ABSTRACT

Structural, conductive and dielectric properties of hybrid Polypyrrole (PPy)-TiO₂ nanocomposite-coated polyamide fabric (PA-PPy/TiO₂) synthesized by in-situ oxidative polymerization of pyrrole on the surface of polyamide in the presence of colloidal TiO₂ NPs (d ~ 4.5 nm) have been studied. Raman spectra confirmed salt form of PPy in both neat PPy and PPy/TiO₂-coated PA fabric and indicated its complete coverage. SEM/EDX analysis confirmed presence of TiO₂ NPs and changes in granular structure of PPy deposited on the surface of PA fiber depending on the amount of TiO₂ NPs. The PA-PPy/TiO₂ nanocomposite sample with lowest content of TiO₂ NPs (6.79 At.% Ti) showed highest conductivity (~10⁻⁶ S/cm) and dissipation factor (tan δ) in the entire frequency range. The lowest amount of TiO₂ NPs in the PA-PPy/TiO₂ nanocomposite induced two to four orders of magnitude higher tan δ value, compared to neat PPy covered PA fabric, depending on the frequency range. Frequency dependence of real (ϵ′) and imaginary part (ϵ″) of the complex permittivity for neat PA and PPy/TiO₂-coated PA fabrics follow the trend of changes in dissipation factor for the same TiO₂ NPs concentrations. The presence of TiO₂ NPs could be exploited for tuning the conductive and dielectric properties of a conductive layer.

摘要

在胶体TiO ₂ NPs存在下，通过吡咯在聚酰胺表面原位氧化聚合合成的杂化聚吡咯（PPy）-TiO ₂纳米复合涂层聚酰胺织物（PA-PPy/TiO ₂）的结构、导电和介电性能(d ~ 4.5 nm) 已被研究。拉曼光谱证实了纯 PPy 和 PPy/TiO ₂涂层 PA 织物中 PPy 的盐形式，并表明其完全覆盖。SEM/EDX 分析证实了 TiO ₂ NPs 的存在以及沉积在 PA 纤维表面上的 PPy 颗粒结构的变化取决于 TiO ₂ NPs的数量。PA-PPy/TiO ₂具有最低 TiO ₂ NPs (6.79 At.% Ti)含量的纳米复合材料样品在整个频率范围内显示出最高的电导率 (~10 ^-6 S/cm) 和损耗因数 (tan δ)。与纯 PPy 覆盖的 PA 织物相比，PA-PPy/TiO ₂纳米复合材料中最低量的 TiO ₂ NP导致 tan δ 值高出两到四个数量级，具体取决于频率范围。纯 PA 和 PPy/TiO ₂涂层 PA 织物的复介电常数的实部 (ϵ') 和虚部 (ϵ") 的频率依赖性遵循相同 TiO ₂ NPs 浓度的耗散因子变化趋势。TiO ₂的存在 NPs 可用于调节导电层的导电和介电特性。