Immobilisation of Fully Sulfonated Polyaniline on Nanostructured Calcium Silicate

Abstract

Up to 7.4% (w/w) of the sulfonated polyaniline, poly(2-methoxyaniline-5-sulfonic acid) (PMAS) can be absorbed onto nanostructured calcium silicates. Spectroscopic and leaching studies on the novel PMAS-silicate nanocomposites obtained indicate that attachment of the PMAS occurs via electrostatic binding of PMAS sulfonate groups to Ca2+ sites on the silicates. The surface area and pore volume of the nanocomposites are comparable to those of pure silicate and increase the surface area of the PMAS polymer by several orders of magnitude. The PMAS emeraldine salt in the nanocomposites retains its chemical reactivity, being readily oxidised and reduced to its pernigraniline and leucoemeraldine forms, respectively. The conductivity of the composite is comparable to that of the pure PMAS, several orders of magnitude higher than that of dried nanostructured calcium silicate.

Redox‐Active Catalyst Based on Poly(Anilinesulfonic Acid)‐ Supported Gold Nanoparticles for Aerobic Alcohol Oxidation in Water

“…In the catalytic reaction under an argon atmosphere (Table 1, entry 4), a significant spectral change was observed after the reaction (Figure 3, a), whereas the yield was poor. The characteristic polaron band (747 nm) [7] disappeared after the reaction, in the meantime a sharp peak appeared at 402 nm, which is assigned to the reduced form of PMAS [8] ( Figure 3, a). The surface plasmon band of Au NPs was observed after the reaction.…”

A Study of the Sorption Characteristics of Nanostructured Calcium Silicate

“…The XPS spectra of the unmodified NCS material are presented in Figure 6.19 and Table 6.5. The spectra are typical of NCS 47 and other calcium silicates. 201,202 The O 1s signal may be assigned to three chemical functionalities within the silicate structure:…”

“…Ethanol was chosen for the final washing in preference to 2-ethoxyethanol as the latter had a tendency to leach extra PANI out of the composite material, most likely due to the 2-ethoxyethanol and the PANI binding to the same sites on the NCS surface. 47 The materials were characterised via TGA and spectroscopic techniques. Composite materials were also prepared containing 15 N-PANI in a similar manner to that described above, using > 98 atom% 15 N aniline.…”

“…For example, Borrmann et al have reported composites of NCS with the sulfonated PANI derivative PMAS (Figure 6.3). 47 The requirement for acidic conditions during the polymerisation of polyaniline precludes the in situ oxidation of the monomer on the NCS surface due to the basic nature of the latter. For this reason, the polymer must be prepared prior to its incorporation onto the NCS material.…”

“…This has been demonstrated before with the NCS-conducting polymer derivatives, using either polypyrrole 176 and the sulfonated polyaniline derivative PMAS. 47 PMAS binds to the NCS through coordination between the sulfonate groups of the polymer and Ca 2+ ions on the NCS surface. However, this mode of coordination means that the PMAS-NCS composite will dissociate under acidic conditions, as protonation of the sulfonate moieties reduces their effectiveness as ligands for Ca 2+ .…”