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Materials Properties of Conducting Polymers PEDOT:PSS/PVA.

机译：导电聚合物的材料特性PEDOT：PSS / PVA。

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摘要

Conducting polymers have wide application as a structural and electrically conducting element in MEMS devices. However, the electrical and mechanical properties of the conducting polymers must be well characterized so that applications can be developed. Thus, the overall focus of the research presented herein is the determination of the electrical and mechanical properties of a conducting polymer that consists of a blend of PEDOT:PSS and PVA. This blend is chosen for this study as previous studies have shown that PEDOT:PSS has a relatively high conductivity of approximately 500 S/cm. This is higher than the conductivity of many other conducting polymers such as polypyrrole (PPy), polyaniline (PANI), polythiophene (PT) and polyacetylene (PA) which have nominal conductivities of respectively, 100, 10, 100 and 350--500 S/cm. However, PEDOT:PSS is very brittle and is, therefore, not useable as a structural element in MEMS devices. Blending with PVA offers a straightforward approach to improve the ductility but, at the same time, leads to a reduction in conductivity. Thus, one of the specific goals of the present study is to determine not only the conductivity and mechanical properties of various weight percentage (wt%) blends but also to determine the range of weight percentage of PEDOT:PSS in PVA that leads to acceptable conductivities while maintaining mechanical properties that would enable the blend to be used as a structural element (for example, as an electrically conducting spring) in a variety of MEMS devices.;The DC electrical properties of the films are determined as a function of weight percentage of PEDOT:PSS in PVA using the four point probe method. The film conductivity increased with increasing weight percentage of PEDOT:PSS. Values of the DC conductivity ranges from varied from 10 S/cm to 3.18x10 -5 S/cm for PEDOT:PSS weight percentages of 10 and 100%. In addition, the effect of the conductivity enhancer, N-Methyl-2-pyrrolidinone (NMP), has been studied and found to lead to an increase in conductivity of the polymer blends by 2 to 5 orders of magnitude (depending on the amount of PVA in the blend). This increase is attributed to a conformational change of PEDOT chains.;However, PEDOT:PSS is too brittle to be employed in many applications. The addition of PVA increases the viscosity of the polymer mix making it easier to spin coat and facilitate micrometer-thick conducting polymer films. PVA also enhances the plasticity of the film, but reduces its electrical conductivity. The mechanical properties of the films as a function of weight percentage of PEDOT:PSS are studied using a uniaxial tensile test to characterize the Young's modulus, fracture strain, tensile strength, and plastic deformation behavior of the blends as a function of the weight fraction of the components. The Young's modulus is found to vary from 0.0413 GPa for pure PVA to 1.6323 GPa for a weight percentage blend of 50% and the elongation % at the break point is found to be 111% for pure PVA and 56% for 50 wt% of PEDOT:PSS.;Blending PEDOT:PSS with PVA is a promising route to reach a reasonable trade-off between electrical and mechanical properties. Based on the results of the DC conductivity and mechanical studies, the current work suggests that a PEDOT:PSS/PVA polymer blend with 30--40 wt% of PEDOT:PSS provides the best trade-off of conductivity and ductility. However, for non free-standing films, higher PEDOT:PSS fractions (70 wt%) might be preferable.;Impedance spectroscopy of the films is also studied using a Gamry Potentiostat. The relaxation time constants, permittivity, dielectric modulus are presented and discussed. The equivalent circuit diagrams are also modeled and shown to demonstrate the space charge polarization and conductive mechanism.
机译：导电聚合物作为MEMS器件中的结构和导电元件具有广泛的应用。但是，必须很好地表征导电聚合物的电气和机械性能，以便可以开发应用程序。因此，本文提出的研究的总体重点是确定由PEDOT：PSS和PVA的混合物组成的导电聚合物的电气和机械性能。选择这种共混物进行此项研究是因为先前的研究表明，PEDOT：PSS具有约500 S / cm的较高电导率。这高于许多其他导电聚合物的电导率，例如聚吡咯（PPy），聚苯胺（PANI），聚噻吩（PT）和聚乙炔（PA），它们的标称电导率分别为100、10、100和350--500 S /厘米。但是，PEDOT：PSS非常脆，因此不能用作MEMS器件中的结构元件。与PVA混合可提供一种直接方法来改善延展性，但同时会导致导电率降低。因此，本研究的具体目标之一是不仅要​​确定各种重量百分比（wt％）的共混物的电导率和机械性能，而且要确定PVA中PEDOT：PSS的重量百分比的范围，该范围会导致可接受的电导率。同时保持机械性能，使该共混物能够用作各种MEMS器件中的结构元件（例如，用作导电弹簧）。薄膜的DC电学性能取决于其重量百分比使用四点探针法的PVA中的PEDOT：PSS。膜电导率随PEDOT：PSS重量百分比的增加而增加。对于PEDOT：PSS重量百分比为10％和100％的直流电导率值，范围从10 S / cm到3.18x10 -5 S / cm。此外，已经研究了电导率增强剂N-甲基-2-吡咯烷酮（NMP）的作用，发现该现象可导致聚合物共混物的电导率提高2至5个数量级（取决于所含的聚乙烯醇（PVA）。这种增加归因于PEDOT链的构象变化。但是，PEDOT：PSS太脆，无法在许多应用中使用。 PVA的添加增加了聚合物混合物的粘度，使其更容易旋涂并促进了微米厚度的导电聚合物膜。 PVA还增强了薄膜的可塑性，但降低了其导电性。使用单轴拉伸试验研究了薄膜的机械性能与PEDOT：PSS重量百分比的关系，从而表征了共混物的杨氏模量，断裂应变，拉伸强度和塑性变形行为与PEDOT：PSS重量分数的关系。组件。发现杨氏模量从纯PVA的0.0413 GPa到50％重量百分比混合物的1.6323 GPa不等，发现纯PVA的断裂点伸长率为111％，PEDOT的50 wt％为56％。 ：PSS .;将PEDOT：PSA与PVA混合是在电气和机械性能之间达成合理折衷的有希望的途径。根据直流电导率和机械研究的结果，当前的工作表明，PEDOT：PSS / PVA聚合物与30--40 wt％的PEDOT：PSS混合可提供最佳的电导率和延展性折衷。但是，对于非自支撑膜，较高的PEDOT：PSS分数（70 wt％）可能更可取。;还使用Gamry恒电位仪研究了膜的阻抗谱。介绍并讨论了弛豫时间常数，介电常数，介电模量。还对等效电路图进行建模和显示，以说明空间电荷的极化和导电机理。

著录项

  • 作者

    Chen, Chang-hsiu.;

  • 作者单位

    University of California, Irvine.;

  • 授予单位 University of California, Irvine.;
  • 学科 Chemistry Polymer.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 123 p.
  • 总页数 123
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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