Nitrogen-contained Nanoporous Hyper-cross-linked Polymer: A New Turn-on Fluorescence Probe for Detection of Ag+ Ions in Aqueous Media

A fluorescence probe was designed using a nitrogen-contained mesoporous hyper-cross-linked polymer precursor (NH2-HCP) in order to selectively detect silver (Ag+) ions. NH2-HCP exhibits fluorescence intensity, but upon the addition of Ag+, a significant enhancement in fluorescence signal is observed. The relationship between fluorescence intensity enhancement and Ag+ concentration shows a linear and monotonic trend. The probe's response to various other cations such as Al3+, Fe3+, Cd2+, Ni2+, Cu2+, Fe2+, Hg2+, Mg2+, Zn2+, Pb2+, Mn2+, Co2+, Ca2+, Na+, and K+, as well as halogen anions like F-, Cl-, Br-, and I- was also investigated. Under optimal conditions, the probe demonstrated a linear range of 0.1-3 μM and a detection limit of 0.01 μM.

Synthesizing Hypercrosslinked Polymers with Deep Eutectic Solvents to Enhance CO2/N2 Selectivity

Hypercrosslinked polymers (HCPs) are widely used in ion exchange, water purification, and gas separation. However, HCP synthesis typically requires hazardous halogenated solvents e. g., dichloroethane, dichloromethane and chloroform which are toxic to human health and environment. Herein we hypothesize that the use of halogenated solvents in HCP synthesis can be overcome with deep eutectic solvents (DES) comprising metal halides-FeCl3, ZnCl2 that can act as both the solvent hydrogen bond donor and catalyst for polymer crosslinking via Friedel Crafts alkylation. We validated our hypothesis by synthesizing HCPs in DESs via internal and external crosslinking strategies. [ChCl][ZnCl2]2 and [ChCl][FeCl3]2 was more suitable for internal and external hypercrosslinking, respectively. The specific surface areas of HCPs synthesized in DES were 20-60 % lower than those from halogenated solvents, but their CO2/N2 selectivities were up to 453 % higher (CO2/N2 selectivity of poly-α,α'-dichloro-p-xylene synthesized in [ChCl][ZnCl2]2 via internal crosslinking reached a value of 105). This was attributed to the narrower pore size distributions of HCPs synthesized in DESs.

Amine functionalized benzene based hypercrosslinked polymer as an adsorbent for CO2/N2 adsorption

In this work, benzene based hypercrosslinked polymer (HCP) as an adsorbent was modified using amine group to enhance CO₂ uptake capability and selectivity. Based on BET analysis result, the HCP and the modified HCP provide surface area of 806 (m² g^-1) and micropore volume of 453 (m² g^-1) and 0.19 (cm³ g^-1) and 0.14 (cm³ g^-1), respectively. The CO₂ and N₂ gases adsorption were performed in a laboratory scale reactor at a temperature between 298 and 328 K and pressure up to 9 bar. The experimental data were evaluated using isotherm, kinetic and thermodynamic models to identify the absorbent behavior. The maximum CO₂ adsorption capacity at 298 K and 9 bar was obtained 301.67 (mg g^-1) for HCP and 414.41 (mg g^-1) for amine modified HCP. The CO₂ adsorption thermodynamic parameters assessment including enthalpy changes, entropy changes, and Gibbs free energy changes at 298 K were resulted - 14.852 (kJ mol^-1), - 0.024 (kJ mol^-1 K^-1), - 7.597 (kJ mol^-1) for HCP and - 17.498 (kJ mol^-1), - 0.029(kJ mol^-1 K^-1), - 8.9 (kJ mol^-1) for amine functionalized HCP, respectively. Finally, the selectivity of the samples were calculated at a CO₂/N₂ composition of 15:85 (v/v) and 43% enhancement in adsorption selectivity at 298 K was obtained for amine modified HCP.

Photo-Modulating CO2 Uptake of Hypercross-linked Polymers Upcycled from Polystyrene Waste

Incorporating photo-switches into skeletal structures of microporous materials or as guest molecules yield photo-responsive materials for low-energy CO₂ capture but at the expense of lower CO₂ uptake. Here, we overcome this limitation by exploiting trans-cis photoisomerization of azobenzene loaded into the micropores of hypercross-linked polymers (HCPs) derived from waste polystyrene. Azobenzene in HCP pores reduced CO₂ uptake by 19 %, reaching 37.7 cm³  g^-1 , but this loss in CO₂ uptake was not only recovered by trans-cis photoisomerization of azobenzene, but also increased by 22 %, reaching 56.9 cm³  g^-1 , when compared to as-prepared HCPs. Computational simulations show that this increase in CO₂ uptake is due to photo-controlled increments in 10-20 Å micropore volume, i. e., adsorption sites and a photo-reversible positive dipole moment. Irradiating these HCPs with visual-range light reverted CO₂ uptake to 33 cm³  g^-1 . This shows that it is feasible to recycle waste polystyrene into advanced materials for low-energy carbon capture.

Surface modification of polypropylene membrane for the removal of iodine using polydopamine chemistry

The development of stable and effective iodine removal systems would be highly desirable in addressing environmental issues relevant to water contamination. In the present research, a novel iodine adsorbent was synthesized by self-polymerization of dopamine (PDA) onto inert polypropylene (PP) membrane. This PP/PDA membrane was thoroughly characterized and its susrface propeties was analyzed by various analytical techniques indcluding field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH), contact angle, and surface free energy measurement. The PP/PDA membranes were subsequently used for batchwise removal of iodine at different temperatures (25-70 °C), pH (2-7), and surface areas (1-10 cm²) to understand the underlying adsorption phenomena and to estimate the membrane capacity for iodine uptake. The increase in temperature and pH both led to higher adsorption of iodine. The present approach showed a removal efficiency of over 75% for iodine using 10 cm² PP/PDA membrane (18.87 m² g^-1) within 2 h at moderate temperatures (∼50 °C) and pH > 4, about 15 fold compared to the PP control membrane. The adsorption kinetics and isotherms were well fitted to the pseudo-second-order kinetic and Langmuir isotherm models (R² > 0.99). This adsorbent can be recycled and reused at least six times with stable iodine adsorption. These findings were attributed to the homogenous monolayer adsorption of the iodide on the surface due to the presence of catechol and amine groups in the PP/PDA membrane. This study proposes an efficient adsorbent for iodine removal.

Exceptionally Stable Microporous Organic Frameworks with Rigid Building Units for Efficient Small Gas Adsorption and Separation

Three microporous organic frameworks (hereafter denoted as MPOF-Ads) based on a rigid adamantane core have been successfully synthesized via Sonogashira-Hagihara polycondensation coupling in high yields, 83.7-94.6%. The obtained amorphous MPOF-Ads networks have high Brunauer-Emmett-Teller surface areas (up to 737.3 m² g^-1), narrow pore size distribution (0.95-1.06 nm), and superior thermal (the initial decomposition temperature T_5% under an N₂ atmosphere can reach 410 °C) and chemical stability (no apparent degradation in common organic solvents or strong acid/base solutions after 7 days). At 273 K and 1.0 bar, these MPOF-Ads networks present good uptake capacities for small gas molecules (13.9 wt % CO₂ and 1.66 wt % CH₄) for which the presence of high surface area, predominant microporosity, and narrow pore size distribution are beneficial. In addition, the as-prepared MPOF-Ads networks possess moderate isosteric heats for CO₂ (Q_st = 19.5-30.3 kJ mol^-1) and show desired CO₂/N₂ and CO₂/CH₄ selectivity (36.3-38.4 and 4.1-4.3 based on Henry's law and 17.88-24.92 and 4.24-5.70 based on ideal adsorbed solution theory, respectively). With the demonstrated properties, the synthesized MPOF-Ads networks display potential for small gas storage and separation that can be used in harsh environments because of their superior physical and chemical stability.

Novel amino-functionalized hypercrosslinked polymer nanoparticles constructed from commercial macromolecule polystyrene via a two-step strategy for CO2 adsorption

Commercial polymers have large cost advantage to drive HCPs to industrialize. The AHCPNPs using commercial PS as main block prove that it still has well-defined microporous structure, high specific surface area and extremely CO₂ capture capacity.

Amino-functionalized hypercrosslinked polymers for highly selective anionic dye removal and CO2/N2 separation

Recently, great improvements have been achieved in the fabrication of adsorbents.

Twisted molecule-based hyper-crosslinked porous polymers for rapid and efficient removal of organic micropollutants from water

Four hyper-crosslinked porous polymers were synthesized by a facile method, and exhibited excellent adsorption performances for organic micropollutant removal from water.

Geometry variation in porous covalent triazine polymer (CTP) for CO2 adsorption

Covalent triazine-based organic polymers (CTPs), a sub class of covalent organic polymers (COPs), are promising materials for CO₂ adsorption although the impact of their dimensionality on the trapping process is not well-understood.