Wood Emma L, Greco Cristina, Ivanov Dimitri A, Kremer Kurt, Daoulas Kostas Ch
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Institute for Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 1, 142432 Chernogolovka, Russia.
J Phys Chem B. 2022 Mar 24;126(11):2285-2298. doi: 10.1021/acs.jpcb.1c10599. Epub 2022 Mar 15.
Board-shaped polymers form sanidic mesophases: assemblies of parallel lamellae of stacked polymer backbones separated by disordered side chains. Sanidics vary significantly with respect to polymer order inside their lamellae, making them "stepping stones" toward the crystalline state. Therefore, they are potentially interesting for studying crystallization and technological applications. Building on earlier mesoscopic models of the most disordered sanidics Σ, we focus on the other extreme, near-crystalline order, and develop a generic model that captures a highly ordered Σ mesophase. Polymers are described by generic hindered-rotation chains. Anisotropic nonbonded potentials, with strengths comparable to the thermal energy, mimic board-like monomer shapes. Lamellae equilibrated with Monte Carlo simulations, for a broad range of model parameters, have intralamellar order typical for Σ mesophases: periodically stacked polymers that are mutually registered along their backbones. Our mesophase shows registration on both monomer and chain levels. We calculate scattering patterns and compare with data published for highly ordered sanidic mesophases of two different polymers: polyesters and polypeptoids. Most of the generic structural features that were identified in these experiments are present in our model. However, our mesophase has correlations between chains located in different lamellae and is therefore closer to the crystalline state than the experimental samples.
由无序侧链分隔的平行堆叠聚合物主链薄片的聚集体。三斜中间相在其薄片内的聚合物有序性方面有显著差异，使其成为通向结晶态的“垫脚石”。因此，它们在研究结晶和技术应用方面具有潜在的吸引力。基于早期对最无序的三斜中间相Σ的介观模型，我们关注另一个极端，即近晶态有序，并开发了一个通用模型来捕捉高度有序的Σ中间相。聚合物由通用的受阻旋转链描述。强度与热能相当的各向异性非键合势模拟了板状单体形状。通过蒙特卡罗模拟对广泛的模型参数进行平衡后的薄片具有Σ中间相典型的层内有序：沿主链相互对齐的周期性堆叠聚合物。我们的中间相在单体和链水平上都显示出对齐。我们计算散射图案并与两种不同聚合物（聚酯和聚肽）的高度有序三斜中间相的已发表数据进行比较。这些实验中确定的大多数通用结构特征在我们的模型中都存在。然而，我们的中间相在位于不同薄片中的链之间存在相关性，因此比实验样品更接近结晶态。
