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Xin-Gui Li

Publications and source records attributed to Xin-Gui Li.

6 recordsLinked to original sources
PubMed2006

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.

Adsorption↗
PubMed2006

Facile synthesis and optimization of conductive copolymer nanoparticles and nanocomposite films from aniline with sulfodiphenylamine.

A new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine-4-sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV-visible spectroscopy, X-ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above-mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought-after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90x10(-4) to 1.15x10(-2) S cm(-1) with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98% of the transparency, 94% of the strength, and 5x10(7) times the conductivity of a pure cellulose diacetate film.

Journal Article↗
PubMed2005

Simple synthesis of aminoquinoline/ethylaniline copolymer semiconducting nanoparticles.

Pure copolymer nanoparticles from 8-aminoquinoline (AQ) and 2-ethylaniline (EA) were easily synthesized by a chemically oxidative polymerization in three different aqueous media. The potential and temperature of polymerization solution were used to successfully follow the polymerization progress. The molecular and morphological structures of the resulting AQ/EA copolymer particles were systematically characterized by IR, UV/Vis, NMR, gel permeation chromatography, laser particle-size analysis, atomic force and transmission electron microscopy. The oxidation potential of the monomers as well as the polymerization yield, structure, and properties of the particles were found to significantly depend on AQ/EA ratio, polymerization temperature and medium. It is surprisingly found that AQ homopolymerization and AQ/EA (50:50) copolymerization at 5 degrees C in HCl simply afford nano-ellipsoids with the major/minor axis diameters of 24/14 nm and 80/67 nm, respectively. A simple method of synthesizing semiconducting pure nanoparticles by introducing the AQ units with positively charged quaternary ammonium groups but in the absence of adscititious stabilizer or sulfonic substituent on the monomers is established first. Both the molecular weight and bulk electroconductivity of the copolymers exhibit a maximum at AQ content of 10 mol %. The solubility and film formability of the copolymers are good in highly polar solvents and reach the optimal at the AQ content of 20 and 10 mol %, respectively.

Journal Article↗
PubMedDate not supplied

Synthesis of electroconducting narrowly distributed nanoparticles and nanocomposite films of orthanilic acid/aniline copolymers.

A unique strategy for synthesis of narrowly distributed and inherently self-stabilized copolymer nanoparticles by a simple emulsifier-free polymerization from orthanilic acid and aniline was developed. The polymerization yield, electrical conductivity, size, and its distribution of the nanoparticles could be simultaneously optimized by facilely regulating the comonomer ratio, oxidant/comonomer ratio, polymerization temperature, and time. In particular, the nanoparticles evermore exhibit a size polydispersity index down to 1.066 and strong redispersibility in water or polymer solutions. This facile synthesis of functional nanoparticles using orthanilic acid as vital comonomer readily affords yields up to 80%. A low percolation threshold of the nanoparticles/cellulose diacetate and poly(vinyl alcohol) nanocomposite films was found to be 0.18 and 0.07 wt %, respectively. This study opens a simple and general route for fabrication of nanostructured polymer materials with controllable size, narrow size distribution, intrinsic self-stability, strong dispersibility, high purity, and regulable electroconductivity.

Aniline Compounds↗
PubMedDate not supplied

Optimization of polymerization conditions of furan with aniline for variable conducting polymers.

A high-throughput multiparameter optimization of chemical oxidative polymerization conditions has been developed for a facile synthesis of furan homopolymers and furan/aniline copolymers using a combinatorial method. The polymerization yield, molecular structure, and properties of the polymers would be optimized against typical polymerization parameters, including oxidant species, medium species, temperature, oxidant/monomer ratio, monomer concentration, dopant concentration, and furan/aniline comonomer ratio. The electrical conductivity, lead ion adsorptivity, chemical resistance, and thermal behavior of the polymers were also elaborated. It is found that only a combination of FeCl(3) and nitromethane as oxidant and medium, respectively, is appropriate for the furan homopolymerization. The homopolymerization yield increases consistently with an increase in the monomer concentration from 0.05 to 0.2 M and the FeCl(3)/furan molar ratio from 0.25 to 1.25. Although the as-prepared polyfuran exhibits very low conductivity, down to 10(-11) S cm(-1), the HCl- and HClO(4)-doped polyfurans possess much higher conductivities of 9.2 x 10(-8) and 2.38 x 10(-5) S cm(-1), respectively. In addition, the conductivity of the furan/aniline copolymer rises steadily with increasing aniline content, although the copolymerization yield shows a minimum at the furan/aniline molar ratio of 60/40, which is evidence of the occurrence of a real copolymerization between the furan and aniline monomers. The difficulty of synthesizing conducting polyfuran could be overcome to some extent by the polymerization in an appropriate condition optimized in this study. Particularly, the difficulty of synthesizing poly(furan-co-aniline) having much higher conductivity than the polyfuran would be largely conquered by chemical oxidative copolymerization of furan with aniline.

Aniline Compounds↗