Nanostructured Polyanilines Using the H₂O₂/CaCl₂ Oxidant System

Abstract

Aniline and its ring-substituted derivatives are oxidatively polymerized by H 2 O 2 to the corresponding electrically conductive emeraldine oxidation state in dilute aqueous acids when 5 M CaCl 2 is added as an ionic strength booster. Evidence consistent with the intermediacy of HOCl as the primary oxidant is presented, which is formed in situ in this system. This study significantly advances the scope of our previous report on aniline polymerization using the H 2 O 2 /NaCl/HCl oxidant system. For example, the H 2 O 2 /CaCl 2 /HCl oxidant system significantly increases the reaction yield and polymer molecular weight and affords entry into a wide range of polyaniline derivatives with technologically interesting nanostructure. Aniline and its derivatives are very sparingly soluble in 5 M CaCl 2 with chain growth occurring almost entirely in the solid state. This opens new opportunities to control the morphology of polyaniline by carefully controlling the corresponding morphology of the freshly precipitated monomer salt.

Revisiting o-Phenylenediamine as a Nanomaterial-Catalyzed Signaling Agent: Dimerization versus Polymerization

“…As the [NaCl] increased from 0.15 M, the initial slope decreased more slowly from 0.19 min –1 , while the polymerization that occurred at 70 min began to take place earlier. The role of NaCl in the OPD polymerization is comparable to the Cl – -boosted aniline polymerization; as observed in the latter, a high ionic strength supports radical cation coupling of monomers even without catalysts. , As the precise contribution of Cl – to the catalytic oxidation of OPD is yet to be fully understood, we broadened our focus to include a range of alkali metal chlorides including LiCl, KCl, RbCl, and CsCl. We also examined inorganic, organic, and polymeric non-halide anions such as nitrate (NO 3 – ), sulfate (SO 4 2– ), acetate (CH 3 COO – ), and poly­(4-styrenesulfonate) (PSS – ) ions to determine their potential effects.…”

“…The role of NaCl in the OPD polymerization is comparable to the Cl − -boosted aniline polymerization; as observed in the latter, a high ionic strength supports radical cation coupling of monomers even without catalysts. 40,41 As the precise contribution of Cl − to the catalytic oxidation of OPD is yet to be fully understood, we broadened our focus to include a range of alkali metal chlorides including LiCl, KCl, RbCl, and CsCl. We also examined inorganic, organic, and polymeric non-halide anions such as nitrate (NO 3 − ), sulfate (SO 4 2−…”

Polymers based on thieno[3,4-c]pyrrole-4,6-dione and pyromellitic diimide by CH–CH arylation reaction for high-performance thin-film transistors

“…Several synthetic methodologies including electrochemical, 1-3 chemical oxidative [4][5][6] and transition metal-catalyzed crosscoupling reactions [7][8][9][10] have been investigated for the synthesis of p-conjugated organic and polymeric materials. Direct C-H arylation reaction has been proved to be a particularly efficient methodology for the formation of carbon-carbon bonds without the use of organometallic nucleophiles.…”