Influence of the Bound Polymer Layer on Nanoparticle Diffusion in Polymer Melts
Influence of the Bound Polymer Layer on Nanoparticle Diffusion in Polymer Melts
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DOI：
10.1021/acsmacrolett.6b00649
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发表时间：
2016-10-01
影响因子：
7.015
通讯作者：
Winey, Karen I.
中科院分区：
文献类型：
--
作者：
Griffin, Philip J.;Bocharova, Vera;Winey, Karen I.
我们测量的质量中心扩散的二氧化硅纳米粒子（NPs）在纠缠的聚（2-乙烯基吡啶）（P2 VP）熔体使用卢瑟福背散射光谱。虽然这些NP的大小范围内，增强，非流体动力学NP运输理论上预测，并已观察到实验（2 R（NP）/d（管）接近3，其中2 R（NP）是NP直径和d（管）是管直径），我们发现，这些NP在P2 VP中的扩散实际上是很好地描述了流体动力学斯托克斯爱因斯坦关系。有效NP直径2 R（eff）显著大于2 RNP，并且强烈依赖于P2 VP分子量，这与NP表面上存在厚度h（eff）接近1.1R（g）的结合聚合物层一致。我们的研究结果表明，绑定的聚合物层显着增加NP流体动力学的大小在聚合物熔体与有吸引力的聚合物NP相互作用，并有效地过渡NP扩散的机制从非流体动力学到流体动力学制度，特别是在高分子量的NP运输预计将显着增强。此外，这些结果提供了第一个实验证明，流体动力学NP在聚合物熔体中的运输需要颗粒的尺寸大于或类似于5D（管），与最近的理论预测一致。
We measure the center-of-mass diffusion of silica nanoparticles (NPs) in entangled poly(2-vinylpyridine) (P2VP) melts using Rutherford backscattering spectrometry. While these NPs are well within the size regime where enhanced, nonhydrodynamic NP transport is theoretically predicted and has been observed experimentally (2R(NP)/d(tube) approximate to 3, where 2R(NP) is the NP diameter and d(tube) is the tube diameter), we find that the diffusion of these NPs in P2VP is in fact well-described by the hydrodynamic Stokes Einstein relation. The effective NP diameter 2R(eff) is significantly larger than 2RNP and strongly dependent on P2VP molecular weight, consistent with the presence of a bound polymer layer on the NP surface with thickness h(eff) approximate to 1.1R(g). Our results show that the bound polymer layer significantly augments the NP hydrodynamic size in polymer melts with attractive polymer NP interactions and effectively transitions the mechanism of NP diffusion from the nonhydrodynamic to hydrodynamic regime, particularly at high molecular weights where NP transport is expected to be notably enhanced. Furthermore, these results provide the first experimental demonstration that hydrodynamic NP transport in polymer melts requires particles of size greater than or similar to 5d(tube), consistent with recent theoretical predictions.