Mobility and glass transition temperature of polymer nanospheres
Mobility and glass transition temperature of polymer nanospheres
复制标题
聚合物纳米球的流动性和玻璃化转变温度
DOI：
10.1016/j.polymer.2012.11.036
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发表时间：
2013
期刊：
影响因子：
4.6
通讯作者：
Rodney D. Priestley
中科院分区：
文献类型：
--
作者：
C. Zhang;V. Boucher;D. Cangialosi;Rodney D. Priestley
最近的研究表明，合作的链段迁移率和聚合物薄膜和纳米复合材料的玻璃化转变温度（Tg）之间的解耦。在这里，我们使用介电谱探测合作的节段迁移率和电容法来确定直径（d）小于400 nm的聚苯乙烯纳米球的Tgof膜。我们发现电容法和量热法都显示出几乎相同的Tgas，纳米球的尺寸减小。在130 nm ≤ d ≤ 400 nm范围内，Tg受限制影响，而与此形成鲜明对比的是，α-弛豫过程的峰位不稳定。此外，当d ≤ 200 nm时，存在一个额外的分子弛豫过程，这在体相中没有观察到。我们解释这些研究结果之间的脱钩TGandcooperative段的流动性纳米球的证据。也就是说，后者可能会受到限制的影响，而前者则不会。
Recent studies have illustrated a decoupling between cooperative segmental mobility and the glass transition temperature (Tg) of thin polymer films and nanocomposites. Here, we use dielectric spectroscopy to probe the cooperative segmental mobility and capacitive dilatometry to determine the Tgof films of polystyrene nanospheres with diameters (d) less than 400 nm. We find that both capacitive dilatometry and calorimetry revealed nearly identical suppressions in Tgas the size of the nanospheres was reduced. While Tgwas impacted by confinement, in the range 130 nm ≤ d ≤ 400 nm, in stark contrast, the cooperative segmental mobility, i.e., the peak position of the α-relaxation process was not. Furthermore, when d ≤ 200 nm, an additional molecular relaxation process, not observed in bulk, was present. We interpret these findings as evidence of a decoupling between Tgand cooperative segmental mobility in nanospheres. That is, the latter may be impacted by confinement under conditions in which the former is not.