolymers.