Glass transition of ion-containing polymer melts in bulk and thin films,Soft Matter

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Glass transition of ion-containing polymer melts in bulk and thin films
Soft Matter ( IF 2.9 ) Pub Date : 2021-08-30 , DOI: 10.1039/d1sm01098k
Wei Li ₁ , Monica Olvera de la Cruz _{1,

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Affiliation

Ion-containing polymers often are good glass formers, and the glass transition temperature is an important parameter to consider for practical applications, which prescribes the working temperature range for different mechanical and dynamic properties. In this work, we present a systematic molecular dynamics simulation study on the coupling of ionic correlations with the glass transition, based on a generic coarse-grained model of ionic polymers. The variation of the glass transition temperature is examined concerning the influence of the electrostatic interaction strength, charge fraction, and charge sequence. The interplay with the film thickness effect is also discussed. Our results reveal a few typical features about the glass transition process that are in qualitative agreement with previous studies, further highlighting the effects of counterion entropy at weak ionic correlations and physical crosslinking of ionic aggregates at strong ionic correlations. Detailed parametric dependencies are displayed, which demonstrate that introducing strong ionic correlations promotes vitrification while adopting a precise charge sequence and applying strong confinement with weak surface affinity reduce the glass transition temperature. Overall, our investigation provides an improved picture towards a comprehensive understanding of the glass transition in ion-containing polymeric systems from a molecular simulation perspective.

中文翻译：

含离子聚合物在块状和薄膜中熔融的玻璃化转变

含离子聚合物通常是良好的玻璃形成剂，玻璃化转变温度是实际应用中需要考虑的重要参数，它规定了不同机械和动态性能的工作温度范围。在这项工作中，我们基于离子聚合物的通用粗粒模型，对离子相关性与玻璃化转变的耦合进行了系统的分子动力学模拟研究。关于静电相互作用强度、电荷分数和电荷序列的影响，检查玻璃化转变温度的变化。还讨论了与膜厚效应的相互作用。我们的结果揭示了玻璃化转变过程的一些典型特征，与之前的研究定性一致，进一步强调了弱离子关联下的反离子熵和强离子关联下离子聚集体的物理交联的影响。显示了详细的参数依赖关系，这表明引入强离子相关性可促进玻璃化，同时采用精确的电荷序列并应用具有弱表面亲和力的强限制可降低玻璃化转变温度。总体而言，我们的研究为从分子模拟的角度全面了解含离子聚合物系统中的玻璃化转变提供了改进的图片。这表明引入强离子相关性可促进玻璃化，同时采用精确的电荷序列并应用具有弱表面亲和力的强限制可降低玻璃化转变温度。总体而言，我们的研究为从分子模拟的角度全面了解含离子聚合物系统中的玻璃化转变提供了改进的图片。这表明引入强离子相关性可促进玻璃化，同时采用精确的电荷序列并应用具有弱表面亲和力的强限制可降低玻璃化转变温度。总体而言，我们的研究为从分子模拟的角度全面了解含离子聚合物系统中的玻璃化转变提供了改进的图片。

更新日期：2021-09-20

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