Nanoparticle Motion within Glassy Polymer Melts
Nanoparticle Motion within Glassy Polymer Melts
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DOI：
10.1103/physrevlett.102.075702
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发表时间：
2009-02-20
影响因子：
8.6
通讯作者：
Leheny, Robert L.
中科院分区：
文献类型：
--
作者：
Guo, Hongyu;Bourret, Gilles;Leheny, Robert L.
采用x射线光子相关光谱法研究了金纳米颗粒在低分子量聚苯乙烯熔体中稀悬液的运动。在高温下，观察到的运动是扩散的，其速率遵循Vogel-Fulcher温度依赖关系。在接近玻璃化转变温度T-g时，扩散被超扩散过程所取代，超扩散过程首先在接近1.1T(g)的交叉温度T-c附近观察到，并与熔体中的非均质应变相识别。在快速冷却到足够低于T-c但仍高于T-g的温度后，超扩散动力学表现出与聚合物玻璃老化相似的时间依赖性。
X-ray photon correlation spectroscopy is employed to investigate the motion of dilute suspensions of gold nanoparticles in low-molecular-weight polystyrene melts. At high temperatures, the observed motion is diffusive, with a rate that follows a Vogel-Fulcher temperature dependence. Closer to the glass transition temperature T-g, diffusion is superseded by a hyperdiffusive process that first becomes observable near a crossover temperature T-c approximate to 1.1T(g) and is identified with heterogeneous strain in the melts. Following rapid cooling to temperatures sufficiently below T-c, but still above T-g, the hyperdiffusive dynamics displays a time dependence similar to aging in polymer glasses.