Glass transition dynamics of stacked thin polymer films.
Glass transition dynamics of stacked thin polymer films.
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DOI：
10.1103/physreve.84.041808
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发表时间：
2011-10
期刊：
影响因子：
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通讯作者：
K. Fukao;Takehide Terasawa;Yuto Oda;Kenji Nakamura;Daisuke Tahara
中科院分区：
文献类型：
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作者：
K. Fukao;Takehide Terasawa;Yuto Oda;Kenji Nakamura;Daisuke Tahara
使用差示扫描量热法和介电弛豫光谱研究了聚苯乙烯和聚（2-氯苯乙烯）堆叠薄膜的玻璃化转变动力学。堆叠的聚苯乙烯薄膜的玻璃化转变温度 T(g) 与块状样品相比明显降低。然而，在高于 T(g) 的高温下退火后，堆叠薄膜在几乎等于本体系统的 T(g) 的温度下表现出玻璃化转变。聚（2-氯苯乙烯）堆叠薄膜的α过程动力学表现出在等温退火过程中从单薄膜动力学到块体动力学的时间演化。随着退火时间的延长，α过程的弛豫率变小。与爬行动力学相比，退火过程中α动力学演化的时间尺度非常长。同时，随着退火时间的增加，α过程弛豫时间的温度依赖性从类阿累尼乌斯依赖性转变为Vogel-Fulcher-Tammann依赖性。随着等温退火退火时间的增加，脆性指数增加，α弛豫时间分布变小。观察到的α过程的变化是关于堆叠聚合物薄膜的薄层之间的界面相互作用进行讨论的。
The glass transition dynamics of stacked thin films of polystyrene and poly(2-chlorostyrene) were investigated using differential scanning calorimetry and dielectric relaxation spectroscopy. The glass transition temperature T(g) of as-stacked thin polystyrene films has a strong depression from that of the bulk samples. However, after annealing at high temperatures above T(g), the stacked thin films exhibit glass transition at a temperature almost equal to the T(g) of the bulk system. The α-process dynamics of stacked thin films of poly(2-chlorostyrene) show a time evolution from single-thin-film-like dynamics to bulk-like dynamics during the isothermal annealing process. The relaxation rate of the α process becomes smaller with increase in the annealing time. The time scale for the evolution of the α dynamics during the annealing process is very long compared with that for the reptation dynamics. At the same time, the temperature dependence of the relaxation time for the α process changes from Arrhenius-like to Vogel-Fulcher-Tammann dependence with increase of the annealing time. The fragility index increases and the distribution of the α-relaxation times becomes smaller with increase in the annealing time for isothermal annealing. The observed change in the α process is discussed with respect to the interfacial interaction between the thin layers of stacked thin polymer films.