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Tension-Induced Nematic Phase Separation in Bidisperse Homopolymer Melts.
ACS Central Science ( IF 12.7 ) Pub Date : 2018-11-06 , DOI: 10.1021/acscentsci.8b00651
Wenlin Zhang 1 , Ronald G Larson 1
Affiliation  

We use an analytical mean-field theory and all-atom molecular dynamics (MD) simulations to predict that external tension, together with the nematic coupling interactions, can drive phase separation of long chains from short ones in bidisperse homopolymer melts. The nematic coupling parameter α for polyethylene (PE) oligomers under applied tension is extracted from the MD simulations and used in the mean-field free energy to predict the phase boundary for bidisperse melts in which the longer chains are stretched by uniaxial tension. The predicted phase diagram is validated by direct MD simulations. We also show that extensional flow, and possibly even shear flow, may lead to nematic phase separation in molten PE oligomers, because the flow can impose a stronger tension on the longer chains than the short ones.

中文翻译:

双分散均聚物熔体中的张力诱导向列相分离。

我们使用分析平均场理论和全原子分子动力学(MD)模拟来预测,外部张力以及向列偶联相互作用可以驱动长链与短链在双分散均聚物熔体中的相分离。从MD模拟中提取了在施加张力下聚乙烯(PE)低聚物的向列偶联参数α,并将其用于平均场自由能中,以预测双分散熔体的相界,其中较长链通过单轴张力拉伸。预测的相图通过直接的MD模拟进行了验证。我们还表明,拉伸流动,甚至可能是剪切流动,可能会导致熔融PE低聚物中向列相分离,因为与长链相比,流动可对长链施加更大的张力。
更新日期:2018-11-06
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