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Electrochemical quartz crystal microbalance studies of electroactive polymer films in gravimetric and viscoelastic regimes

机译：重力和粘弹性体系中电活性聚合物薄膜的电化学石英晶体微天平研究

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摘要

Under rigid film conditions the Electrochemical Quartz Crystal Microbalance (EQCM) acts as a gravimetric probe for mass changes occurring during electroactive film redox switching. The sensitivity of the technique allows one to monitor redox driven population changes of both ion and solvent between an electroactive film and its bathing solution. The interpretation of EQCM data to date has mainly been of a qualitative nature. The approach taken here is a quantitative one and attempts to provide kinetic information (rate constants) for specific electro(chemical) steps.;The model to be considered is an electroactive redox polymer under permselective conditions. A new 3D vector (U) representation is developed to describe the redox and compositional state of a system in terms of injected electronic charge (Q), potential (E) and a mobile species population parameter (E), which can be calculated from film mass changes (AM). Poly(vinylferrocene) is then used as a model system to validate the methodology. The kinetics of redox switching of poly(vinylferrocene) are analysed using cyclic voltammetry and quantitative data is extracted from the relative fluxes of water and counter ion during the redox cycle. Solvent populations are extracted from the data and a new theoretical model shows solvent activity parameter effects (polymer/solvent interactions) are evident during redox switching.;Crystal impedance spectra provide a diagnostic for rigid vs. viscoelastic film behaviour. The evolution from gravimetric to viscoelastic responses of poly(3-methylthiophene)-loaded thickness shear mode resonators was investigated. The relationship between ion and solvent populations (composition) and shear moduli (dynamics) was explored. Extraction of viscoelastic film characteristics, i.e. shear modulus, film thickness and film density is achieved by equivalent circuit modelling. The problem of the uniqueness of fit is tackled by a new approach in which impedance and coulometric data from the acoustically thin regime define a solvent swelling factor. Extrapolation into the acoustically thick regime using the solvent swelling factor defines the film thickness and film density. The method is validated using crystal impedance data for poly(3-methylthiophene) films exposed to propylene carbonate.
机译：在硬膜条件下，电化学石英晶体微天平（EQCM）用作重量探针，用于检测电活性膜氧化还原切换过程中发生的质量变化。该技术的灵敏性使人们可以监视氧化还原驱动的电活性膜及其沐浴溶液之间离子和溶剂的总体变化。迄今为止，对EQCM数据的解释主要是定性的。这里采用的方法是一种定量方法，试图为特定的电（化学）步骤提供动力学信息（速率常数）。要考虑的模型是在选择性渗透条件下的电活性氧化还原聚合物。开发了一种新的3D矢量（U）表示形式，可以根据注入的电荷（Q），电势（E）和可移动的物种种群参数（E）来描述系统的氧化还原和组成状态，可以从胶片计算得出质量变化（AM）。然后将聚乙烯基二茂铁用作模型系统以验证该方法。使用循环伏安法分析了聚乙烯二茂铁的氧化还原转换动力学，并从氧化还原循环中水和抗衡离子的相对通量中提取了定量数据。从数据中提取溶剂总数，并建立了一个新的理论模型，表明在氧化还原转换过程中溶剂活性参数的影响（聚合物/溶剂相互作用）很明显。晶体阻抗谱可用于诊断刚性膜与粘弹性膜的行为。研究了由聚（3-甲基噻吩）加载的厚度剪切模式谐振器从重量响应到粘弹性响应的演变。探索了离子和溶剂的数量（组成）与剪切模量（动力学）之间的关系。通过等效电路建模来提取粘弹性膜的特性，即剪切模量，膜厚度和膜密度。拟合唯一性的问题通过一种新方法解决，在该新方法中，来自声学薄区域的阻抗和库仑数据定义了溶剂溶胀因子。使用溶剂溶胀系数外推到声学上较稠密的区域可定义薄膜厚度和薄膜密度。使用暴露于碳酸亚丙酯的聚（3-甲基噻吩）薄膜的晶体阻抗数据验证了该方法的有效性。

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    Jackson, Angela;

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  • 年度 2001
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