Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymeriz...Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequen-tial addition of vinyl monomers and ethylene oxide(EO).It still remains challenging to achieve altogether high block efficiency,high polymerization efficiency,and high molar mass for PEO.Here,we report a one-pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)-b-PEO,in which PI/PS are formed by sBuLi-initiated anionic vinyl-addition polymerization,then in situ employed as macroinitiators for the anionic ring-opening polymerization(ROP)of EO aided by an organic Lewis pair.The cooperative(dual-ion-complexing)catalytic effect of organobase and triethylborane is proven,for thefirst time,effective for lithium alkoxide initiator system,allowing to achieve at room temperature high ROP activity(complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h),narrow molar mass distribution,controlled block lengths and composition.Density functional the-ory calculation shows that phosphazene bases are particularly effective,compared with N-heterocyclic bases,for complexing with Li+and enhancing the nucleophilic-ity of oxyanion.The rate of ROP is also affected by Li+-induced aggregation of the chain-end ion pairs,which though can be offset by adequate catalyst loadings.The versatility of this approach is further demonstrated in the one-pot synthesis of tri-/tetrablock ter-/quaterpolymers constituted by PI,PS,PEO,and poly(propylene oxide).Of great interest,PS-b-PI-b-PEO triblock terpolymer with a specific com-position is found to form internally microphase-separated micellar aggregates when dispersed in water.展开更多
For living anionic polymerization(LAP),solvent has a great influence on both reaction mechanism and kinetics.In this work,by using the classical butyl lithium-styrene polymerization as a model system,the effect of sol...For living anionic polymerization(LAP),solvent has a great influence on both reaction mechanism and kinetics.In this work,by using the classical butyl lithium-styrene polymerization as a model system,the effect of solvent on the mechanism and kinetics of LAP was revealed through a strategy combining density functional theory(DFT)calculations and kinetic modeling.In terms of mechanism,it is found that the stronger the solvent polarity,the more electrons transfer from initiator to solvent through detailed energy decomposition analysis of electrostatic interactions between initiator and solvent molecules.Furthermore,we also found that the stronger the solvent polarity,the higher the monomer initiation energy barrier and the smaller the initiation rate coefficient.Counterintuitively,initiation is more favorable at lower temperatures based on the calculated results ofΔG_(TS).Finally,the kinetic characteristics in different solvents were further examined by kinetic modeling.It is found that in benzene and n-pentane,the polymerization rate exhibits first-order kinetics.While,slow initiation and fast propagation were observed in tetrahydrofuran(THF)due to the slow free ion formation rate,leading to a deviation from first-order kinetics.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
Anionic ring-opening polymerization(AROP)of N-sulfonyl aziridines is an important synthetic route to linear polyethyleneimine(PEI)and its derivatives.In most cases,inert atmosphere and dry solvent were needed because ...Anionic ring-opening polymerization(AROP)of N-sulfonyl aziridines is an important synthetic route to linear polyethyleneimine(PEI)and its derivatives.In most cases,inert atmosphere and dry solvent were needed because of the oxygen-and water-sensitive initiators/catalysts used.Therefore,the AROP of N-sulfonyl aziridines that can be entirely operated in air atmosphere is still a challenging task.Herein,we report a series of sulfanions,including xanthates,dithiocarbamates,dithiobenzoates,thioacetates,and thiolates,as the initiators for the AROP of N-sulfonyl aziridines.Due to their good stability,openvessel polymerization was achieved with high livingness,affording a range of well-definedα-,ω-telechelic poly(N-sulfonyl aziridine)homopolymers and block copolymers with narrow dispersities and tunable molecular weights.Theα-end group of these polyaziridines was readily converted to thiol group,which enabled further post-polymerization functionalization with benzyl acrylate and poly(ethylene glycol)via thiol-ene click chemistry.The establishment of open-vessel sulfanion-initiated AROP of N-sulfonyl aziridines thus lays a solid foundation for the bulk preparation and application of poly(N-sulfonyl aziridine)s and PEI derivatives.展开更多
The initiation reactions in the anionic non-equilibrium polymerization of octamethy- lcyclotetrasiloxane (D4) initiated by silazyllithiums were investigated. It was found that the structure of the substituents on the...The initiation reactions in the anionic non-equilibrium polymerization of octamethy- lcyclotetrasiloxane (D4) initiated by silazyllithiums were investigated. It was found that the structure of the substituents on the Si atom had great influences on the initiation activity of silazyllithiums.展开更多
An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of A...An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.展开更多
20 wt% polyamide 12 （PA1212） pellets were dissolved in molten caprolactam. The caprolactam was then catalyzed at 180℃ and polymerized by means of anionic ring-opening polymerization to produce in situ blends of the...20 wt% polyamide 12 （PA1212） pellets were dissolved in molten caprolactam. The caprolactam was then catalyzed at 180℃ and polymerized by means of anionic ring-opening polymerization to produce in situ blends of the resultant polyamide 6 （PA6） and PA 1212. Mechanical blends with same ingredient were prepared through melt blending on a twin-screw extruder. Scanning electron microscopy （SEM） observation revealed that contrary to the mechanical blends with small spherulites embedded in the matrix, no phase-separation existed in the in situ blends. The results of thermal analysis by differential scanning calorimetry （DSC） showed that single melting peak and crystallization peak existed for the in situ blends, while two melting and crystallization peaks appeared for the mechanical blends. The in situ blend film and the mixed blend film, both cast from a dilute formic acid solution with a concentration of 0.5 g/L, remained similar crystallization and melting behavior as above. It is proved by solution 13C-NMR analysis that transamidation took place during the in situ blending, and it is suggested that the combination of temperature increasing and the basic surrounding derived from NaOH during polymerization resulted in the occurrence of transamidation. Furthermore, it is proposed that the interchange reaction between PA 1212 and PA6 also resulted from the degradative reaction during the anionic polymerization.展开更多
In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_...In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.展开更多
The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PC...The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.展开更多
Ring-opening polymerization of ε-caprolactone has been carried out by using rare earth Schiff base complexes： lanthanide tris（N-phenyl-3,5-di-t-butylsalicylaldiminato）s [Ln（OPBS）3] as single component catalyst f...Ring-opening polymerization of ε-caprolactone has been carried out by using rare earth Schiff base complexes： lanthanide tris（N-phenyl-3,5-di-t-butylsalicylaldiminato）s [Ln（OPBS）3] as single component catalyst for the first time. The influences of different rare earth elements, monomer and catalyst concentration as well as reaction time on the polymerization were investigated. Mechanism studies showed that monomer inserts into the active site with the acyl-oxygen bond scission rather than the break of alkyl-oxygen bond.展开更多
A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yie...A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst (PTC) at 0 'C . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 °C and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.展开更多
Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first tim...Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPLexhibits higher activity than native PPL. Along wth the increasing enzyme concentration, the molecular weigh of resultingPDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For thethird recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyletime for the synthesis of PDTC. The ~1H-NMR spectra indicate that decarboxylation does not occur during the ring-openingpolymerization.展开更多
Highly active calcium chloride（CaCl2） doped Zn-Co^Ⅲdouble metal-cyanide（Ca-DMC） catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield（54 kg polymer/g catalyst） at relative low temperatur...Highly active calcium chloride（CaCl2） doped Zn-Co^Ⅲdouble metal-cyanide（Ca-DMC） catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield（54 kg polymer/g catalyst） at relative low temperature（80-115℃） toward ringopening polymerization（ROP） of propylene oxide（PO） than did DMC catalysts without modification.展开更多
Single component rare earth phenolates substituted by various alkyl groups have been prepared and the correlation between the aryloxides＇ structure and catalytic activity in the ring-opening polymerization of D,L-lac...Single component rare earth phenolates substituted by various alkyl groups have been prepared and the correlation between the aryloxides＇ structure and catalytic activity in the ring-opening polymerization of D,L-lactide has also been investigated.The catalytic activity of all rare earth aryloxides,characteristics of the ring-opening polymerization as well as polymerization kinetics and mechanism were investigated.The results showed that both phenolates＇ catalytic activities and polymerization characteristics changed regularly,keeping in good concordance with variations in substitutents＇ number on phenol and structure of aryloxide ligands.The stronger ability of electron-donation of alkyl groups,the higher catalytic activity.Moreover,the more numbers of substituted alkyl on phenyl ring,the higher catalytic activity.The analyses of polymer ends revealed that the polymerization proceeded via a coordination-acyl-oxygen bond cleavage-insertion mechanism.展开更多
Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through s...Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through salt metathesis. This complex was successfully used to initiate the ring-opening polymerization of ε-caprolactone. The initiation conditions in different temperature, monomer-to-initiator ratio and time were investigated. Under the condition： [ε-caprolactone]：[catalyst] = 600, 56 ℃, toluene： 2 ml, poly（ε-caprolactone） （PCL） with Mw = 11,2782 and PDI = 1.96 was achieved.展开更多
Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were ...Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.展开更多
Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized b...Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized by RuCl_2(=CHPh)(PCy_3)_2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol(SHP)and hindered amine(HLAS)groups via ring-opening metathesis polymerization(ROMP).The resulting copolymers were characterized by gel permeation chromatography(GPC),~1H-NMR and differen...展开更多
Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO...Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO/BF3.OEt2 on the molecular weights and yield of PBCMO were investigated. The polymerization in ionic liquids proceed to high conversions, although molecular weights are limited, similar to polymerization in organic solvent such as CH2Cl2. Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF4 is superior to [bmim]PF6. Extracting [bmim]PF6 from the product using organic solvent as extractant limits its advantage as a green reaction media.展开更多
The ring-opening polymerization of 1,4-dioxan-2-one （PDO） was carried out by lanthanum tris（2,6-di-tert-butyl-4- methylphenolate） （La（OAr）3） as novel single component initiaLor. The influences of polymerizatio...The ring-opening polymerization of 1,4-dioxan-2-one （PDO） was carried out by lanthanum tris（2,6-di-tert-butyl-4- methylphenolate） （La（OAr）3） as novel single component initiaLor. The influences of polymerization reaction temperature and the molar ratio of monomer to initiator on the monomer conversion and molecular weight of poly（1,4-dioxan-2-one） （PPDO） were explored. PPDO with high viscosity average molecular weight of 1.95×10^5 can be prepared at 40℃ when [PDO]/ [La（OAr）3] molar ratio was 800. Mechanism investigation shows that the polymerization proceeds through a ＂coordination- insertion＂ mechanism with selective rupture of acyl-oxygen be,nd of PDO.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:52022031Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates,Grant/Award Number:2023B1212060003Hunan Provincial Natural Science Foundation of China,Grant/Award Number:2023JJ40620。
文摘Polyolefin-b-poly(ethylene oxide)(PEO)represents the most widely investigated amphiphilic block copolymers.So far,one-pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequen-tial addition of vinyl monomers and ethylene oxide(EO).It still remains challenging to achieve altogether high block efficiency,high polymerization efficiency,and high molar mass for PEO.Here,we report a one-pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)-b-PEO,in which PI/PS are formed by sBuLi-initiated anionic vinyl-addition polymerization,then in situ employed as macroinitiators for the anionic ring-opening polymerization(ROP)of EO aided by an organic Lewis pair.The cooperative(dual-ion-complexing)catalytic effect of organobase and triethylborane is proven,for thefirst time,effective for lithium alkoxide initiator system,allowing to achieve at room temperature high ROP activity(complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h),narrow molar mass distribution,controlled block lengths and composition.Density functional the-ory calculation shows that phosphazene bases are particularly effective,compared with N-heterocyclic bases,for complexing with Li+and enhancing the nucleophilic-ity of oxyanion.The rate of ROP is also affected by Li+-induced aggregation of the chain-end ion pairs,which though can be offset by adequate catalyst loadings.The versatility of this approach is further demonstrated in the one-pot synthesis of tri-/tetrablock ter-/quaterpolymers constituted by PI,PS,PEO,and poly(propylene oxide).Of great interest,PS-b-PI-b-PEO triblock terpolymer with a specific com-position is found to form internally microphase-separated micellar aggregates when dispersed in water.
基金financially supported by the National Natural Science Foundation of China(U21A20313,22222807)。
文摘For living anionic polymerization(LAP),solvent has a great influence on both reaction mechanism and kinetics.In this work,by using the classical butyl lithium-styrene polymerization as a model system,the effect of solvent on the mechanism and kinetics of LAP was revealed through a strategy combining density functional theory(DFT)calculations and kinetic modeling.In terms of mechanism,it is found that the stronger the solvent polarity,the more electrons transfer from initiator to solvent through detailed energy decomposition analysis of electrostatic interactions between initiator and solvent molecules.Furthermore,we also found that the stronger the solvent polarity,the higher the monomer initiation energy barrier and the smaller the initiation rate coefficient.Counterintuitively,initiation is more favorable at lower temperatures based on the calculated results ofΔG_(TS).Finally,the kinetic characteristics in different solvents were further examined by kinetic modeling.It is found that in benzene and n-pentane,the polymerization rate exhibits first-order kinetics.While,slow initiation and fast propagation were observed in tetrahydrofuran(THF)due to the slow free ion formation rate,leading to a deviation from first-order kinetics.
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.
基金the National Natural Science Foundation of China(21905171,21774077)Shanghai Municipal Government(18JC1410800)。
文摘Anionic ring-opening polymerization(AROP)of N-sulfonyl aziridines is an important synthetic route to linear polyethyleneimine(PEI)and its derivatives.In most cases,inert atmosphere and dry solvent were needed because of the oxygen-and water-sensitive initiators/catalysts used.Therefore,the AROP of N-sulfonyl aziridines that can be entirely operated in air atmosphere is still a challenging task.Herein,we report a series of sulfanions,including xanthates,dithiocarbamates,dithiobenzoates,thioacetates,and thiolates,as the initiators for the AROP of N-sulfonyl aziridines.Due to their good stability,openvessel polymerization was achieved with high livingness,affording a range of well-definedα-,ω-telechelic poly(N-sulfonyl aziridine)homopolymers and block copolymers with narrow dispersities and tunable molecular weights.Theα-end group of these polyaziridines was readily converted to thiol group,which enabled further post-polymerization functionalization with benzyl acrylate and poly(ethylene glycol)via thiol-ene click chemistry.The establishment of open-vessel sulfanion-initiated AROP of N-sulfonyl aziridines thus lays a solid foundation for the bulk preparation and application of poly(N-sulfonyl aziridine)s and PEI derivatives.
文摘The initiation reactions in the anionic non-equilibrium polymerization of octamethy- lcyclotetrasiloxane (D4) initiated by silazyllithiums were investigated. It was found that the structure of the substituents on the Si atom had great influences on the initiation activity of silazyllithiums.
基金funded by National Natural Science Foundation of China(22278023,22208010)Beijing Municipal Science and Technology Planning Project(Z221100002722002)+3 种基金Bingtuan Science and Technology Program(2022DB025)Beijing Natural Science Foundation(2222015)Sinopec Group(323034)the long-term from the Ministry of Finance and the Ministry of Education of PRC。
文摘An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.
基金This work was financially supported by the National Natural Science Foundation of China(No.50373037).
文摘20 wt% polyamide 12 （PA1212） pellets were dissolved in molten caprolactam. The caprolactam was then catalyzed at 180℃ and polymerized by means of anionic ring-opening polymerization to produce in situ blends of the resultant polyamide 6 （PA6） and PA 1212. Mechanical blends with same ingredient were prepared through melt blending on a twin-screw extruder. Scanning electron microscopy （SEM） observation revealed that contrary to the mechanical blends with small spherulites embedded in the matrix, no phase-separation existed in the in situ blends. The results of thermal analysis by differential scanning calorimetry （DSC） showed that single melting peak and crystallization peak existed for the in situ blends, while two melting and crystallization peaks appeared for the mechanical blends. The in situ blend film and the mixed blend film, both cast from a dilute formic acid solution with a concentration of 0.5 g/L, remained similar crystallization and melting behavior as above. It is proved by solution 13C-NMR analysis that transamidation took place during the in situ blending, and it is suggested that the combination of temperature increasing and the basic surrounding derived from NaOH during polymerization resulted in the occurrence of transamidation. Furthermore, it is proposed that the interchange reaction between PA 1212 and PA6 also resulted from the degradative reaction during the anionic polymerization.
基金This work was financially supported by the Special Fund for Major State Basic Research Project(G1999064801)the National Natural Science Foundation of China(Nos.20174033 and 20434020)
文摘In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.
基金supported by the National Natural Science Foundation of China.(Grant No.20174033 and 20254001)the Special Found for Major State Basic Research Project(Grant No.G1999064801)the Committee of Science and Technology of Zhejiang Province.
文摘The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.
基金This work was financially supported by the Key Program of National Natural Science Foundation of China(No.G 20434020)the Special Funds for Major Basic Research Projects(No.G 2005 CB623802)the Committee of Science and Technology of Zhejiang Province.
文摘Ring-opening polymerization of ε-caprolactone has been carried out by using rare earth Schiff base complexes： lanthanide tris（N-phenyl-3,5-di-t-butylsalicylaldiminato）s [Ln（OPBS）3] as single component catalyst for the first time. The influences of different rare earth elements, monomer and catalyst concentration as well as reaction time on the polymerization were investigated. Mechanism studies showed that monomer inserts into the active site with the acyl-oxygen bond scission rather than the break of alkyl-oxygen bond.
基金This project was supported by the National Natural Science Foundation of China (No. 20084001).
文摘A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst (PTC) at 0 'C . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 °C and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China (No. 20104005) and Hubei Province Natural Science Foundation of China (No. 2001B053) and a grant from National Key Fundamental Research Program of Chin
文摘Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPLexhibits higher activity than native PPL. Along wth the increasing enzyme concentration, the molecular weigh of resultingPDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For thethird recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyletime for the synthesis of PDTC. The ~1H-NMR spectra indicate that decarboxylation does not occur during the ring-openingpolymerization.
基金the financial supports of the National Science Foundation of the People's Republic of China(No.20704034)Provincial Natural Science Foundation of Zhejiang(No.Y4090047)
文摘Highly active calcium chloride（CaCl2） doped Zn-Co^Ⅲdouble metal-cyanide（Ca-DMC） catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield（54 kg polymer/g catalyst） at relative low temperature（80-115℃） toward ringopening polymerization（ROP） of propylene oxide（PO） than did DMC catalysts without modification.
基金Funded by the Natural Science Foundation of Shanxi Province (No.2006011069)the Opening Foundation of Key Laboratory of Shanxi Province (No.2009011059-7)
文摘Single component rare earth phenolates substituted by various alkyl groups have been prepared and the correlation between the aryloxides＇ structure and catalytic activity in the ring-opening polymerization of D,L-lactide has also been investigated.The catalytic activity of all rare earth aryloxides,characteristics of the ring-opening polymerization as well as polymerization kinetics and mechanism were investigated.The results showed that both phenolates＇ catalytic activities and polymerization characteristics changed regularly,keeping in good concordance with variations in substitutents＇ number on phenol and structure of aryloxide ligands.The stronger ability of electron-donation of alkyl groups,the higher catalytic activity.Moreover,the more numbers of substituted alkyl on phenyl ring,the higher catalytic activity.The analyses of polymer ends revealed that the polymerization proceeded via a coordination-acyl-oxygen bond cleavage-insertion mechanism.
基金The authors acknowledge the financial supports from National Nature Science Foundation（Nos. 20674071, 20774078 and 20434020） ；the Special Funds for Major State Basic Research Projects （No.2005CB623802）.
文摘Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through salt metathesis. This complex was successfully used to initiate the ring-opening polymerization of ε-caprolactone. The initiation conditions in different temperature, monomer-to-initiator ratio and time were investigated. Under the condition： [ε-caprolactone]：[catalyst] = 600, 56 ℃, toluene： 2 ml, poly（ε-caprolactone） （PCL） with Mw = 11,2782 and PDI = 1.96 was achieved.
基金This work was supported by the National Natural Science Foundation of China (No. 29674027, No. 29844002), the Ministry of National Education (G98402) and Organometallic Laboratory of Institute of Organic Chemistry of Chinese Academy of Sciences.
文摘Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.
基金Sasakawa Scientific Research Grant from the Japan Science Society.
文摘Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized by RuCl_2(=CHPh)(PCy_3)_2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol(SHP)and hindered amine(HLAS)groups via ring-opening metathesis polymerization(ROMP).The resulting copolymers were characterized by gel permeation chromatography(GPC),~1H-NMR and differen...
基金financially supported by the Key Project of Chinese Ministry of Education(No.105075)the National Natural Science Foundation of China(No.20503016).
文摘Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO/BF3.OEt2 on the molecular weights and yield of PBCMO were investigated. The polymerization in ionic liquids proceed to high conversions, although molecular weights are limited, similar to polymerization in organic solvent such as CH2Cl2. Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF4 is superior to [bmim]PF6. Extracting [bmim]PF6 from the product using organic solvent as extractant limits its advantage as a green reaction media.
基金Supported by the National Natural Science Foundation of China( No.2 0 174 0 33and2 0 2 5 4 0 0 1) and the Ministry of Sci-ence and Technology of China( No.19990 6 4 80 1)
基金This work was financially supported by the financial support of National Natural Science Foundation of China (No. 20434020)
文摘The ring-opening polymerization of 1,4-dioxan-2-one （PDO） was carried out by lanthanum tris（2,6-di-tert-butyl-4- methylphenolate） （La（OAr）3） as novel single component initiaLor. The influences of polymerization reaction temperature and the molar ratio of monomer to initiator on the monomer conversion and molecular weight of poly（1,4-dioxan-2-one） （PPDO） were explored. PPDO with high viscosity average molecular weight of 1.95×10^5 can be prepared at 40℃ when [PDO]/ [La（OAr）3] molar ratio was 800. Mechanism investigation shows that the polymerization proceeds through a ＂coordination- insertion＂ mechanism with selective rupture of acyl-oxygen be,nd of PDO.
