Effect of polymerization conditions ono-phenylenediamine ando-phenetidine oxidative copolymers

Revisiting the Structure and Electrochemical Performance of Poly(o-phenylenediamine) as an Organic Cathode Material

Poly(o-phenylenediamine) (PoPDA) has been recognized as a low-cost electroactive organic material and studied as a cathode for aqueous zinc batteries or as an anode for nonaqueous lithium batteries. However, there remains a lot of confusion about its synthesis, structure, and electrochemical application. Especially, the previously studied PoPDA samples were mostly synthesized at room temperature, which were proved by us to be just a dimer, that is, 2,3-diaminophenazine (DAPZ). By various characterization methods including elemental analysis and mass spectrometry, we verified that the product synthesized at high temperature, PoPDA-H, was a polymer based on DAPZ as the structural repeat unit and with some imperfect substitutes (OH and NH₃⁺CH₃COO^-). Based on the reversible redox reaction of phenazine units and the stable polymer structure within 1.3-3.8 V vs Li⁺/Li, PoPDA-H was more appropriate to be applied as a cathode rather than as an anode for lithium batteries. It achieved a high energy density of 490 Wh kg^-1 (2.12 V × 231 mAh g^-1) at 50 mA g^-1 and a high cycling stability (79%@1000th cycle) at 500 mA g^-1, both of which were comparable to previously reported expensive pyrazine- and carbonyl-based polymers. This work clarifies many misunderstandings of PoPDA, which is important to its further development toward practical application in energy-storage devices.

Constructing green mercury-free catalysts with single pyridinic N species for acetylene hydrochlorination and mechanism investigation

A green bifunctional polymer for acetylene hydrochlorination is directly used as a catalyst and then used as a precursor to prepare an N-doped carbon catalyst.

Tuning the optical properties of poly(o-phenylenediamine-co-pyrrole) via template mediated copolymerization

Tailoring of conjugated monomers via copolymerization is a facile method to obtain tunable spectral, morphological and optical properties. To investigate the effect of copolymerization of pyrrole with o-phenylenediamine on the optoelectronic properties of the synthesized copolymers, the present work reports the synthesis of copolymers of o-phenylenediamine with pyrrole with varying mol ratios via chemical polymerization in methylene blue (MB) medium. Copolymerization was confirmed by Fourier transform infrared spectroscopy and ultraviolet-visible studies. Ultraviolet-visible spectroscopy revealed variation in the optical properties with the change in the monomer ratio. Fluorescence studies showed that the copolymer containing 80% poly(o-phenylenediamine) revealed highest quantum yield among all the copolymers. The emission color could therefore be tuned by careful selection of narrow band co-monomers, which could help in designing tunable fluorescence emitting materials for potential application in OLED devices.

pH manipulation: a facile method for lowering oxidation state and keeping good yield of poly(m-phenylenediamine) and its powerful Ag+ adsorption ability

A method of pH manipulation has been used to improve chemically oxidative polymerization of m-phenylenediamine (mPD) through concurrent addition of NaOH when adding oxidant (NH(4))(2)S(2)O(8). pH detection and open-circuit potential technique were adopted to monitor the polymerization process of mPD and to explain the oxidation state-pH and yield-pH relationships. Results from Fourier transformed infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies indicate that a low oxidation state is under control by regulating NaOH concentration. At 2.5 M NaOH, the oxidation state of poly(m-phenylenediamine) (PmPD) is 64.7 mol % (measured by molar content of quinoid imine from XPS), while the yield is 84%. The synthesized PmPD possesses better Ag(+) adsorption performance when lowering its oxidation state. Moreover, the Ag(+) adsorbance of PmPD can reach 1693 mg g(-1). Meanwhile, Ag(+) adsorption mechanism was studied by pH tracking, X-ray diffraction (XRD) patterns, and X-ray photoelectron spectroscopy. The adsorption process includes redox reaction, chelation, and physical adsorption.

Poly(o-phenylenediamine) submicrosphere-supported gold nanocatalysts: synthesis, characterization, and application in selective oxidation of benzyl alcohol

A facile solution route was proposed for the successful synthesis of uniform poly(o-phenylenediamine) (PoPD) submicrospheres with an average diameter of 700 nm. Utilizing the reactivity of dedoped PoPD submicrospheres for gold salt HAuCl4, gold nanoparticles can be synthesized in the presence of PoPD without additional reductant for HAuCl4. Furthermore, PoPD submicrospheres with abundant amino groups and pi electrons in benzene rings on their surfaces can significantly stabilize gold nanoparticles, which will lead to the formation of PoPD submicrosphere-supported gold nanoparticles. Reaction conditions, such as addition of poly(vinylpyrrolidone) and concentration of HAuCl4, were found to affect the size of gold nanoparticles. Products were characterized by Fourier-transform infrared (FT-IR) and X-ray diffraction (XRD) spectroscopies. The synthesized PoPD submicrosphere-supported gold nanoparticles with different size were used to evaluate their catalytic performances for benzyl alcohol. Results revealed that PoPD submicrosphere-supported gold nanoparticles showed high yield and selectivity for benzyl alcohol to aldehyde conducted under air and in water media. The factors, such as catalyst size and amount, solvent, temperature, alkali type, and reaction time, were all systematically investigated to elucidate their effects on the yield and selectivity of catalytic benzyl alcohol reactions.

Powerful reactive sorption of silver(I) and mercury(II) onto poly(o-phenylenediamine) microparticles

The strong adsorbability of Ag(I) and Hg(II) ions onto fine poly(o-phenylenediamine) (PoPD) microparticles synthesized through a chemically oxidative polymerization of o-phenylenediamine was systematically examined and PoPD/Ag nanocomposites were facilely prepared through the reactive sorption method. The effect of the (NH4)2S2O8 oxidant/o-phenylenediamine monomer ratio on the polymerization yield, macromolecular structure, conductivity, and insolubility of the PoPD microparticles was studied. The Ag(I) adsorbability of the microparticles was significantly optimized by varying the oxidant/monomer ratio, doping state, Ag(I) concentration, sorption time, and solution pH. The Ag(I) adsorbance steadily increases with changing oxidant/monomer molar ratio from 3/1 to 1/1, reaching up to the highest Ag(I) adsorbance of 533 mg.g(-1) at the oxidant/monomer ratio of 1/1. The sorption process fits the pseudosecond-order kinetics. The sorption is rapid because both the adsorbance and adsorptivity within 30 min reach up to 76% of the final values. The initial sorption rate of silver ions obtained from the pseudosecond-order equation is 12.9 mg.g(-1).min(-1). The highest adsorptivity of silver ions is up to 99.1%. The optimal solution pH for Ag(I) sorption is around 5.0. The sorption mechanism may include the chelation and redox reaction between Ag(I) ions and amine/imine groups on the PoPD chains. Similarly, the microparticles also have powerful Hg(II) adsorbability with 96.7% adsorptivity at an initial Hg(II) concentration of 4 mM. Competitive sorption between Ag(I) and Hg(II) in their mixture solution onto the microparticles was studied, exhibiting a preferential sorption toward Ag(I). The microparticles as a cost-effective sorbent demonstrate a promising application in the removal and even recovery of heavy-metal ions from wastewater. The PoPD/Ag nanocomposites possess (1) high Ag content of 34.8 wt %, (2) small diameter of Ag nanoparticles of around 10-20 nm, (3) narrow size distribution, (4) intrinsic electrical conductivity that is much higher than that of original PoPD microparticles without Ag.