Preparation of xerogel based on syndiotactic polystyrene (sPS)/MWCNTs hybrid polymer gel for application as a dielectric material with high dielectric permittivity

Abstract

MWCNTs were dispersed in sPS gel in both pristine as well as functionalized form to observe its effect on structure, morphology, thermal as well as dielectric properties of the resulting hybrid polymer gel. Since, the ortho-xylene induces clathration in pure sPS polymer in α-phase leading to thermoreversible gelation resulting in the δ-crystalline phase (sPS gel). Therefore, the removal of solvent from solvated δ-crystalline phase gives non-solvated δe-crystalline phase (sPS xerogel). The three dimensional fibrillar networks, as observed with scanning electron microscopy (SEM) and atomic force microscopy (AFM), have the polymer chains with s(2/1)2 helical conformation which makes the gel elastic. Fourier transform infra red spectroscopy (FTIR) shows the conformation change from trans planar to s(2/1)2 helical as indicated by the disappearance of peak at 541 cm−1 and appearance of peak at 537 cm−1 and 571 cm−1. The peak at 7.9° confirms the δ-crystalline phase presence whereas the absence of solvent is indicated by peak absence at 10°. Differential scanning calorimetry (DSC) thermogram confirms the δ to γ phase transition in the 100–150 °C temperature range. As we get an intermingled structure of gel fibers and MWCNTs, therefore, the dielectric behavior showed the percolative nature of the hybrid sPS xerogel. The pure sPS xerogel displayed no response to the frequency change whereas due to interfacial polarization, hybrid sPS xerogel responded to frequency change.