Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica

Abstract

Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723 K) of the deposited PAN was analyzed. It was found that at about 523 K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623 K, were responsible for the high sorption capacity in the methylethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface.Keywords Thermal transformation of polyacrylonitrile Á SBA-15 support Á Thermogravimetry Á X-ray photoelectron spectroscopy Á Diffuse reflectance Fourier transform spectroscopy Á Adsorption of volatile organic compounds

Control of amine functionality distribution in polyvinylamine/SBA-15 hybrid catalysts for Knoevenagel condensation

“…SBA-15 mesoporous silica was synthesized by the organic template method, according to the procedure described earlier by Janus et al [11]. Polymer chains were deposited onto SBA-15 by in situ polymerization.…”

Lithium Storage in Heat‐Treated SnF2/Polyacrylonitrile Anode

“…The change in relative intensity of these two peaks demonstrates breakage of the CN bond and formation of a CN bond (the peak at 285 eV in the inset of Figure 5 a). The symmetrical peak at 399.2 eV in the N 1s spectrum of commercial PAN is attributed to its CN group 17. Heating PAN at 230 °C does not change the N 1s binding energy but decreases the symmetry of its peak shape.…”

“…They are combined into a broad band and shift to lower frequencies in heat‐treated SnF 2 /PAN (H‐SnF 2 /PAN). These two peaks become much stronger with increasing heat treatment temperature and duration 17. On the contrary, the intensity of the CN band drastically diminishes in the H‐SnF 2 /PAN electrode in comparison with commercial PAN and PAN heated at 230 °C (H‐PAN).…”

“…The C 1s spectrum of commercial PAN has two components at 284.8 and 286.1 eV (Figure 5 a). These two peaks are assigned to the C atoms of the CH 2 and CC groups in the polymer backbone17 and the CN bond, respectively. After heat treatment at 230 °C of the PAN powder or the H‐SnF 2 /PAN electrode, the peak at 286.1 eV becomes weaker while that at 284.8 eV becomes stronger.…”

“…These two peaks become much stronger with increasing heat treatment temperature and duration. [17] On the contrary,t he intensity of the CNb and drastically diminishes in the H-SnF 2 /PAN electrode in comparison with commercial PANa nd PANh eated at 230 8C( H-PAN). These spectral features are consistent with those reported in ref.…”