Hydrophobic Porous Polymer Research Articles

Adsorption Properties of Hydrophobic Porous Coordination Polymers of Zinc-Oxalic Acid with Triazole and Amino Triazole Mixture Ligands

The porous coordination polymers were prepared from Zn2+ and oxalic acid with 2 linker ligands, 1,2,4-triazole (Taz) and 3-amino-1,2,4-triazole (ATaz). The adsorption of N2 after adsorption of degassed CO2 in the pore frameworks increased by 3 times. The flexibility of this structure is due to the interaction of CO2 molecules with the amine groups contained in it, thereby increasing its porosity.

Hydrophobic hypercrosslinked polymers prepared by secondary pore-forming method as excellent toluene adsorbents

In this work, inspired by molecular imprinting technology, we developed a secondary pore-forming method to chemically etch three hypercrosslinked polymers which are constructed from three novel hexapolar monomers containing imine groups, resulting in three novel hydrophobic porous hyper-crosslinked polymers (HCPs) pGly-TPA, pP-TPA and pBP-TPA. The structures were determined by FT-IR and solid-state 13C NMR spectroscopic techniques. The specific surface areas of pGly-TPA, pP-TPA and pBP-TPA are 694.1, 197.9 and 497.7 m2/g, respectively. All three porous polymers exhibit high hydrophobic properties with wetting angles of much greater than 90°. The breakthrough adsorption experiments revealed that the three prepared polymers exhibited significant adsorption capacity for toluene (322.05 mg/g for pGly-TPA, 114.43 mg/g for pP-TPA and 279.14 mg/g for pBP-TPA), but showed almost no adsorption for ethyl acetate, cyclohexane, and n-hexane, exhibiting certain molecular size and polarity selectivity. The adsorption behaviors of toluene on pGly-TPA, pP-TPA and pBP-TPA can be fit by the Boltzmann model and the Yoon-Nelson model, suggesting that the fixed bed has low mass transfer resistance. The adsorption rate is controlled by both external diffusion and intraparticle diffusion, as shown by the intraparticle diffusion model analysis. In addition, the adsorption capacity of toluene on pGly-TPA is almost unchanged under high humidity (70 %) or five adsorption–desorption processes, which demonstrates exceptional water-resistance and stability. This work is a reference for preparing novel hydrophobic HCPs using the secondary pore-forming method for removing VOCs from humid air.

Highly efficient catalysts for CO2 hydrogenation to formic acid in water catalyzed by hydrophobic porous polymers containing stable metal–hydride

Hydrophobic porous polymers can protect the active metal-hydride intermediate, bring highly efficient catalyst for CO2 hydrogenation to formic acid in water. An higher conversion can be achieved using p-PNP-Ir in aqueous solution.

Photoelectrocatalysis Synthesis of Ammonia Based on a Ni-Doped MoS2/Si Nanowires Photocathode and Porous Water with High N2 Solubility

The synthesis of ammonia through photocatalysis or photoelectrochemistry (PEC) and nitrogen reduction reaction (NRR) has become one of the recent research hotspots in the field, where the catalyzed materials and strategies are critical for the NRR. Herein, a Ni-doped MoS2/Si nanowires (Ni-MoS2/Si NWs) photocathode is prepared, where the Si NWs are formed on the surface of a Si slice by the metal-assisted chemical etching method, and the hydrothermally synthesized Ni-MoS2 nanosheets are then cast-coated on the Si NWs electrode. Porous water with high solubility of N2 is prepared by treating a hydrophobic porous coordination polymer with hydrophilic bovine serum albumin for subsequent aqueous dispersing. The relevant electrodes and materials are characterized by electrochemistry, UV-vis spectrophotometry, scanning electron microscopy/energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller method, and zeta potential method. The uses of the Ni-MoS2/Si NWs photocathode and the porous water with high nitrogen solubility for PEC-NRR give a yield of NH3 of 12.0 mmol h-1 m-2 under optimal conditions (e.g., at 0.25 V vs RHE), and the obtained apparent Faradaic efficiency higher than 100% is discussed from the inherent photocurrent-free photocatalysis effect of the photoelectrodes and the suggested classification of three kinds of electrons in PEC, which may have some reference value in understanding and improving other PEC-based processes.

Porous-polymer monolith decorated with dithizone for greener visual and spectrophotometric sensing of Hg(II)

This paper describes a hydrophobic porous polymer monolith for visual and spectrophotometric determination of Hg(II). The monolith was synthesized in the coffins of 2.0 mm i.d. transparent polypropylene ink-pen tubes using stearyl methacrylate (SMA) as the functional monomer and ethylene glycol dimethacrylate (EDMA) as the crosslinker by fast UV-mediated polymerization. The poly(SMA-co-EDMA) monolith retained dithizone, an anchor for the Hg(II) and colorimetric reagent. Besides the monolith's fast preparation, the polypropylene transparency enabled the naked-eye visualization of all color changes occurring in the solid phase extraction steps (conditioning, loading, washing and elution). This feature also enabled the unprecedented use of a simple ruler for detection since the distance occupied by Hg(II) inside the column was linearly related to Hg(II) concentration. Loading the column with 12.0 mL of sample and elution with 1.0 mL of ethanol contributed to the green analytical chemistry and provided a detection limit of 7.9 µg L−1, which was enough to determine Hg(II) in certified estuarine sediment (ERM-CC580) and urine samples. A sample volume of 45 mL provides a detection limit of 0.59 μg L−1, allowing the detection of trace Hg(II) levels in the Billings reservoir waters, an anthropized water reservoir located in the São Paulo Metropolitan Area of São Paulo State (Brazil), thus attending the maximum concentration levels preconized by the United States Environmental Protection Agency (1.0 µg L−1) and World Health Organization (6.0 µg L−1). The proposed method is simple, cheap and can be easily implemented in field measurements for sample trials.

Hydrophobic porous polymer containing isoxazoline and siloxane groups for 2,4,6-trinitrotoluene (TNT) adsorption via synergistic effect of Lewis acid-base, dipole-π, and π-π interactions

A series of hydrophobic porous polymer containing isoxazoline and siloxane groups were successfully prepared via catalyst-free click polymerization and freeze-drying technology. In addition to hydrophobicity, synergistic effect of three molecular aborption interactions, namely point-to-point Lewis acid-base, point-to-face dipole-π, and face-to-face π-π interactions, endowed the resulting porous polymer with good 2,4,6-trinitrotoluene (TNT) adsorption efficiency from wastewater. At the same time, the adsorption efficiency of the resulting porous polymer in different natural/polluted water samples was similar to those in laboratory, and about 80% of the initial adsorption capacity remained after five adsorption-desorption cycles. The results showed that hydrophobic porous polymer containing isoxazoline and siloxane groups is a promising adsorbent for the treatment of TNT wastewater.

Three-dimensional hydrophobic porous organic polymers confined Pd nanoclusters for phase-transfer catalytic hydrogenation of nitroarenes in water

Fabrication of catalysts based on metal nanoclusters has attracted intensive research attention due to their superior catalytic activity. Herein, two three-dimensional hydrophobic porous organic polymers (3D-HPOPs-1 and 3D-HPOPs-2, respectively) that exhibited high specific surface areas and unique microporous-mesoporous structures were fabricated. Ultrafine Pd nanoclusters were successfully confined into the N atoms containing cages of 3D-HPOPs via impregnation and subsequent reduction. Besides, the 3D-HPOPs exhibited excellent hydrophobicity, thus can preferentially adsorb and enrich organic reactants in the pores of the catalyst, this in turn leads to the catalytic reaction as only in the organic phase. High conversion and selectivity were observed for the catalytic hydrogenation of nitroarenes over as-obtained Pd(0.7%)@3D-HPOPs-1 in water under mild reaction conditions. Moreover, the prepared catalyst can be easily recovered and reused without loss of activity. This study may provide a feasible strategy for fabricating noble-metal-nanocluster-based catalysts for various reactions under mild and environmentally friendly conditions.

Highly Stable and Efficient Lead Halide Perovskite Nanocrystals for Light-Emitting Diodes Displays

All inorganic lead halide perovskite nanocrystals (NCs), CsPbX3 (X=Cl, Br, I), have been attracting increasing attention because of their excellent optical properties, such as tunable emission wavelength, high photoluminescence quantum yield (PLQY), narrow full width at half maximum (fwhm), and high defect tolerance. Therefore, the NCs have great potential application in light-emitting diodes for display. However, the NCs suffer from poor stability due to the hydrolytic degradation and fluorescence quenching in the solid agglomerations state. To improve the photoluminescence (PL) stability of the NCs, the ammonium bromide, alkyl phosphate, microscale Cs4PbX6, and super hydrophobic porous organic polymers (SHOP) were used as frameworks to from the composites with NCs. Specially, the CsPbBr3-super hydrophobic polymers composites not only preserve a high PLQY (60%) and narrow band emission (fwhm~16nm) but also inherit the outstanding water-resistant property of SHOP to protect the NCs from hydrolytic degradation. The PLQY of the composites was maintained at 91% of the initial one after being immersed in water for 31 days. Even after being immersed in water for six months, the composites still retain bright green emission. A white light-emitting diode (WLEDs) device was prepared by combining green-emitting composites and red-emitting K2SiF6:Mn4+ phosphors with a blue LED chip. The device exhibits a high luminous efficiency of 50 lm/W and a wide color gamut (127% of the National Television System Committee and 95% Rec. 2020). This work provides an alternative approach to solve the challenging stability issue of perovskite QDs; therefore, it has a positive implication for their practical application in liquid crystal display backlights.

Enhanced water permeability and osmotic power generation with sulfonate-functionalized porous polymer-incorporated thin film nanocomposite membranes

In this study, a hydrophobic porous organic polymer (PP) synthesized via Friedel-Crafts alkylation of dichloro-p-xylene, was functionalized with hydrophilic sulfonate functional group to form PP-SO3H, prior to incorporation into the polyamide layer of a hollow fiber pressure retarded osmosis (PRO) TFN membrane. Sulfonate functionalization of the PP material improved the compatibility of the nanomaterial with the aqueous amine precursor during the in situ interfacial polymerization, leading to a decrease in aggregation of the nanoparticles. The effect of nanomaterial loading on the membranes' performance was also elucidated. PP-SO3H incorporation resulted in significant improvement of surface hydrophilicity, which along with improved porosity, facilitated enhanced water transport across the membrane and maintained an acceptable salt rejection of the selective layer. The best-performing membrane with PP-SO3H loading of 0.002 wt% showed a 46.3 L m−2 h−1 water flux and power density of 14.6 W m−2, which are both the highest values recorded. This study suggests that the functionality and chemical properties of the nanomaterial in a TFN membrane is essential in improving altogether the osmotic performance and salinity gradient power harvesting capability during PRO.

One-step photolytic synthesis of hydrophobic porous polymer materials by the copolymerization of the dimethacrylate—alkyl methacrylate system in the presence of methanol

Hydrophobic porous polymer materials were synthesized by one-step visible light polymerization from compositions consisting of phthalate-containing oligoester di(meth)acrylate MDP-2, methanol, and alkyl methacrylate (butyl methacrylate, ethylhexyl methacrylate, iso-decyl methacrylate, lauryl methacrylate, and stearyl methacrylate) compositions. The highest hydrophobization effect is observed for stearyl methacrylate. The maximum MDP-2 block photopolymerization rate is by 16–50 times higher than that of alkyl methacrylates. The specific surface areas of the synthesized porous polymers reach 4.2 m2 g−1, and the pore size ranges from 5.5 to 17 µm. The addition of stearyl methacrylate to the composition leads to the pore size distribution narrowing. The principal possibility of using these photopolymerizable compositions as stationary phases for liquid chromatography is shown.

Emulsion Templating: Porous Polymers and Beyond

Emulsion templating presently extends far beyond the original hydrophobic porous polymers that were synthesized within surfactant-stabilized water-in-oil high internal phase emulsions (HIPEs) by us...

Amphiphilic fluorinated block-copolymer coating for the preparation of hydrophobic porous materials

A new approach to the preparation of hydrophobic porous polymers has been proposed. Three series of porous polymers which pores equally well-absorbed as water and organic liquids (benzene and iso-octane) were synthesized by visible light polymerization from compositions based on three different dimethacrylic esters with n-butanol. Three block copolymers based on N-vinylpyrrolidone and 2,2,3,3-tetrafluoropropyl methacrylate, differing in the length of the poly-(2,2,3,3-tetrafluoropropyl methacrylate) block, were synthesized for the purpose of hydrophobization of such porous polymers. A distinctive feature of synthesized block copolymers is that they are soluble only in methanol. It has been found that the treatment of porous polymers only with 2 wt.% of block copolymer methanol solution leads to a decrease water uptake by an order of magnitude, and the absorption of organic liquids does not change. In the course of the study it was possible to obtain a hydrophobic porous polymer sample that has water contact angle θ = 121° and a low value of the polar component of the surface Gibbs energy ( $$ {\gamma}_s^p=0.2 $$ mJ·m−2). The fundamental possibility of using such material for purification of organic liquids from water is shown.

Microwave-assisted synthesis of amine functionalized mesoporous polydivinylbenzene for CO2 adsorption

We report microwave assisted synthesis of a series of highly hydrophobic porous organic polymers of poly divinylbenzene (PDVB), for the first time, which were modified by amine-rich co-monomers of vinyl imidazole (VI) and vinyl triazole (VT) resulting in PDVB-VI and PDVB-VT adsorbents. There is an optimum amount of incorporated co-monomer and initiator which led to high adsorptive activity of the material towards CO2. Atmospheric CO2 adsorption was enhanced by the addition of amine moieties while maintaining an optimum surface area and pore volume. A certain amount of initiator led to better incorporation of VT monomer while surface area and pores remain accessible. A maximum CO2 adsorption of 2.65mmolg-1 at 273K/1bar was achieved for triazole based adsorbent (PDVB-VT) with 0.7g of VT and 0.07g of initiator. In comparison with a non-functionalized material (PDVB) with 1.2mmolg-1 CO2 uptake, the adsorption efficiency was enhanced more than twice. The adsorbent maintained its efficiency up to seven cycles. Theoretical modeling confirms the active site is nitrogen on the imidazole/triazole ring and that incorporation of VT to the polymeric networks enhanced the adsorptive properties better than vinyl imidazole (VI) due to more active sites.

Coating sponge with a hydrophobic porous coordination polymer containing a low-energy CF3-decorated surface for continuous pumping recovery of an oil spill from water

For the remediation of oil spills and organic solvent leakage into water, it is desirable to develop not only advanced sorbents with a high adsorption capability but also labor- and time-saving apparatuses that can work continuously without human intervention. In this work, we synthesized a novel and highly stable porous coordination polymer (PCP, also called metal-organic framework), University of Science and Technology of China-6 (USTC-6), with a corrugated -CF3 surface that features high hydrophobicity. The uniform growth of USTC-6 throughout a graphene oxide (GO)-modified sponge was achieved and yielded a macroscopic USTC-6@GO@sponge sorbent, which repels water and exhibits a superior adsorption capacity for diverse oils and organic solvents. Remarkably, the sorbent can be further assembled with tubes and a self-priming pump to build a model apparatus that affords consecutive and efficient oil recovery from water. The easy and fast recovery of oils/organic solvents from water based on such an apparatus indicates that it has great potential for future water purification and treatment. A non-stick coordination polymer coating helps sponges absorb and recover up to 40 times their own weight in oil under extreme temperatures. Using passive sorbents to clean up toxic spills normally requires specially engineered materials, such as biomimetic surfaces with nanoscale rough features, to repel water molecules and attract oil particles. Now, Hai-Long Jiang from the University of Science and Technology of China and co-workers have developed a way to achieve these properties using porous coordination polymers containing copper ions and fluorinated organic ligands. After dipping a commercial sponge in graphene oxide to enhance copper binding, the team grew their coordination polymer coating in situ and found it yielded a corrugated surface with high hydrophobicity. Intriguingly, a prototype assembled from the coated sponge and a self-priming pump enabled labor-free cleanup of oil spills from water. A hydrophobic porous coordination polymer (PCP) has been synthesized and its growth throughout the graphene oxide (GO)-modified sponge yields a macroscopic PCP@GO@sponge sorbent, which repels water and exhibits superior adsorption for diverse oils. Remarkably, the sorbent is further assembled with tubes and a self-priming pump to build a model apparatus that can afford consecutive and efficient oil recovery from water.

Accurate Ex-situ Measurements of PEM Fuel Cells Catalyst Layer Dry Diffusivity

Polymer electrolyte membrane fuel cells (PEMFC) efficiently convert the reaction energy of hydrogen and oxygen to electricity, water and heat. The oxygen reduction reaction occurs in composite nanostructured catalyst layers (CL) formed from Pt nanoparticles supported on a network of carbon particle agglomerates. Oxygen reaches the reaction site through diffusion. Understanding the diffusion properties of CL is vital to proper design and operation of CL and PEMFC. Measuring the diffusivity of thin porous layers is challenging, as is selecting a suitable substrate and appropriate CL coating procedures. In this work, CL is coated on 70 μm thick hydrophobic porous polymer substrates with a Mayer bar coater. Several samples are prepared and their thickness are measured accurately. The diffusivity of the CL and the substrate are measured using a dry diffusivity test bed and the resulting CL-diffusivity values are determined for different Pt loadings.

Accurate Ex-situ Measurements of PEM Fuel Cells Catalyst Layer Dry Diffusivity

Polymer electrolyte membrane fuel cells (PEMFC) efficiently convert the reaction energy of hydrogen and oxygen to electricity, water and heat. The oxygen reduction reaction occurs on a composite nanostructured catalyst layers (CL) formed from Pt nanoparticles supported on a network of carbon particle agglomerates. Oxygen reaches the reaction site through diffusion. Understanding the diffusion properties of CL is vital to proper design of CL. Measuring the diffusivity of thin porous layers is challenging, as is selecting a suitable substrate and appropriate CL coating procedures. There are very few CL gas diffusivity experimental studies in the current literature. In this work, CL is coated on 70 μm thick hydrophobic porous polymer substrates with Mayer bar. Diffusivity of CL and the substrate is measured using dry diffusivity test bed and after decoupling diffusivity values are reported for different CL thicknesses.

Analysis of polycyclic aromatic hydrocarbons in water with gold nanoparticles decorated hydrophobic porous polymer as surface-enhanced Raman spectroscopy substrate

A method for surface-enhanced Raman spectroscopy (SERS) sensing of polycyclic aromatic hydrocarbons (PAHs) is reported. Gold nanoparticles (AuNPs) decorated hydrophobic porous glycidyl methacrylate–ethylene dimethacrylate (GMA–EDMA) polymer is developed as the SERS substrate. GMA–EDMA material with porosity and permeability shows rapid and efficient adsorption of PAHs through presumed hydrophobic interaction, which brings the analytes close to the substrate. Meanwhile, the three dimensional porous morphology might benefit AuNPs distribution for high SERS enhancement. Studies on the effects of AuNPs surface coverage on the substrate and time of PAHs–substrate interaction are presented. The qualitative analysis and quantitative tendency of this method for PAHs detection are investigated with anthracene, phenanthrene and pyrene as probe molecules, showing that the characteristic fingerprint vibrational peaks of each PAH can be readily identified, and the limit of detections are 0.93×10−7, 4.5×10−7 and 1.1×10−7M respectively. Moreover, the substrate exhibits high reproducibility with the relative standard deviation about 16% in spot and spot SERS intensity. Using this method for rapid screening of PAHs mixture in some water samples are performed well, which might be useful for environmental pollutions monitoring.

Synthesis and CO2 Adsorption Properties of Hydrophobic Porous Coordination Polymer Featuring [Zn9(MeBTZ)12]6+ Building Units

Abstract A hydrophobic porous coordination polymer, [Zn9(MeBTZ)12(BPDC)3] where MeBTZ is 5-methylbenzotriazolate and BPDC is 4,4′-biphenyldicarboxylate, was obtained through a one-pot solvothermal reaction of zinc nitrate hexahydrate, 5-methyl-1H-benzotriazole and 4,4′-biphenyldicarboxylic acid in N,N-dimethylacetamide. The structure of [Zn9(MeBTZ)12(BPDC)3] was built from trigonal antiprismatic [Zn9(MeBTZ)12]6+ nodes connected with linear BPDC linkers, having 4669 net topology. The working capacity for CO2 adsorption on [Zn9(MeBTZ)12(BPDC)3] over the pressure range between 0.1 and 1.6 MPa at 40 °C was 3.4 mol kg−1 after the preintroduction of high humidity.

Humidity sensors based on Li-loaded nanoporous polymers

Nanoporous polymer based on divinylbenzene was synthesized by radical polymerization with a solvothermal route. The nanoporous characteristic of the resultant polymer poly(divinylbenzene) (PDVB) was determined by a series of characterizations. The hydrophobic porous polymer was used as the host to prepare composited humidity sensitive materials. Different levels of LiCl were loaded into the nanoporous polymer and their humidity sensing properties were researched. Humidity sensitivities of the composites were greatly improved by LiCl loading compared with pure PDVB. The sensor based on 5wt% LiCl/PDVB showed the best sensing properties to relative humidity (RH). The impedance of the optimum sensor changed three orders of magnitude over the whole humidity range, with a good linearity and rapid response. The mechanism by the complex impedance plots suggests the protons are the domination carrier in low humidities and ions (Li+ and Cl−) in a high humidity range. The results demonstrate nanoporous polymers are a new kind of promising materials for humidity sensors.

A study on the system of nonaqueous microchip electrophoresis with on‐line peroxyoxalate chemiluminescence detection

This article describes a further development of our previously reported miniaturized analysis system of microchip electrophoresis with on-line chemiluminescence detection. The system, developed first time for nonaqueous microchip electrophoresis with peroxyoxalate chemiluminescence detection, consists of a suction pressure device for sample or reagent introduction, a constant voltage supplied for electrophoretic separation, an either hydrophilic or hydrophobic porous polymer plug for preventing chemiluminescence reagent flowing upstream and a spiral detection channel for enhancement of both detection sensitivity and reproducibility. Especially, by using organic solvent as BGE medium, the developed system avoided the interface problem between aqueous running buffer and low-water-content chemiluminescence solvent in previous reports. The influencing factors on chemiluminescence signal were optimized using rhodamine 6G as model molecule. The system performance was further investigated in the experiment of separation of hydrophilic rhodamine dyes and analysis of hydrophobic polycyclic aromatic hydrocarbon, providing the detection limit (S/N = 3) of 3.5 nmol/L for rhodamine 123, 6.8 nmol/L for rhodamine 6G, and 60 nmol/L for 1-aminopyrene, respectively. The experimental results showed the system offered a number of benefits, including compact structure, high sensitivity, good reproducibility, and a wide range of application prospect.