Gas‐phase fluorination of conjugated microporous polymer microspheres for effective interfacial stabilization in lithium metal anodes

Lithium(Li)metal anodes have attracted extensive attention due to their ultrahigh theoretical capacity and low potential.However,the uneven deposition of Li near the unstable electrode/electrolyte interfaces leads to the growth of Li dendrites and the degradation of active electrodes.Herein,we directly fluorinate alkyne-containing conjugated microporous polymers(ACMPs)microspheres with fluorine gas(F_(2))to introduce a novel fluorinated interlayer as an interfacial stabilizer in lithium metal batteries.Using density functional theory methods,it is found that as-prepared fluorinated ACMP(FACMP)has abundant partially ionic C–F bonds.The C–F bonds with electrochemical lability yield remarkable lithiophilicity during cycling.The in situ reactions between the active C–F bonds and Li ions enable transfer of lithium fluoride microcrystals to the solid electrolyte interphase(SEI)layers,guaranteeing effective ionic distribution and smooth Li deposition.Consequently,Li metal electrodes with the fluorinated interlayers demonstrate excellent cycling performances in both half-batteries and full cells with a lithium bis(trifluoromethanesulfonyl)imide electrolyte as well as a nonfluorinated lithium bis(oxalate)borate electrolyte system.This strategy is highly significant in customizable SEI layers to stabilize electrode interfaces and ensure high utilization of Li metal anodes,especially in a nonfluorinated electrolyte.

Effect of Porogenic Agents on Properties of Microporous Mullite Aggregates

Microporous mullite aggregates were prepared from bauxite by dry pressing and firing at 1700℃for 3 h with corn starch,PMMA microspheres or rice husk powder as the porogenic agent.The effects of some porogenic agents and their additions(mass fraction of 0,5%,10%,15%and 20%,respectively)on the properties of the microporous mullite aggregates were analyzed by XRD,SEM and Image-Pro Plus software.The results show that the comprehensive performance of the sample with 10%rice husk powder is the best:the closed porosity is 7.1%;the bulk density is 2.63 g·cm^(-3);the compressive strength is 122 MPa;the median pore size is 15.16μm;and the thermal conductivity at 500℃is 2.30 W·m^(-1)·K^(-1).

High-Performance Na-Ion Storage of S-Doped Porous Carbon Derived from Conjugated Microporous Polymers

Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.

Preparation and Characterization of Microporous Nano-Tungsten Trioxide and Its Photocatalytic Activity after Doping Rare Earth

Aqueous sols and gels of tungstic acid were prepared from Na2WO4 with protonated cation-exchange resin. Nano-tungsten oxide of a microporous lamella was synthesized by means of washing of WO3· 2H2O with distilled water under ultrasonic wave agitation and centrifuging repeatedly, and the specific surface area tended to increase gradually with washing and centrifuging. The sample of centrifuged 7 h has more than 2 times highs specific surface area and more high photocatalytic activity . The mechanisms are also discussed.

Facile synthesis of microporous carbon through a soft-template pathway and its performance in desulfurization and denitrogenation

Wormlike/lamellar microporous carbons were prepared by using long alkyl chain primary amine hydrochloride as the template and resorci- nol/formaldehyde as the carbon source under highly acidic conditions. The template can be eliminated by high temperature treatment under an inert atmosphere. The obtained carbon materials were characterized by N2 adsorption-desorption, transmission electron microscopy, ther- mogravimetry and scanning electron microscopy. The results show that dodecylamine hydrochloride surfactant can be used as the template of wormlike micropores structure while octadecylamine hydrochloride results in both lamellar and wormlike micropores. The obtained carbon materials have the similar pore size in the range of 0.5-0.59 nm, but with various morphologies such as monolith, spheres, and coralline. The microporous carbon obtained from dodecylamine hydrochloride surfactant shows good adsorption performance to remove the refractory sulfur compounds and nitrogen-containing compounds in fuel.

Improvement of antifouling characteristics in a bioreactor of polypropylene microporous membrane by the adsorption of Tween 20

Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes （PPMMs）. Attenuated total reflection-Fourier transform infrared spectroscopy （ATR/FT-IR） and field emission scanning electron microscope （FE- SEM） were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor （MBR）, filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied.

Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries

Lithium-sulfur（Li-S） batteries belong to one of the promising technologies for high-energy-density rechargeable batteries.However,sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles.Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues.Mesoporous and microporous carbons have been widely used for sulfur accommodation,but mesoporous carbons have poor sulfur confinement,whereas microporous carbons are impeded by low sulfur loading rates.Here,a core-shell carbon,combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement,was prepared by coating the mesoporous CMK-3 with a microporous carbon（MPC） shell and served as the carbon host（CMK-3 @MPC） to accommodate sulfur.After sulfur infusion,the as-obtained S/（CMK-3@MPC） cathode delivered a high initial capacity of up to 1422 mAh·g-1 and sustained 654 mAh·g-1 reversible specific capacity after 36 cycles at 0.1 C.The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix,in which sulfur can be effectively confined within the meso/microporous carbon host,thus achieving simultaneously high electrochemical utilization.

Large-scale carambola-like V_(2)O_(5) nanoflowers arrays on microporous reed carbon as improved electrochemical performances lithium-ion batteries cathode

To search for new cathode materials with high energy density of Lithium-ion batteries(LIBs) is one of the most challenging issues. Vanadium pentoxide(V2 O5) with high theoretical specific capacity is believed to be a promising candidate for the next generation cathode materials, yet still suffers from low lithium ion diffusion coefficient and poor electronic conductivity resulting in low cycling life and poor rate performances. Here, we report new large-scale carambola-like V2 O5 nanoflowers arrays anchored on microporous reed carbon as high performances LIBs cathode. Each individual pore space of the microporous reed carbon is like a hexagonal cylinder, and the area of each carbon wall is more than103 um2, which is favorable for the growth of V2 O5 nanostructure arrays. After hydrothermal, the largescale carambola-like V2 O5 nanoflowers arrays can directly grow on the surface of microporous carbon.Due to the novel composite structures, the V2 O5 nanoflowers arrays@microporous carbon stabilizes at273 mA h g^(-1) after 100 cycles at 0.2 C. When cycling at 1.0 C over 500 cycles, the capacity still maintains at 180 mAh g^(-1). The demonstrated approach in this work paves the way for the development of high rate capability and excellent cycling stability V2 O5-based cathode materials.

SURFACE MODIFICATION OF POLYPROPYLENE MICROPOROUS MEMBRANES BY THE ADSORPTION OF NON-IONIC SURFACTANTS

Surface modification by physical adsorption of a series of non-ionic surfactants including Tween 20, Tween 40, Tween 60, Tween 80 and Tween 85, was accomplished on polypropylene microporous hollow fiber and flat membranes. The adsorption curve of the membrane surface was analyzed by weight measurements and the typical results showed a twoplatform character similarly. Differences in the degree and curve shape of adsorption resulting from such factors as concentration, temperature, as well as water cleaning time were observed for Tween 85 among other Tweens. Attenuated total reflection - Fourier transform infrared spectroscopy analysis and field emission scanning electron microscopy observation showed that the adsorption of Tween on polypropylene microporous membrane （PPMM） is effective and occurs mainly in the pores of PPMMs at low adsorption amount, and on the membrane surface also at high adsorption value.

Surface Modification of Polypropylene Microporous Membrane by Atmospheric-pressure Plasma Induced N-vinyl-2-pyrrolidone Graft Polymerization

Membrane surfaces modified with poly（N-vinyl-2-pyrrolidone） （PNVP） can be endowed with hydrophilicity, biocompatibility and functionality. In this work, atmospheric pressure dielectric barrier discharge plasma graft polymerization of N-vinyl-2-pyrrolidone （NVP） onto polypropylene （PP） microporous membrane surface was studied. The experimental results reveal that plasma treatment conditions, such as discharge power, treatment time and adsorbed NVP amount, have remarkable effects on the grafting degree of NVP. Structural and morphological changes on the membrane surfaces were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscope （XPS） and field emission scanning electron microscopy （FE-SEM）. Water contact angles of the membrane surfaces were also measured by the sessile drop method. Water contact angles on the membrane surfaces decrease with the increase of NVP grafting degree, which indicates an enhanced hydrophilicity for the modified membranes. The effects of grafting degrees on pure water fluxes were also measured. It is shown that pure water fluxes increase with grafting degree firstly and then decrease adversely. Finally, filtration of bovine serum albumin （BSA） solution and platelets adhesion of the PNVP modified membranes show good protein resistance and potential biocompatibility due to the enhancement of surface hydrophilicity.

FORMATION AND MICROSTRUCTURE OF POLYETHYLENE MICROPOROUS MEMBRANES THROUGH THERMALLY INDUCED PHASE SEPARATION

Microporous membranes of low-high density polyethylene and their blends were prepared bythermally-induced phase separation of polymer/long-aliphatic chain alcohol (diluent) mixtures.The microstructures of this particular membrane, which depends on the diluent properties,polymer concentration and cooling rate, were observed by scanning electron microscopy.'Beehive-type,'leafy-like, and lacy porous structure morphologies can be formed,depending onthe blend composition and phase separation conditions, which were discussed by the polymer anddiluent crystallization processes.

SURFACE MODIFICATION OF POLYPROPYLENE MICROPOROUS MEMBRANE BY TETHERING POLYPEPTIDES

Two kinds of polypeptides were tethered onto the surface of polypropylene microporous membrane （PPMM） through a ring opening polymerization of L-glutamate N-carboxyanhydride initiated by amino groups which were introduced by ammonia plasma and y-aminopropyl triethanoxysilane treatments. X-ray photoelectron spectroscopy （XPS）, attenuated total reflectance Fourier transform infrared spectroscopy （FT-IR/ATR）, scanning electron microscopy （SEM）, together with water contact angle measurements were used to characterize the modified membranes. XPS analyses and FT-IR/ATR spectra demonstrated that polypeptides are actually grafted onto the membrane surface. The wettability of the membrane surface increases at first and then decreases with the increase in grafting degrees of polypeptide. Platelet adhesion and murine macrophage attachment experiments reveal an enhanced hemocompatibility for the polypeptide modified PPMMs. All these results give evidence that polypeptide grafting can simultaneously improve the hemocompatibility as well as reserve the hydrophobicity for the membrane, which will provide a potential approach to improve the performance of polypropylene hollow fiber microporous membrane used in artificial oxygenator.

An Ultra-microporous Carbon Material Boosting Integrated Capacitance for Cellulose-Based Supercapacitors

A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials.Herein,an ultramicroporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacterial cellulose(BC)precursor followed by nitrogen/sulfur dual doping is reported.The microporous carbon possesses highly concentrated micropores(~2 nm)and a considerable amount of sub-micropores(<1 nm).The unique porous structure provides high specific surface area(1554 m^2 g^-1)and packing density(1.18 g cm^-3).The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport.As a result,the remarkable specific capacitances,including ultrahigh gravimetric and volumetric capacitances(430 F g^-1 and 507 F cm^-3 at 0.5 A g^-1),and excellent cycling and rate stability even at a high current density of 10 A g^-1(327 F g^-1 and 385 F cm^-3)are realized.Via compositing the porous carbon and BC skeleton,a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density(~0.77 mWh cm^-2),volumetric energy density(~17.8 W L^-1),and excellent cyclic stability.

Surface Modification of Polypropylene Microporous Membrane by Atmospheric-Pressure Plasma Immobilization of N,N-dimethylamino Ethyl Methacrylate

Surface modification of polypropylene microporous membrane （PPMM） was performed by atmospheric pressure dielectric barrier discharge plasma immobilization of N,Ndimethylamino ethyl methacrylate （DMAEMA）. Structural and morphological changes on the membrane surface were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscope （XPS） and field emission scanning electron microscopy （FE-SEM）. Water contact angles of the membrane surfaces were also measured by the sessile drop method. Results reveal that both the plasma-treating conditions and the adsorbed DMAEMA amount have remarkable effects on the immobilization degree of DMAEMA. Peroxide determination by 1,1-diphenyl-2-picrvlhydrazyl （DPPH） method verifies the exsistence of radicals induced by plasma, which activize the immobilization reaction. Pure water contact angle on the membrane surface decreased with the increase of DMAEMA immobilization degree, which indicates an enhanced hydrophilicity for the modified membranes. The effects of immobilization degrees on pure water fluxes were also measured. It is shown that pure water fluxes first increased with immobilization degree and then decreased. Finally, permeation of bovine serum albumin （BSA） and lysozyme solution were measured to evaluate the antifouling property of the DMAEMA-modified membranes, from which it is shown that both hydrophilicity and electrostatic repulsion are beneficial for membrane antifouling.

MICROPOROUS PVDF-HFP-BASED POLYMER MEMBRANES FORMED FROM SUPERCRITICAL CO_2 INDUCED PHASE SEPARATION

Microporous poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)membranes following supercritical CO_2 induced phase separation process were prepared using four solvents.The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte.The effect of the solvents on the morphology and structure,electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated.It was approved that all the membrane had the similar...

Affinity Adsorption of Bilirubin on Cibacron Blue F3GA-modified Microporous Polytetrafluoroethylene Capillary

Bilirubin removal from human plasma was obtained via an affinity microporous polytetrafluoroethylene（MPTFE） capillary. The new adsorbent comprised grafted glycidyl methacrylate（GMA） via radiation-induced polymerization as hydrophilic coating and reactive sites; ethylenediamine（EDA） as a spacer arm; Cibacron Blue F3GA（CB F3GA） as an affinity ligand; MPTFE capillary as the supporting matrix. The average density of CB F3GA attachment to MPTFE capillaries was found to be 136.5 μmol/g. The capacity of bilirubin adsorbed on affinity MPTFE capillaries is 76.1 mg bilirubin/g polymer（at 25℃）. This new adsorbent has advantages over both membrane and traditional micro-column, and this system is stable and easy to operate. The results of blood tests suggest the CB F3GA affinity capillary has good blood compatibility.

PREPARATION AND CHARACTERIZATION OF PVDF-HFP MICROPOROUS MEMBRANE BY TEMPLATE METHOD

Porous poly（vinylidene fluoride-co-hexafluoropropylene） （PVDF-HFP） membranes were successfully prepared using dibutyl phthalate （DBP）, polyvinylpyrrolidone （PVP-K30）, polyethylene glycol 200 （PEG200） as templates. SEM was used to examine the morphology of the PVDF-HFP porous membranes. It was found that these membranes have an asymmetric structure and the blends of PVDF-HFP/DBP formed nanoporous membranes, whereas the blends of PVDF- HFP/PVP-K30 formed ＂sponge-like＂ and microporous membranes. Moreover, the average pore size and porosity was about 0.3 μm and 48.7%, respectively. The crystallinity, thermal stability and mechanical strength of membranes were characterized by XRD, DSC, TGA and stress-strain tests. The results showed that the membranes are a crystals with excellent thermal stability. It was an effective way to regulate pore size and morphology of the PVDF-HFP membranes.

Knitted Microporous Polymers as Efficient Adsorbents for Wastewater Treatment: Effects of Skeleton Structure and Pore Distribution

Hyper-cross-linked microporous organic polymers(MOP) with controlled skeleton structure and pore distribution were prepared by Friedel-Crafts alkylation reaction. The hyper-cross-linked polymers(HCPs) produced by knitting aromatic functional groups posses the typical micro-and meso-porous composite structure and specific surface areas of up to 957 m^2·g^(-1). The obtained materials were evaluated as adsorbents for methylene blue(MB) and subjected to several batch adsorption tests to investigate the effects of adsorbent dosage, concentration of MB, temperature, and pH on MB removal. The maximum adsorbed capacity(q_m) of KAPs-Ph(381 mg·g^(-1), knitted using benzene) exceeded those of less mesoporous KAPs-PhPh_3(310 mg·g^(-1) knitted using 1,3,5-triphenylbenzene) and chloromethyl polystyrene resin(58 mg·g^(-1)). Moreover, KAPs-Ph could be regenerated by Soxhlet extraction with ethanol and reused for up to 15 times with minimal loss of adsorption capacity. The results illustrate that adsorption performance can be improved by controlling the pore structure of the adsorbing materials, and KAPs-Ph has a potential application values for the industrial removal of organic dyes from wastewater.

Influence of Microporous Magnesia-rich Spinel Aggregates on Properties of Low Carbon MgO-C Refractories

Two types of low carbon MgO - C refractories with 6% graphite were prepared using microporous magnesiarich spinel （5 - 3 and 3 - 1 mm ） and fused magnesia （5 - 3 and 3 - 1 mm ） as coarse aggregates, respectively, fused magnesia （ ≤1 mm） as fine aggregate, magnesia powder （≤ 0. 088 mm ） , flake graphite powder （ ≤0. 088 mm）, metal Al powder （ 〈0. 074 mm） as matrix, and phenol resin as binder. After curing at 220 ℃ and coke-embedded firing at 1 500 ℃ , the apparent porosity, cold crushing strength, cold modulus of rupture, permanent linear change on heating, thermal shock resistance and slag resistance of the specimens were studied comparatively. The results indicate that： （ 1 ） after curing at 220 ℃ and coke-embedded firing at 1 500 ℃, the specimen with microporous magnesia-rich spinel replacing fused magnesia has lower bulk density and higher apparent porosity than the common low car- bon MgO - C specimen. After curing at 220 ℃, the specimen with microporous aggregate has lower strength than common low carbon MgO - C specimen, but after coke-embedded firing at 1 500℃, it has higher strength and lower permanent linear change on heating; （2） low carbon MgO - C specimen using microporous magnesia-rich spinel to replace fused magnesia aggregate has better thermal shock resistance but worse slag resistance.

Fabrication of Microporous Film and Microspheres Hybrids

Hybrids consisting of a microporous film and polymeric microspheres were fabricated via a simple method without a special apparatus. Highly ordered microporous polymer films with honeycomb structure were fabricated by a dissipative process utilizing amphiphilic poly(acrylic acid)- block-polystyrene, which was synthesized by atom transfer radical polymerization followed by an acid-catalyzed ester cleavage reaction. In order to embed the microsphere efficiently, the dried microporous films should be soaked in methanol to alter the surface functionality and to improve the wettability of the film surface. The introduction of amino functionality to polystyrene microspheres by seeded polymerization of N,N-dimethylaminoethyl methacrylate drastically improved the embedding efficiency. The effect of open pore size was also investigated.