Synthesis of poly(1,5-diaminonaphthalene) microparticles with abundant amino and imino groups as strong adsorbers for heavy metal ions.

Poly(1,5-diaminonaphthalene) microparticles with abundant reactive amino and imino groups on their surface were synthesized by one-step oxidative polymerization of 1,5-diaminonaphthalene using ammonium persulfate as the oxidant. The molecular, supramolecular, and morphological structures of the microparticles were systematically characterized by IR and UV-vis spectroscopies, elementary analysis, wide-angle X-ray diffractometry, and transmission electron microscopy. The microparticles demonstrate electrical semiconductivity and high resistance to strong acid and alkali, and strong adsorption capability for lead(II), mercury(II), and silver(I) ions. The experimental conditions for adsorption of Pb(II) were optimized by varying the persulfate/monomer ratio, adsorption time, sorbent concentration, and pH value of the Pb(II) solution. The maximum adsorption capacity is 241 mg·g-1 for particles after a 24 h-exposure to a solution at an initial Pb(II) concentration of 29 mM. The adsorption data fit a Langmuir isotherm and follow a pseudo-second-order reaction kinetics. This indicates a chemical adsorption that is typical for a chelation interaction between Pb(II) and amino/imino groups on the sorbent. Graphical abstract Poly(1,5-diaminonaphthalene) microparticles with abundant functional amino and imino groups have been synthesized by one-step direct polymerization of non-volatile 1,5-diaminonaphthalene in aqueous medium for sustainable preparation of high-performance adsorbents to strongly adsorb lead(II), mercury(II), and silver(I) ions.

High energy-efficiency decomplexation of metal-complexes by H*-mediated electro-reduction on hydroxyphenyl Co-porphyrin catalysts.

Electrochemical reduction of metal-organic complex pollutants has been recognized as an environmental benign method that operates at mild condition. However, the selective reduction of metal complexes and energy consumption in cathodic process are still a big challenge. Herein, we found that hydroxyphenyl Co-porphyrin catalyst (CoTH@NG) realizes the highly selective decomplexation of metal-organic complexes by H* -mediated reduction, and simultaneously the impressive recovery efficiency of metal ions. Density functional theory (DFT) confirms the generation and capturing ability of H* on CoTH@NG, verifying the dominant role of H* -mediated reduction in the selective decomplexation of Cu-EDTA. CoTH@NG realizes the superior energy efficiency for Cu-EDTA removal (279.3 g kWh-1 of EEOCu-EDTA) and Cu recovery (48.6 g kWh-1 of EEOCu), which are remarkably 3.3 × 102 and 9.7 × 102 times higher than traditional carbon cloth electrode. Moreover, the recovered Cu0(s) nanowires on the electrode surface can be efficiently regenerated in HCOOH by a galvanic reaction through the electron channel of CoTH@NG, regenerating catalytic electrode. This is one of the pioneer studies on H* -mediated electro-reduction decomplexation of metal-complexes, metal recovery, and electrode regeneration on CoTH@NG, which providing a technical strategy for developing efficient electrocatalytic system for pollution control. Environmental Implication Metal complexes is a dramatic increase in the electroplating and mining industries, and seriously affect both public health and environmental sustainability. Our work reported a new hydroxyphenyl Co-porphyrin catalyst (CoTH@NG) which achieves the selective decomplexation of metal-organic complexes, and simultaneously the recovery of metal ions. CoTH@NG realizes the superior energy efficiency for Cu-EDTA removal (279.3 g kWh-1) and Cu0(s) recovery (48.6 g kWh-1), which are remarkably 3.3 × 102 and 9.7 × 102 times higher than traditional carbon cloth electrode. Moreover, the recovered Cu0(s) can be efficiently regenerated in HCOOH by a galvanic reaction through the electron channel of CoTH@NG, regenerating catalytic electrode.

Perspective into ion storage of pristine metal-organic frameworks in capacitive deionization.

Metal-organic frameworks (MOFs), featuring tunable conductivity, tailored pore/structure and high surface area, have emerged as promising electrode nanomaterials for ion storage in capacitive deionization (CDI) and garnered tremendous attention in recent years. Despite the many advantages, the perspective from which MOFs should be designed and prepared for use as CDI electrode materials still faces various challenges that hinder their practical application. This summary proposes design principles for the pore size, pore environment, structure and dimensions of MOFs to precisely tailor the surface area, selectivity, conductivity, and Faradaic activity of electrode materials based on the ion storage mechanism in the CDI process. The account provides a new perspective to deepen the understanding of the fundamental issues of MOFs electrode materials to further meet the practical applications of CDI.

Porphyrin-based covalent organic frameworks from design, synthesis to biological applications.

Covalent organic frameworks (COFs) constitute a class of highly functional porous materials composed of lightweight elements interconnected by covalent bonds, characterized by structural order, high crystallinity, and large specific surface area. The integration of naturally occurring porphyrin molecules, renowned for their inherent rigidity and conjugate planarity, as building blocks in COFs has garnered significant attention. This strategic incorporation addresses the limitations associated with free-standing porphyrins, resulting in the creation of well-organized porous crystal structures with molecular-level directional arrangements. The unique optical, electrical, and biochemical properties inherent to porphyrin molecules endow these COFs with diversified applications, particularly in the realm of biology. This review comprehensively explores the synthesis and modulation strategies employed in the development of porphyrin-based COFs and delves into their multifaceted applications in biological contexts. A chronological depiction of the evolution from design to application is presented, accompanied by an analysis of the existing challenges. Furthermore, this review offers directional guidance for the structural design of porphyrin-based COFs and underscores their promising prospects in the field of biology.

Lead-ion potentiometric sensor based on electrically conducting microparticles of sulfonic phenylenediamine copolymer.

A potentiometric sensor to detect lead ions using newly synthesized conducting copolymer microparticles as an ionophore in self-supporting poly(vinyl chloride) membrane matrix plasticized with dioctyl phthalate was developed. The copolymer microparticles containing many ligating functional groups including amino, imino and sulfonic groups were synthesized by a chemical oxidative copolymerization of m-phenylenediamine (mPD) and p-sulfonic-m-phenylenediamine (SPD) in pure water. Due to the presence of -NH-, -N=, -NH2, and -SO3H ligating groups on the microparticles, a linear Nernstian response is obtained within a Pb(II) activity range from 1.00 × 10(-6) M to 1.00 × 10(-3) M. The Pb(II)-sensor containing the mPD/SPD (95/5) copolymer microparticles with the maximal electrical conductivity demonstrates a superior detection limit down to 1.26 × 10(-7) M, short response time to 14 s, and long lifetime of up to 4 months. The Pb(II)-sensor also exhibits a selective response to Pb(II) over 9 other metal ions and a pH independent plateau between 2.7 and 5.0. These advantages could make for a robust sensor performing credible analysis of Pb(II) concentration in real-world samples at trace levels.

Soft-hard interface design in super-elastic conductive polymer hydrogel containing Prussian blue analogues to enable highly efficient electrochemical deionization.

The poor cycling stability of faradaic materials owing to volume expansion and stress concentration during faradaic processes limits their use in large-scale electrochemical deionization (ECDI) applications. Herein, we developed a "soft-hard" interface by introducing conducting polymer hydrogels (CPHs), that is, polyvinyl alcohol/polypyrrole (PVA/PPy), to support the uniform distribution of Prussian blue analogues (e.g., copper hexacyanoferrate (CuHCF)). In this design, the soft buffer layer of the hydrogel effectively alleviates the stress concentration of CuHCF during the ion-intercalation process, and the conductive skeleton of the hydrogel provides charge-transfer pathways for the electrochemical process. Notably, the engineered CuHCF@PVA/PPy demonstrates an excellent salt-adsorption capacity of 22.7 mg g-1 at 10 mA g-1, fast salt-removal rate of 1.68 mg g-1 min-1 at 100 mA g-1, and low energy consumption of 0.49 kW h kg-1. More importantly, the material could maintain cycling stability with 90% capacity retention after 100 cycles, which is in good agreement with in situ X-ray diffraction tests and finite element simulations. This study provides a simple strategy to construct three-dimensional conductive polymer hydrogel structures to improve the desalination capacity and cycling stability of faradaic materials with universality and scalability, which promotes the development of high-performance electrodes for ECDI.

Ultrasensitive Pb(II) potentiometric sensor based on copolyaniline nanoparticles in a plasticizer-free membrane with a long lifetime.

A newly designed Pb(II) potentiometric sensor based on intrinsically conducting nanoparticles of solid poly(aniline-co-2-hydroxy-5-sulfonic aniline) possessing many ligating functional groups like -NH-, -N=, -OH, -SO(3)H, -NH(2) as ionophores in plasticizer-free vinyl resin solid membranes has been fabricated. A linear Nernstian response is obtained within a wide Pb(II) activity range from 1.0 × 10(-3) to 1.0 × 10(-10) M with a detection limit as low as 2.2 × 10(-11) M. The pH independent plateau ranges between 3.5 and 7.0. After 15 months' usage, the sensor maintains 95% performance parameters. Its anti-interference ability to Cu(II), Cd(II), Ag(I), and Hg(II) is much stronger than other sensors with a detection limit at (sub)nanomolar level. Electrochemical impedance spectroscopy reveals that the solid sensing membrane has a diffusion coefficient of around 5 × 10(-14) to 1 × 10(-13) cm(2) s(-1). The much lower diffusion coefficient for Pb(II) is highly beneficial for the elimination of Pb(II) flux across the membrane. The wide detection concentration range, low detection limit, high selectivity, extensive pH window, and long lifetime make for a robust sensor giving reliable measurement of Pb(II) content with potential application in real-world samples at trace levels.

Interfacial synthesis and functionality of self-stabilized polydiaminonaphthalene nanoparticles.

A simple and effective template-free synthesis method for nanosized conducting polymers with self-stability and functionality is a main challenge. Herein, a strategy is reported for the facile synthesis of poly(1,5-diaminonaphthalene) nanospherical particles by an interfacial miniemulsion oxidative polymerization of 1,5-diaminonaphthalene at mobile microinterfaces between a stirred biphase without external emulsifiers. The size of the nanospheres was carefully optimized by controlling the polymerization conditions. Formation and self-stabilization mechanisms of the nanoparticles are proposed. The constantly movable and refreshed microinterface is a key to successful synthesis of the nanospheres, for significantly suppressing secondary growth leading to agglomerated particles because vigorous stirring makes as-formed self-stabilized nanospheres instantly leave the microinterfaces. The resulting nanospheres possess several advantages: clean surface, self-stability, redispersibility, semiconductivity, electroactivity, and fluorescence emission. The fluorescence emission can be quenched by specific quenchers, thus enabling low-cost, high-performance chemosensors to be obtained for the sensitive detection of Zn(II) ions in a wide linear concentration range of more than five orders of magnitude with a superior detection limit down to 1 nM.

Carbon nanotube/polyaniline composite nanofibers: facile synthesis and chemosensors.

An initiator is applied to synthesize single-walled carbon nanotube/polyaniline composite nanofibers for use as high-performance chemosensors. The composite nanofibers possess widely tunable conductivities (10(-4) to 10(2) S/cm) with up to 5.0 wt % single-walled carbon nanotube (SWCNT) loadings. Chemosensors fabricated from the composite nanofibers synthesized with a 1.0 wt % SWCNT loading respond much more rapidly to low concentrations (100 ppb) of HCl and NH(3) vapors compared to polyaniline nanofibers alone (120 s vs 1000 s). These nanofibrillar SWCNT/polyaniline composite nanostructures are promising materials for use as low-cost disposable sensors and as electrodes due to their widely tunable conductivities.

Hormetic dose-response of halogenated organic pollutants on Microcystis aeruginosa: Joint toxic action and mechanism.

Quinolones (QNs), dechloranes (DECs), and chlorinated paraffins (CPs) are three kinds of new halogenated organic pollutants (HOPs), which originate from the use of flame retardants, lubricants and pesticides. Since QNs, DECs, and CPs are frequently detected in waters and sediments, it is necessary to investigate the toxic effects of these HOPs with dwelling phytoplankton, especially for cyanobacteria, to explore their potential hormetic effects and contributions to algal blooms. In the present study, we investigate single and joint toxicity of QNs, DECs and CPs on Microcystis aeruginosa (M. aeruginosa), a cyanobacterium that is frequently implicated with algal blooms. The results indicate single QNs and DECs induce marked hormetic effects on the proliferation of M. aeruginosa but CPs do not. The stimulatory effect of hormesis is linked with accelerated replication of DNA, which is considered to stem from the moderate rise in intracellular reactive oxygen species (ROS). Joint toxicity tests reveal that both QNs & CPs mixtures and DECs & CPs mixtures show hormetic effects on M. aeruginosa, but QNs & DECs mixtures show no hormetic effect. QNs & DECs mixtures exhibit synergistic toxic actions, which may be caused by a sharp rise in intracellular ROS simultaneously produced by the agents. Joint toxic actions of both QNs & CPs, and DECs & CPs shift from addition to antagonism as concentration increases, and this shift may mainly depend on the influence of CPs on cell membrane hydrophobicity of M. aeruginosa. This study provides data and toxic mechanisms for the hormetic phenomenon of single and joint HOPs on M. aeruginosa. The hormetic effects of HOPs may benefit the proliferation of M. aeruginosa in the aquatic environment, aggravating the formation of algal blooms. This study also reflects the important role of hormesis in environmental risk assessment of pollutants.

Investigations on the influence of energy source on time-dependent hormesis: A case study of sulfadoxine to Aliivibrio fischeri in different cultivation systems.

Hormesis is a biphasic dose-response relationship featured by low-dose stimulation and high-dose inhibition. Although the hormetic phenomenon has been extensively studied over the past decades, there is little information regarding the influence of energy source on the occurrence of hormesis, especially the time-dependent one. In this study, to explore the role of cultivation system's energy source in time-dependent hormesis, the toxic dose-responses of Aliivibrio fischeri (A. fischeri) bioluminescence to Sulfadoxine (SDX) during 24 h were determined in four cultivation systems with different energy source conditions. The results indicated that the time-dependent hormetic effects were induced by SDX in all cultivation systems: SDX triggered hormetic phenomenon on the bioluminescence at each growth stage over 24 h in the cultivation systems with sufficient and insufficient energy source; due to the diauxic growth of A. fischeri under multiple energy source conditions, the hormetic effects of SDX gradually disappeared after the preferred energy source was used up. It was speculated that the inhibitory action of SDX was derived from its interaction with DHPS to impede the synthesis of proteins, and SDX bound with AC to upregulate the quorum sensing (QS) system to exhibit the stimulatory action. Comparing the time-dependent hormesis in each cultivation system, it was obtained that the energy source could impact the hourly maximum stimulatory rate, the EC50 of SDX, and the time point that hormesis occurred, which might result from the influence of energy source on the stimulatory and inhibitory actions of SDX through regulating the metabolic system (individual level) and QS system (group level) of bacteria. This study clarifies the importance of energy source for hormesis occurrence, which may further promote the development of hormesis.

Purely Organic Room-Temperature Phosphorescence Endowing Fast Intersystem Crossing from Through-Space Spin-Orbit Coupling.

Purely organic room-temperature phosphorescence endowing very fast intersystem crossing from through-space systems has not been well investigated. Here we report three space-confined bridged phosphors, where phenothiazine is linked with dibenzothiophene, dibenzofuran, and carbazole by a 9,9-dimethylxanthene bridge. Nearly pure phosphorescence is observed in the crystals at room temperature. Interestingly, phosphorescence comes solely from the phenothiazine segment. Experimental results indicate that bridged counterparts of dibenzothiophene, dibenzofuran, and carbazole contribute as close-lying triplet states with locally excited (LE) character. The through-space spin-orbit coupling principle is proposed in these bridged systems, as their 1LE and 3LE states have intrinsic spatial overlap, degenerate energy levels, and tilting face-to-face alignment. The resulting effective through-space spin-orbit coupling leads to efficient intersystem crossing a with rate constant as high as 109 s-1 and an overwhelming triplet decay channel of the singlet excited state.

Redox sorption and recovery of silver ions as silver nanocrystals on poly(aniline-co-5-sulfo-2-anisidine) nanosorbents.

Poly[aniline(AN)-co-5-sulfo-2-anisidine(SA)] nanograins with rough and porous structure demonstrate ultrastrong adsorption and highly efficient recovery of silver ions. The effects of five key factors-AN/SA ratio, Ag(I) concentration, sorption time, ultrasonic treatment, and coexisting ions-on Ag(I) adsorbability were optimized, and AN/SA (50/50) copolymer nanograins were found to exhibit much stronger Ag(I) adsorption than polyaniline and all other reported sorbents. The maximal Ag(I) sorption capacity of up to 2034 mg g(-1) (18.86 mmol g(-1)) is the highest thus far and also much higher than the maximal Hg-ion sorption capacity (10.28 mmol g(-1)). Especially at or=99.98 % adsorptivity, and thus achieve almost complete Ag(I) sorption. The sorption fits the Langmuir isotherm well and follows pseudo-second-order kinetics. Studies by IR, UV/Vis, X-ray diffraction, polarizing microscopy, centrifugation, thermogravimetry, and conductivity techniques showed that Ag(I) sorption occurs by a redox mechanism mainly involving reduction of Ag(I) to separable silver nanocrystals, chelation between Ag(I) and -NH-/-N=/-NH(2)/-SO(3)H/-OCH(3), and ion exchange between Ag(I) and H(+) on -SO(3) (-)H(+). Competitive sorption of Ag(I) with coexisting Hg, Pb, Cu, Fe, Al, K, and Na ions was systematically investigated. In particular, the copolymer nanoparticles bearing many functional groups on their rough and porous surface can be directly used to recover and separate precious silver nanocrystals from practical Ag(I) wastewaters containing Fe, Al, K, and Na ions from Kodak Studio. The nanograins have great application potential in the noble metals industry, resource reuse, wastewater treatment, and functional hybrid nanocomposites.

Simple efficient synthesis of strongly luminescent polypyrene with intrinsic conductivity and high carbon yield by chemical oxidative polymerization of pyrene.

A wholly aromatic polypyrene was synthesized by direct chemical oxidative polymerization of pyrene with ferric chloride as oxidant in hexane/nitromethane. Successful synthesis of polypyrene was thoroughly confirmed by IR, UV/Vis, 1D (1)H NMR, 2D (1)H-(1)H COSY, 2D (1)H-(13)C HSQC, MALDI-TOF MS, elemental analysis, and X-ray diffraction methods. The results indicated that the polypyrene was formed mainly through dehydro coupling between 2- or 1- and 2'- or 1'-positions on pyrene rings having a degree of polymerization of around 24. The polypyrene was purified and then separated into THF-soluble (ca. 10 %) and THF-insoluble (ca. 90 %) fractions. Compared with insulating pyrene monomer, the polypyrene is a controllably conducting polymer that has low conductivity of 3.4x10(-8) S cm(-1) in its virgin state, moderate conductivity of 2.28x10(-4) S cm(-1) upon iodine doping, but much higher conductivity of up to 81.2 S cm(-1) after the insoluble polypyrene was heated up to 1300 degrees C in nitrogen with a high char yield of 70.6 %. In particular, the soluble polypyrene demonstrates much stronger visible color fluorescence and much lower toxicity than pyrene. The soluble polypyrene would be advantageous for detecting Fe(3+) with almost no interference of other metal ions. The soluble and insoluble polypyrene fractions have potential applications as intrinsically luminescent and highly conducting carbon materials, respectively.

Highly emissive phenylene-expanded [5]radialene.

A pentagonal macrocycle (MC5-PER) with radialene topology was facilely synthesized through a selective one-pot Suzuki-Miyaura cross-coupling reaction. The resulting product is endowed with a pentagonal architecture as revealed by its single crystal structure, which affords the smallest ring strain and the best conjugation. As tetraphenylethene subunits are embedded, MC5-PER is highly emissive in the solid state due to the aggregation-induced emission effect. Because of the flexible structure and preferable fibre-like self-assembly, the aggregate of MC5-PER displays interesting polymorphism-dependent emission and acts as a sensitive fluorescence sensor for explosives detection.

Strong adsorbability of mercury ions on aniline/sulfoanisidine copolymer nanosorbents.

The highest Hg-ion adsorbance so far, namely up to 2063 mg g(-1), has been achieved by poly(aniline-co-5-sulfo-2-anisidine) nanosorbents. Sorption of Hg ions occurs mainly by redox and chelation mechanisms (see scheme), but also by ion exchange and physisorption.Poly(aniline (AN)-co-5-sulfo-2-anisidine (SA)) nanoparticles were synthesized by chemical oxidative copolymerization of AN and SA monomers, and their extremely strong adsorption of mercury ions in aqueous solution was demonstrated. The reactivity ratios of AN and SA comonomers were found to be 2.05 and 0.02, respectively. While AN monomer tends to homopolymerize, SA monomer tends to copolymerize with AN monomer because of the great steric hindrance and electron-attracting effect of the sulfo groups, despite the effect of conjugation of the methoxyl group with the benzene ring. The effects of initial mercury(II) concentration, sorption time, sorption temperature, ultrasonic treatment, and sorbent dosage on mercury-ion sorption onto AN/SA (50/50) copolymer nanoparticles with a number-average diameter of around 120 nm were significantly optimized. The results show that the maximum Hg-ion sorption capacity on the particulate nanosorbents can even reach 2063 mg of Hg per gram of sorbent, which would be the highest Hg-ion adsorbance so far. The sorption data fit to the Langmuir isotherm, and the process obeys pseudo-second-order kinetics. The IR and UV/Vis spectral data of the Hg-loaded copolymer particles suggest that some mercury(II) was directly reduced by the copolymer to mercury(I) and even mercury(0). A mechanism of sorption between the particles and Hg ions in aqueous solution is proposed, and a physical/ion exchange/chelation/redox sorption ratio of around 2/3/45/50 was found. Copolymer nanoparticles may be one of the most powerful and cost-effective sorbents of mercury ions, with a wide range of potential applications for the efficient removal and even recovery of the mercury ions from aqueous solution.

Facile optimal synthesis of inherently electroconductive polythiophene nanoparticles.

The straight dope: Polythiophene (PTh) nanoparticles with a narrow size distribution were successfully synthesized by a chemical oxidative polymerization (see image). The highest conductivity of virgin PTh is 3.1x10(-4) S cm(-1) and can be dramatically enhanced to 50 S cm(-1) by doping in iodine vapor.Polythiophene (PTh) nanoparticles were successfully synthesized by a simple chemical oxidative polymerization in the presence of a very small amount of cetyltrimethylammonium bromide (CTAB). The polymerization yield, particle size, bulk electrical conductivity, and solubility of the PTh nanoparticles have been optimized by adjusting the CTAB/FeCl(3) oxidant/thiophene monomer ratio, thiophene concentration, polymerization temperature, and reaction time. The structure of the PTh nanoparticles was systematically characterized by IR and UV/Vis spectroscopy, wide-angle X-ray diffraction, laser particle-size analysis, field-emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that the number-average diameter (D(n)) and size polydispersity index (PDI) of the particles decrease significantly from 4.19 microm and 1.21 to 203 nm and 1.056, respectively, with a slightly increasing CTAB concentration. SEM and TEM reveal that the PTh particle size is reduced to 67 and 36 nm, respectively. The conductivity increases on raising the FeCl(3)/thiophene ratio or on lowering the CTAB concentration and polymerization temperature. A moderate monomer concentration and polymerization time are very beneficial for achieving highly conducting PTh. The highest conductivity of virgin PTh is 3.1x10(-4) S cm(-1) and can be further elevated to 50 S cm(-1) by doping in iodine vapor. Under optimized polymerization conditions, the significant variation of the conductivity of the PTh particles in virgin and doped states was well confirmed by the intensity and wavelength of the UV/Vis spectral band owing to the large pi conjugation. The PTh particles demonstrate uncommon characteristics including easy synthesis, low cost of production, large pi-conjugated structure, high conductivity, solution processability, and extensive potential for further application.

Interfacial synthesis and widely controllable conductivity of polythiophene microparticles.

Fine polythiophene (PTh) microparticles were successfully synthesized by a novel interfacial polymerization at a dynamic interface between two immiscible solvents, i.e., n-hexane and acetonitrile or nitromethane containing thiophene and oxidant, respectively. The polymerization yield, size, and electrical conductivity of the microparticles are optimized by facilely regulating the medium species, oxidant species, oxidant/monomer ratio, monomer concentration, and polymerization temperature. The microparticles were thoroughly characterized by IR, UV-vis spectroscopy, wide-angle X-ray diffractometry, laser particle-size analyzer, and simultaneous TG-DSC technique. The yield rises with increasing oxidant/monomer ratio, monomer concentration, and polymerization temperature. However, low monomer concentration, low polymerization temperature, and modest oxidant/monomer ratio are all favorable for the formation of the PTh with good, large pi-conjugation and high conductivity. With decreasing the thiophene concentration from 200 to 50 mM at a fixed FeCl3/thiophene molar ratio of 3 at 0 degrees C in hexane/nitromethane biphase system, the PTh obtained exhibits a steadily enhanced conductivity from 10(-12) to 0.01 S cm(-1) and gradually darkening color from crimson to black. Under the same conditions, the PTh obtained in hexane/acetonitrile usually possesses lower yield but higher conductivity than that in hexane/nitromethane. The conductivity will be further enhanced to 1.1 and 4.4 S cm(-1) if the PTh powders are doped in iodine vapor and simply carbonized at 25 through 999 degrees C in nitrogen, respectively. The PTh is fine particles with the number-average diameter of 2.67-3.95 microm and low size polydispersity index between 1.12 and 1.23. The black particles carbonized at 25 to 999 degrees C are much smaller than original PTh particles, with the number-average diameter of 279 nm and size polydispersity index of 1.09. This interfacial approach provides an optimal synthesis of unique PTh microparticles with large pi-conjugation, high conductivity, black color, uniform size, good insolubility, excellent infusibility, high thermostability, and high yield of electrically conducting char at 999 degrees C.

Self-stabilized nanoparticles of intrinsically conducting copolymers from 5-sulfonic-2-anisidine.

Novel copolymer nanoparticles with inherent self-stability, narrow size distribution, and high electrical conductivity are facilely and productively synthesized by the oxidative precipitation polymerization of 5-sulfonic-2-anisidine and aniline in acidic medium without any external stabilizer. The structures of the copolymer particles are systematically characterized by IR and UV/Vis spectroscopy, X-ray diffraction, laser particle-size analysis, atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The comonomer ratio, oxidant/monomer ratio, and polymerization temperature and medium can be used to optimize the size and conductivity of the nanoparticles. It is found that the nanoparticles exhibit a minimal size and polydispersity index of around 53 nm and 1.045, respectively. Nanocomposite films of the nanoparticles with diacetyl and ethyl celluloses show good thermostability and a low percolation threshold of 0.08 wt%, at which the films retain 89% of the transparency, 96-98% of the strength, and 10(8) times the conductivity of the matrix film. The synthesis of sulfoanisidine copolymer nanoparticles is thus achieved without the use of external stabilizer, which opens up a simple and general route to the fabrication of nanostructured polymer materials with controllable size, narrow size distribution, intrinsic self-stability, strong dispersibility, high purity, and optimizable electroconductivity.

Facile high-yield synthesis of polyaniline nanosticks with intrinsic stability and electrical conductivity.

Chemical oxidative polymerization at 15 degrees C was used for the simple and productive synthesis of polyaniline (PAN) nanosticks. The effect of polymerization media on the yield, size, stability, and electrical conductivity of the PAN nanosticks was studied by changing the concentration and nature of the acid medium and oxidant and by introducing organic solvent. Molecular and supramolecular structure, size, and size distribution of the PAN nanosticks were characterized by UV/Vis and IR spectroscopy, X-ray diffraction, laser particle-size analysis, and transmission electron microscopy. Introduction of organic solvent is advantageous for enhancing the yield of PAN nanosticks but disadvantageous for formation of PAN nanosticks with small size and high conductivity. The concentration and nature of the acid medium have a major influence on the polymerization yield and conductivity of the nanosized PAN. The average diameter and length of PAN nanosticks produced with 2 M HNO(3) and 0.5 M H(2)SO(4) as acid media are about 40 and 300 nm, respectively. The PAN nanosticks obtained in an optimal medium (i.e., 2 M HNO(3)) exhibit the highest conductivity of 2.23 S cm(-1) and the highest yield of 80.7 %. A mechanism of formation of nanosticks instead of nanoparticles is proposed. Nanocomposite films of the PAN nanosticks with poly(vinyl alcohol) show a low percolation threshold of 0.2 wt %, at which the film retains almost the same transparency and strength as pure poly(vinyl alcohol) but 262 000 times the conductivity of pure poly(vinyl alcohol) film. The present synthesis of PAN nanosticks requires no external stabilizer and provides a facile and direct route for fabrication of PAN nanosticks with high yield, controllable size, intrinsic self-stability, strong redispersibility, high purity, and optimizable conductivity.