Effects of Asymmetric Molecular Architecture on Chain Stretching and Dynamics in Miktoarm Star Copolymers
Effects of Asymmetric Molecular Architecture on Chain Stretching and Dynamics in Miktoarm Star Copolymers
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不对称分子结构对 Miktoarm 星形共聚物链拉伸和动力学的影响
DOI：
10.1021/acs.macromol.0c01858
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发表时间：
2021
期刊：
影响因子：
5.5
通讯作者：
Sangoro, Joshua
中科院分区：
文献类型：
--
作者：
Kinsey, Thomas;Mapesa, Emmanuel Urandu;Wang, Weiyu;Hong, Kunlun;Mays, Jimmy;Kilbey, S. Michael;Sangoro, Joshua
我们使用宽带介电谱（BDS）和小角X射线散射（SAXS）来研究杂臂星星共聚物中的结构不对称性对介电聚合物弛豫的影响。所研究的杂臂共聚物含有一个或两个恒定分子量的聚苯乙烯（PS）链和两个相同的聚（顺式-1，4-异戊二烯）（PI）链具有不同的分子量。使用PI嵌段中的链作为介电探针，我们发现，结构上不对称的杂臂星星共聚物系统（PSPI 2）的特征分布在链弛豫时间和介电弛豫强度，不依赖于分子量或形态，在形成鲜明对比的对称二嵌段系统（PS-b-PI或PS2 PI 2）观察到的形态限制的影响。沿着来自SAXS测量的关于相分离的证据，这些结果归因于嵌段共聚物系统的高斯链模型的框架内的链拉伸的影响。因此，嵌段共聚物中的分子结构恰好是控制聚合物链动力学的通用手柄，并且最终控制结构复杂聚合物中的宏观物理化学性质。
We use broad-band dielectric spectroscopy (BDS) and small-angle X-ray scattering (SAXS) to investigate the impact of architectural asymmetry in the miktoarm star copolymer on the dielectric polymer relaxations. The miktoarm copolymers studied contain one or two polystyrene (PS) chains of constant molecular weight and two identical poly(cis-1,4-isoprene) (PI) chains with varied molecular weights. Using the chains in the PI block as dielectric probes, we find that the architecturally asymmetric miktoarm star copolymer systems (PSPI2) feature distributions in chain relaxation times and dielectric relaxation strengths that are not dependent on molecular weight or morphology, in stark contrast to the effects of morphological confinement observed for symmetric diblock systems (PS-b-PI or PS2PI2). Along with evidence from the SAXS measurements regarding phase separation, these results are attributed to influences from chain stretching within the framework of the Gaussian chain model for block copolymer systems. As such, the molecular architecture in block copolymers happens to be a versatile handle to control polymer chain dynamics and, ultimately, the macroscopic physicochemical properties in architecturally complex polymers.