Comparative studies on effects of silica and titania nanoparticles on crystallization and complex segmental dynamics in poly(dimethylsiloxane)
Comparative studies on effects of silica and titania nanoparticles on crystallization and complex segmental dynamics in poly(dimethylsiloxane)
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DOI：
10.1016/j.polymer.2010.09.054
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发表时间：
2010-10-29
期刊：
影响因子：
4.6
通讯作者：
Pissis, P.
中科院分区：
文献类型：
--
作者：
Klonos, P.;Panagopoulou, A.;Pissis, P.
采用差示扫描量热法、热激去极化电流和宽带介电弛豫谱技术研究了直径分别为5 nm和20~40 nm的原位合成二氧化硅和纳米二氧化钛对聚二甲基硅氧烷网络玻璃化转变和链段动力学的影响。分散良好的填料和聚合物之间的强相互作用抑制了结晶度，并显著影响了纳米复合材料中玻璃化转变的演变。除了与大块无定形聚合物组分的玻璃化转变相关的α松弛外，还记录到另外两个链段松弛，分别来自于限制在凝聚晶区之间的高分子链(α(C)松弛)和界面层中的半结合聚合物，由于与纳米粒子表面的羟基相互作用而大大降低了迁移率(α‘松弛)。研究发现，在Mania的情况下，与聚合物的相互作用比二氧化硅更强，导致二氧化硅的相互作用长度估计约为2 nm，二氧化钛纳米复合材料的相互作用长度至少增加一倍。(C)2010爱思唯尔有限公司。保留所有权利。
Effects of in situ synthesized silica and titania nanoparticles, 5 and 20-40 nm in diameter, respectively, on glass transition and segmental dynamics of poly(dimethylsiloxane) networks were studied by employing differential scanning calorimetry, thermally stimulated depolarization currents and broadband dielectric relaxation spectroscopy techniques. Strong interactions between the well dispersed fillers and the polymer suppress crystallinity and affect significantly the evolution of the glass transition in the nanocomposites. Next to the alpha relaxation associated with the glass transition of the bulk amorphous polymer fraction, two more segmental relaxations were recorded, originating from polymer chains restricted between condensed crystal regions (alpha(c)-relaxation) and the semi-bound polymer in an interfacial layer with strongly reduced mobility due to interactions with hydroxyls on the nanoparticle surface (alpha' relaxation), respectively. Interactions with the polymer were found to be stronger in the case of Mania than silica, leading to an estimated interaction length of around 2 nm for silica and at least double for titania nanocomposites. (C) 2010 Elsevier Ltd. All rights reserved.