New Role of Layered Silicates as Phase Transfer Catalyst for In Situ Polymerization of Poly(ethylenetetrasulfide) Nanocomposite

Abstract

In this study, polyethylenetetrasulfide/montmorillonite nanocomposite (PETS/nanoclay) is synthesized from ethylene dichloride and sodium tetrasulfide monomers by in situ polymerization method. The effect of phase-transfer catalyst (PTC) on polymerization kinetics in addition to the structure of resulting PETS containing nanoclay is investigated. The results show that surface-modified montmorillonites by methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride could properly act as PTC. Therefore, it is demonstrated that the addition of nanoclay as PTC reduces the reaction time and increases the polymerization rate during the production of final nanocomposite. The samples were characterized using Fourier transform infrared and Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nuclear magnetic resonance spectroscopy besides energy-dispersive X-ray spectroscopy (EDS) combined with SEM (SEM–EDX). In addition, thermal behavior of nanocomposite was perused by differential scanning calorimetry and thermogravimetric analysis. XRD and AFM results show proper dispersion of clay in PETS matrix and SEM–EDX results demonstrate suitable distribution of clay in polymer matrix. PETS/nanoclay nanocomposite show a better thermal stability, and also higher glass transition and melt temperature compared to pure polysulfide polymer. The solubility of nanocomposite is also studied and results show that the solubility depends on solvent concentration in addition to reinforcement (nanoclay) deals.