Abstract

In the domain of high-performance engineering polymers, the enhancement of mechanical flexibility in poly(phenylene sulfide) (PPS) resins has long posed a significant challenge. A novel molecular structure, designated as PP-He-IS, wherein imide rings and an aliphatic hexylene chain are covalently incorporated into the PPS backbone to enhance its flexibility, is introduced in this study. Molecular dynamics (MD) simulations are employed to systematically explore the effects of diversifying the backbone chain structures by substituting phenyl units with alkyl chains of varying lengths, referred to as PP-A-IS where “A” signifies the distinct intermediary alkyl chain configurations. Computational analyses reveal a discernable decrement in the glass transition temperature (T_g) and elastic modulus, counterbalanced by an increment in yield strength as the alkyl chain length is extended. Notably, the PP-He-IS variant is shown to exhibit superior yield strength while simultaneously maintaining reduced elastic modulus and T_g values, positioning it as an advantageous candidate for flexible PPS applications. Mesoscopic analyses further indicate that structures such as PP-He-IS, PP-Pe-IS, and PP-Bu-IS manifest remarkable flexibility, attributable to the presence of freely rotatable carbon-carbon single bonds. Experimental validation confirms that a melting temperature of 504 K which is lower than that of conventional PPS, and lower crystallinity are exhibited by PP-He-IS, thereby affording enhanced processability without compromising inherent thermal stability. Novel insights into the strategic modification of PPS for mechanical flexibility are thus furnished by this study, which also accentuates the pivotal role played by molecular dynamics simulations in spearheading high-throughput investigations in polymer material modifications.

中文翻译：

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主链碳链结构对改性聚芳硫醚树脂柔韧性的影响：分子动力学模拟和介观分析

摘要

在高性能工程聚合物领域，聚苯硫醚（PPS）树脂机械柔韧性的增强长期以来一直是一个重大挑战。本研究引入了一种新型分子结构，命名为PP-He-IS，其中酰亚胺环和脂肪族己烯链共价结合到PPS主链中以增强其柔韧​​性。采用分子动力学 (MD) 模拟来系统地探索通过用不同长度的烷基链取代苯基单元来使主链结构多样化的效果，称为PP-A-IS ，其中“ A ”表示不同的中间烷基链构型。计算分析表明，随着烷基链长度的延长，玻璃化转变温度 ( T _g ) 和弹性模量明显下降，而屈服强度的增加则抵消了这一下降。值得注意的是，PP-He-IS 变体表现出优异的屈服强度，同时保持降低的弹性模量和T _{g值，使其成为柔性}PPS应用的有利候选者。介观分析进一步表明，PP-He-IS、PP-Pe-IS和PP-Bu-IS 等结构表现出显着的灵活性，这归因于可自由旋转的碳-碳单键的存在。实验验证证实， PP-He-IS的熔化温度为 504 K，低于传统PPS，并且具有较低的结晶度，从而在不影响固有热稳定性的情况下提供增强的加工性能。因此，这项研究为PPS机械柔性的战略改性提供了新颖的见解，这也强调了分子动力学模拟在引领聚合物材料改性高通量研究中所发挥的关键作用。