An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),ty...An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),typically requires much lower temperature(-25℃)and multistep monomer feeding to achieve higher number-average molecular weight(M_(n))block copolymers.However,the anionic copolymerization of AMS and St under the mild temperature remains largely unexplored.This study systematically investigated the anionic copolymerization of AMS and St using n-BuLi in nonpolar solvent(-25℃ to 25℃)through both one-step and two-step approaches.We demonstrated that one-step copolymerization at 25℃ yielded only 1-3 terminal AMS units,with higher feed ratios(5 wt%-20 wt%)increasing AMS incorporation but reducing the exact molecular weight(MW)due to enhanced depolymerization,as evidenced by MALDI-TOF MS.Temperature-controlled AMS conversion at-15℃ achieved 98%AMS conversion(5 wt% feed)by suppressing side reactions and lowering the[M]_(e),while 50℃(near T_(C))almost prevented incorporation.Despite t-BuOK regulation induced broader PDI(1.24)via reactive[(polymer-Li)OR]K intermediates,while other systems showed narrow distributions,t-BuOK outperformed THF in enhancing AMS incorporation via efficient ion pair dissociation.In comparison,the two-step polymerization approach demonstrated superior performance,achieving both higher AMS conversion efficiency and preferential incorporation at the initiation end.At a 20 wt%AMS feed ratio,this method yielded copolymer chains containing up to 6 AMS units on average.Thermal analysis revealed a composition-dependent single T_(g),which exhibited a systematic increase with higher AMS incorporation content.These results collectively demonstrate the precise control over AMS incorporation and heat resistance achievable through the manipulation of polymerization conditions.展开更多
The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segme...The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segmental mobility and limits ionic conductivity,whereas interfacial instability against lithium metal anodes jeopardizes long-term cycling.Based on orthogonal polymerization technology combined with electrolyte structural design concepts,this work achieved a one-step fabrication of a polyester-based block copolymer electrolyte(BCPE)system comprising fluorinated segments(PTFEA)and poly(ε-caprolactone)(PCL).Structurally,this design enables a dual breakthrough in electrochemical performance:on one hand,the introduction of fluorinated segments with steric hindrance effects can effectively disrupt the regular arrangement of the PCL main chain,reduce the crystallinity of PCL within the polymer electrolyte,and significantly enhance the segmental mobility of the polymer matrix;on the other hand,during the charge/discharge cycles of lithium batteries,fluorinated segments can induce the formation of a LiF-rich solid electrolyte interphase(SEI)through in situ decomposition reactions,achieving interface stabilization and homogeneous lithiumion deposition regulation.展开更多
To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polym...To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.展开更多
Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effectiv...Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.展开更多
Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive ...Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive monomers.Herein,we report a one-pot multicomponent polymerization method that directly produces main-chain charged polyelectrolytes with intrinsic AIE characteristics from non-emissive building blocks.By optimizing the monomer structures and reaction conditions,a series of soluble high-molecular-weight polymers with welldefined backbones were obtained in high yields.The resulting polyelectrolytes displayed robust AIE behavior,exhibiting fluorescence enhancement up to about 60-fold in an aqueous environment,and maintained excellent thermal stability.Owing to their cationic backbones,these polymers interact strongly with microbial surfaces and exhibit remarkable antimicrobial activities.This study establishes a synthetically efficient route to AIE polyelectrolytes and highlights their potential applications as multifunctional materials for bioimaging,antimicrobial therapy,and other applications.展开更多
Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catal...Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.展开更多
Thermosetting polymers exhibit outstanding mechanical properties,thermal stability,and chemical resistance due to their permanently cross-linked network structures.However,the irreversible nature of covalent cross-lin...Thermosetting polymers exhibit outstanding mechanical properties,thermal stability,and chemical resistance due to their permanently cross-linked network structures.However,the irreversible nature of covalent cross-linking renders these materials non-reprocessable and non-recyclable,posing significant environmental challenges.Although healable polymers based on dynamic covalent bonds and supramolecular interactions have emerged as promising alternatives,a broadly applicable strategy utilizing metal-ligand coordination in thermoset systems remains underexplored.In this work,we present a robust and healable thermoset system fabricated via ring-opening metathesis polymerization(ROMP)of commercially available chelating norbornene comonomers.Cross-linking is accomplished through O-donor coordination to Lewis acidic metal centers,yielding polydicyclopentadiene(PDCPD)-based networks that demonstrate high mechanical strength(up to 60.8 MPa)and effective self-healing performance.This methodology offers a simple and scalable approach to developing high-performance,sustainable thermosetting materials.展开更多
Objectives:Drug resistance is the major determinant of chemotherapy failure,leading to relapse and tumor progression,demonstrating the urgent need for novel antineoplastic drugs.This study aimed to evaluate the antica...Objectives:Drug resistance is the major determinant of chemotherapy failure,leading to relapse and tumor progression,demonstrating the urgent need for novel antineoplastic drugs.This study aimed to evaluate the anticancer potential of two novel pyrazole derivatives,P3C.1 and P3C.2,and to elucidate their mechanism of action in cancer cells.Methods:The cytotoxicity of the compounds was evaluated across 27 different cancer cell lines via a nuclear staining assay.Subsequent flow cytometric and biochemical analyses were performed to assess reactive oxygen species(ROS)generation,apoptosis induction,mitochondrial integrity,and cell cycle progression.Additional studies included transcriptome analyses and immunoassays to characterize the molecular mechanisms underlying drug activity.Results:Two novel pyrazole derivatives,P3C.1 and P3C.2,were identified with potent cytotoxicity on a variety of cancer cell lines.Among the adherent cell lines tested,the triple-negative breast cancer(TNBC)cell line MDA-MB-231 exhibited the highest sensitivity to both compounds and was therefore selected for further experimentation.In vitro assays demonstrated that both compounds induced ROS generation,mitochondrial membrane depolarization,cell cycle arrest and apoptosis.Whole-transcriptome sequencing of P3C.1 and P3C.2-treated MDA-MB-231 and two lymphoblastic leukemia cell lines revealed four genes in common associated with cell signaling and membrane dynamics.Connectivity Map(CMAP)database comparisons of shared genes for each cancer subtype revealed a strong similarity between the two compounds with tubulin inhibitors,and subsequent assays confirmed that these compounds act as microtubule-disrupting agents.Moreover,protein phosphorylation analysis indicated that both compounds induced hyperphosphorylation of JNK,and ERK1/2,along with hypophosphorylation of p38 kinases.Conclusions:P3C.1 and P3C.2 emerged as promising anti-breast cancer agents with dual mechanisms of action involving microtubule disruption and altered kinase signaling,leading to induction of apoptosis.展开更多
Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford prod...Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.展开更多
Organocatalyzed atom transfer radical polymerization(O-ATRP)is a pivotal technique for the synthesis of polymers with well-defined structures that are devoid of metallic residues.A major challenge in this area is the ...Organocatalyzed atom transfer radical polymerization(O-ATRP)is a pivotal technique for the synthesis of polymers with well-defined structures that are devoid of metallic residues.A major challenge in this area is the reduction of catalyst loading while maintaining precise control over polymer architecture and properties.Herein,we systematically evaluate the efficacy of six pyrazino[2,3-f][1,10]phenanthroline(pyzPhen)-based photoredox catalysts in photoinduced O-ATRP.Experimental results indicate that the introduction of various substituents markedly influences the photophysical properties and redox behavior of the catalysts,thereby resulting in differing catalytic efficiencies in the O-ATRP of methyl methacrylate(MMA).Following additional optimization,two highly efficient O-ATRP photocatalysts capable of exhibiting thermally activated delayed fluorescence(TADF)were successfully identified.Under visible light irradiation,TADF catalysts effectively mediated the controlled polymerization of MMA at a low loading level of 50 ppm,particularly when used in conjunction with the initiator DBMM.The catalytic systems demonstrate excellent temporal control,broad monomer applicability,and favorable compatibility with various initiators and solvent systems.This work offers new insights into the development of efficient,low-catalyst-loading,metal-free ATRP systems.展开更多
The hydroxyl-terminated polybutadiene （HTPB） possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene, using alkyllithium containing silicon-protected hydroxyl group as initiator a...The hydroxyl-terminated polybutadiene （HTPB） possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene, using alkyllithium containing silicon-protected hydroxyl group as initiator and cyclohexane as solvent. The polymers were characterized by GPC, IR and 1H-NMR. The mechanical properties of cured films were also evaluated. The results show that the content of 1,4-units for HTPBs made by anionic polymerization reaches up to 90%. The molecular weight distribution is very narrow （〈 1.05）. The functionality of hydroxyl groups approaches 2. Compared with free radical HTPB, the elongation at break of anionic HTPB films increased by 70%, while the tensile strength remained nearly unchanged. This new HTPB can be very useful in solid propellant.展开更多
A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）...A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）, poly（4-methoxystyrene） and poly（4-trimethylsilylstyrene） were synthesized by living anionic polymerization based on diphenylethylene （DPE） chemistry. The DPE-functionalized polymers were synthesized by iterative methodology, and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers. The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide （MePVSO） initiated from the in situ formed polymer anion with two or three polymer segments. The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well. Both approaches could afford the target heteroarm star polymers with predetermined molecular weight, narrow molecular weight distribution （Mw/Mn 〈 1.03） and desired composition, evidenced by SEC, 1H-NMR and SLS analyses. These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.展开更多
Copolymers of 1,3-butadiene and p-methylstyrene （p-MS） were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and ...Copolymers of 1,3-butadiene and p-methylstyrene （p-MS） were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and gradient composition alonglthe copolymer chain. The overall composition and microstructure could be controlled and well characterized by GPC and H-NMR. The p-MS was distributed from gradient to random with increasing the content of the benzophenone-potassium complex, and the 1,2-microstrucmre in the polybutadiene sequence increased at the same time. The hydrogenation of the copolymer of 1,3-butadiene and p-MS resulted in the corresponding saturated copolymer with well- defined structure and narrow molecular weight distribution.展开更多
Three-arm and four-arm star-like polybutadienes （PBds） were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the az...Three-arm and four-arm star-like polybutadienes （PBds） were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 ℃ in toluene in the presence of the reducing agent Cu（0）, proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1.展开更多
Thermal,mechanical,and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure.The use of polar modifier in association with alkyllithium is a well-known me...Thermal,mechanical,and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure.The use of polar modifier in association with alkyllithium is a well-known method to obtain polybutadiene with a high vinyl con tent.Another approach is to use bimetallic initiating species such as alkyllithium combined to heavier alkali metal alkoxide(RONa,ROK...).The polymerization control is n evertheless not achieved and several parameters were found to influe nee it.Using bimetallic in itiating systems based on alkyllithium and a potassium alkoxide,alkyllithium structure,initiator preformation time,and initiator composition were identified as parameters influencing the anionic polymerization process of butadiene and/or polybutadiene microstructure.In addition,the use of trimetallic systems based on alkyllithium,potassium alkoxide,and alkylaluminum was investigated in order to prevent side reactions regardless of the[K]/[Li]ratio and of the initiator preformation time.展开更多
Lithium amides have been proved to be effective anionic initiators for the anionic polymerization of acrylonitrile to get high molecular weight polyacrylonitrile in this study. Polyacrylonitrile with weightaverage mol...Lithium amides have been proved to be effective anionic initiators for the anionic polymerization of acrylonitrile to get high molecular weight polyacrylonitrile in this study. Polyacrylonitrile with weightaverage molecular weight ranging from 1.02 × 10~6 g/mol to 1.23 ×10~6 g/mol (M_w/M_n= 1.9-2.2) could be prepared utilizing lithium amides derived from diisopropylamine, diethylamine, hexamethyldisilazane,dicyclohexylamine, and 2,2,6,6-tetramethylpiperidine as initiators. The polymerization of acrylonitrile proceeded in a homogeneous manner in N,N-di methyl for mamide and insignificant contribution of side reactions was confirmed.展开更多
Anionic polyacrylamide dispersions were prepared by dispersion polymerization in an aqueous salt medium, using acrylamide（AM） and acrylic acid（AA） as monomers and anionic polyelectrolytes as stabilizer. Effects of...Anionic polyacrylamide dispersions were prepared by dispersion polymerization in an aqueous salt medium, using acrylamide（AM） and acrylic acid（AA） as monomers and anionic polyelectrolytes as stabilizer. Effects of salt concentration, and molecular weight and concentration of stabilizers on the stability of the dispersions were investigated using a HAAKE rheometer and optical microscopy. The results showed that stable anionic polyacrylamide dispersions, consisting of smooth, spherical, polydisperse particles, could be obtained under the conditions of salt concentration ranging from 26 wt% to 30 wt%, concentration of stabilizers from 1.2 wt% to 1.8 wt%, and intrinsic viscosity of stabilizers from 2.98 dL·g^-1 to 3.74 dL·g^-1. The apparent viscosity of the stable dispersions changed very little with the shear rate, showing Newton fluid behavior.展开更多
Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxid...Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxide, three stages are identified by kinetic study including(1) fast cationic polymerization with slow anionic one,(2) fast anionic polymerization with dormant cationic one, and(3)reactivation of cationic polymerization with coupling of anionic and cationic chain ends. In this work, density functional theory(DFT)calculation is employed to investigate the reaction details of ionic polymerization and dormancy. A “tripedal crow” configuration is proposed to illustrate the unique high-coordinated ligand exchange configuration in anionic polymerization in different stages. The trigger of dormancy is determined as chain structures rather than concentration of triflate anion according to both calculation and experimental results.展开更多
The anionic polymerization of N-vinylcarbazole（NVC） by using optically active anionic initiators such as the lithium salts of（S）-1-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-1-FIDH） and（S）-2-（9H...The anionic polymerization of N-vinylcarbazole（NVC） by using optically active anionic initiators such as the lithium salts of（S）-1-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-1-FIDH） and（S）-2-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-2-FIDH） and complexes of（-）-Sparteine with n-butylithium（n-Bu Li-（-）-Sp） or fluorenyl lithium（FILi-（-）-Sp） was achieved. The yield and specific rotation of poly（N-vinylcarbazole）s（poly（NVC）s） were considerably affected by the molar ratio of（S）-FIDH to NVC. The highest yield and specific rotation were obtained with Li-（S）-1-FIDH as an initiator, with a molar ratio of monomer and initiator [M]/[I] = 10/1. The effects of the chiral initiators, type of solvent and the polymerization temperature were investigated. The obtained optical activity of polymers was attributed to asymmetric induction of the chiral initiators.展开更多
Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polyme...Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity （1.51 ）, decreased melting temperature （218 ℃） and lower crystallinity （24.2%）. The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52373052)Fundamental Research Funds for the Central Universities(No.DUT24MS011)。
文摘An effective strategy for enhancing the heat resistance of polystyrene(PS)with regard to its glass transition temperature(T_(g))involves the anionic solution copolymerization of a-methylstyrene(AMS)with styrene(St),typically requires much lower temperature(-25℃)and multistep monomer feeding to achieve higher number-average molecular weight(M_(n))block copolymers.However,the anionic copolymerization of AMS and St under the mild temperature remains largely unexplored.This study systematically investigated the anionic copolymerization of AMS and St using n-BuLi in nonpolar solvent(-25℃ to 25℃)through both one-step and two-step approaches.We demonstrated that one-step copolymerization at 25℃ yielded only 1-3 terminal AMS units,with higher feed ratios(5 wt%-20 wt%)increasing AMS incorporation but reducing the exact molecular weight(MW)due to enhanced depolymerization,as evidenced by MALDI-TOF MS.Temperature-controlled AMS conversion at-15℃ achieved 98%AMS conversion(5 wt% feed)by suppressing side reactions and lowering the[M]_(e),while 50℃(near T_(C))almost prevented incorporation.Despite t-BuOK regulation induced broader PDI(1.24)via reactive[(polymer-Li)OR]K intermediates,while other systems showed narrow distributions,t-BuOK outperformed THF in enhancing AMS incorporation via efficient ion pair dissociation.In comparison,the two-step polymerization approach demonstrated superior performance,achieving both higher AMS conversion efficiency and preferential incorporation at the initiation end.At a 20 wt%AMS feed ratio,this method yielded copolymer chains containing up to 6 AMS units on average.Thermal analysis revealed a composition-dependent single T_(g),which exhibited a systematic increase with higher AMS incorporation content.These results collectively demonstrate the precise control over AMS incorporation and heat resistance achievable through the manipulation of polymerization conditions.
基金financially supported by the National Natural Science Foundation of China(No.52573079)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(No.B21003).
文摘The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segmental mobility and limits ionic conductivity,whereas interfacial instability against lithium metal anodes jeopardizes long-term cycling.Based on orthogonal polymerization technology combined with electrolyte structural design concepts,this work achieved a one-step fabrication of a polyester-based block copolymer electrolyte(BCPE)system comprising fluorinated segments(PTFEA)and poly(ε-caprolactone)(PCL).Structurally,this design enables a dual breakthrough in electrochemical performance:on one hand,the introduction of fluorinated segments with steric hindrance effects can effectively disrupt the regular arrangement of the PCL main chain,reduce the crystallinity of PCL within the polymer electrolyte,and significantly enhance the segmental mobility of the polymer matrix;on the other hand,during the charge/discharge cycles of lithium batteries,fluorinated segments can induce the formation of a LiF-rich solid electrolyte interphase(SEI)through in situ decomposition reactions,achieving interface stabilization and homogeneous lithiumion deposition regulation.
基金the support from the Jiangsu Provincial Senior Talent Program (Dengfeng,Jiangsu University)the support from the National Key R&D Program of China (No.2024YFB3612600)+3 种基金the National Natural Science Foundation of China (Nos.22275098,62288102)Basic Research Program of Jiangsu (No.BK20243057)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (No.NY222097)the National Natural Science Foundation of China (No.62205035)。
文摘To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.
基金financially supported by the National Natural Science Foundation of China(No.52473338)the National Natural Science Foundation of China(Nos.52173004 and 51873055)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0540000)Advanced Materials-National Science and Technology Major Project(No.2025ZD0614000)Hebei Natural Science Foundation(No.E2022202015)Anhui Province Science and Technology Innovation Tackling Key Project(No.202423i08050025)。
文摘Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.
基金supported by the National Natural Science Foundation of China(No.22431004)Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates(No.2023B1212060003)。
文摘Aggregation-induced emission(AIE)polymers have been extensively studied;however,the integration of AIE units into polyelectrolytes remains largely limited by the laborious multistep synthesis of pre-designed emissive monomers.Herein,we report a one-pot multicomponent polymerization method that directly produces main-chain charged polyelectrolytes with intrinsic AIE characteristics from non-emissive building blocks.By optimizing the monomer structures and reaction conditions,a series of soluble high-molecular-weight polymers with welldefined backbones were obtained in high yields.The resulting polyelectrolytes displayed robust AIE behavior,exhibiting fluorescence enhancement up to about 60-fold in an aqueous environment,and maintained excellent thermal stability.Owing to their cationic backbones,these polymers interact strongly with microbial surfaces and exhibit remarkable antimicrobial activities.This study establishes a synthetically efficient route to AIE polyelectrolytes and highlights their potential applications as multifunctional materials for bioimaging,antimicrobial therapy,and other applications.
基金financial support from the National Natural Science Foundation of China(Nos.22401274,U23B6011)the Jilin Provincial Science and Technology Department Program(No.20250102070JC)。
文摘Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0540000)the National Natural Science Foundation of China(Nos.22301294,52025031 and 22261142664)the USTC Research Funds of the Double First-Class Initiative(No.YD9990002030)。
文摘Thermosetting polymers exhibit outstanding mechanical properties,thermal stability,and chemical resistance due to their permanently cross-linked network structures.However,the irreversible nature of covalent cross-linking renders these materials non-reprocessable and non-recyclable,posing significant environmental challenges.Although healable polymers based on dynamic covalent bonds and supramolecular interactions have emerged as promising alternatives,a broadly applicable strategy utilizing metal-ligand coordination in thermoset systems remains underexplored.In this work,we present a robust and healable thermoset system fabricated via ring-opening metathesis polymerization(ROMP)of commercially available chelating norbornene comonomers.Cross-linking is accomplished through O-donor coordination to Lewis acidic metal centers,yielding polydicyclopentadiene(PDCPD)-based networks that demonstrate high mechanical strength(up to 60.8 MPa)and effective self-healing performance.This methodology offers a simple and scalable approach to developing high-performance,sustainable thermosetting materials.
基金supported by NIH grant 1R16GM149379 to Renato J.Aguilerasupported by the core facilities of the BBRC,funded by the Research Centers in Minority Institutions grant 5U54MD007592 from the National Institute on Minority Health and Health Disparities to Robert A.Kirkensupported Denisse A.Gutierrez,Ana P.Betancourt,Elisa Robles-Escajeda and Armando Varela-Ramirez。
文摘Objectives:Drug resistance is the major determinant of chemotherapy failure,leading to relapse and tumor progression,demonstrating the urgent need for novel antineoplastic drugs.This study aimed to evaluate the anticancer potential of two novel pyrazole derivatives,P3C.1 and P3C.2,and to elucidate their mechanism of action in cancer cells.Methods:The cytotoxicity of the compounds was evaluated across 27 different cancer cell lines via a nuclear staining assay.Subsequent flow cytometric and biochemical analyses were performed to assess reactive oxygen species(ROS)generation,apoptosis induction,mitochondrial integrity,and cell cycle progression.Additional studies included transcriptome analyses and immunoassays to characterize the molecular mechanisms underlying drug activity.Results:Two novel pyrazole derivatives,P3C.1 and P3C.2,were identified with potent cytotoxicity on a variety of cancer cell lines.Among the adherent cell lines tested,the triple-negative breast cancer(TNBC)cell line MDA-MB-231 exhibited the highest sensitivity to both compounds and was therefore selected for further experimentation.In vitro assays demonstrated that both compounds induced ROS generation,mitochondrial membrane depolarization,cell cycle arrest and apoptosis.Whole-transcriptome sequencing of P3C.1 and P3C.2-treated MDA-MB-231 and two lymphoblastic leukemia cell lines revealed four genes in common associated with cell signaling and membrane dynamics.Connectivity Map(CMAP)database comparisons of shared genes for each cancer subtype revealed a strong similarity between the two compounds with tubulin inhibitors,and subsequent assays confirmed that these compounds act as microtubule-disrupting agents.Moreover,protein phosphorylation analysis indicated that both compounds induced hyperphosphorylation of JNK,and ERK1/2,along with hypophosphorylation of p38 kinases.Conclusions:P3C.1 and P3C.2 emerged as promising anti-breast cancer agents with dual mechanisms of action involving microtubule disruption and altered kinase signaling,leading to induction of apoptosis.
基金financially supported by National Key R&D Program Young Scientists Project(No.2023YFC3903100)the National Natural Science Foundation of China(No.22322503)analytical and testing assistance from the Analysis and Testing Center of HUST。
文摘Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.
基金financially supported by the National Natural Science Foundation of China (No. 22271044).
文摘Organocatalyzed atom transfer radical polymerization(O-ATRP)is a pivotal technique for the synthesis of polymers with well-defined structures that are devoid of metallic residues.A major challenge in this area is the reduction of catalyst loading while maintaining precise control over polymer architecture and properties.Herein,we systematically evaluate the efficacy of six pyrazino[2,3-f][1,10]phenanthroline(pyzPhen)-based photoredox catalysts in photoinduced O-ATRP.Experimental results indicate that the introduction of various substituents markedly influences the photophysical properties and redox behavior of the catalysts,thereby resulting in differing catalytic efficiencies in the O-ATRP of methyl methacrylate(MMA).Following additional optimization,two highly efficient O-ATRP photocatalysts capable of exhibiting thermally activated delayed fluorescence(TADF)were successfully identified.Under visible light irradiation,TADF catalysts effectively mediated the controlled polymerization of MMA at a low loading level of 50 ppm,particularly when used in conjunction with the initiator DBMM.The catalytic systems demonstrate excellent temporal control,broad monomer applicability,and favorable compatibility with various initiators and solvent systems.This work offers new insights into the development of efficient,low-catalyst-loading,metal-free ATRP systems.
文摘The hydroxyl-terminated polybutadiene （HTPB） possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene, using alkyllithium containing silicon-protected hydroxyl group as initiator and cyclohexane as solvent. The polymers were characterized by GPC, IR and 1H-NMR. The mechanical properties of cured films were also evaluated. The results show that the content of 1,4-units for HTPBs made by anionic polymerization reaches up to 90%. The molecular weight distribution is very narrow （〈 1.05）. The functionality of hydroxyl groups approaches 2. Compared with free radical HTPB, the elongation at break of anionic HTPB films increased by 70%, while the tensile strength remained nearly unchanged. This new HTPB can be very useful in solid propellant.
基金supported by the National Natural Science Foundation of China(Nos.20844001 and 20874067)the Key Project of Chinese Ministry of Education(No.209049)Natural Science Fund for Colleges and Universities of Jiangsu Province(No.08KJB150015).
文摘A series of 3-arm ABC and AA＇B and 4-arm ABCD, AA＇BC and AA＇A＂B heteroarm star polymers comprising one poly（4-methylphenyl vinyl sulfoxide） segment and other segments such as polystyrene, poly（a-methylstyrene）, poly（4-methoxystyrene） and poly（4-trimethylsilylstyrene） were synthesized by living anionic polymerization based on diphenylethylene （DPE） chemistry. The DPE-functionalized polymers were synthesized by iterative methodology, and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers. The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide （MePVSO） initiated from the in situ formed polymer anion with two or three polymer segments. The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well. Both approaches could afford the target heteroarm star polymers with predetermined molecular weight, narrow molecular weight distribution （Mw/Mn 〈 1.03） and desired composition, evidenced by SEC, 1H-NMR and SLS analyses. These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.
基金the National Natural Science Foundation of China(Nos.51073149 and 51233005)
文摘Copolymers of 1,3-butadiene and p-methylstyrene （p-MS） were synthesized via anionic polymerization. A benzophenone-potassium complex was added to tune the reactivity ratio of the two monomers, leading to random and gradient composition alonglthe copolymer chain. The overall composition and microstructure could be controlled and well characterized by GPC and H-NMR. The p-MS was distributed from gradient to random with increasing the content of the benzophenone-potassium complex, and the 1,2-microstrucmre in the polybutadiene sequence increased at the same time. The hydrogenation of the copolymer of 1,3-butadiene and p-MS resulted in the corresponding saturated copolymer with well- defined structure and narrow molecular weight distribution.
基金financially supported by the National Natural Science Foundation of China(Nos.51233005,21004060 and 51073149)
文摘Three-arm and four-arm star-like polybutadienes （PBds） were synthesized via the combination of living anionic polymerization and the click coupling method. Kinetic study showed that the click reaction between the azido group terminated PBd-t-N3 and the alkyne-containing multifunctional linking reagent was fast and highly efficient. All coupling reactions were fully accomplished within 40 min at 50 ℃ in toluene in the presence of the reducing agent Cu（0）, proven by 1H-NMR, FTIR and GPC measurements. For the coupling reactions between the PBd-t-N3 polymer and dialkyne-containing compound, the final conversion of the coupled PBd-PBd polymer was ca. 97.0%. When a PBd-t-N3 polymer was reacted with trialkyne-containing or tetraalkyne-containing compound, the conversion of three-arm or four-arm PBd was around 95.5% or 87.0%, respectively. Several factors influencing the coupling efficiency were studied, including the molecular weight of the initial PBd-t-N3, arm numbers and the molar ratio of the azido group to the alkynyl group. The results indicated that the conversion of the target products would be promoted when the molecular weight of the PBd-t-N3 was low and the molar ratio of the azido to alkynyl groups was close to 1.
文摘Thermal,mechanical,and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure.The use of polar modifier in association with alkyllithium is a well-known method to obtain polybutadiene with a high vinyl con tent.Another approach is to use bimetallic initiating species such as alkyllithium combined to heavier alkali metal alkoxide(RONa,ROK...).The polymerization control is n evertheless not achieved and several parameters were found to influe nee it.Using bimetallic in itiating systems based on alkyllithium and a potassium alkoxide,alkyllithium structure,initiator preformation time,and initiator composition were identified as parameters influencing the anionic polymerization process of butadiene and/or polybutadiene microstructure.In addition,the use of trimetallic systems based on alkyllithium,potassium alkoxide,and alkylaluminum was investigated in order to prevent side reactions regardless of the[K]/[Li]ratio and of the initiator preformation time.
文摘Lithium amides have been proved to be effective anionic initiators for the anionic polymerization of acrylonitrile to get high molecular weight polyacrylonitrile in this study. Polyacrylonitrile with weightaverage molecular weight ranging from 1.02 × 10~6 g/mol to 1.23 ×10~6 g/mol (M_w/M_n= 1.9-2.2) could be prepared utilizing lithium amides derived from diisopropylamine, diethylamine, hexamethyldisilazane,dicyclohexylamine, and 2,2,6,6-tetramethylpiperidine as initiators. The polymerization of acrylonitrile proceeded in a homogeneous manner in N,N-di methyl for mamide and insignificant contribution of side reactions was confirmed.
文摘Anionic polyacrylamide dispersions were prepared by dispersion polymerization in an aqueous salt medium, using acrylamide（AM） and acrylic acid（AA） as monomers and anionic polyelectrolytes as stabilizer. Effects of salt concentration, and molecular weight and concentration of stabilizers on the stability of the dispersions were investigated using a HAAKE rheometer and optical microscopy. The results showed that stable anionic polyacrylamide dispersions, consisting of smooth, spherical, polydisperse particles, could be obtained under the conditions of salt concentration ranging from 26 wt% to 30 wt%, concentration of stabilizers from 1.2 wt% to 1.8 wt%, and intrinsic viscosity of stabilizers from 2.98 dL·g^-1 to 3.74 dL·g^-1. The apparent viscosity of the stable dispersions changed very little with the shear rate, showing Newton fluid behavior.
基金financially supported by the National Natural Science Foundation of China (No. 21871232)the Zhejiang Provincial Natural Science Foundation of China (No. LR15B040001)
文摘Janus polymerization is featured as a combination of cationic and anionic growing ends in one living polymer chain. In the copolymerization of THF and CL catalyzed by lutetium triflates and initiated by propylene oxide, three stages are identified by kinetic study including(1) fast cationic polymerization with slow anionic one,(2) fast anionic polymerization with dormant cationic one, and(3)reactivation of cationic polymerization with coupling of anionic and cationic chain ends. In this work, density functional theory(DFT)calculation is employed to investigate the reaction details of ionic polymerization and dormancy. A “tripedal crow” configuration is proposed to illustrate the unique high-coordinated ligand exchange configuration in anionic polymerization in different stages. The trigger of dormancy is determined as chain structures rather than concentration of triflate anion according to both calculation and experimental results.
基金financially supported by the open project program of Key Laboratory of Environmentally Friendly ChemistryApplications of the Ministry of Education,China(No.09HJYH04)Xiangtan University Doctoral Scientific Research Fund
文摘The anionic polymerization of N-vinylcarbazole（NVC） by using optically active anionic initiators such as the lithium salts of（S）-1-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-1-FIDH） and（S）-2-（9H-fluoren-2-yl）-4-isopropyl-4,5-dihydrooxazole（（S）-2-FIDH） and complexes of（-）-Sparteine with n-butylithium（n-Bu Li-（-）-Sp） or fluorenyl lithium（FILi-（-）-Sp） was achieved. The yield and specific rotation of poly（N-vinylcarbazole）s（poly（NVC）s） were considerably affected by the molar ratio of（S）-FIDH to NVC. The highest yield and specific rotation were obtained with Li-（S）-1-FIDH as an initiator, with a molar ratio of monomer and initiator [M]/[I] = 10/1. The effects of the chiral initiators, type of solvent and the polymerization temperature were investigated. The obtained optical activity of polymers was attributed to asymmetric induction of the chiral initiators.
基金supported by a grant from the National High Technology Research and Development Program of China(No.2014AA021201)the National Basic Research Program of China(No.2012CB721104)+1 种基金China Postdoctoral Science Foundation(No.2014M551574)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity （1.51 ）, decreased melting temperature （218 ℃） and lower crystallinity （24.2%）. The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.
