Li Yedi, Guo Hongxia
Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
J Phys Chem B. 2023 Nov 9;127(44):9642-9655. doi: 10.1021/acs.jpcb.3c05826. Epub 2023 Oct 30.
The slip phenomena and the individual configuration dynamics of interfacial copolymer chains in the entangled polymer-polymer interface under fast shear flow are analyzed using mDPD simulations on ternary blends of A/B/CD with different incompatibilities or interface strengths. We observe two distinct power-law regions of slip velocity against interfacial shear stress: from ∼ σ to ∼ σ at an increasing shear rate with the interface strength. At the micro level, the two regions correspond to the integrated and incomplete interfacial entanglement network with the shear-induced disentanglement of interfacial chains, respectively. For the individual chain dynamics of interfacial copolymers, we clarify that for the weak incompatibility, the tumbling event of interfacial copolymer chains is irregular and occasional and includes six processes: align and flip, collapse, tumble, stretch, reflip, and recoil and tumble. For the system with strong incompatibility, the interfacial copolymer chain undergoes the stretched-coil conformational transition via elastic retraction. As the interfacial entanglement network disintegrates, the hairpin-like configuration is dominant during the tumbling motion or elastic retraction of the interfacial copolymer chain.
利用mDPD模拟方法，对具有不同不相容性或界面强度的A/B/CD三元共混物进行研究，分析了快速剪切流动下纠缠聚合物-聚合物界面中界面共聚物链的滑移现象和个体构象动力学。我们观察到滑移速度与界面剪切应力存在两个不同的幂律区域：随着界面强度增加，在剪切速率增加时，从σ到σ。在微观层面，这两个区域分别对应于界面缠结网络的完整和不完整状态以及界面链的剪切诱导解缠结。对于界面共聚物的个体链动力学，我们阐明，对于弱不相容性，界面共聚物链的翻滚事件是不规则且偶然的，包括六个过程：排列与翻转、塌陷、翻滚、拉伸、再翻转以及反冲与翻滚。对于具有强不相容性的体系，界面共聚物链通过弹性回缩经历拉伸-卷曲构象转变。随着界面缠结网络解体，发夹状构象在界面共聚物链的翻滚运动或弹性回缩过程中占主导地位。
