在聚乙烯中对受控聚合物结晶的分子模拟
William S Fall1,2, Jörg Baschnagel1, Olivier Benzerara1
1Institut Charles Sadron, Université de Strasbourg and CNRS, 23 rue du Loess, 67034 Strasbourg Cedex, France.
ACS macro letters
|June 5, 2023
概括
研究人员模拟了化的聚合物晶体生长,揭示了分支和冷却方法如何影响多层状结构. 自播产生了对齐的晶体,澄清了受聚合物链分支影响的早期球状石形成.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 计算化学的计算化学
背景情况:
- 聚合物从融中结晶是材料性质的基础.
- 了解分子结构和加工条件对晶体形态学的影响至关重要.
- 以前的研究往往缺乏能够详细观察早期晶体形成的分辨率.
研究的目的:
- 通过分子动力学模拟,研究从融中形成的多层聚合物晶体的形成.
- 探索聚合物链分支和结晶协议对晶体结构的影响.
- 阐明球状岩石形成和晶体岩石演变的早期阶段.
主要方法:
- 分子动力学模拟采用联合单体模型,拥有超过150万个单体.
- 模拟具有不同长短链比率和短丁分支的双组合聚合物系统.
- 采用两种不同的冷却方案:连续冷却和自我播种.
主要成果:
- 从融中成功生长多层聚合物晶体,这是模拟中首次出现的.
- 根据分支含量和冷却协议观察到截然不同的多层状结构.
- 自播种协议产生了良好的结晶,清楚地显示了结晶体大小和形状的分支效应.
- 持续的冷却掩盖了分支对早期球状岩石形成的微妙影响.
- 在晶体层中观察到的延长链段 (多达100个单体).
结论:
- 结晶协议在很大程度上决定了由此产生的多层聚合物晶体形态.
- 聚合物链的分支微妙地影响了晶体的演变,在自我播种条件下尤其明显.
- 分子动力学模拟提供了一种强大的工具,用于在分子水平上研究复杂的聚合物结晶现象.
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