Investigation on enhancement of electrical, dielectric and ion transport properties of nanoclay-based blend polymer nanocomposites

Abstract

An intercalated blend polymer nanocomposite (PNC) films based on blend (PEO–PVC), LiPF6 as salt and modified montmorillonite (MMMT) as nanoclay are prepared via solution cast method. The impact of the nanoclay on the morphology, structure, polymer–polymer, polymer–ion interactions, ionic conductivity, voltage stability window, glass transition temperature, dielectric permittivity, and ac conductivity has been explored. The structural analysis evidenced the formation of blended and intercalated polymer nanocomposites. The FTIR analysis confirmed the interaction between polymer–ion-nanoclay, and polymer intercalation is evidenced by the out-of-the-plane mode [Si–O mode] of MMMT. An increase in the fraction of free anions with clay addition is confirmed. The highest ionic conductivity of about ~ 8.2 × 10−5 S cm−1 (at RT) and 1.01 × 10−3 S cm−1 (at 100 °C) is exhibited by 5 wt% MMMT based PNC. A strong correlation is observed between the glass transition temperature, crystallinity, melting temperature (Tm), ionic conductivity, relaxation time, and dielectric strength. The dielectric data have been fitted and enhanced dielectric strength and lowering of the relaxation time ($$ \tau_{{\varepsilon^{\prime} }} \;{\text{and}}\;\tau_{\text{m}} $$) with clay addition evidences the faster segmental motion of polymer chain. The intercalated PNC shows thermal stability up to ~ 300 °C, high ion transference number (~ 1), and broad voltage stability window of ~ 5 V. An absolute agreement between ion mobility (μ), diffusion coefficient (D), and ionic conductivity is observed. An ion transport mechanism has been proposed on the basis of experimental results. Therefore, the proposed PNC can be adopted as electrolyte cum separator for energy storage devices.