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The Synthesis and Electrical Properties of Functional Polymer Nanocomposites

Zhang, Guoqiang
http://rave.ohiolink.edu/etdc/view?acc_num=case149010222646324

Abstract Details

2017, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
The marriage between organic polymers and inorganic nanoparticles (NPs) is believed to give birth to polymer nanocomposites that feature both their merits. Sometimes, polymer nanocomposites can even exhibit novel structures, properties, functionalities and applications which are not observed in neither polymers nor inorganic NPs. Specifically, polymer nanodielectrics have attracted intense interests in recent years for the search of high-performance energy storage materials, because they are anticipated to combine high permittivity (¿r) from inorganic NPs, and high breakdown strength (Eb), low dielectric loss from the polymer matrix. Although the apparent ¿r and total energy density have so far been sufficiently improved in nanodielectrics, their relatively large dielectric losses limit real applications. More importantly, the underlying mechanisms are somehow overlooked. In the first part of this dissertation, a large AC dielectric loss and decreased Ebs observed in a common ceramics/polymer nanocomposite dielectrics were systematically studied. The composite dielectrics were prepared by uniformly embedding 70 nm polyhedral oligomeric silsesquioxane (POSS)-modified BaTiO3 NPs in polypropylene linear dielectric polymer. We found that a large dielectric contrast between high-¿ semiconducting nanofiller and low-¿ insulating polymer would result in the local field enhancement and generate interfacial charge carriers at the nanofiller/polymer interface. Therefore, a deteriorated dielectric performance was observed because of the formation of extended conduction pathway and substantial AC internal current. By employing a medium-¿ TiO2 as a buffer layer between nanofiller and polymer, unfavorable interfacial polarization could, to some extent, be mitigated to give better performance. In the second part, the dielectric loss/conduction mechanism in conductor-polymer system was addressed. Two series of PP/aluminum (Al) composites were prepared and investigated regarding their ¿r, Eb, and energy storage performance. Three conduction regimes were identified as applied electric field increased. The field electron emission could happen at much lower field, and accounted for significantly decreased Eb. Therefore, conductor-insulator composites was believed not appropriate for energy storage applications. During nanocomposite manufacturing or in real applications, the stability of nanoparticles was deemed very important, otherwise compromised properties and/or unwanted degradation might occur. By combining block copolymer micellar nanoreactors and core-crosslinking, we demonstrated a facile and effective way to substantially improve the thermal stability of metallic NPs in organic solvents, as given in the final part of this dissertation.
Lei Zhu (Advisor)
Micheal Hore (Committee Member)
Singer Kenneth (Committee Member)
Alex. Jamieson (Committee Member)
229 p.
Chemistry; Engineering; Materials Science; Nanotechnology; Polymer Chemistry; Polymers

Recommended Citations

Citations

  • Zhang, G. (2017). The Synthesis and Electrical Properties of Functional Polymer Nanocomposites [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case149010222646324

    APA Style (7th edition)

  • Zhang, Guoqiang. The Synthesis and Electrical Properties of Functional Polymer Nanocomposites. 2017. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case149010222646324.

    MLA Style (8th edition)

  • Zhang, Guoqiang. "The Synthesis and Electrical Properties of Functional Polymer Nanocomposites." Doctoral dissertation, Case Western Reserve University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case149010222646324

    Chicago Manual of Style (17th edition)

case149010222646324
466
© 2017, some rights reserved.Creative Commons License The Synthesis and Electrical Properties of Functional Polymer Nanocomposites by Guoqiang Zhang is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.