Preparation of Triple-Functionalized Montmorillonite Layers Promoting Thermal Stability of Polystyrene

Abstract

The objective of this study was to investigate the effect of three different treatments on the morphology, microstructure, and the thermal characteristics of a montmorillonite (Mt) sample, by using hydrochloric acid (HCl), tributyl tetradecyl phosphonium chloride (TTPC) surfactant, and γ-methacryloxypropyltrimethoxysilane (γ-MPS). The resultant nanofillers were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption–desorption analysis, X-ray fluorescence spectrometry (XRF), and thermogravimetric analysis (TGA). The results showed that the amount of chemical grafting of the γ-MPS was increased after the acid treatment, whereas the amount of intercalation of the TTPC surfactant was decreased. The preintercalation of TTPC or silylation of γ-MPS, for the Mt sample, had a certain hindrance effect on its subsequent silylation or intercalation treatments. Furthermore, the effect of four different nanofillers on the thermal stability properties of the polystyrene (PS) matrix were also investigated. The results showed an increase in thermal stability for the triple-functionalized Mt, compared with the double-functionalized samples. The onset decomposition temperatures and the maximum mass loss temperatures of the PS nanocomposites were increased by 27 °C and 32 °C, respectively, by the incorporation of triple-modified Mt, as a result of the good exfoliation and dispersion of the nanolayers, more favorable polymer–nanofiller interaction, as well as the formation of a more remarkable tortuous pathway in the continuous matrix.

Impact of the functionalized clay nanofillers on the properties of the recycled polyethylene terephthalate nanocomposites

“…Adding alkylammonium ions or quaternary ammonium ions to montmorillonite clays is a common way to change the clay through cation exchange. 16,17 The clay lattice's exchangeable cations undergo a process known as cation exchange whereby other cations take their place. Organic cations like alkylammonium and quaternary ammonium ions can be used to change the surface properties of clay by swapping places with inorganic cations like sodium or calcium ions that are already in the clay.…”

“…Organic cations like alkylammonium and quaternary ammonium ions can be used to change the surface properties of clay by swapping places with inorganic cations like sodium or calcium ions that are already in the clay. 16,17 The modification of montmorillonite clays with organosilanes is typically carried out through a two-step process: The clay is first treated with a silane coupling agent to introduce reactive sites on the clay surface (surface modification). [16][17][18] The coupling agent can be chosen based on the type of organic group desired and may include compounds such as aminoalkylsilanes or alkoxysilanes.…”

“…16,17 The modification of montmorillonite clays with organosilanes is typically carried out through a two-step process: The clay is first treated with a silane coupling agent to introduce reactive sites on the clay surface (surface modification). [16][17][18] The coupling agent can be chosen based on the type of organic group desired and may include compounds such as aminoalkylsilanes or alkoxysilanes. The silane coupling agent reacts with the hydroxyl groups on the clay surface to form covalent bonds, which can improve the compatibility between the clay and the organic matrix.…”

“…This can lead to better mechanical and thermal properties. 14,[16][17][18] Modification of montmorillonite clays by grafted polymer brushes is an alternative approach to the traditional method of modification by organosilanes. [19][20][21] This method involves the covalent attachment of polymer chains to the clay surface through a process called "grafting."…”

Enhancing the Properties of Water-Soluble Copolymer Nanocomposites by Controlling the Layer Silicate Load and Exfoliated Nanolayers Adsorbed on Polymer Chains

“…In recent years, water-soluble polymer nanocomposites are increasingly being used in EOR [ 4 , 5 , 6 , 7 ]. Montmorillonite (MMt) is a common inorganic phase in the synthesis of water-soluble polymer nanocomposites, and its nano-effects have received considerable research attention [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. MMt is a natural two-dimensional layered silicate material whose crystal structure is composed of two sheets of silicon–oxygen tetrahedra sandwiched between sheets of aluminum–oxygen octahedra [ 18 , 19 , 20 ].…”