arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2104.08893cond-mat.soft
收藏

熔融状态下粗晶软团簇的非扩散性

Coarse-grained Soft-Clusters Remain non-Diffusing in the Melt State

Qing-Zhi Zou, Yihui Zhu, Yifu Ruan, Rui Zhang, GengXin Liu

摘要:

用分子动力学模拟研究了三维树枝状珠弹簧即粗晶软团簇的熔化过程。目标是阐明大分子,或者一般来说,三维结构聚合物的独特动力学。当由超过约200个珠的临界数量构成时,软簇不能在远高于其玻璃化转变温度的温度下扩散或松弛,尽管松弛可以在珠的水平上发生。每个软簇只能在相邻软簇形成的笼中旋转。这样的非扩散状态将在异常高的温度(例如,玻璃化转变温度的10倍)下转变为液态。与实验相比,3D层次结构导致了独特的动力学,特别是它们随着珠子数量的不同而不同的弛豫时间。这些独特的动力学与一维链状聚合物形成鲜明对比。我们将这种特殊的状态命名为“合作玻璃”,因为3D连接的珠子的“合作”。软簇的设计也可能类似于合作重排区域,其中合作性是由低温贡献的,从而提供了对玻璃问题的进一步见解。

英文摘要:

Melts of 3-dimensional dendritic beads-springs, namely coarse-grained soft-clusters, are studied by molecular dynamics simulations. The goal is to elucidate the unique dynamics of giant molecules, or generally speaking, 3-dimensional architectured polymers. When constituted by more than the critical number around 200 beads, soft-clusters cannot diffuse or relax far above their glass transition temperature, although relaxation can happen on the level of beads. Each soft-cluster can only rotate in the cage formed by neighboring soft-clusters. Such a non-diffusing state would transform to the liquid state at exceptionally high temperature, e.g. 10 times the glass transition temperature. Agreeing with experiments, 3D hierarchies lead to unique dynamics, especially their divergent relaxation times with the number of beads. These unique dynamics are in sharp contrast with 1-dimensional chain-like polymers. We name such a special state as 'cooperative glass', because of the 'cooperation' of the 3D-connected beads. The design of soft-clusters may also resemble cooperative rearranging regions where cooperativeness is contributed by low temperature, thus offer further insights into the glass problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑