Polymers bearing associative groups (APs) are characterized by their fantastic viscoelastic behaviors. In a work recently published by our group [Jiang et al., Macromolecules 53, 3438–3451 (2020)], a single chain sticky Rouse model (SRM) is proposed to describe the linear viscoelasticity of APs without the entanglement effect. In this work, equilibrium molecular dynamics simulation of an unentangled melt of an AP with uniformly distributed stickers is carried out, and the dynamic properties are simultaneously analyzed from the SRM. A chain model with capped stickers is proposed so that a well-defined association chemistry is promised in the simulation system. The relative effective frictional coefficient of stickers, which is the key parameter in the SRM, is extracted from the chain center-of-mass diffusion, and it is found to be consistent with the dynamics of associative reaction in the fully gelated network. Based on this, a linear relaxation modulus and segmental diffusion functions are predicted from the SRM without fitting parameters, and these are found to quantitatively agree with the simulation results, showing the effectiveness of the SRM in connecting the dynamic properties at different molecular levels. The change in relaxation modes and the definition of the effective chain center are found to be crucial in the scenario of the SRM. Finally, the above analysis from the SRM is successfully extended to the simulation system with asymmetric chains. All these simulation results strongly support the SRM as a molecular model for the linear rheology of AP.

中文翻译：

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缔合聚合物的分子动力学模拟：从粘性 Rouse 模型中了解线性粘弹性

带有缔合基团 (AP) 的聚合物的特点是其奇妙的粘弹性行为。在我们小组最近发表的一项工作中 [Jiang et al. ,大分子 53, 3438–3451 (2020)]，提出了单链粘性 Rouse 模型（SRM）来描述无缠结效应的 AP 的线性粘弹性。在这项工作中，对具有均匀分布贴纸的 AP 的未缠结熔体进行了平衡分子动力学模拟，同时从 SRM 分析了动力学特性。提出了一种带有封盖贴纸的链模型，以便在模拟系统中承诺定义明确的关联化学。贴纸的相对有效摩擦系数是 SRM 中的关键参数，它是从链质心扩散中提取的，发现它与完全凝胶网络中的缔合反应动力学一致。基于此，从没有拟合参数的 SRM 预测线性松弛模量和分段扩散函数，发现这些在定量上与模拟结果一致，表明 SRM 在连接不同分子水平的动态特性方面的有效性。发现松弛模式的变化和有效链中心的定义在 SRM 场景中至关重要。最后，以上来自 SRM 的分析成功地扩展到具有非对称链的仿真系统。所有这些模拟结果都强烈支持 SRM 作为 AP 线性流变学的分子模型。发现松弛模式的变化和有效链中心的定义在 SRM 场景中至关重要。最后，以上来自 SRM 的分析成功地扩展到具有非对称链的仿真系统。所有这些模拟结果都强烈支持 SRM 作为 AP 线性流变学的分子模型。发现松弛模式的变化和有效链中心的定义在 SRM 场景中至关重要。最后，以上来自 SRM 的分析成功地扩展到具有非对称链的仿真系统。所有这些模拟结果都强烈支持 SRM 作为 AP 线性流变学的分子模型。