Hyper-crosslinked Conjugated Microporous Polymers with Increased Micropores Promotes Confining Polymerization for Electromagnetic Absorption Application

Conjugated microporous polymers have excellent skeleton structures but poor electrical conductivity limits their applications in microwave absorption.To solve this problem,a strategy of molecular expansion and confining polymerization is proposed in this work to synthesize conductive hyper-crosslinked conjugated microporous polymer.The topology of the conjugated microporous polymer is changed into a three-dimensional skeleton structure with high specific surface area by using molecular expansion technique,and the controlled growth of polypyrrole in the channel constructs a unique network structure.The balance of excellent composite backbone structure,proper conductivity,attenuation capability and impedance matching enable the material to exhibit electromagnetic wave absorption performance.As a result,with low filler loading of 10 wt%,a strongest reflection loss of-52.68 d B and a maximum effective bandwidth of 5.76 GHz.Additionally,CST simulations of the radar scattering cross section have been carried out to verify the excellent material properties.This study provides new concepts for new conductive polymers and broadens the application of hyper-crosslinked conjugated microporous polymer in the field of electromagnetic wave absorption.

Porous solid inspired hyper-crosslinked polymer liquids with highly efficient regeneration for gas purification

Separation media that combine the desired material properties within a single material for a given process remain an ongoing challenge for the gas separations in industry.Process integration of porous solid adsorbents is difficult due to their limited volumetric capacity,whereas issues of volatility and high regeneration temperatures exist for liquid amines and physical solvents.Herein,we report a family of polymer liquids inspired by hyper-crosslinked polymers(HCPs),a class of highly swellable network polymers.Compared with a chemically similar porous solid,the HCP-liquids demonstrate good volumetric capacity and improved selectivity of carbon dioxide over methane.Uptake appears to be enhanced by intramolecular swelling of the HCP-liquids at elevated pressures,while guests are strongly rejected from the HCP-liquids at slightly elevated temperatures,leading to highly efficient regeneration.Heat of adsorption and specific heat capacity of the HCP-liquids are also low,further suggesting favourable process thermodynamics.Additionally being easily prepared at scale,the presented HCP-liquids represent a promising step towards a material with the requisite properties to replace conventional scrubbing solvents to drastically reduce the footprint and energy needs of gas separations.

Preparation and Catalytic Performance of Microporous Polymer/Au Nanoparticles Composite Microspheres

Polystyrene crosslinked microspheres were prepared by soap-free emulsion polymerization using styrene (St) and divinylbenzene (DVB) as monomers;then,the microporous structure was knitted by the Friedel-Crafts alkylation reaction,and the Au nanoparticles (AuNPs) were loaded into the pores through thermal reduction,to obtain AuNPs/ hyper-crosslinked microporous polymer composite microspheres.SEM and particle-size test results show that the microspheres show good monodispersity.The micropore analysis indicates that the specific surface area and the pore volume of the microporous polymer microspheres decrease with increasing DVB content,and when the DVB content is 0.1%,the specific surface area reaches a maximum of 1 174.6 m2/g.After loading AuNPs,the specific surface area and the amount of micropores of the composite microspheres decrease obviously.The results of XRD and XPS analyses suggest that HAuCl4 is reduced to AuNPs.The composite microspheres show a good catalytic performance for the reduction catalyst of 4-nitrophenol.

Fabrication of fire-retardant building materials via a hyper-crosslinking chemical conversion process from waste polystyrenes

Polystyrene(PS)is rich in plastic materials,but it produces a large amount of waste every year,causing a huge burden on the environment.Although PS plastic is the source of a common"white pollution"in daily life,it still has a high utilization value.At the same time,the flammability of PS material determines that it cannot be applicated in places where fire accidents occur frequently.As a result,its application has been greatly limited.In order to realize the efficient utilization of waste PS and broaden its scope of application,PS was modified by hyper-crosslinking in order to improve its fire-retardant performance.In this method,the PS solution with high purity was obtained by dissolving waste PS foam with 1,2-dichloroethane(DCE),and then the hyper-crosslinked polymer with high specific surface area was prepared by adding cross-linking agent formaldehyde dimethyl acetal(FDA)and a Lewis-acid catalyst ferric chloride(FeCl_(3)).Further studies showed that the effects of the amount of cross-linking agent FDA,catalyst FeCl_(3) and PS on the reaction products were different.In addition,compared the as-prepared fire-retardant materials with PS foam from the aspects of flame retardancy and thermal insulation,it can be concluded that the fire-retardant performance of the materials prepared by this method has been significantly enhanced.And it is proved that this method is feasible towards the preparation of a large number of fire-retardant composite materials by using a scale-up experiment.

Robust perfluorinated porous organic networks: Succinct synthetic strategy and application in chlorofluorocarbons adsorption

Fluorinated porous organic networks(F-PONs)have demonstrated unique properties and applications,but approaches capable of affording F-PONs with high fluorine content and robust nanoporous architecture under metal-free and easy handling conditions are still rarely reported.Herein,using polydivinylbenzene(PDVB)as an easily available precursor,a novel and straightforward approach was developed to afford F-PONs via a dehydrative Friedel-Crafts reaction using perfluorinated benzylic alcohols as the cross-linking agent promoted by Bronsted acid(trifluoromethanesulfonic acid).The afforded material(F-PDVB)featured high fluorine content(22 at.%),large surface area(771 m^(2)·g^(-1)),and good chemical/thermal stability,rendering them as promising candidates for the adsorption of CO_(2),hydrocarbons,fluorocarbons,and chlorofluorocarbons,with weight capacities up to 520 wt.%being achieved.This simple methodology can be extended to fabricate fluorinated hyper-crosslinked polymers(F-HCPs)from rigid aromatic monomers.The progress made in this work will open new opportunities to further expand the involvement of fluorinated materials in large scale applications.

Adsorption selectivity of salicylic acid and 5-sulfosalicylic acid onto hypercrosslinked polymeric adsorbents

Both bottle-point and column-feeding experi-ments involving different solutes and sorbents were carried out to investigate the adsorption selectivity and separation performance of salicylic acid and 5-sulfosalicylic acid.Their adsorption isotherms onto such hypercrosslinked polymeric adsorbents as NDA-100 and NDA-99 could be well described by the Freundlich equations whose characteristics describe extrathermic and favorable adsorption processes.The adsorp-tion towards NDA-100 mainly depended on the p-p interac-tion,while that towards NDA-99 was extremely influenced by the static-electric interaction.Additionally,the adsorptive capacity of salicylic acid on NDA-99 decreased while it increased on NDA-100 with the presence of 5-sulfosalicylic acid in the adsorptive environment as the competitive component.Comparatively,the adsorption capacity of 5-sulfosalicylic acid decreased on both resins with salicylic acid as the competitive component.In fact,the difference in the interaction between adsorbent and adsorbate resulted in the straight antagonism on the effective adsorption sites on the adsorbent.In conclusion,the adsorption selectivity of salicylic acid onto NDA-100 was obviously larger than that onto NDA-99 with the existence of 5-sulfosalicylic acid in the adsorptive environment.A satisfactory separation and recovery of tested solutes in aqueous phase could be foresee-ably achieved by the sequencing adsorption technique involving NDA-100 as well as NDA-99.