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NMR Characterization of Canopy Dynamics in Nanoscale Ionic Materials

机译：纳米离子材料冠层动力学的NMR表征

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摘要

Nanoscale ionic materials (NIMs) are organic-inorganic hybrids in which a core nanoparticle is functionalized with a covalently attached corona and an ionically tethered polymer canopy. NIMs exhibit liquid-like character under ambient conditions in the absence of solvent and are of interest for a variety of applications. We have used nuclear magnetic resonance (NMR) relaxation and pulsed-field gradient (PFG) diffusion experiments to measure the canopy dynamics of NIMs prepared from 18-nm silica nanoparticles. NMR studies show that the fast (ns) local dynamics of the canopy are insensitive to the presence of the silica nanoparticles. Canopy diffusion in the NIMs is slowed relative to the neat copolymer, but not all canopy molecules are slowed equally due to crowding at the nanoparticle surface, resulting in a strongly bound fraction at the surface and a weakly bound outer sphere. Electrostatic interactions with other ionic (Na~+) species alter the dynamics by screening interactions with the nanoparticle.
机译：纳米级离子材料（NIM）是有机-无机杂化材料，其中核心纳米颗粒被共价连接的电晕和离子束缚的聚合物冠层官能化。 NIM在没有溶剂的环境条件下表现出类似液体的特性，并且在各种应用中引起人们的兴趣。我们已经使用核磁共振（NMR）弛豫和脉冲场梯度（PFG）扩散实验来测量由18 nm二氧化硅纳米粒子制备的NIM的冠层动力学。 NMR研究表明，冠层的快速（ns）局部动力学对二氧化硅纳米粒子的存在不敏感。相对于纯共聚物，NIM中的冠层扩散较慢，但由于纳米粒子表面的拥挤，并非所有冠层分子均会减慢，导致表面上的键合牢固，而外部球的键合弱。与其他离子（Na〜+）物种的静电相互作用通过筛选与纳米粒子的相互作用来改变动力学。

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  • 来源
  • 会议地点 Honolulu HI(US);Honolulu HI(US)
  • 作者

    Michael L. Jespersen; Peter A. Mirau; Ernst von Meerwall; Richard A. Vaia; Robert Rodriguez; Nikhil J. Fernandes; Emmanuel P. Giannelis;

  • 作者单位

    Materials and Manufacturing Directorate, Air Force Research Laboratory,Wright-Patterson AFB, OH 45433,UES, Inc., Dayton, OH 45432;

    Materials and Manufacturing Directorate, Air Force Research Laboratory,Wright-Patterson AFB, OH 45433;

    Department of Physics, University of Akron, Akron, OH 44325;

    Materials and Manufacturing Directorate, Air Force Research Laboratory,Wright-Patterson AFB, OH 45433;

    Department of Materials Science and Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853,Current address: Intel Corp., 2501 NW 229th Ave., Hillsoboro, OR 97124;

    Department of Materials Science and Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853;

    Department of Materials Science and Engineering and School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 聚合反应过程;
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