Multiscale Dynamics of Small, Attractive Nanoparticles and Entangled Polymers in Polymer Nanocomposites
Multiscale Dynamics of Small, Attractive Nanoparticles and Entangled Polymers in Polymer Nanocomposites
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DOI：
10.1021/acs.macromol.8b02646
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发表时间：
2019-02
期刊：
影响因子：
5.5
通讯作者：
E. Bailey;Philip J. Griffin;R. Composto;K. Winey
中科院分区：
文献类型：
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作者：
E. Bailey;Philip J. Griffin;R. Composto;K. Winey
在由非常小（半径≈0.9 nm）的八氨基苯基多面体低聚硅氧烷（OAPS） NPs和不同分子量的聚（2-乙烯基吡啶）（P2VP）组成的聚合物纳米复合材料（PNC）中，直接测量了聚合物的片段动力学、质心链扩散和纳米颗粒（NP）扩散。随着OAPS浓度的增加，片段重定向弛豫率（通过介电光谱测量）和聚合物链质心扩散系数（通过弹性反冲检测测量）都大幅降低，在25 vol % OAPS时，相对于体积的降低分别达到80%和60%。这种相应的片段松弛和链扩散过程的减缓与由较大的、不移动的纳米颗粒组成的pnc的情况根本不同，在pnc中，尽管链扩散显著减少，但大多数片段的运动保持相对不变。接下来，使用卢瑟福后向散射光谱法探测…
Polymer segmental dynamics, center-of-mass chain diffusion, and nanoparticle (NP) diffusion are directly measured in a series of polymer nanocomposites (PNC) composed of very small (radius ≈ 0.9 nm) octa(aminophenyl) polyhedral oligomeric silsesquioxane (OAPS) NPs and poly(2-vinylpyridine) (P2VP) of varying molecular weight. With increasing OAPS concentration, both the segment reorientational relaxation rate (measured by dielectric spectroscopy) and polymer chain center-of-mass diffusion coefficient (measured by elastic recoil detection) are substantially reduced, with reductions relative to bulk reaching ∼80% and ∼60%, respectively, at 25 vol % OAPS. This commensurate slowing of both the segmental relaxation and chain diffusion process is fundamentally different than the case of PNCs composed of larger, immobile nanoparticles, where the motion of most segments remains relatively unaltered even though chain diffusion is significantly reduced. Next, using Rutherford backscattering spectrometry to probe the...