Synthesis, characterization, and dielectric properties of bentonite clay modified with (3-chloropropyl)triethoxysilane and Co(ii) porphyrin complex for technological and electronic device applications

Abstract

The present work reports the dielectric behavior of bentonite clay, (3-chloropropyl)triethoxysilane-modified bentonite clay (CPTES-modified bentonite clay), and a 5,10,15,20-tetrakis-(4-hydroxyphenyl)porphyrinatocobalt(II) complex covalently bonded to CPTES-modified bentonite clay ([Co(II)TP-OHPP]/CPTES–bentonite clay). The structures and morphologies of these composites were characterized by techniques such as ¹H NMR spectroscopy, UV/vis spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), TGA, DSC, and BET analysis. We meticulously analyzed their dielectric properties and AC conductivities, considering the effects of frequency and temperature. The dielectric constant (ε′), dielectric loss (ε′′), and AC conductivity (σ_AC) were determined over a frequency range of f = 10³–10⁵ Hz and at temperatures ranging from 30 °C to 200 °C. The results show that bentonite clay exhibits the highest values of ε′ and ε′′ at 30 °C, particularly at low frequencies (10³ Hz). However, the dielectric constants of CPTES–bentonite clay and [Co(II)TP-OHPP]/CPTES–bentonite clay enhanced the dielectric loss (ε′′) and showed an adjustment in ε′ values with a corresponding acceptable loss. Functionalizing bentonite clay with CPTES and subsequently complexing it with [Co(II)TP-OHPP] enhances its thermal resistance, making the modified bentonite clay more stable both under thermal conditions and at high frequencies. These composites are, therefore, promising candidates for high-temperature applications.