Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials to...Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials toward practical coal mining applications.Herein,a novel phenolic composite material filled with modified fly ash(MFA)geopolymer has been proposed to address the above issues.By modifying fly ash(FA)particles with siloxanes,robust interfacial bonding between the organic PF polymer and inorganic geopolymer network has been established,which enables modulation of their micro-morphologies to optimize their macro performances.The foam structure of PF evolves from an open-cell to a closed-cell morphology with the incorporation of MFA,leading to a decreased pulverization ratio(41%)while enhanced mechanical properties(15%).Compared with neat PF,the composite exhibits faster gelation dynamics during curing,with a maximum reaction temperature as low as only 40°C.PF/MFA composite show high reliability against gas leakage during a laboratory designed coal mine plugging test.Furthermore,the formation of a silica hybrid char layer with higher graphitization degree and a multiple continuous closed-cell structure following the combustion of PF/MFA effectively inhibits the release of combustible volatiles and toxic gases.It is provided that this strategy of geopolymer filled polymer cross-linking networks with tunable morphology opens up an avenue for advanced mining phenolic filling materials.展开更多
Heteroatom-doped porous carbon materials have been widely studied due to their high specific surface area and high heteroatom content,but it is difficult to achieve high specific surface area and high heteroatom conte...Heteroatom-doped porous carbon materials have been widely studied due to their high specific surface area and high heteroatom content,but it is difficult to achieve high specific surface area and high heteroatom content at the same time.Herein,a simple method is introduced to prepare N/O co-doped hierarchical porous carbon materials(DNZKs).Phthalonitrile resins(DNZs)were prepared by using 1,3-bis(3,4-dicyanophenoxy)benzene as raw material and ZnCl_(2)/urea as composite curing agent,and then using KOH as activator to successfully prepare DNZKs with high specific surface area,developed pores and high N/O content.The porous carbon material(DNZK@400)obtained at a curing temperature of 400℃ has the highest N content(4.97%(mass)),a large specific surface area(2026 m^(2)·g^(-1)),a high micropore proportion(0.9),a high O content(7.53%(mass)),and the best specific capacitance(up to 567 F·g^(-1) at 0.1 A·g^(-1)),which can be attribute to the high temperature resistance of the nitrogencontaining aromatic heterocyclic structure in DNZs.When the mass ratio of resin and KOH is 1:1,the specific capacitance of the sample tested by the acid three-electrode system is obtained,and it is found that the material has high cycling stability(119%specific capacitance retention after 100,000 cycle tests).This work proposes a simple and easy-to-operate method for the preparation of multifunctional porous carbon.展开更多
Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lacton...Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lactones is a simple,and in most cases controlled method to synthesize polyesters with alicyclic moieties in the polymer backbone.The stereochemistry of the alicyclic structures has a great effect on the polymer properties,which can be regulated by varying the polymerization conditions.Here,we report a systematic investigation on the ROP of 2-oxabicyclo[2.2.2]octan-3-one([2.2.2]VL)under different conditions.When initiated byn-butyl lithium(n-BuLi)or catalyzed by trifluoromethanesulfonic acid(TfOH)in the presence of benzyl alcohol,P[2.2.2]VLs containing all cis^(-1),4 disubstituted cyclohexane ring were obtained.However,P[2.2.2]VLs initiated by sodium methoxide(MeONa)or catalyzed by organic superbase contained both cis and trans isomeric structural units.The cis to trans transformation mechanism under these conditions was manifested,and the effect of stereochemical variations on the properties ofP[2.2.2]VLwas revealed.The stereoregularP[2.2.2]VLs,bothcisandtrans,exhibited higher crystallinity and melting temperatures(Tm)than those of the stereoirregular isomers.Finally,the degradation of P[2.2.2]VL with acid at high temperature could recover 3-cyclohexenecarboxylic acid.展开更多
New liquid crystalline monomer,2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully synthesized.Polyacrylate with laterally attached mesogens via ei;ter linkage was also derived.This polymer forms ...New liquid crystalline monomer,2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully synthesized.Polyacrylate with laterally attached mesogens via ei;ter linkage was also derived.This polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematic phase with respect to the crystalline state.However,its liquid crystallinity is very low as compared to that of poly{2,5-bis[(4'-methoxyphenoxy)carbonyl]-styrene}.展开更多
In order to meet the demand for infrared stealth materials in the military field,conjugated polymers containing Schiff base moieties were designed and prepared.Various dialdehyde monomers were introduced and their eff...In order to meet the demand for infrared stealth materials in the military field,conjugated polymers containing Schiff base moieties were designed and prepared.Various dialdehyde monomers were introduced and their effect on the comprehensive properties were systematically characterized.The resulted polymers could be cast in solution to prepare polymer coatings.The coatings exhibited high thermal stability up to 400℃ at 5%weight loss,and excellent mechanical performance with high Young’s modulus and hardness.The infrared emissivity values varied from 0.587 to 0.627 at wavelength of 8-14μm and ranged from 0.595 to 0.609 at wavelength of 2-22μm.Specifically,it was found that the ATTPAL structure with carbazole moieties had a lower band gap and better electrical conductivity by photoelectric test and DFT theoretical analysis.Meanwhile,the infrared emissivity value of ATTPAL coating was the lowest compared with p-phenyl and pyridyl containing analogues,suggesting it was potential material for the future development of infrared stealth technology.The combined results showed that reducing the band gap and improving the electrical conductivity of the structure were both beneficial to the reduction of infrared emissivity.It would positively provide new ideas for the design of infrared stealth materials.展开更多
A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene)(PEO_(113)-b-PVBC_(130)-b-Pt BS_(x)or E_(113)V_(130)T_(x))triblock terpolymers with various lengths x(=20,33,66,104,215...A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene)(PEO_(113)-b-PVBC_(130)-b-Pt BS_(x)or E_(113)V_(130)T_(x))triblock terpolymers with various lengths x(=20,33,66,104,215)of Pt BS block were synthesized via a two-step reversible addition-fragmentation chain transfer(RAFT)polymerization.The E_(113)V_(130)T_(x)triblock terpolymers were non-crystalline because the PVBC and Pt BS blocks strongly hindered the crystallization of PEO block.The effects of Pt BS block length x on the phase structures of E_(113)V_(130)T_(x)triblock terpolymers were investigated by combined techniques of small-angle X-ray scattering(SAXS)and transmission electron microscopy(TEM).It was found that with increasing x from20 to 215,the phase structure of E_(113)V_(130)T_(x)triblock terpolymers became more ordered and changed from disordered structure,hexagonally-packed cylinder(HEX),hexagonally perforated layer(HPL),to lamellar(LAM)phase structures.Temperature-variable SAXS measurements showed that the HEX,HPL and LAM phase structures obtained for E_(113)V_(130)T_(66),E_(113)V_(130)T_(104)and E_(113)V_(130)T_(215)by thermal annealing,respectively,were thermodynamically stable in the temperature range of 30-170℃.展开更多
Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of...Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of ABRP and AIRP in various feed ratios were carried out with SbCl_5 and BF_3OEt_2 as catalyst at low temperatures.The copolymer structure was characterized by means of ^(1)H,^(13)C NMR spectroscopy and specific rotation.When SbCl_(5)was used as catalyst,the copolymer obtained had completely 1,4-β-pyranosidic structure,i.e.,cellulosetype structure.However,when BF_(3)OEt_2 was used as catalyst,the copolymer had a mixed structure of furanosidic and pyranosidic units.展开更多
The general characteristics of the active center of the catalysts（including zinc-cobalt（III） double metal cyanide complex [Zn-Co（Ⅲ） DMCC]） for the copolymerization reaction of carbon dioxide（CO2） with epoxide...The general characteristics of the active center of the catalysts（including zinc-cobalt（III） double metal cyanide complex [Zn-Co（Ⅲ） DMCC]） for the copolymerization reaction of carbon dioxide（CO2） with epoxide are summarized. By comparing the active center, catalytic performance of the Zn-Co（Ⅲ） DMCC（and other catalysts） with HCAII enzyme in the organism for activating CO2（COS and CS2）, we proposed that the metal-hydroxide bond（M-OH）, which is the real catalytic center of human carbonic anhydride Ⅱ（HCAⅡ）, is also the catalytic（initiating） center for the copolymerization. It accelerates the copolymerization and forms a closed catalytic cycle through the chain transfer reaction to water（and thus strictly meets the definition of the catalyst）. In addition, the metal-hydroxide bond catalysis could well explain the oxygen/sulfur exchange reaction（O/S ER） in metal（Zn, Cr）-catalyzed copolymerization of COS（and CS2） with epoxides. Therefore, it is very promising to learn from HCAⅡ enzyme to develop biomimetic catalyst for highly active CO2/epoxide copolymerization in a well-controlled manner under mild conditions.展开更多
Exploring new polymerization strategy for current available monomers is a big challenge in polymer science. Here we re-investigate radical polymerization of monovinyl monomer(MVM) initiated by uniform branched polyfun...Exploring new polymerization strategy for current available monomers is a big challenge in polymer science. Here we re-investigate radical polymerization of monovinyl monomer(MVM) initiated by uniform branched polyfunctional initiator(PFI), which is termed non-linear radical additions-coupling polymerization(NLRAs CP). In NLRAs CP, both addition and coupling reactions of radical contribute to the construction of the polymer chains, which leads to continuous growth of branch topology. Theoretical analysis of NLRAs CP predicts that the gelation is determined by the functionality of PFI(a), the extent of initiation of the PFI(q) and the termination factor of radical(φ). NLRAs CPs of styrene and methyl methacrylate promoted by Cu(0)/MeTREN or Mn_(2)(CO)_(10)/visible light were conducted. After the cleavage of incorporated PFI fragment or junctions in the network, the network was transformed to linear chains having almost the same structure as segmental chains in the precursor network. This allows the reverse deducing the network structure from its cleaved products. It has been proven that NLRAs CP includes stepwise initiation of PFI, chain-growth of segmental chains and successive endlinking of macroradicals derived from PFI. The three parameters related to the gelation process, a, q and φ, were adjusted via binary PFI, the feed ratio of [Mn_(2)(CO)_(10)]/[PFI] and addition of non-homopolymerizable comonomer respectively. The minimum values of a and q, and the minimum amount of comonomer required for gelation were determined,which can be applied to estimate φ of various macroradicals. NLRAs CP opens a general and facile strategy for synthesis of a variety of polymer networks with heritable architecture by one-pot polymerization of various MVMs.展开更多
Toughening the petroleum-based epoxy resin blends with bio-based modifiers without compromising their modulus,mechanical strength,and other properties is still a big challenge in view of the sustainability.In this stu...Toughening the petroleum-based epoxy resin blends with bio-based modifiers without compromising their modulus,mechanical strength,and other properties is still a big challenge in view of the sustainability.In this study,a bio-based liquid crystal epoxy resin(THMT-E P)with an s-triazine ring structure was utilized to modify a petroleum-based bisphenol A epoxy resin(E51)with 4,4'-diaminodiphenylsulfone(DDS)as a curing agent,and the blended systems were evaluated for their thermal stability,mechanical properties,and flame retardancy.The results showed that the impact strength of the blended system initially increased and then decreased with the increase in THMT-EP content,and it reached the a maximum value of 26.5 kJ/m^(2)when the THMT-EP content was 5%,which was 31.2%higher than that of E51/DDS.Notably,the flexural strength,modulus,and glass transition tem perature of the blended system were all simultaneously improved with the addition of THMT-EP.At the same time,the addition of THMT-EP enhanced the flame retardancy of the system by increasing the char yield at 700℃and decreasing the peak heat release rate and total heat release rate.This work paves the way for a more sustainable improvement in the comprehensive performance of epoxy resin.展开更多
Recovering alcohols from dilute fermentation broth is an emergent task in bio-fuel production process. Since they are primary planned for fuels, energy required to separate these alcohols should be considered in evalu...Recovering alcohols from dilute fermentation broth is an emergent task in bio-fuel production process. Since they are primary planned for fuels, energy required to separate these alcohols should be considered in evaluating the potential of a separation technology. A membrane-based process, pervaporation, is of special interest because of its environmental friendliness and easy integrating character. This review probes into the fundamentals of pervaporation especially in terms of the heat required for evaporation. Meanwhile, the separation data of the most representative alcohol-selective pervaporation membranes reported in the literatures are collected and compared with the vapor–liquid equilibrium curve, which represents the distillation selectivity. They include:inorganic membranes, silicon rubber based membranes, Mixed Matrix Membranes and some other special materials. By doing so, the status of alcohol recovery via pervaporation would be more clear for researchers.For ethanol recovery, it is selectivity rather than flux that is in urgent need of solution. While for butanol recovery,membranes with satisfactory selectivity have been developed, increasing the separation capacity would be more pressing.展开更多
An unusual reduction of some aromatic aldehydes and ketones by sodium borohydride was discovered.In a THF/H2O or DMSO/H2O solvent system the aromatic aldehydes and ketones with acyloxy substituent on the orthoposition...An unusual reduction of some aromatic aldehydes and ketones by sodium borohydride was discovered.In a THF/H2O or DMSO/H2O solvent system the aromatic aldehydes and ketones with acyloxy substituent on the orthoposition to the carbonyl group can be reduced to the corresponding alkyl phenols.This unusual reduction is applicable also to the corresponding alcohols of all the above aldehydes and ketones.A putative mechanism was suggested.In addition to the above aldehydes,ketones and benzyl alcohols,certain 4acyloxybenzyl esters(probably also the 2substituted analogues)such as 4benzoyloxybenzyl benzoate was also found to be reduced to methylphenol by this unusual reduction.展开更多
We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols.Four poly(dithioacetal)s(P1-P4)were prepared via the base-catalyzed thiol-yne"...We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols.Four poly(dithioacetal)s(P1-P4)were prepared via the base-catalyzed thiol-yne"click"polyaddition of two dithiols(1,4-butanedithiol(4S)and 1,5-pentanedithiol(5S))and two alkynones(3-butyn-2-one(Y1)and 1-phenyl-2-propyn-1-one(Y2))at high concentrations.We systematically investigated the base-catalyzed polymerization of 4S and Y1(for polymer PI)under different conditions,and found that this polymerization was a highly concentration-dependent dynamic system:polymer PI was formed at high concentration,while seven-membered dithioacetal,1-(1,3-dithiepan-2-yl)propan-2-one(C1),was obtained at low concentration.The polymerization of 4S and Y2(for polymer P4)displayed similar polymerization behavior,generating 2-(1,3-dithiepan-2-yl)-1-phenylethanone(C4)at low concentration.On the contrary,polymer P2(from Y1 and 5S)was exclusively obtained with no formation of eight-membered dithioacetal.The polymerizations of Y1 with 1,2-ethanedithiol(2S)and 1,3-dimercaptopropane(3S)only afforded corresponding five-and six-membered dithioacetals,1-(1,3-dithiolan-2-yl)propan-2-one(C2)and 1-(1,3-dithian-2-yl)propan-2-one(C3).This dynamic behavior of PI and P4 was attributed to the concentration-dependent retro-Michael addition reaction between a thiol and a β-sulfido-α,β-unsaturated carbonyl compound catalyzed by bases.Furthermore,polymers P1 and P4 could be depolymerized into Cl and C4 in yields of 58% and 95%,respectively.The ring-opening polymerization of Cl at high concentration could successfully regenerate polymer PI.Thus,a new type of closed-loop recyclable poly(dithioacetal)s was developed.展开更多
Compared to fluorescence imaging,chemiluminescence imaging does not need external excitation light,and hence presents high imaging depth and signal-to-noise ratio without autofluorescence and phototoxicity,making it a...Compared to fluorescence imaging,chemiluminescence imaging does not need external excitation light,and hence presents high imaging depth and signal-to-noise ratio without autofluorescence and phototoxicity,making it a promising tool for biological detection and analysis.However,the target-specific activatable near-infrared emission chemiluminescent probes still need to be developed for the precise diagnosis of diseases.In this paper,we synthesized four direct near-infrared emission Schaap’s chemiluminophores(AINCL,AIFCL,ABTCL,and APYCL)by incorporating different electronic acceptors,respectively,and studied the effect of the acceptors on the optical properties of the chemiluminophores.To achieve the specific detection of hydrogen sulfide(H_(2)S)-related diseases,we used H_(2)S-cleavable 2,4-dinitrophenylsulfonate to cage the phenol groups in the chemiluminophores.It was demonstrated that the endogenous H_(2)S in inflammations and tumors could activate effectively the chemiluminescence with high specificity,which provided the precise location of nidus in chemiluminescence imaging and allowed us to perform surgical resection.展开更多
Phenols are extremely difficult to release the hydrogen radical(H^(·))due to the disfavored O-H bond dissociation energy(BDE)and undergo O-H homolysis under strong ultraviolet-C(UVC)light.In this work,we provided...Phenols are extremely difficult to release the hydrogen radical(H^(·))due to the disfavored O-H bond dissociation energy(BDE)and undergo O-H homolysis under strong ultraviolet-C(UVC)light.In this work,we provided a method to modulate the O-H BDE of phenols byπ-conjugation to electron-donating heteroaromatics.Calculations on a phenol-cored photosensitizer(BTP-1)revealed drastic declines of O-H BDE(80.5 vs.28.1 kcal mol^(-1))by comparing the ground state(S_(0))and triplet excited state(T_(1)).Consequently,BTP-1 was sensitive to visible light and generated H^(·)after O-H scission.With glutathione(GSH)serving as an ultimate H^(·)donor,the BTP-1-based photosystem was efficient in catalyzing H^(·)generation under physiological conditions.This kind of hydrogen atom-based photochemistry is distinct from traditional typeⅠ/Ⅱphotosensitizing pathways that are electron or energy transfer-based.We applied the photosystem to solve the obstacle in hypoxia-activated prodrugs(HAPs)that face a dilemma with the heterogeneously hypoxic level of tumors.In vitro studies demonstrated that the photosystem boosted the chemotherapy performance of TH-302(a representative HAP)under moderate hypoxia.With the capability to target redox bonds in HAPs and good compatibility with near-infrared two-photon laser,the photosystem is promising for cancer precision therapy.展开更多
Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution,which satisfies the needs of sustainable social development.In this study,a...Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution,which satisfies the needs of sustainable social development.In this study,a bio-based epoxy thermoset precursor(MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process.And the fully bio-based epoxy thermoset(MGOL-EP-SC) was obtained by self-curing without adding any other hardener.MGOL-EP-SC revealed an extremely high glass-transition temperature(T_(g)) of 265℃ and char yield of 53.2%(in N;),which were at the highest level among the fully bio-based epoxy thermosets reported so far.In addition,when the MGOL-EP was cured with 4,4’-methylenedianiline(DDM),T_(g)of the MGOL-EP/DDM was decreased by 61℃ and the other comprehensive performance had also been decreased,which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents.Moreover,the MGOL-EP-SC presented certain killing rate(48.4%) to Staphylococcus aureus.These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.展开更多
We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yi...We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yield, respectively.展开更多
To date,how the shape of nanomaterials infuences their biological properties is poorly understood,due to the insufcient controllability of current preparative methods,especially in the shape and size of nanomaterials....To date,how the shape of nanomaterials infuences their biological properties is poorly understood,due to the insufcient controllability of current preparative methods,especially in the shape and size of nanomaterials.In this paper,we achieved the precise syntheses of nanoscale unimolecular cylindrical polymer brushes(CPBs)and spherical polymer nanoparticles(SPNPs)with the same volume and surface chemistry,which ensured that shape was essentially the only variable when their biological performance was compared.Accurate shape efects were obtained.Impressively,the CPBs had remarkable advantage in tissue penetration over the SPNPs.Te CPBs also exhibited higher cellular uptake and rapider body clearance than the SPNPs,whereas the SPNPs had longer blood circulation time,rapider tumor vascular extravasation,and higher tumor accumulation than the CPBs.Additionally,this work also provided a controllable synthesis strategy for nanoscale unimolecular SPNPs by integrating 21 CPBs to a�-cyclodextrin core,whose diameter in dry state could be up to 45 nm.展开更多
基金supported by the National Natural Science Foundation of China(No.U22A20151)Taiyuan Major Science and Technology Project in 2021.
文摘Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials toward practical coal mining applications.Herein,a novel phenolic composite material filled with modified fly ash(MFA)geopolymer has been proposed to address the above issues.By modifying fly ash(FA)particles with siloxanes,robust interfacial bonding between the organic PF polymer and inorganic geopolymer network has been established,which enables modulation of their micro-morphologies to optimize their macro performances.The foam structure of PF evolves from an open-cell to a closed-cell morphology with the incorporation of MFA,leading to a decreased pulverization ratio(41%)while enhanced mechanical properties(15%).Compared with neat PF,the composite exhibits faster gelation dynamics during curing,with a maximum reaction temperature as low as only 40°C.PF/MFA composite show high reliability against gas leakage during a laboratory designed coal mine plugging test.Furthermore,the formation of a silica hybrid char layer with higher graphitization degree and a multiple continuous closed-cell structure following the combustion of PF/MFA effectively inhibits the release of combustible volatiles and toxic gases.It is provided that this strategy of geopolymer filled polymer cross-linking networks with tunable morphology opens up an avenue for advanced mining phenolic filling materials.
基金supported by the National Natural Science Foundation of China(51673033 and 52073038)the Fundamental Research Funds for the Central Universities(DUT22LAB605).
文摘Heteroatom-doped porous carbon materials have been widely studied due to their high specific surface area and high heteroatom content,but it is difficult to achieve high specific surface area and high heteroatom content at the same time.Herein,a simple method is introduced to prepare N/O co-doped hierarchical porous carbon materials(DNZKs).Phthalonitrile resins(DNZs)were prepared by using 1,3-bis(3,4-dicyanophenoxy)benzene as raw material and ZnCl_(2)/urea as composite curing agent,and then using KOH as activator to successfully prepare DNZKs with high specific surface area,developed pores and high N/O content.The porous carbon material(DNZK@400)obtained at a curing temperature of 400℃ has the highest N content(4.97%(mass)),a large specific surface area(2026 m^(2)·g^(-1)),a high micropore proportion(0.9),a high O content(7.53%(mass)),and the best specific capacitance(up to 567 F·g^(-1) at 0.1 A·g^(-1)),which can be attribute to the high temperature resistance of the nitrogencontaining aromatic heterocyclic structure in DNZs.When the mass ratio of resin and KOH is 1:1,the specific capacitance of the sample tested by the acid three-electrode system is obtained,and it is found that the material has high cycling stability(119%specific capacitance retention after 100,000 cycle tests).This work proposes a simple and easy-to-operate method for the preparation of multifunctional porous carbon.
基金financially supported by the National Natural Science Foundation of China(Nos.21871014 and 21971005)。
文摘Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lactones is a simple,and in most cases controlled method to synthesize polyesters with alicyclic moieties in the polymer backbone.The stereochemistry of the alicyclic structures has a great effect on the polymer properties,which can be regulated by varying the polymerization conditions.Here,we report a systematic investigation on the ROP of 2-oxabicyclo[2.2.2]octan-3-one([2.2.2]VL)under different conditions.When initiated byn-butyl lithium(n-BuLi)or catalyzed by trifluoromethanesulfonic acid(TfOH)in the presence of benzyl alcohol,P[2.2.2]VLs containing all cis^(-1),4 disubstituted cyclohexane ring were obtained.However,P[2.2.2]VLs initiated by sodium methoxide(MeONa)or catalyzed by organic superbase contained both cis and trans isomeric structural units.The cis to trans transformation mechanism under these conditions was manifested,and the effect of stereochemical variations on the properties ofP[2.2.2]VLwas revealed.The stereoregularP[2.2.2]VLs,bothcisandtrans,exhibited higher crystallinity and melting temperatures(Tm)than those of the stereoirregular isomers.Finally,the degradation of P[2.2.2]VL with acid at high temperature could recover 3-cyclohexenecarboxylic acid.
基金This project was supported by China Postdoctoral Science Foundation and National Natural Science Foundation of China(No.59873001).
文摘New liquid crystalline monomer,2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate was successfully synthesized.Polyacrylate with laterally attached mesogens via ei;ter linkage was also derived.This polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematic phase with respect to the crystalline state.However,its liquid crystallinity is very low as compared to that of poly{2,5-bis[(4'-methoxyphenoxy)carbonyl]-styrene}.
文摘In order to meet the demand for infrared stealth materials in the military field,conjugated polymers containing Schiff base moieties were designed and prepared.Various dialdehyde monomers were introduced and their effect on the comprehensive properties were systematically characterized.The resulted polymers could be cast in solution to prepare polymer coatings.The coatings exhibited high thermal stability up to 400℃ at 5%weight loss,and excellent mechanical performance with high Young’s modulus and hardness.The infrared emissivity values varied from 0.587 to 0.627 at wavelength of 8-14μm and ranged from 0.595 to 0.609 at wavelength of 2-22μm.Specifically,it was found that the ATTPAL structure with carbazole moieties had a lower band gap and better electrical conductivity by photoelectric test and DFT theoretical analysis.Meanwhile,the infrared emissivity value of ATTPAL coating was the lowest compared with p-phenyl and pyridyl containing analogues,suggesting it was potential material for the future development of infrared stealth technology.The combined results showed that reducing the band gap and improving the electrical conductivity of the structure were both beneficial to the reduction of infrared emissivity.It would positively provide new ideas for the design of infrared stealth materials.
基金the National Natural Science Foundation of China(Nos.21875214,21674097 and 21774111)for financial support。
文摘A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene)(PEO_(113)-b-PVBC_(130)-b-Pt BS_(x)or E_(113)V_(130)T_(x))triblock terpolymers with various lengths x(=20,33,66,104,215)of Pt BS block were synthesized via a two-step reversible addition-fragmentation chain transfer(RAFT)polymerization.The E_(113)V_(130)T_(x)triblock terpolymers were non-crystalline because the PVBC and Pt BS blocks strongly hindered the crystallization of PEO block.The effects of Pt BS block length x on the phase structures of E_(113)V_(130)T_(x)triblock terpolymers were investigated by combined techniques of small-angle X-ray scattering(SAXS)and transmission electron microscopy(TEM).It was found that with increasing x from20 to 215,the phase structure of E_(113)V_(130)T_(x)triblock terpolymers became more ordered and changed from disordered structure,hexagonally-packed cylinder(HEX),hexagonally perforated layer(HPL),to lamellar(LAM)phase structures.Temperature-variable SAXS measurements showed that the HEX,HPL and LAM phase structures obtained for E_(113)V_(130)T_(66),E_(113)V_(130)T_(104)and E_(113)V_(130)T_(215)by thermal annealing,respectively,were thermodynamically stable in the temperature range of 30-170℃.
文摘Two kinds of 1,4-anhydroribose derivatives,1,4-anhydro-2,3-O-benzylidene-T-D-ribopyranose(ABRP)and 1,4-anhydro-2,3-O-isopropylidene-T-D-ribopyranose(AIRP)were prepared fromD-ribose.The ringopening copolymerizations of ABRP and AIRP in various feed ratios were carried out with SbCl_5 and BF_3OEt_2 as catalyst at low temperatures.The copolymer structure was characterized by means of ^(1)H,^(13)C NMR spectroscopy and specific rotation.When SbCl_(5)was used as catalyst,the copolymer obtained had completely 1,4-β-pyranosidic structure,i.e.,cellulosetype structure.However,when BF_(3)OEt_2 was used as catalyst,the copolymer had a mixed structure of furanosidic and pyranosidic units.
基金financially supported by the National Natural Science Foundation of China(No.21474083)the Distinguished Young Investigator Fund of Zhejiang Province(No.LR16B040001)
文摘The general characteristics of the active center of the catalysts（including zinc-cobalt（III） double metal cyanide complex [Zn-Co（Ⅲ） DMCC]） for the copolymerization reaction of carbon dioxide（CO2） with epoxide are summarized. By comparing the active center, catalytic performance of the Zn-Co（Ⅲ） DMCC（and other catalysts） with HCAII enzyme in the organism for activating CO2（COS and CS2）, we proposed that the metal-hydroxide bond（M-OH）, which is the real catalytic center of human carbonic anhydride Ⅱ（HCAⅡ）, is also the catalytic（initiating） center for the copolymerization. It accelerates the copolymerization and forms a closed catalytic cycle through the chain transfer reaction to water（and thus strictly meets the definition of the catalyst）. In addition, the metal-hydroxide bond catalysis could well explain the oxygen/sulfur exchange reaction（O/S ER） in metal（Zn, Cr）-catalyzed copolymerization of COS（and CS2） with epoxides. Therefore, it is very promising to learn from HCAⅡ enzyme to develop biomimetic catalyst for highly active CO2/epoxide copolymerization in a well-controlled manner under mild conditions.
文摘Exploring new polymerization strategy for current available monomers is a big challenge in polymer science. Here we re-investigate radical polymerization of monovinyl monomer(MVM) initiated by uniform branched polyfunctional initiator(PFI), which is termed non-linear radical additions-coupling polymerization(NLRAs CP). In NLRAs CP, both addition and coupling reactions of radical contribute to the construction of the polymer chains, which leads to continuous growth of branch topology. Theoretical analysis of NLRAs CP predicts that the gelation is determined by the functionality of PFI(a), the extent of initiation of the PFI(q) and the termination factor of radical(φ). NLRAs CPs of styrene and methyl methacrylate promoted by Cu(0)/MeTREN or Mn_(2)(CO)_(10)/visible light were conducted. After the cleavage of incorporated PFI fragment or junctions in the network, the network was transformed to linear chains having almost the same structure as segmental chains in the precursor network. This allows the reverse deducing the network structure from its cleaved products. It has been proven that NLRAs CP includes stepwise initiation of PFI, chain-growth of segmental chains and successive endlinking of macroradicals derived from PFI. The three parameters related to the gelation process, a, q and φ, were adjusted via binary PFI, the feed ratio of [Mn_(2)(CO)_(10)]/[PFI] and addition of non-homopolymerizable comonomer respectively. The minimum values of a and q, and the minimum amount of comonomer required for gelation were determined,which can be applied to estimate φ of various macroradicals. NLRAs CP opens a general and facile strategy for synthesis of a variety of polymer networks with heritable architecture by one-pot polymerization of various MVMs.
基金financially supported by the National Natural Science Foundation of China(Nos.52073038 and 51873027)the Fundamental Research Funds for the Central Universities(No.DUT22LAB605)。
文摘Toughening the petroleum-based epoxy resin blends with bio-based modifiers without compromising their modulus,mechanical strength,and other properties is still a big challenge in view of the sustainability.In this study,a bio-based liquid crystal epoxy resin(THMT-E P)with an s-triazine ring structure was utilized to modify a petroleum-based bisphenol A epoxy resin(E51)with 4,4'-diaminodiphenylsulfone(DDS)as a curing agent,and the blended systems were evaluated for their thermal stability,mechanical properties,and flame retardancy.The results showed that the impact strength of the blended system initially increased and then decreased with the increase in THMT-EP content,and it reached the a maximum value of 26.5 kJ/m^(2)when the THMT-EP content was 5%,which was 31.2%higher than that of E51/DDS.Notably,the flexural strength,modulus,and glass transition tem perature of the blended system were all simultaneously improved with the addition of THMT-EP.At the same time,the addition of THMT-EP enhanced the flame retardancy of the system by increasing the char yield at 700℃and decreasing the peak heat release rate and total heat release rate.This work paves the way for a more sustainable improvement in the comprehensive performance of epoxy resin.
基金Supported by the National Natural Science Foundation of China(No.21706003)The Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions(CIT&TCD20170305)
文摘Recovering alcohols from dilute fermentation broth is an emergent task in bio-fuel production process. Since they are primary planned for fuels, energy required to separate these alcohols should be considered in evaluating the potential of a separation technology. A membrane-based process, pervaporation, is of special interest because of its environmental friendliness and easy integrating character. This review probes into the fundamentals of pervaporation especially in terms of the heat required for evaporation. Meanwhile, the separation data of the most representative alcohol-selective pervaporation membranes reported in the literatures are collected and compared with the vapor–liquid equilibrium curve, which represents the distillation selectivity. They include:inorganic membranes, silicon rubber based membranes, Mixed Matrix Membranes and some other special materials. By doing so, the status of alcohol recovery via pervaporation would be more clear for researchers.For ethanol recovery, it is selectivity rather than flux that is in urgent need of solution. While for butanol recovery,membranes with satisfactory selectivity have been developed, increasing the separation capacity would be more pressing.
文摘An unusual reduction of some aromatic aldehydes and ketones by sodium borohydride was discovered.In a THF/H2O or DMSO/H2O solvent system the aromatic aldehydes and ketones with acyloxy substituent on the orthoposition to the carbonyl group can be reduced to the corresponding alkyl phenols.This unusual reduction is applicable also to the corresponding alcohols of all the above aldehydes and ketones.A putative mechanism was suggested.In addition to the above aldehydes,ketones and benzyl alcohols,certain 4acyloxybenzyl esters(probably also the 2substituted analogues)such as 4benzoyloxybenzyl benzoate was also found to be reduced to methylphenol by this unusual reduction.
基金This work was financially supported by the National Key Research and Development Program of China(No.2016YFA0201400)the National Natural Science Foundation of China(Nos.21971005 and 21534001).
文摘We report a dynamic polymerization system based on the reversible nucleophilic Michael polyaddition of activated alkynes and dithiols.Four poly(dithioacetal)s(P1-P4)were prepared via the base-catalyzed thiol-yne"click"polyaddition of two dithiols(1,4-butanedithiol(4S)and 1,5-pentanedithiol(5S))and two alkynones(3-butyn-2-one(Y1)and 1-phenyl-2-propyn-1-one(Y2))at high concentrations.We systematically investigated the base-catalyzed polymerization of 4S and Y1(for polymer PI)under different conditions,and found that this polymerization was a highly concentration-dependent dynamic system:polymer PI was formed at high concentration,while seven-membered dithioacetal,1-(1,3-dithiepan-2-yl)propan-2-one(C1),was obtained at low concentration.The polymerization of 4S and Y2(for polymer P4)displayed similar polymerization behavior,generating 2-(1,3-dithiepan-2-yl)-1-phenylethanone(C4)at low concentration.On the contrary,polymer P2(from Y1 and 5S)was exclusively obtained with no formation of eight-membered dithioacetal.The polymerizations of Y1 with 1,2-ethanedithiol(2S)and 1,3-dimercaptopropane(3S)only afforded corresponding five-and six-membered dithioacetals,1-(1,3-dithiolan-2-yl)propan-2-one(C2)and 1-(1,3-dithian-2-yl)propan-2-one(C3).This dynamic behavior of PI and P4 was attributed to the concentration-dependent retro-Michael addition reaction between a thiol and a β-sulfido-α,β-unsaturated carbonyl compound catalyzed by bases.Furthermore,polymers P1 and P4 could be depolymerized into Cl and C4 in yields of 58% and 95%,respectively.The ring-opening polymerization of Cl at high concentration could successfully regenerate polymer PI.Thus,a new type of closed-loop recyclable poly(dithioacetal)s was developed.
基金supported by the National Natural Science Foundation of China(Nos.52173129,52373140,and 52103157)the China Postdoctoral Science Foundation(No.2023T160301).
文摘Compared to fluorescence imaging,chemiluminescence imaging does not need external excitation light,and hence presents high imaging depth and signal-to-noise ratio without autofluorescence and phototoxicity,making it a promising tool for biological detection and analysis.However,the target-specific activatable near-infrared emission chemiluminescent probes still need to be developed for the precise diagnosis of diseases.In this paper,we synthesized four direct near-infrared emission Schaap’s chemiluminophores(AINCL,AIFCL,ABTCL,and APYCL)by incorporating different electronic acceptors,respectively,and studied the effect of the acceptors on the optical properties of the chemiluminophores.To achieve the specific detection of hydrogen sulfide(H_(2)S)-related diseases,we used H_(2)S-cleavable 2,4-dinitrophenylsulfonate to cage the phenol groups in the chemiluminophores.It was demonstrated that the endogenous H_(2)S in inflammations and tumors could activate effectively the chemiluminescence with high specificity,which provided the precise location of nidus in chemiluminescence imaging and allowed us to perform surgical resection.
基金supported by the National Natural Science Foundation of China(22277054,22077065,21973041,22173045)the CAS-Croucher Funding Scheme for Joint Laboratories。
文摘Phenols are extremely difficult to release the hydrogen radical(H^(·))due to the disfavored O-H bond dissociation energy(BDE)and undergo O-H homolysis under strong ultraviolet-C(UVC)light.In this work,we provided a method to modulate the O-H BDE of phenols byπ-conjugation to electron-donating heteroaromatics.Calculations on a phenol-cored photosensitizer(BTP-1)revealed drastic declines of O-H BDE(80.5 vs.28.1 kcal mol^(-1))by comparing the ground state(S_(0))and triplet excited state(T_(1)).Consequently,BTP-1 was sensitive to visible light and generated H^(·)after O-H scission.With glutathione(GSH)serving as an ultimate H^(·)donor,the BTP-1-based photosystem was efficient in catalyzing H^(·)generation under physiological conditions.This kind of hydrogen atom-based photochemistry is distinct from traditional typeⅠ/Ⅱphotosensitizing pathways that are electron or energy transfer-based.We applied the photosystem to solve the obstacle in hypoxia-activated prodrugs(HAPs)that face a dilemma with the heterogeneously hypoxic level of tumors.In vitro studies demonstrated that the photosystem boosted the chemotherapy performance of TH-302(a representative HAP)under moderate hypoxia.With the capability to target redox bonds in HAPs and good compatibility with near-infrared two-photon laser,the photosystem is promising for cancer precision therapy.
基金supported by the National Natural Science Foundation of China (Nos. 51873027, 52073038 and 51673033)the Natural Science Foundation of Liaoning Province (No. 2019-ZD-0139)+1 种基金the Fundamental Research Funds for the Central Universities (No. DUT20TD114)the National Key Research and Development Program of China (No. 2017YFB0307600)。
文摘Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution,which satisfies the needs of sustainable social development.In this study,a bio-based epoxy thermoset precursor(MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process.And the fully bio-based epoxy thermoset(MGOL-EP-SC) was obtained by self-curing without adding any other hardener.MGOL-EP-SC revealed an extremely high glass-transition temperature(T_(g)) of 265℃ and char yield of 53.2%(in N;),which were at the highest level among the fully bio-based epoxy thermosets reported so far.In addition,when the MGOL-EP was cured with 4,4’-methylenedianiline(DDM),T_(g)of the MGOL-EP/DDM was decreased by 61℃ and the other comprehensive performance had also been decreased,which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents.Moreover,the MGOL-EP-SC presented certain killing rate(48.4%) to Staphylococcus aureus.These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.
基金supported by the National Natural Science Foundation of China(Grant No.50073018 and 90101008)
文摘We present an efficient synthetic route towards two kinds of perylene-porphyrin arrays. Starting from 5, 10, 15, 20-meso-tetraphenylporphyrin, two novel 9a and 9b were designed and synthesized with 40.3% and 35.1% yield, respectively.
基金This work was supported by the National Natural Science Foundation of China[Grants nos.51773090,51690153,51422303,and 21720102005]the National Key R&D Program of China[Grant no.2017YFA0205400,2017YFA0701301].We thank Professor Zhibo Li for his help in the TEM observation.
文摘To date,how the shape of nanomaterials infuences their biological properties is poorly understood,due to the insufcient controllability of current preparative methods,especially in the shape and size of nanomaterials.In this paper,we achieved the precise syntheses of nanoscale unimolecular cylindrical polymer brushes(CPBs)and spherical polymer nanoparticles(SPNPs)with the same volume and surface chemistry,which ensured that shape was essentially the only variable when their biological performance was compared.Accurate shape efects were obtained.Impressively,the CPBs had remarkable advantage in tissue penetration over the SPNPs.Te CPBs also exhibited higher cellular uptake and rapider body clearance than the SPNPs,whereas the SPNPs had longer blood circulation time,rapider tumor vascular extravasation,and higher tumor accumulation than the CPBs.Additionally,this work also provided a controllable synthesis strategy for nanoscale unimolecular SPNPs by integrating 21 CPBs to a�-cyclodextrin core,whose diameter in dry state could be up to 45 nm.
