A Hidden Relaxation Process in Poly(2-vinylpyridine) Homopolymers, Copolymers, and Nanocomposites
A Hidden Relaxation Process in Poly(2-vinylpyridine) Homopolymers, Copolymers, and Nanocomposites
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DOI：
10.1021/acs.macromol.2c00789
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发表时间：
2022-07
期刊：
影响因子：
5.5
通讯作者：
Walter W. Young;Hiromu Tabuchi;Ryo Iguchi;T. Konishi;K. Fukao;Reika Katsumata
中科院分区：
文献类型：
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作者：
Walter W. Young;Hiromu Tabuchi;Ryo Iguchi;T. Konishi;K. Fukao;Reika Katsumata
在宽带介电谱实验中，我们发现，在顶部电极和聚合物样品之间引入空气间隙大大降低了DC电导率，从而可以研究低频弛豫，否则其信号将被DC电导率信号隐藏。在聚（2-乙烯基吡啶）（P2 VP）中观察到一个比α-弛豫过程慢的额外过程，这与一些早期的报道一致。在两个异质系统中研究了这种“较慢的过程”，以检查2 VP和其他物质之间的相互作用，以阐明较慢的过程信号背后的机制。在苯乙烯和2 VP的无规共聚物中，在低2 VP摩尔分数下，相对于α-过程的较慢过程的松弛强度显著增加。此外，在P2 VP和八（氨基苯基）倍半硅氧烷（OAPS）的复合材料中，OAPS的存在增加了较慢过程的强度和时间尺度，使α-弛豫过程相对不变。这表明，较慢的过程可能是由协同聚合物弛豫耦合到非均相组分和杂质的运输。需要进一步的研究来探索这种较慢的过程及其对界面性质的影响的分子水平的机制。
In broadband dielectric spectroscopy experiments, we find that introducing an air gap between the top electrode and the polymer sample reduces DC conductivity substantially, allowing the study of low-frequency relaxations, whose signal would otherwise be hidden by the DC conductivity signal. An extra process slower than the α-relaxation process is observed in poly(2-vinylpyridine) (P2VP), consistent with some earlier reports. This “slower process” was studied in two heterogeneous systems to examine the interaction between the 2VP and other species to elucidate the mechanism behind the slower process signal. In a random copolymer of styrene and 2VP, the relaxation strength of the slower process relative to the α-process increases substantially at low 2VP mole fractions. Additionally, in a composite of P2VP and octa(aminophenyl) silsesquioxane (OAPS), the presence of OAPS increases both the strength and timescale of the slower process, leaving the α-relaxation process relatively unchanged. This suggests that the slower process could be caused by cooperative polymer relaxation coupled to the transport of heterogeneous components and impurities. Further studies are needed to probe the molecular-level mechanism of this slower process and its effect on interfacial properties.