Poly(4-methoxyaniline) composites: Investigating structure–property relationship towards semiconducting applications

Conjugated polymers are essential materials for the organic optoelectronic industry, serving a pivotal role in cutting-edge technologies. In this study, we conducted an integrated characterization approach, including spectroscopic techniques coupled with X-ray diffraction analysis to explore the structure–property relationship of poly(4-methoxyaniline), commonly referred to as poly(p-anisidine) or PPA, along with two distinct ceramic composites: PPA/α-Al₂O₃ and PPA/Eu₂O₃. From powder X-ray diffraction analysis, a triclinic unit cell in space group P1 is proposed, after the whole powder pattern decomposition (WPPD) refinement is employed for the semicrystalline regions of the polymeric phases. Fractal-like structures are observed, following analysis of small-angle X-ray scattering (SAXS) data and scanning electron microscopy (SEM) from which we could infer the approximate sizes of the fractal clusters. Pure PPA displays a glass transition temperature (T_g) of approximately 80°C and an electrical conductivity slightly above 10⁻⁵ S/cm. In contrast, the composite materials do not exhibit a glass transition temperature but perform better in terms of crystallinity and thermal stability. PPA/Eu₂O₃ present conductivity enhancement exceeding tenfold, surpassing 10⁻⁴ S/cm. These findings provide the baseline for further explorations on the development of organic electronic devices and sensors.