Critical Role of the Interfacial Layer in Associating Polymers with Microphase Separation
Critical Role of the Interfacial Layer in Associating Polymers with Microphase Separation
复制标题
DOI：
10.1021/acs.macromol.1c00275
复制
发表时间：
2021-04-27
期刊：
影响因子：
5.5
通讯作者：
Sokolov, Alexei P.
中科院分区：
文献类型：
--
作者：
Ge, Sirui;Samanta, Subarea;Sokolov, Alexei P.
具有动态（瞬态）键的聚合物，通常称为缔合聚合物，由于其独特的粘弹性、自修复能力和可回收性，近年来引起了人们的广泛关注。然而，由于动态键引入了更高的复杂性，对控制其宏观特性的机制和因素的理解仍然有限。在这项研究中，应用小角 X 射线散射 (SAXS)、宽带介电谱 (BDS) 和流变学来揭示不同分子量的遥爪缔合聚合物的结构和动力学。 SAXS 测量显示功能端基的相分离，平均簇大小约为 2-3 nm，簇之间的距离由链长控制。借用聚合物纳米复合材料领域的BDS数据的界面层模型分析，我们证明了这些团簇周围存在厚度约为0.7-0.9 nm的界面聚合物层。流变测量定量表明，界面层的存在显着改变了这些材料的粘弹性行为，表明界面层在定义所研究的远爪材料的宏观力学性能方面发挥着至关重要的作用。研究结果强调，缔合聚合物中官能团的相分离导致粘弹性能发生非常显着的变化，为新型功能材料的设计开辟了一条有前途的途径。
Polymers with dynamic (transient) bonds, often called associating polymers, have been attracting significant attention in recent years due to their unique viscoelastic properties, self-healing ability, and recyclability. Nevertheless, understanding the mechanisms and the factors controlling their macroscopic properties remains limited due to the higher complexity introduced by the dynamic bonds. In this study, small-angle X-ray scattering (SAXS), broadband dielectric spectroscopy (BDS), and rheology were applied to unravel the structure and dynamics of telechelic associating polymers with different molecular weights. SAXS measurements revealed phase separation of the functional end groups with an average cluster size of similar to 2-3 nm and the distance between clusters controlled by the chain length. Borrowing the interfacial layer model analysis of BDS data from the polymer nanocomposite field, we demonstrated the presence of an interfacial polymer layer with a thickness of similar to 0.7-0.9 nm surrounding these clusters. Rheological measurements showed quantitatively that the presence of the interfacial layer significantly alters the viscoelastic behavior of these materials, indicating the crucial role of the interfacial layer in defining the macroscopic mechanical properties of the studied telechelic materials. The presented results emphasize that phase separation of the functional groups in associating polymers leads to very significant changes of the viscoelastic properties, opening a promising avenue in the design of novel functional materials.