Semi-Continuous Heterophase Polymerization to Synthesize Nanocomposites of Poly(acrylic acid)-Functionalized Carbon Nanotubes

Abstract

Two materials, pure poly(acrylic acid) (PAA) and nanocomposites with a matrix of PAA and carbon nanotubes (CNTs) as reinforcing agent were synthesized by semi-continuous heterophase polymerization (SHP). CNTs were prepared by a chemical vapor deposition technique and purified by steam. CNTs were characterized by a high resolution scanning electron microscopy (HRSEM) and Raman and Fourier transform infrared spectroscopies. Nanocomposites were prepared with: (i) purified CNTs (CNTs p ) or (ii) purified and functionalized CNTs possessing an acyl chloride moiety (CNTs OCl ). In both cases, the nanocomposites synthesis was carried out by in situ polymerization of acrylic acid (AA) by SHP. When CNTs OCl were used previously to the polymerization of AA, a series of specific amounts of CNTs OCl and AA were mixed to induce a chemical reaction between the carboxyl group of AA and the acyl chloride group of the CNTs OCl . The product, acrylic acid grafted to CNTs OCl (CNTs OCl -AA), was used to prepare the PAA-CNTs OCl nanocomposites. The PAA-CNTs OCl nanocomposites were characterized by HRSEM, Raman, FTIR and CPMAS 13 C-NMR spectroscopies and also by thermogravimetric analysis (TGA). The results reveal that PAA-CNTs OCl nanocomposites were formed by PAA macromolecules grafted to CNTs OCl . The kinetic behavior observed for the synthesis of pure PAA or PAACNTs OCl nanocomposites by SHP was similar. Latexes of PAA-CNTs OCl nanocomposites were stable without formation of a precipitate of CNTs OCl for over 1.5 years, while latex prepared with CNTs p and PAA, was unstable and formation of a precipitate of CNTs p was observed immediately after its preparation. PAA-CNTs p nanocomposites were characterized only by TGA. Moreover, latex of the PAA-CNTs p nanocomposite that did not precipitate immediately after its preparation, turned into a gel; this gelation never occurred with the PAA-CNTs OCl nanocomposite latex.

Preparation and characterization of nanocomposites made from chemoenzymatically prepared polyester urethanes and functionalized multiwalled carbon nanotubes

“…Acyl chloride groups are detected on oxidized CNTs treated with oxalyl chloride. Three contribution are distinguished: (i) C‐Cl stretching band detected at 745 cm −1 ; (ii) a band produced by the torsion out of the plane of dimers of the carboxylic acid groups observed at 915 cm −1 ; and (iii) stretching vibration of a di‐carbonyl group detected by a weak small shoulder in the band observed at 1,630 cm −1 . However, the high hydrolytic reactivity of ‐COCl in air tended to convert them back into carboxylate ions, and so detection of the stretching vibration of ‐COCl is extremely difficult to identify .…”

Effect of polyethylene glycol and nano clay on swelling, diffusion, network parameters and drug release behavior of interpenetrating network copolymer

“…The homo polyacrylamide (PAM) has been reported to show a strong characteristic chemical shift in between 33 and 45 ppm for its CH 2 CH and another chemical shift at around 181 ppm for the carbonyl of its amide unit 44 . Similarly, polyacrylic acid (PAA) has been reported to show a characteristic chemical shift at around 179 ppm for its carbonyl functionality 45 . Accordingly, the CP5P24 shows a chemical shift at 43.23 ppm which may be due to CH 2 CH of its PAAM moiety while carbonyl peak of PAA and acrylamide of PAM merges to a single major peak at 181.96 ppm in CP5P24.…”

Synthesis, characterization, and mechanical performance of various functionalized carbon nanotubes‐polyurethanes nanocomposites

“…In Figure (c), the FTIR spectrum of the CNTs OCl presence of acyl chloride groups and other functional groups were clearly detected. Thus, the band detected at 745 cm −1 is due to CCl stretching vibrations, and the small weak shoulder resolved at about 1695 cm −1 is due to stretching vibrations of the di‐carbonyl group . For the high hydrolytic reactivity of COCl group to the ambient moisture, the detection of the stretching vibration of COCl is extremely difficult to identify .…”