Azo-linked Polymers Research Articles

A Novel Azo-Linked Polymer Bearing Trifluoromethyl Groups for I2 Capture.

In this work, a novel three nitro-group-bearing monomer 3,6-dinitro-9-(2-trifluoromethyl-4-nitrophenyl)-carbazole (Car-3NO2 -CF3 ) via a CN coupling reaction between 3,6-dinitro-9H-carbazole (Car-2NO2 ) and 2-chloro-5-nitrobenzotrifluoride is synthesized, and obtained single crystal and single crystal analysis data for this compound. The crystal system of Car-3NO2 -CF3 is monoclinic and it has a P 21/c space group. This new monomer (Car-3NO2 -CF3 ) is also utilized to synthesize a novel azo-linked polymer (Azo-Car-CF3 ). The trifluoromethyl group has polar CF bonds, and thus it is an effective functional group for the capture of iodine. Azo-Car-CF3 has great thermal stability with a mass loss of only 10% at 414°C, as well as good chemical stability as is demonstrated by its low solubility in common organic solvents such as tetrahydrofuran (THF), acetone, methanol, ethanol, and N,N-dimethylformamide (DMF). The specific surface area of Azo-Car-CF3 can reach as high as 335m2 g-1 . Azo-Car-CF3 exhibits an excellent capacity for iodine adsorption and can reach up to 1198mgg-1 in cyclohexane solution, and its adsorption capacity for iodine vapor can get to 2100mgg-1 . In addition, ethanol can be used to trigger the release of the captured iodine to be easily released from Azo-Car-CF3 .

Synthesis of azo-linked porous polymers as fillers to enhance the performance of mixed-matrix membranes for the separation of bioethanol fermentation tail gas

Bioethanol has received widespread attention as an alternative to conventional fossil fuels. However, bioethanol fermentation produces tail gas containing an ethanol/CO2 gas mixture, which must be efficiently separated to recover ethanol and reduce the greenhouse effect. In this study, we propose using vapor permeation membrane technology to separate ethanol from CO2. Four azo-linked polymers (ALPs) were successfully synthesized and characterized, which were mixed with polydimethylsiloxane (PDMS) to fabricate mixed-matrix membranes (MMMs). The performances of different ALP/PDMS MMMs were characterized and compared in the separation of 0.2 wt% ethanol/CO2 modeling fermentation tail gas. ALP-1(synthesized by tetramethylbenzidine)/PDMS MMMs exhibited the highest selectivity and high ethanol permeability, and characterizations such as Raman spectroscopy, differential scanning calorimetry, and X-ray diffraction were thus conducted for ALP-1/PDMS MMMs with different ALP contents. Results showed that ALP-1/PDMS MMMs with 1 wt% ALP-1 content possessed selectivity and permeability of 15.8 and 30,074 Barrer, which are 98% and 40% higher than pure PDMS, respectively. The effects of operation parameters, such as feed concentration, temperature, permeate pressure, and stability, on the performance of ALP-1/PDMS MMMs were also studied. This study provides a new method for the efficient treatment of fermentation tail gas that has excellent industrial prospects.

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N 5 Site for Enhanced Electrocatalytic Reaction

Decrypting the Influence of Axial Coordination on the Electronic Microenvironment of Co-N ₅ Site for Enhanced Electrocatalytic Reaction

Synthesis and characterization of triphenylpyridine containing azo-linked polymer materials

Synthesis and characterization of triphenylpyridine containing azo-linked polymer materials

Redox-Active Porous Organic Polymers as Novel Electrode Materials for Green Rechargeable Sodium-Ion Batteries.

The use of redox-active organic materials in rechargeable batteries has the potential to transform the field by enabling lightweight, flexible, green batteries while replacing lithium with sodium would mitigate the limited supplies and high cost of lithium. Herein, we report the first use of highly porous azo-linked polymers (ALPs) as a new redox-active electrode material for rechargeable sodium-ion batteries. ALPs are highly cross-linked polymers and therefore eliminate the solubility issue of organic electrodes in common electrolytes, which is prominent in small organic molecules and leads to fast capacity fading. Moreover, the high surface area coupled with the π-conjugated microporous nature of ALPs facilitates electrolyte adsorption in the pores and assists in fast ionic transport and charge transfer rates. An average specific capacity of 170 mA h g-1 at 0.3 C rate was attained while maintaining 96% Coulombic efficiency over 150 charge/discharge cycles.

Pyrene Bearing Azo-Functionalized Porous Nanofibers for CO2 Separation and Toxic Metal Cation Sensing.

A novel luminescent azo-linked polymer (ALP) has been constructed from 1,3,6,8-tetra(4-aminophenyl)pyrene using a copper(I)-catalyzed oxidative homocoupling reaction. The polymer displays high porosity with a Brunauer–Emmett–Teller surface area of 1259 m2 g–1 and narrow pore size distribution (1.06 nm) and is able to take up a significant amount of CO2 (2.89 mmol g–1) at 298 K and 1.00 bar with a high isosteric heat of adsorption of 27.5 kJ mol–1. Selectivity studies applying the ideal adsorbed solution theory revealed that the novel polymer has moderately good selectivities for CO2/N2 (55.1) and CO2/CH4 (10.9). Furthermore, the ALP shows fluorescence quenching in the presence of Hg2+, Pb2+, Tl+, and Al3+ ions. Compared with these ions, the ALP showed no sensitivity to light metal ions such as Na+, K+, and Ca2+ in ethanol–water solution, clearly indicating the high selectivity of the ALP toward heavy metal ions. The exceptional physiochemical stability, high porosity, and strong luminescence make this polymer an excellent candidate as a fluorescent chemical sensor for the detection of heavy metal ions.

Synthesis and characterization of nitrogen-rich azo-linked conjugated polymer materials

ABSTRACTEfficient azo-linked polymers of 2,4,6-tris(4-nitrophenyl)pyridine-melamine (TNPP-M), and 2,4,6-tris(4-nitrophenyl)pyridine-sulfanilamide (TNPP-S) were prepared by condensation polymerization technique from TNPP-based monomer reacting with amines as melamine and sulfanilamide. The synthesized polymer structure was confirmed by various experimental techniques, such as Fourier transform infrared spectroscopy, solid-state 13C NMR, and X-ray diffraction (XRD). Particle size was calculated using Williamson–Hall (W–H) plot from powder XRD pattern. The thermal analysis and scanning electron microscopy of TNPP-S polymer displayed an excellent thermal stability and capsule-like morphology was observed. UV/visible absorptions of TNPP-S and TNPP-M polymers exhibit two bands, a strong band at 365 nm, and a shoulder at 385 nm for TNPP-M; these polymeric semiconducting materials could be useful for solar fuel cell applications.

From Azo-Linked Polymers to Microporous Heteroatom-Doped Carbons: Tailored Chemical and Textural Properties for Gas Separation.

Heteroatom-doped porous carbons with ultrahigh microporosity were prepared from a nitrogen-rich azo-linked polymer (ALP-6) as a precursor for gas separation applications. Direct carbonization and chemical activation of ALP-6 with ZnCl2 and KOH were successfully applied to obtain three different classes of porous carbons (ALPDCs). Synthetic processes were conducted at relatively mild temperatures (500-800 °C),which resulted in retention of appreciable levels of nitrogen content (4.7-14.3 wt %). Additionally, oxygen functionalities were found to be present in chemically activated samples. The resultant porous carbons feature a diverse range of textural properties with a predominant microporous nature in common. The highest CO2 uptake value of 5.2 mmol g(-1) at 1 bar and 298 K in ALPDCK600 was originated from well-developed porosity and basic heteroatoms (N and O) on the pore walls. The highest heteroatom doping level (12 wt % nitrogen and 20 wt % oxygen) coupled with the high level of microporosity (84%) for ALPDCK500 led to notable CO2/N2 (62) and CO2/CH4 (11) selectivity values and a high CO2 uptake capacity (1.5 mmol g(-1), at 0.15 bar) at 298 K. This study illustrates the effective use of a single-source precursor with robust nitrogen bonds in combination with diverse carbonization methods to tailor the chemical and textural properties of heteroatom-doped porous carbons for CO2 capture and separation applications.

Synthesis and evaluation of porous azo-linked polymers for carbon dioxide capture and separation

The correlation between the CO2-capturing ability of porous azo-linked polymers and their structural properties was investigated.

Copper(I)-Catalyzed Synthesis of Nanoporous Azo-Linked Polymers: Impact of Textural Properties on Gas Storage and Selective Carbon Dioxide Capture

A new facile method for synthesis of porous azo-linked polymers (ALPs) is reported. The synthesis of ALPs was accomplished by homocoupling of aniline-like building units in the presence of copper(I) bromide and pyridine. The resulting ALPs exhibit high surface areas (SABET = 862–1235 m2 g–1), high physiochemical stability, and considerable gas storage capacity especially at high-pressure settings. Under low pressure conditions, ALPs have remarkable CO2 uptake (up to 5.37 mmol g–1 at 273 K and 1 bar), as well as moderate CO2/N2 (29–43) and CO2/CH4 (6–8) selectivity. Low pressure gas uptake experiments were used to calculate the binding affinities of small gas molecules and revealed that ALPs have high heats of adsorption for hydrogen (7.5–8 kJ mol–1), methane (18–21 kJ mol–1), and carbon dioxide (28–30 kJ mol–1). Under high pressure conditions, the best performing polymer, ALP-1, stores significant amounts of H2 (24 g L–1, 77 K/70 bar), CH4 (67 g L–1, 298 K/70 bar), and CO2 (304 g L–1, 298 K/40 bar).