Diffusion and Relaxation Dynamics of Supercooled Polymer Melts

doi:10.1007/s10118-018-2132-9

CORC > 化学研究所 > 中国科学院化学研究所

	Diffusion and Relaxation Dynamics of Supercooled Polymer Melts
	Pan, Deng 1,2; Sun, Zhao-Yan 1,3
刊名	CHINESE JOURNAL OF POLYMER SCIENCE
	2018-10-01
卷号	36 期号:10 页码:1187-1194
关键词	Supercooled Polymer Melt Molecular Dynamics Simulation Diffusion Relaxation
ISSN号	0256-7679
DOI	10.1007/s10118-018-2132-9
英文摘要	The dynamic properties of polymer melts are investigated in the range of normal liquid regime to the supercooled liquid regime. The polymer is modeled as a coarse-grained bead-spring model with chain length ranging from 5 to 160. The mean squared displacement and non-Gaussian parameter are used to describe the self diffusion of polymer beads. We find slow dynamics with decreasing temperature and increasing chain length. The time evolution of non-Gaussian parameters shows two peaks (or one peak one shoulder) in the alpha-relaxation time, tau (alpha) , regime and sub-diffusion time regime, respectively, where the first primary peak indicates the dynamic heterogeneity stemmed from the motion of beads, and the secondary peak is the result of correlated motion along a polymer chain. Moreover, the relaxation of polymer beads shows clear two-step decay in supercooled melts and the dynamics shows growing heterogeneity with decreasing temperature. As chain length is increased, a peak of the dynamic susceptibility occurs, and the peak height, chi(4), increases and then reaches a plateau. The curves of the height of the first peak of alpha (2) alpha(2), versus tau (alpha) and the curves of chi*(4) versus tau (alpha) follow two master curves for different chain lengths. Our results indicate the similarity of dynamic heterogeneity dominated by the motion of single bead even the chain length is different. It is interesting to find that the Stokes-Einstein (SE) relation between tau (alpha) and diffusion coefficient D, D similar to tau (q) (-1) , is highly length-scale dependent. The SE relation breaks down in both normal melts regime and supercooled regime at large magnitude of wave vectors, attributed to the non-Brownian motion arising from the chain connectivity and growing heterogeneity due to supercooling. However, the SE relation is reconstructed when the probing length scale is large (at small magnitude of wave vectors). Our results show a hierarchical physical picture of the supercooled polymeric dynamics.
语种	英语
出版者	SPRINGER
WOS记录号	WOS:000442503500011
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/42387]
专题	中国科学院化学研究所
通讯作者	Sun, Zhao-Yan
作者单位	1.Chinese Acad Sci, State Key Lab Polymer Phys & Chem, Changchun Inst Appl Chem, Changchun 130022, Jilin, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Yili Normal Univ, Xinjiang Lab Phase Transit & Microstruct Condense, Coll Phys Sci & Technol, Yining 835000, Peoples R China
推荐引用方式 GB/T 7714	Pan, Deng,Sun, Zhao-Yan. Diffusion and Relaxation Dynamics of Supercooled Polymer Melts[J]. CHINESE JOURNAL OF POLYMER SCIENCE,2018,36(10):1187-1194.
APA	Pan, Deng,&Sun, Zhao-Yan.(2018).Diffusion and Relaxation Dynamics of Supercooled Polymer Melts.CHINESE JOURNAL OF POLYMER SCIENCE,36(10),1187-1194.
MLA	Pan, Deng,et al."Diffusion and Relaxation Dynamics of Supercooled Polymer Melts".CHINESE JOURNAL OF POLYMER SCIENCE 36.10(2018):1187-1194.