A soluble ladder copolymer from m-phenylenediamine and ethoxyaniline

Fabrication and Formation Mechanism of Ag Nanoplate-Decorated Nanofiber Mats and Their Application in SERS

We report a new simple method to fabricate a highly active SERS substrate consisting of poly-m-phenylenediamine/polyacrylonitrile (PmPD/PAN) decorated with Ag nanoplates. The formation mechanism of Ag nanoplates is investigated. The synthetic process of the Ag nanoplate-decorated PmPD/PAN (Ag nanoplates@PmPD/PAN) nanofiber mats consists of the assembly of Ag nanoparticles on the surface of PmPD/PAN nanofibers as crystal nuclei followed by in situ growth of Ag nanoparticles exclusively into nanoplates. Both the reducibility of the polymer and the concentration of AgNO3 are found to play important roles in the formation and the density of Ag nanoplates. The optimized Ag nanoplates@PmPD/PAN nanofiber mats exhibit excellent activity and reproducibility in surface-enhanced Raman scattering (SERS) detection of 4-mercaptobenzoic acid (4-MBA) with a detection limit of 10(-10)  m, making the Ag nanoplates@PmPD/PAN nanofiber mats a promising substrate for SERS detection of chemical molecules. In addition, this work also provides a design and fabrication process for a 3D SERS substrate made of a reducible polymer with noble metals.

Sustainable synthesis of hollow Cu-loaded poly(m-phenylenediamine) particles and their application for arsenic removal

A new Cu-catalyzed air oxidation method was successfully developed to prepare Cu-loaded poly(m-phenylenediamine) (PmPD) with monomer conversion rates close to 100%.

Synthesis of semiconducting polymer microparticles as solid ionophore with abundant complexing sites for long-life Pb(II) sensors

Intrinsically electrically semiconducting microparticles of semiladder poly(m-phenylenediamine-co-2-hydroxy-5-sulfonic aniline) structures containing abundant functional groups, like -NH-, -N=, -NH2, -OH, -SO3H as complexation sites, were efficiently synthesized by chemical oxidative copolymerization of m-phenylenediamine and 2-hydroxy-5-sulfonic aniline. The obtained copolymers were found to be nonporous spherical microparticles that were able to achieve greater π-conjugated structure, smaller particle aggregate size, and stronger interaction with Pb(II) ions than poly(m-phenylenediamine) containing only -NH-, -N=, and -NH2. A potentiometric Pb(II) sensor was fabricated on the basis of the copolymer microparticles as a crucial solid ionophore component within plasticized PVC. The sensor exhibited a Nernstian response to Pb(II) ions over a wide concentration range, together with a fast response, a wide pH range capability, a long lifetime of up to 5 months, and good selectivity over a wide variety of other ions and redox species. The process for synthesizing the microparticles and fabricating the Pb(II)-sensor can be facilely scaled-up for use in the straightforward long-term online monitoring of Pb(II) ions in heavily polluted wastewaters. This study develops an understanding of the facile synthesis of conducting microparticles bearing many functional groups and their structures governing the potentiometric susceptibility toward interaction between Pb(II) ions and the microparticles for fabricating robust long-lived Pb(II)-sensor, signifying the potential suitability of such novel materials for inexpensive sensitive detection of Pb(II) ions.

High-yield synthesis of poly(m-phenylenediamine) hollow nanostructures by a diethanolamine-assisted method and their enhanced ability for Ag+ adsorption

DEA induces the formation of PmPD hollow nanostructures which exhibit improved adsorption performance.

Reactive sorption of mercury(II) on to poly(m-phenylenediamine) microparticles

Poly(m-phenylenediamine) (PmPD) microparticles, from the monomer with two amino groups, were synthesized through chemical oxidation, and the strong adsorbability of mercury ions on to PmPD was systematically examined. The results revealed a rapid adsorption process with an equilibrium time of 30 minutes. Also, the adsorption behaviour showed that the adsorption kinetics was in good agreement with the pseudo-second-order equation. The maximum uptake capacity for mercury (Q(max)) reached approximately 955 mg g(-1) at 0.02 M NaNO3 and 25 degrees C, which decreased appreciably with the increasing of salt concentration. The amount of mercury sorbed at equilibrium steadily increased as the temperature rose from 25 to 45 degrees C, which can be indicative of an endothermic process. The pH value of the solution seemed to exhibit little influence on the adsorption capacity. The adsorption mechanisms, including Hg2+ complexation with nitrogen and ion exchange between Hg2+ and H+ on PmPD chains, are proposed on the basis of Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis.

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.

Efficient multicyclic sorption and desorption of lead ions on facilely prepared poly(m-phenylenediamine) particles with extremely strong chemoresistance

Nitric acid, hydrochloric acid and EDTA were carefully chosen as desorbent to systematically evaluate the adsorption/desorption performance of the Pb(2+)-adsorbing fine microparticles of poly(m-phenylenediamine). The sorption/desorption efficiency was maximized by optimizing desorption condition including the desorbent concentration, contact time, and desorption mode. The variation of the solution pH with Pb(2+) desorption was recorded to speculate the desorption mechanism. The practical reusability of the microparticles was elaborated through the sorption-desorption cycle experiments in an optimum condition. It was found that the desorption was very rapid with an equilibrium time of several minutes. A strong dependence of the desorbability on the species and concentration of the desorbents was observed. When 20 mM EDTA was chosen as the desorbent, the highest desorptivity was up to 94.2% that was much higher than those using nitric and hydrochloric acids. A successive sorption-desorption study employing nitric acid indicated that the microparticles could be simply regenerated and reutilized for more than 5 cycles together with Pb(2+) re-adsorption efficiency of about 50% and accumulative Pb(2+) adsorption capacity of up to 720.4 mg L(-1). Facilely prepared, extremely chemoresistant and cost-effective PmPD microparticles would be potentially used for multicyclic sorption of lead ions from aqueous solution.

Rapid and Effective Adsorption of Lead Ions on Fine Poly(phenylenediamine) Microparticles

Fine microparticles of poly(p-phenylenediamine) (PpPD) and poly(m-phenylenediamine) (PmPD) were directly synthesized by a facile oxidative precipitation polymerization and their strong ability to adsorb lead ions from aqueous solution was examined. It was found that the degree of adsorption of the lead ions depends on the pH, concentration, and temperature of the lead ion solution, as well as the contact time and microparticle dose. The adsorption data fit the Langmuir isotherm and the process obeyed pseudo-second-order kinetics. According to the Langmuir equation, the maximum adsorption capacities of lead ions onto PpPD and PmPD microparticles at 30 degrees C are 253.2 and 242.7 mg g(-1), respectively. The highest adsorptivity of lead ions is up to 99.8 %. The adsorption is very rapid with a loading half-time of only 2 min as well as initial adsorption rates of 95.24 and 83.06 mg g(-1) min(-1) on PpPD and PmPD particles, respectively. A series of batch experiment results showed that the PpPD microparticles possess an even stronger capability to adsorb lead ions than the PmPD microparticles, but the PmPD microparticles, with a more-quinoid-like structure, show a stronger dependence of lead-ion adsorption on the pH and temperature of the lead-ion solution. A possible adsorption mechanism through complexation between Pb(2+) ions and ==N-- groups on the macromolecular chains has been proposed. The powerful lead-ion adsorption on the microparticles makes them promising adsorbents for wastewater cleanup.