Interfacial interactions and complex segmental dynamics in systems based on silica-polydimethylsiloxane core shell nanoparticles: Dielectric and thermal study
Interfacial interactions and complex segmental dynamics in systems based on silica-polydimethylsiloxane core shell nanoparticles: Dielectric and thermal study
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DOI：
10.1016/j.polymer.2014.12.037
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发表时间：
2015-02-10
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.;Sulym, I. Ya.;Pissis, P.
采用差示扫描量热法（DSC）和介电法（DRS，TSDC）研究了不同热处理条件下，两种不同孔隙率的SiO2颗粒对聚二甲基硅氧烷（PDMS）在两种聚合物含量（40和80 wt%）的核壳纳米复合材料中链段迁移率的影响。填料形态和聚合物-颗粒相互作用被发现影响PDMS结晶度和链段流动性。介电技术允许检测与玻璃化转变相关的链段动力学的四个贡献，按照流动性降低的顺序，从硅胶孔中的受限聚合物链（α（p）弛豫），从本体聚合物链。（未受影响的）无定形聚合物部分（a relaxation），来自限制在凝聚晶体区域之间的聚合物链（α（c））和来自靠近纳米颗粒表面的界面层中的半结合聚合物（α ′）。对于高PDMS含量（80wt%）的核壳型纳米复合材料，界面α '弛豫过程与传统的PDMS/SiO2纳米复合材料具有相似的特征，而对于低PDMS含量（40wt%）的核壳型纳米复合材料，界面α'弛豫过程表现出明显的差异。实验结果进行了讨论，提出的模型吸附到固体表面上的聚合物的构象的描述。(C)2014爱思唯尔有限公司版权所有。
Effects of two types of silica particles, with different characteristics of porosity, on segmental mobility of poly(dimethylsiloxane), PDMS, in core-shell nanocomposites with two contents of polymer, 40 and 80 wt%, were studied by employing thermal (DSC) and dielectric (DRS, TSDC) techniques, under different annealing procedures. Filler morphology and polymer-particle interactions were found to affect PDMS crystallinity and segmental mobility. The dielectric techniques allowed the detection of four contributions to the segmental dynamics associated with the glass transition arising, in the order of decreasing mobility, from confined polymer chains in the pores of silica gel (alpha(p) relaxation), from the bulk (unaffected) amorphous polymer fraction (a relaxation), from polymer chains restricted between condensed crystal regions (alpha(c)) and from semibound polymer in an interfacial layer close to the nanoparticle surface (alpha'). For the core-shell nanocomposites with high PDMS content (80 wt%) the interfacial alpha' relaxation process is found to have similar characteristics with that in conventional PDMS/silica nanocomposites, for lower PDMS content (40 wt%), however, the interfacial relaxation process exhibits distinct differences. The experimental findings are discussed in terms of models proposed for the description of conformations of polymers adsorbed onto a solid surface. (C) 2014 Elsevier Ltd. All rights reserved.