Grafting of 3 mercaptopropyl triethoxysilane onto dodecylamuonium intercaled Algerian montmorillonite; characterizations and application for synthesis of polystyrene/organoclay hybrid material by radical polymerization

Abstract

High grafting efficiency (98%) of 3-mercaptopropyl triethoxysilane (MPTES) onto Algerian montmorillonite was
achieved. Before grafting process, the Algerian montmorillonite was sodified, fractionated (<2μm) and intercaled with
dodecylamine (DDA) salts. The obtained grafted clay was used to prepare polystyrene/organoclay hybrid material by radical
polymerization of styrene monomer. X-ray Fluorescence (XRF) results showed a successful homoionisation of clay and
insersion of DDA salts onto montmorillonite. CHN micro-analysis was revealed evolution of the carbon ratio during
modification of clay by DDA, grafting and polymerization reactions.
Fourier transform infrared (FTIR) spectrums were mainly confirmed the presence of DDA salts, the grafting of MPTES
and polystyrene polymer and increasing of hydrophobicity of clay during modifications process (intercalation, grafting and
polymerization). The characterization (XRD) was revealed that DDA salts, 3-mercaptopropyl triethoxysilane molecules and
polystyrene polymer were respectively intercaled, grafted and polymerized onto montmorillonite galleries by increasing of
d001 from 12.69 Å for homoionisated clay to 15.33 Å for intercaled clay and to 21.47 Å for grafted clay and to 25.08 Å for
polystyrene/organoclay hybrid material. Thermogravimetic analysis (TGA) showed High grafting efficiency (98%) of
MPTES. It showed also that the grafted clay sample have higher thermal stability than intercaled sample and that the
thermal stability of prepared organoclay hybrid material is greatly higher than pur polystyrene polymer and that
hydrophobicity hybrid organoclay≈ hydrophobicity grafted clay ˃
hydrophobicity intercaled clay˃
hydrophobicity fractinated sodic clay. The polymer was
recovered by hydrofluoric acid attack, analyzed by FTIR and compared to hybrid organoclay FTIR spectra