A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reac...A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.展开更多
Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with flexibility,easy processability,low cost and especially strong ability to dissolve lithium salts have been regarded as promising alternatives to tradi...Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with flexibility,easy processability,low cost and especially strong ability to dissolve lithium salts have been regarded as promising alternatives to traditional flammable liquid electrolytes in next-generation highsafety and high-energy-density lithium metal batteries.However,the inferior mechanical strength and thermostability of PEO-based SPEs will raise the lithium dendritic penetration issue,further leading to the short circuit in batteries.In this work,aiming at enhancing the interfacial stability against Li dendrites of PEO-based SPEs,poly(mphenylene isophthalamide)(PMIA)is introduced as a reinforcing phase for the rational design of PEO/PMIA composite electrolyte.Impressively,PMIA chain with meta-type benzene-amide linkages significantly improves the mechanical strength(1.60 MPa),thermal stability(260℃)and ability to inhibit the growth of lithium dendrites(>300 h at 0.1 mA·cm^(-2))of SPEs.Meanwhile,allsolid-state LiFePO_(4)‖PEO/PMlA‖Li cell demonstrates superior electrochemical performance in terms of high specific capacity(159.1 mAh·g^(-1)),remarkable capacity retention(82.2%after 200 cycles at 0.5 C)and excellent safety characteristics.No burning or explosion occurs under pressing,bending and cutting conditions.This work opens a new door in developing high-performance PEObased electrolytes for advanced all-solid-state lithium metal batteries.展开更多
A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO)and polybenzimidazole(PBI)for vanadium redox flow battery(VRFB)application.An acid-base pair...A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO)and polybenzimidazole(PBI)for vanadium redox flow battery(VRFB)application.An acid-base pair structure formed between the imidazole of PBI and sulfonic acid of S-L-PPO resulted in lowered swelling ratio.It favors to reduce the vanadium permeation.While,the increased sulfonic acid concentration ensured that proton conductivity was still at a high level.As a result,a better balance between the vanadium ion permeation(6.1×10^-9 cm^2·s^-1)and proton conductivity(50.8 m S·cm^-1)in the S-L-PPO/PBI-10%membrane was achieved.The VRFB performance with S-L-PPO/PBI-10%membrane exhibited an EE of 82.7%,which was higher than those of pristine S-L-PPO(81.8%)and Nafion 212(78.0%)at 120 m A·cm^-2.In addition,the S-LPPO/PBI-10%membrane had a much longer self-discharge duration time(142 h)than that of Nafion 212(23 h).展开更多
The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C0_2, CH_4 and N_2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is fo...The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C0_2, CH_4 and N_2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is found that P, D, and S of the membranes to all the three gases vary with the extent of bromination. S increases with the increase of the percent of bromine in each case, but D to CO_2 increases remarkably only at higher degree of brominafion, and therefore, P to CO_2 is increased by more than 100% over a wide range ofpressure in the case. The solubility data are well described by the dual mode sorption model. It is found that the gas molecules sorbed by the Langmuir mode are relatively more immobilized and the contribution of the nonequilibrinm character of the polymer to gas permeation increases obviously for CO_2 and is hardly changed for CH_4 with increasing bromine content. These observations are interpreted in terms of changes in specific free volume (SFV)and the cohesive energy density (CED) of the polymers.展开更多
This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the ...This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the final product in themixed solvent so that the sulfonation may take place between the bulk solutions and PPO powders even at higher sulfonationdegree. It is shown that the addition of a proper amount of dimethyl formide (DMF) to the conventional PPO-chloroformsystem can actually enhance the sulfonation effect. The solvent composition is then correlated with the sulfonation degreebased on the solubility parameters. It is interesting to find that solubility parameters between the mixed solvent and theprecipitated products keep an approximately unchanged value at about 4.9, which is just equal to that when pure chloroformis used, though the solubility parameters of both solvents increase with the content of DMF in solution. This may be the mainreason why the addition of DMF can reduce the precipitation and improve the ion exchange capacity (IEC) of SPPOpolymer.展开更多
In this paper the percolation theory is employed to study the insulator-to-conductortransition in sulphonated poly（phenylene oxide）（SPPO） polymer membranes.The membranes withdifferent sulphonation degree were prep...In this paper the percolation theory is employed to study the insulator-to-conductortransition in sulphonated poly（phenylene oxide）（SPPO） polymer membranes.The membranes withdifferent sulphonation degree were prepared and infrared characterized.The transition thresholdwas calculated by the experimental data of membrane conductivities and the coordination numberwas thus estimated.The functional group-SO<sub>3</sub>H distribution in the membrane was evaluated inaccordance with the calculations and showed a non-random dispersion on the microscopic scale.展开更多
The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of po...The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.展开更多
Herein,a modified screen printed carbon electrode(SPCE)based on a composite material,graphene oxide-gold nanoparticles(GO-AuNPs),and poly(3-aminobenzoic acid)(P3ABA)for the detection of paraquat(PQ)is introduced.The m...Herein,a modified screen printed carbon electrode(SPCE)based on a composite material,graphene oxide-gold nanoparticles(GO-AuNPs),and poly(3-aminobenzoic acid)(P3ABA)for the detection of paraquat(PQ)is introduced.The modified electrode was fabricated by drop casting of the GO-AuNPs,followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA.The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy(SEM)for each step of modification.The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode.In addition,the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate,which stimulate redox reaction on the modified electrode,thus improving the sensitivity of PQ analysis.The SPCE/GOAuNPs/P3ABA offered a wide linear range of PQ determination(10^(−9)-10^(−4) mol/L)and low limit of detection(LOD)of 0.45×10^(−9) mol/L or 0.116μg/L,which is far below international safety regulations.The modified electrode showed minimum interference effect with percent recovery ranging from 96.5%to 116.1%after addition of other herbicides,pesticides,metal ions,and additives.The stability of the SPCE/GO-AuNPs/P3ABA was evaluated,and the results indicated negligible changes in the detection signal over 9 weeks.Moreover,this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.展开更多
Experiments including C-13 spin-lattice relaxation, C-13 heteronuclear dipolar dephasing and H-1 spin diffusion are performed on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). The results show that the rotation of the...Experiments including C-13 spin-lattice relaxation, C-13 heteronuclear dipolar dephasing and H-1 spin diffusion are performed on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). The results show that the rotation of the methyl groups in solid PPO is partially restricted, which results in a surprisingly efficient spin diffusion between the aromatic proton and methyl proton characterized by a diffusion time of 150 mu s. The results also show that the aromatic ring in solid PPO is rigid and twisted, which causes all aromatic carbons to be chemically unequivalent.展开更多
Sulfate adsorption by poly（m-phenylenediamine）s（PmPDs） with various oxidation states synthesized through chemically oxidative polymerization was investigated.Series of sorption experiments were conducted,and the a...Sulfate adsorption by poly（m-phenylenediamine）s（PmPDs） with various oxidation states synthesized through chemically oxidative polymerization was investigated.Series of sorption experiments were conducted,and the adsorption mechanism and the relationship between oxidation state and adsorption performance were studied with the characterization of Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）,pH tracking and energy calculation.The results show that the adsorption performance in acidic solution is improved with the decrease of oxidation state of poly（m-phenylenediamine）（PmPD）.The rate constant is as high as 425.5 mg/（g·min） in the short equilibrium time of 30 min.The estimated highest adsorptivity of sulfate ions is 95.1%.According to the Langmuir equation,the adsorbance is 108.5 mg/g.The sulfate desorption efficiency is about 95% and the accumulative adsorbance is up to 487.95 mg/g in 5 cycles.展开更多
Electrospun fiber mats (EFM) integrated proteins and biocompatible polymers have been widely used as tissue scaffold, wound dressing and food packaging. The morphology of EFM has strong correlation with the structure ...Electrospun fiber mats (EFM) integrated proteins and biocompatible polymers have been widely used as tissue scaffold, wound dressing and food packaging. The morphology of EFM has strong correlation with the structure and rheology of the solutions. We studied the structure and rheology of polyethylene oxide (PEO) and zein in 80% ethanol aqueous solutions and the resulted EFM. In solutions, zein with rod-like conformation tends to aggregate and form oligomer, the number of proteins in the oligomer spans from 2.5 to 55.2, while PEO always behaves like Gaussian chain in good solvent. Zein preferred to distribute along PEO chains in their mixed solutions, and the structures decomposed from small angle X-ray scattering have consistent relaxation spatial-temporal characteristics with rheological behaviors.Further, the aging of zein solutions enhanced shear thinning and resulted thicker fibers in EFM, which are attributed to the rod-like growth of zein aggregates. Aggregates in viscous media with long enough relaxation time are probably crucial for the formation of continuous electrospun fibers or ribbons. This study provides a clear correlation of the structure, rheology of solutions with the morphologies of EFM made up of proteins and polymers.展开更多
It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease of Molecular weight of the poly(2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) during the pol...It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease of Molecular weight of the poly(2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) during the polymerization, which ultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPV prepared under dry conditions has an external quantum efficiency of above 2.0%.展开更多
The aluminum oxide(AlOx)coatings were deposited on poly(ethylene terephthalate)(PET)surface by reactive magnetron sputtering for improving its barrier property.With O2 flux increasing,three modes including metallic mo...The aluminum oxide(AlOx)coatings were deposited on poly(ethylene terephthalate)(PET)surface by reactive magnetron sputtering for improving its barrier property.With O2 flux increasing,three modes including metallic mode,transition mode and oxide mode exist in sputtering.The properties of the aluminum oxide(AlOx)coatings prepared at different modes were discussed.Also,the influences of oxygen flux on the stoichiometry,structure,gas permeation of the coatings were investigated.The chemical composition of AlOx films fabricated in transition mode is different as oxygen flux varies slightly,and the gas barrier property is better as the stoichiometry is closer to 1.5 with oxygen flux increasing.The coating uniformity,roughness and particle size depend remarkably upon oxygen flux.The coatings deposited at oxide mode have a good barrier performance to oxygen and water,and the permeability to oxygen decreases by sixty times and water vapor ten times compared with uncoated展开更多
A novel copolymer of polyaniline-poly(propylene oxide) (PAN-PPO) was prepared by cyclic voltammetry (CV) and characterized by FTIR and SEM. It showed good electroactivity for methanol oxidation in H2SO4 solution.
Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic ac...Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.展开更多
Cobalt porphyrin complexes （TPPConIX） （TPP = 5,10,15,20-tetraphenyl-porphyrin; X = halide） in combination with bis（triphenylphosphine） iminium chloride （PPNC1） were used for the eopolymerization of cyelohexene...Cobalt porphyrin complexes （TPPConIX） （TPP = 5,10,15,20-tetraphenyl-porphyrin; X = halide） in combination with bis（triphenylphosphine） iminium chloride （PPNC1） were used for the eopolymerization of cyelohexene oxide and CO2. The highest turnover frequency of 67.2 h^-1 was achieved after 13 h at 20℃, and the obtained poly（1,2-cyclohexylene carbonate） （PCHC） showed number average molecular weight （Mn） of 10 × 10^3. Though the obtained PCHC showed atactie structure, the m-centered tetrads content reached 58.1% at CO2 pressure of 1.0 MPa, and decreased to 51.9% at CO2 pressure of 6.0 MPa, indicating that it was inclined to form atactic polymer at high CO2 pressure.展开更多
A series of nanocomposites based on poly（ε-caprolactone） （PCL） and graphene oxide （GO） were prepared by in situ polymerization. Scanning electron microscopy observation revealed not only a well dispersion of GO...A series of nanocomposites based on poly（ε-caprolactone） （PCL） and graphene oxide （GO） were prepared by in situ polymerization. Scanning electron microscopy observation revealed not only a well dispersion of GO but also a strong interfacial interaction between GO and the PCL matrix, as evidenced by the presence of some GO nanosheets embedded in the matrix. Effects of GO nanofillers on the crystal structure, crystallization behavior and spherulitic morphology of the PCL matrix were investigated in detail. The results showed that the crystallization temperature of PCL enhanced significantly due to the presence of GO in the nanocomposites, however, the addition of GO did not affect the crystal structure greatly. Thermal stability of PCL remarkably increased with the addition of GO nanosheets, compared with that of pure PCL. Incorporation of GO greatly improved the tensile strength and Young＇s modulus of PCL without a significant loss of the elongation at break.展开更多
The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane thr...The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na2SO4 〉 MgSO4 〉 NaC1 〉 MgC12, which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium（VI） solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium（VI） could be effectively removed from chromiumcontaining wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.展开更多
Poly（4-vinylpyridinium tribromide） was prepared from poly（4-vinylpyridin） and used for the selective oxidation of a variety of sulfides to the corresponding sulfoxides. The oxidation reaction was carried out heter...Poly（4-vinylpyridinium tribromide） was prepared from poly（4-vinylpyridin） and used for the selective oxidation of a variety of sulfides to the corresponding sulfoxides. The oxidation reaction was carried out heterogeneously in acetone/water, as green solvent, at room temperature.展开更多
Poly（phenylene sulfide/ether） （PPSE） was synthesized from 4,4＇-dihydroxydiphenyl sulfide and 4,4＇-dichlorodiphenyl sulfide in solution by nucleophilic substitution reaction. The resulting polymer was characteriz...Poly（phenylene sulfide/ether） （PPSE） was synthesized from 4,4＇-dihydroxydiphenyl sulfide and 4,4＇-dichlorodiphenyl sulfide in solution by nucleophilic substitution reaction. The resulting polymer was characterized by viscosity measurement, elemental analysis, FT-IR, ^1H NMR, X-ray diffraction and thermal analysis. The results showed that the viscosities of the resulting polymer were above 0.68 dL/g, and the linear chain structure of product was confirmed. PPSE had the same reflex indices as poly（p-phenylene sulfide）, an orthorhombic crystalline with unit cell a=0.853, b=0.562, c=1.026nm. The melting temperature, glass transition temperature and initial decomposition temperature were found to be 228℃, 85℃ and 325℃, respectively. The product was soluble in common organic solvents such as NMP, N, N＇-dimethylformamide, N, N＇-dimethylacetamide and 1,2-dichloroethane.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No. 50473042)the Beijing Natural Science Foundation (No. 2042017).
文摘A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.
基金financially supported by the Natural Science Foundation of Zhejiang Province(Nos.LY21E020005,2022C01173 and LD22E020006)China Postdoctoral Science Foundation(Nos.2020M671785 and 2020T130597)+1 种基金the National Natural Science Foundation of China(Nos.U20A20253,51777194,21972127 and 21905249)Zhejiang Provincial Special Support Program for High-level Talents(No.2020R51004)。
文摘Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)with flexibility,easy processability,low cost and especially strong ability to dissolve lithium salts have been regarded as promising alternatives to traditional flammable liquid electrolytes in next-generation highsafety and high-energy-density lithium metal batteries.However,the inferior mechanical strength and thermostability of PEO-based SPEs will raise the lithium dendritic penetration issue,further leading to the short circuit in batteries.In this work,aiming at enhancing the interfacial stability against Li dendrites of PEO-based SPEs,poly(mphenylene isophthalamide)(PMIA)is introduced as a reinforcing phase for the rational design of PEO/PMIA composite electrolyte.Impressively,PMIA chain with meta-type benzene-amide linkages significantly improves the mechanical strength(1.60 MPa),thermal stability(260℃)and ability to inhibit the growth of lithium dendrites(>300 h at 0.1 mA·cm^(-2))of SPEs.Meanwhile,allsolid-state LiFePO_(4)‖PEO/PMlA‖Li cell demonstrates superior electrochemical performance in terms of high specific capacity(159.1 mAh·g^(-1)),remarkable capacity retention(82.2%after 200 cycles at 0.5 C)and excellent safety characteristics.No burning or explosion occurs under pressing,bending and cutting conditions.This work opens a new door in developing high-performance PEObased electrolytes for advanced all-solid-state lithium metal batteries.
基金supported by the National Natural Science Foundation of China(U1808209)Fundamental Research Funds for the Central Universities(DUT18JC40)Liaoning Province Science and Technology Department(201601037)。
文摘A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO)and polybenzimidazole(PBI)for vanadium redox flow battery(VRFB)application.An acid-base pair structure formed between the imidazole of PBI and sulfonic acid of S-L-PPO resulted in lowered swelling ratio.It favors to reduce the vanadium permeation.While,the increased sulfonic acid concentration ensured that proton conductivity was still at a high level.As a result,a better balance between the vanadium ion permeation(6.1×10^-9 cm^2·s^-1)and proton conductivity(50.8 m S·cm^-1)in the S-L-PPO/PBI-10%membrane was achieved.The VRFB performance with S-L-PPO/PBI-10%membrane exhibited an EE of 82.7%,which was higher than those of pristine S-L-PPO(81.8%)and Nafion 212(78.0%)at 120 m A·cm^-2.In addition,the S-LPPO/PBI-10%membrane had a much longer self-discharge duration time(142 h)than that of Nafion 212(23 h).
文摘The apparent solubility (S), concentration-average diffusivity (D), and permeability (P), for C0_2, CH_4 and N_2 through PPO and aryl-brominated PPO at 35℃ for pressure ranging from 1 to 26 atm are reported. It is found that P, D, and S of the membranes to all the three gases vary with the extent of bromination. S increases with the increase of the percent of bromine in each case, but D to CO_2 increases remarkably only at higher degree of brominafion, and therefore, P to CO_2 is increased by more than 100% over a wide range ofpressure in the case. The solubility data are well described by the dual mode sorption model. It is found that the gas molecules sorbed by the Langmuir mode are relatively more immobilized and the contribution of the nonequilibrinm character of the polymer to gas permeation increases obviously for CO_2 and is hardly changed for CH_4 with increasing bromine content. These observations are interpreted in terms of changes in specific free volume (SFV)and the cohesive energy density (CED) of the polymers.
基金The authors graefully acknowledge financial support from the National Natural Science Foundation of China (29976040), Natural Science Foundation of Anhui Province (99045431), Key Foundation of Anhui Educational Comrnittee (2000j1255zd), the Foundation of
文摘This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the final product in themixed solvent so that the sulfonation may take place between the bulk solutions and PPO powders even at higher sulfonationdegree. It is shown that the addition of a proper amount of dimethyl formide (DMF) to the conventional PPO-chloroformsystem can actually enhance the sulfonation effect. The solvent composition is then correlated with the sulfonation degreebased on the solubility parameters. It is interesting to find that solubility parameters between the mixed solvent and theprecipitated products keep an approximately unchanged value at about 4.9, which is just equal to that when pure chloroformis used, though the solubility parameters of both solvents increase with the content of DMF in solution. This may be the mainreason why the addition of DMF can reduce the precipitation and improve the ion exchange capacity (IEC) of SPPOpolymer.
基金Supported by the Chinese Postdoctoral Foundation.
文摘In this paper the percolation theory is employed to study the insulator-to-conductortransition in sulphonated poly（phenylene oxide）（SPPO） polymer membranes.The membranes withdifferent sulphonation degree were prepared and infrared characterized.The transition thresholdwas calculated by the experimental data of membrane conductivities and the coordination numberwas thus estimated.The functional group-SO<sub>3</sub>H distribution in the membrane was evaluated inaccordance with the calculations and showed a non-random dispersion on the microscopic scale.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2023B0101200006)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011926)+1 种基金Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates,Guangzhou 510640,China(South China University of Technology)(No.2023B1212060003)State Key Laboratory of Applied Microbiology Southern China(No.SKLAM008-2022)。
文摘The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.
基金supported by the ProgramManagement Unit on Area Based Development (PMUA),Thailand (No.4594393)the National Science and Technology Development Agency (NSTDA),Thailand (No.P2250367).
文摘Herein,a modified screen printed carbon electrode(SPCE)based on a composite material,graphene oxide-gold nanoparticles(GO-AuNPs),and poly(3-aminobenzoic acid)(P3ABA)for the detection of paraquat(PQ)is introduced.The modified electrode was fabricated by drop casting of the GO-AuNPs,followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA.The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy(SEM)for each step of modification.The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode.In addition,the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate,which stimulate redox reaction on the modified electrode,thus improving the sensitivity of PQ analysis.The SPCE/GOAuNPs/P3ABA offered a wide linear range of PQ determination(10^(−9)-10^(−4) mol/L)and low limit of detection(LOD)of 0.45×10^(−9) mol/L or 0.116μg/L,which is far below international safety regulations.The modified electrode showed minimum interference effect with percent recovery ranging from 96.5%to 116.1%after addition of other herbicides,pesticides,metal ions,and additives.The stability of the SPCE/GO-AuNPs/P3ABA was evaluated,and the results indicated negligible changes in the detection signal over 9 weeks.Moreover,this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.
文摘Experiments including C-13 spin-lattice relaxation, C-13 heteronuclear dipolar dephasing and H-1 spin diffusion are performed on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). The results show that the rotation of the methyl groups in solid PPO is partially restricted, which results in a surprisingly efficient spin diffusion between the aromatic proton and methyl proton characterized by a diffusion time of 150 mu s. The results also show that the aromatic ring in solid PPO is rigid and twisted, which causes all aromatic carbons to be chemically unequivalent.
基金Project(50925417) supported by China National Funds for Distinguished Young ScientistsProject(50830301) supported by the National Natural Science Foundation of China+1 种基金Project(2009ZX07212-001-01) supported by Major Science and Technology Program for Water Pollution Control and Treatment of ChinaProject(2011) supported by Hunan Nonferrous Fundamental Research Fund
文摘Sulfate adsorption by poly（m-phenylenediamine）s（PmPDs） with various oxidation states synthesized through chemically oxidative polymerization was investigated.Series of sorption experiments were conducted,and the adsorption mechanism and the relationship between oxidation state and adsorption performance were studied with the characterization of Fourier transform infrared spectroscopy（FTIR）,X-ray photoelectron spectroscopy（XPS）,pH tracking and energy calculation.The results show that the adsorption performance in acidic solution is improved with the decrease of oxidation state of poly（m-phenylenediamine）（PmPD）.The rate constant is as high as 425.5 mg/（g·min） in the short equilibrium time of 30 min.The estimated highest adsorptivity of sulfate ions is 95.1%.According to the Langmuir equation,the adsorbance is 108.5 mg/g.The sulfate desorption efficiency is about 95% and the accumulative adsorbance is up to 487.95 mg/g in 5 cycles.
基金supported by the National Natural Science Foundation of China(Nos. 21374117 and 21774128)Major State Basic Research Development Program(No.2015CB655302)+1 种基金Key Research Program of Frontier Sciences (No. QYZDY-SSW-SLH027)One Hundred Person Project of the Chinese Academy of Sciences
文摘Electrospun fiber mats (EFM) integrated proteins and biocompatible polymers have been widely used as tissue scaffold, wound dressing and food packaging. The morphology of EFM has strong correlation with the structure and rheology of the solutions. We studied the structure and rheology of polyethylene oxide (PEO) and zein in 80% ethanol aqueous solutions and the resulted EFM. In solutions, zein with rod-like conformation tends to aggregate and form oligomer, the number of proteins in the oligomer spans from 2.5 to 55.2, while PEO always behaves like Gaussian chain in good solvent. Zein preferred to distribute along PEO chains in their mixed solutions, and the structures decomposed from small angle X-ray scattering have consistent relaxation spatial-temporal characteristics with rheological behaviors.Further, the aging of zein solutions enhanced shear thinning and resulted thicker fibers in EFM, which are attributed to the rod-like growth of zein aggregates. Aggregates in viscous media with long enough relaxation time are probably crucial for the formation of continuous electrospun fibers or ribbons. This study provides a clear correlation of the structure, rheology of solutions with the morphologies of EFM made up of proteins and polymers.
基金This work were supported by the National Natural Science Foundation of China (Project No29992530-6) and the Natural Science Foundation of Guangdong Province (Grant No. 990623).
文摘It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease of Molecular weight of the poly(2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) during the polymerization, which ultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPV prepared under dry conditions has an external quantum efficiency of above 2.0%.
基金Key Projects in the National Science&Technology Pillar Program during the Eleventh Five-year Plan Period(2006BAD05A05)
文摘The aluminum oxide(AlOx)coatings were deposited on poly(ethylene terephthalate)(PET)surface by reactive magnetron sputtering for improving its barrier property.With O2 flux increasing,three modes including metallic mode,transition mode and oxide mode exist in sputtering.The properties of the aluminum oxide(AlOx)coatings prepared at different modes were discussed.Also,the influences of oxygen flux on the stoichiometry,structure,gas permeation of the coatings were investigated.The chemical composition of AlOx films fabricated in transition mode is different as oxygen flux varies slightly,and the gas barrier property is better as the stoichiometry is closer to 1.5 with oxygen flux increasing.The coating uniformity,roughness and particle size depend remarkably upon oxygen flux.The coatings deposited at oxide mode have a good barrier performance to oxygen and water,and the permeability to oxygen decreases by sixty times and water vapor ten times compared with uncoated
文摘A novel copolymer of polyaniline-poly(propylene oxide) (PAN-PPO) was prepared by cyclic voltammetry (CV) and characterized by FTIR and SEM. It showed good electroactivity for methanol oxidation in H2SO4 solution.
文摘Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.
基金financially supported by the National Natural Science Foundation of China(Nos.20634040 and 50903084)
文摘Cobalt porphyrin complexes （TPPConIX） （TPP = 5,10,15,20-tetraphenyl-porphyrin; X = halide） in combination with bis（triphenylphosphine） iminium chloride （PPNC1） were used for the eopolymerization of cyelohexene oxide and CO2. The highest turnover frequency of 67.2 h^-1 was achieved after 13 h at 20℃, and the obtained poly（1,2-cyclohexylene carbonate） （PCHC） showed number average molecular weight （Mn） of 10 × 10^3. Though the obtained PCHC showed atactie structure, the m-centered tetrads content reached 58.1% at CO2 pressure of 1.0 MPa, and decreased to 51.9% at CO2 pressure of 6.0 MPa, indicating that it was inclined to form atactic polymer at high CO2 pressure.
基金financially supported by the National Natural Science Foundation of China(No.31000427)the Fundamental Research Funds for the Central Universities(DUT12JB09)
文摘A series of nanocomposites based on poly（ε-caprolactone） （PCL） and graphene oxide （GO） were prepared by in situ polymerization. Scanning electron microscopy observation revealed not only a well dispersion of GO but also a strong interfacial interaction between GO and the PCL matrix, as evidenced by the presence of some GO nanosheets embedded in the matrix. Effects of GO nanofillers on the crystal structure, crystallization behavior and spherulitic morphology of the PCL matrix were investigated in detail. The results showed that the crystallization temperature of PCL enhanced significantly due to the presence of GO in the nanocomposites, however, the addition of GO did not affect the crystal structure greatly. Thermal stability of PCL remarkably increased with the addition of GO nanosheets, compared with that of pure PCL. Incorporation of GO greatly improved the tensile strength and Young＇s modulus of PCL without a significant loss of the elongation at break.
基金supported by the High Technology Research and Development Program (863) of China(No. 2007AA06Z339)the National Key Technologies R&D Program of China (No. 2006BAD01B02-02,2006BAJ08B00)
文摘The feasibility of employing nanofiltration for the removal of chromium（VI） from wastewater was investigated. Poly （m-phenylene isophthalamide） （PMIA） was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy （SEM） and atomic force microscopy （AFM） were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na2SO4 〉 MgSO4 〉 NaC1 〉 MgC12, which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium（VI） solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium（VI） could be effectively removed from chromiumcontaining wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.
基金Financial support for this work by the Ilam University,Ilam,Iran is gratefully acknowledged
文摘Poly（4-vinylpyridinium tribromide） was prepared from poly（4-vinylpyridin） and used for the selective oxidation of a variety of sulfides to the corresponding sulfoxides. The oxidation reaction was carried out heterogeneously in acetone/water, as green solvent, at room temperature.
文摘Poly（phenylene sulfide/ether） （PPSE） was synthesized from 4,4＇-dihydroxydiphenyl sulfide and 4,4＇-dichlorodiphenyl sulfide in solution by nucleophilic substitution reaction. The resulting polymer was characterized by viscosity measurement, elemental analysis, FT-IR, ^1H NMR, X-ray diffraction and thermal analysis. The results showed that the viscosities of the resulting polymer were above 0.68 dL/g, and the linear chain structure of product was confirmed. PPSE had the same reflex indices as poly（p-phenylene sulfide）, an orthorhombic crystalline with unit cell a=0.853, b=0.562, c=1.026nm. The melting temperature, glass transition temperature and initial decomposition temperature were found to be 228℃, 85℃ and 325℃, respectively. The product was soluble in common organic solvents such as NMP, N, N＇-dimethylformamide, N, N＇-dimethylacetamide and 1,2-dichloroethane.
