Preparation and characterization of PVAc-MMT-DOAB

Abstract

Polyvinyl acetate (PVAc) is considered to be a type of environmental friendly adhesive, and montmorillonite (MMT) is a cheap and accessible natural nanomineral. MMT was first organically activated by dioctadecyl dimethyl ammonium bromide (DOAB). The intercalated nanocomposite of MMT-DOAB was added during the synthesis of PVAc in conventional laboratory conditions. The PVAc-MMT-DOAB was mainly studied by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, static tension, and the rheology was also investigated by the power-law function equation and the Cross—Williamson model viscous equation. The exfoliated nanocomposite of PVAc-MMT-DOAB could be obtained. Linear macromolecular chains of PVAc were formed in the layers of MMT-DOAB. MMT-DOAB was exfoliated into nanoparticles of layers or sheets, randomly dispersed in the matrix of PVAc. The particle diameter of MMT-DOAB ranged from 25 to 75 nm, they randomly dispersed with PVAc particles. In addition, the smaller MMT-DOAB particles were adsorbed around the bigger PVAc particles; they formed the ‘strawberry’ structure. PVAc and PVAc-MMT-DOAB were pseudo-plastic non-Newtonian fluids and they all possessed the normal stress effect (or Weissenberg effect), that was the pole-climbing phenomenon. The reasonable addition of MMT-DOAB in polymerization was found to be not more than 2.0 wt.% of VAc.

Using Vinyl Acetate, N‐Hydroxymethyl Acrylamide, and Montmorillonite Intercalated by a Dioctadecyl Dimethyl Ammonium Bromide Surfactant to Prepare Exfoliated Nanocomposite through In Situ Polymerization

“…The WAXRD pattern of pristine MMT featured a peak at 7.00° for the 2 θ , corresponding to a basal space of 1.26 nm; that of MMT‐DOAB exhibited a diffraction angle at 2.22° for the 2 θ , corresponding to a basal space of 3.98 nm–much larger than that of pristine MMT . This observation implies that DOAB had entered and opened the MMT layer to form a larger gallery distance, as confirmed through the signals of DOAB in the FTIR spectrum of the intercalated OMMT sample.…”

“…For the PVAc‐NMA and PVAc‐NMA‐MMT‐DOAB, neither of them presented the transmittance peak at 1635 cm −1 for C=C stretching vibration, showing NMA had participated the reaction and produced the cross‐linkable polymer of PVAc‐NMA with VAc (Scheme d). The characteristic Si–O–Si (siloxane) transmittance of MMT remained near 1100 cm −1 , and caused the wide transmittance peak of PVAc into two sharp transmittance peaks for PVAc‐NMA‐MMT‐DOAB . All of them have shown that the in situ polymerization was successfully completed and the obtained PVAc‐NMA‐MMT‐DOAB had high structural stability in the synthesis.…”

“…In contrast, the organic surfactant (DOAB)‐intercalated MMT decomposed more readily, with the weight loss of MMT‐DOAB (ca. 53%) caused mainly by the pyrolysis of DOAB at temperatures up to 600°C, at which point the intercalator had been pyrolyzed …”

“…In our previous studies, we prepared copolymers from VAc and N ‐hydroxymethyl acrylamide (NMA), and exfoliated nanocomposites from VAc and OMMT . OMMT improved the properties of PVAc limitedly.…”

“…Then the exfoliated nanocomposites of PVAc‐NMA‐MMT‐DOAB were prepared from VAc, NMA, and MMT‐DOAB using different synthesis precursors (Scheme ). In the preparation, MMT‐DOAB was 2% and NMA was 1%, both based on VAc . The structures, rheology, and mechanical properties were investigated using wide‐angle X‐ray diffraction (WAXRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), power‐law function equation, Newtonian fluid flow equation, Cross–Williamson model viscous equation, Hooke's law, and Poisson's ratio equation.…”