Lee Jeongin, Lee Soohyun, Lee Keonchang, Joung Hyeyoung, Choi Seung Kun, Kim Myungwoong, Yang Jaesung, Paeng Keewook
Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Department of Chemistry, Yonsei University, Wonju, Gangwon 26493, Republic of Korea.
J Chem Phys. 2024 Mar 28;160(12). doi: 10.1063/5.0189494.
This study investigated the segmental dynamics of polymers near polymer-polymer interfaces by probing the rotation of polymer-tethered fluorescent molecules using imaging rotational fluorescence correlation microscopy. Multilayered films were utilized to provide spatial selectivity relative to different polymer-polymer interfaces. In the experimental setup, for the overlayer polymer, polystyrene (PS) was employed and a 15 nm-thick probe-containing layer was placed ≈25 nm apart from different underlayer polymers with glass transition temperatures (Tg) either lower or higher than that of PS. The underlayer of poly-n-butyl methacrylate had 72 K lower Tg than that of PS, whereas polymethyl methacrylate and polysulfone had 22 and 81 K higher Tg, respectively, than that of PS. Two key dynamic features of the glass transition, the non-Arrhenius temperature dependence and stretched relaxation, were examined to study the influence of soft and hard confinements on the segmental dynamics of the overlayer polymer near the polymer-polymer interfaces. Although complications exist in the probing location owing to the diffusion of the polymer-tethered probe during the annealing protocol to consolidate the multilayers, the results suggest that either the segmental dynamics of the polymer near the polymer-polymer interface do not change owing to the soft and hard confinements or the interfacial perturbation is very short ranged.
本研究通过使用成像旋转荧光相关显微镜探测聚合物连接的荧光分子的旋转，研究了聚合物 - 聚合物界面附近聚合物的链段动力学。利用多层膜来提供相对于不同聚合物 - 聚合物界面的空间选择性。在实验装置中，对于上层聚合物，采用了聚苯乙烯（PS），并将一个15 nm厚的含探针层放置在与玻璃化转变温度（Tg）低于或高于PS的不同下层聚合物相距约25 nm处。聚甲基丙烯酸正丁酯下层的Tg比PS低72 K，而聚甲基丙烯酸甲酯和聚砜的Tg分别比PS高22 K和81 K。研究了玻璃化转变的两个关键动力学特征，即非阿累尼乌斯温度依赖性和拉伸弛豫，以研究软限制和硬限制对聚合物 - 聚合物界面附近上层聚合物链段动力学的影响。尽管由于聚合物连接探针在退火过程中扩散以巩固多层结构，探测位置存在复杂性，但结果表明，聚合物 - 聚合物界面附近聚合物的链段动力学要么由于软限制和硬限制而不变，要么界面扰动范围非常短。
