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Rheological Tuning of Entangled Polymer Networks by Transient Cross-links
The Journal of Physical Chemistry B ( IF 3.3 ) Pub Date : 2019-01-24 , DOI: 10.1021/acs.jpcb.8b09357
Xue-Zheng Cao 1 , M. Gregory Forest 1
Affiliation  

The remarkable functionalities of transiently cross-linked, biopolymer networks are increasingly becoming translated into synthetic materials for biomedical and materials science applications. Various computational and theoretical models, representing different transient cross-linking mechanisms, have been proposed to mimic biological and synthetic polymer networks, and to interpret experimental measurements of rheological, transport, and self-repair properties. Herein, we employ molecular dynamics simulations of a baseline entangled polymer melt coupled with parametrized affinities for binding and unbinding of transient cross-links (CLs). From these assumptions alone, we determine the emergent CL mean density and fluctuations, and the induced rheology, across the 2-parameter space of binding and unbinding affinities for a moderately long chain, entangled the polymer melt. For sufficiently weak (short-lived) CLs, nonmonotonicity emerges with respect to the affinity to form CLs: the stress relaxation, viscous, and elastic moduli all shift above the baseline if CLs form rapidly, reverse below the baseline as CLs form slowly, and reverse again, recovering the baseline as CLs form very slowly. For sufficiently strong (long-lived) CLs and sufficiently fast CL formation, a dramatic rise emerges in the viscous and elastic moduli at all frequencies, more prominently in the elastic moduli at medium to high frequencies, inducing a sol–gel transition. These results are placed in context with the experimental and theoretical literature on transient polymer networks.

中文翻译:

瞬态交联法纠缠聚合物网络的流变学调整

瞬态交联的生物聚合物网络的卓越功能正越来越多地转变为用于生物医学和材料科学应用的合成材料。已经提出了代表不同瞬态交联机制的各种计算和理论模型来模拟生物和合成聚合物网络,并解释流变,传输和自我修复特性的实验测量结果。在这里,我们采用分子缠结的基线缠结的聚合物熔体的分子动力学模拟与参数化的亲和力,以进行瞬态交联(CL)的结合和解结合。仅根据这些假设,我们就确定了中等长链的结合和非结合亲和力的2参数空间中出现的CL平均密度和波动以及诱导的流变学,缠结聚合物熔体。对于足够弱的(短寿命的)CL,相对于形成CL的亲和力会出现非单调性:如果CL迅速形成,应力松弛,粘性和弹性模量都将移至基线之上,而当CL缓慢形成时,应力松弛,粘性和弹性模量都将移至基线之下再次反转,恢复基线,因为CL的形成非常缓慢。对于足够强的(长寿命的)CL和足够快的CL形成,在所有频率下,粘弹性模量和弹性模量都会显着上升,在中高频下,弹性模量会更加明显,从而引起溶胶-凝胶转变。这些结果与有关瞬态聚合物网络的实验和理论文献相结合。如果CL迅速形成,应力松弛,粘性和弹性模量都将移至基线之上; CL缓慢形成时,应力松弛,粘性和弹性模量都将反转至基线以下;然后CL缓慢形成时,应力松弛,粘性和弹性模量将再次恢复基线。对于足够强的(长寿命的)CL和足够快的CL形成,在所有频率下,粘弹性模量和弹性模量都会显着上升,在中高频下,弹性模量会更加明显,从而引起溶胶-凝胶转变。这些结果与有关瞬态聚合物网络的实验和理论文献相结合。如果CL迅速形成,应力松弛,粘性和弹性模量都将移至基线之上; CL缓慢形成时,应力松弛,粘性和弹性模量都将反转至基线以下;然后CL缓慢形成时,应力松弛,粘性和弹性模量将再次恢复基线。对于足够强的(长寿命的)CL和足够快的CL形成,在所有频率下,粘弹性模量和弹性模量都会显着上升,在中高频下,弹性模量会更加明显,从而引起溶胶-凝胶转变。这些结果与有关瞬态聚合物网络的实验和理论文献相结合。对于足够强的(长寿命的)CL和足够快的CL形成,在所有频率下,粘弹性模量和弹性模量都会显着上升,在中高频下,弹性模量会更加明显,从而引起溶胶-凝胶转变。这些结果与有关瞬态聚合物网络的实验和理论文献相结合。对于足够强的(长寿命的)CL和足够快的CL形成,在所有频率下,粘弹性模量和弹性模量都会显着上升,在中高频下,弹性模量会更加明显,从而引起溶胶-凝胶转变。这些结果与有关瞬态聚合物网络的实验和理论文献相结合。
更新日期:2019-02-06
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