Anion-exchange membranes(AEMs)with high conductivity and stability are essential components of hydrogen related water electrolysis and fuel cell applications.During the past decades,polynorbornene(PNB)-based AEMs have...Anion-exchange membranes(AEMs)with high conductivity and stability are essential components of hydrogen related water electrolysis and fuel cell applications.During the past decades,polynorbornene(PNB)-based AEMs have shown excellent performance due to their saturated all-carbon-based backbones and diverse strategies to prepare cross-linked membranes.However,nearly all previously reported PNB-based AEMs rely on the alkyl-substituted norbornene monomers,whose low-yielding synthesis leads to high-cost of the AEMs.In addition,the crosslinked PNB-based AEMs usually suffered from mechanical brittleness.Herein,we propose a novel semi-interpenetrating polymer network(s-IPN)strategy to simultaneously enhance mechanical modulus and ionic conductivity,while using commercial 5-vinyl-2-norbornene(VNB)as the single norbornene derivatives to prepare high-performance AEMs.A diallylphenol quaternary ammonium salt was used for photo-induced crosslinking with poly-VNB and various dithiols to produce AEMs with s-IPN structures.The resultant membranes have excellent hydroxide conductivities and alkaline stability in 1 mol/L KOH at 80℃,and are successfully applied in alkaline anion-exchange membrane water electrolyzers to stably operateforover150h.展开更多
An unprecedented single-stranded polynorbornene with the pendant group containing benzenedicarboxaldehyde and a long alkyl chain（12） was synthesized by ring-open metathesis polymerization（ROMP） of the correspondin...An unprecedented single-stranded polynorbornene with the pendant group containing benzenedicarboxaldehyde and a long alkyl chain（12） was synthesized by ring-open metathesis polymerization（ROMP） of the corresponding monomer（11）,which was obtained via the esterification of two crucial intermediates,namely,2-hexadecyloxy-5-hydroxymethyl-1,3-benzenedicarboxaldehyde（7,obtained via 6 steps） and 4-（4-aza-tricyclo[5.2.1.0 2.6 ]-dec-8en-4-yl）benzoic acid（10）.The target compound and all the intermediates were characterized by infrared（IR）,1 H NMR and high resolution mass spectroscopy（HRMS） analysis.展开更多
Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers t...Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.展开更多
The development of synthetic polymers that mimic the double-stranded helical structure of DNA is a fascinating topic in polymer science.In this study,we designed and synthesized two chiral norbornene monomers containi...The development of synthetic polymers that mimic the double-stranded helical structure of DNA is a fascinating topic in polymer science.In this study,we designed and synthesized two chiral norbornene monomers containing adenine and thymine,which were mixed to form a hydrogen-bonding complementary complex,by which a ring-opening metathesis polymerization(ROMP)was performed.High-resolution transmission electron microscopy(HRTEM)undoubtedly showed the self-assembly of the optically active complementary nucleobasefunctionalized polynorbornenes into a double helix.Computer simulations and a two-dimensional nuclear Overhauser effect spectroscopy(2DNOESY)experiment showed that the doublestranded helical polynorbornene was derived from a copolymer of alternating adenine and thymine units.展开更多
Polynorbornenes were synthesized in the presence of an iron based catalyst, 2,6-bis[1-(2,6-diisopropyl-phenylimino)ethyl]pyridine iron(Ⅱ) dichloride. The FTIR, 1H NMR and 13C NMR analysis results revealed t...Polynorbornenes were synthesized in the presence of an iron based catalyst, 2,6-bis[1-(2,6-diisopropyl-phenylimino)ethyl]pyridine iron(Ⅱ) dichloride. The FTIR, 1H NMR and 13C NMR analysis results revealed that the structure of the obtained polynorbornenes consisted of vinyl addition polymer substructures without any ring-opening structures. The polymers were amorphous with a short-range order, displayed in the WAXD(wide angle X-ray diffraction) diagrams. The glass transition temperatures ranged from 200 to 400 ℃. The effects of the polymerization reaction conditions, such as Al/Fe molar ratio and toluene/CH_2Cl_2 volume ratio, on the activity, intrinsic viscosity and T_g were also studied.展开更多
In order to realize a metal containing nano-structure, a block-copolymer containing alkynyl groups in one block was designed and synthesized by living ring opening metathesis polymerization (ROMP) technique. The newly...In order to realize a metal containing nano-structure, a block-copolymer containing alkynyl groups in one block was designed and synthesized by living ring opening metathesis polymerization (ROMP) technique. The newly developed bis-3-bromopyridine complex of Grubbs catalyst was employed in the series of polymerization and it yielded the desired polymers with great molecular weight control and narrow polydispersities. The characteristics of the block copolymers were investigated by gel permeation chromatography, H- and 13H- NMR spectroscopy. Complexation of the alkynyl group containing block copolymers by treatment with dicobalt octacarbonyl occurred smoothly in 5 min at room temperature. GPC analysis before and after cobalt complexation indicated a significant increase of the hydrodynamic volume. AFM images of the films before and after the complexation also showed a noticeable change in its morphology where grain sizes become smaller and more regular upon complexation.展开更多
The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) u...The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II). Both catalysts were used to synthesize random and block high molecular weight copolymers which were further hydrogenated using a Wilkinson’s catalyst. Then, the saturated copolymers were modified by reacting with sodium 4-hydroxybenzene-sulfonate dihydrate to generate new ionomers with fluoro-sulfonic acid pendant groups.展开更多
基金financially supported by the Ministry of Science and Technology of China under the National Key R&D Program of China (No.2023YFB3811200)the National Natural Science Foundation of China (No.22075292).
文摘Anion-exchange membranes(AEMs)with high conductivity and stability are essential components of hydrogen related water electrolysis and fuel cell applications.During the past decades,polynorbornene(PNB)-based AEMs have shown excellent performance due to their saturated all-carbon-based backbones and diverse strategies to prepare cross-linked membranes.However,nearly all previously reported PNB-based AEMs rely on the alkyl-substituted norbornene monomers,whose low-yielding synthesis leads to high-cost of the AEMs.In addition,the crosslinked PNB-based AEMs usually suffered from mechanical brittleness.Herein,we propose a novel semi-interpenetrating polymer network(s-IPN)strategy to simultaneously enhance mechanical modulus and ionic conductivity,while using commercial 5-vinyl-2-norbornene(VNB)as the single norbornene derivatives to prepare high-performance AEMs.A diallylphenol quaternary ammonium salt was used for photo-induced crosslinking with poly-VNB and various dithiols to produce AEMs with s-IPN structures.The resultant membranes have excellent hydroxide conductivities and alkaline stability in 1 mol/L KOH at 80℃,and are successfully applied in alkaline anion-exchange membrane water electrolyzers to stably operateforover150h.
基金Supported by the National Natural Science Foundation of China(No.20902002)the Natural Science Foundation of Anhui Province,China(No.10040606Q04)
文摘An unprecedented single-stranded polynorbornene with the pendant group containing benzenedicarboxaldehyde and a long alkyl chain（12） was synthesized by ring-open metathesis polymerization（ROMP） of the corresponding monomer（11）,which was obtained via the esterification of two crucial intermediates,namely,2-hexadecyloxy-5-hydroxymethyl-1,3-benzenedicarboxaldehyde（7,obtained via 6 steps） and 4-（4-aza-tricyclo[5.2.1.0 2.6 ]-dec-8en-4-yl）benzoic acid（10）.The target compound and all the intermediates were characterized by infrared（IR）,1 H NMR and high resolution mass spectroscopy（HRMS） analysis.
基金financially supported by the National Natural Science Foundation of China(Nos.21801236 and U1862206)。
文摘Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.
基金The authors thank the National Natural Science Foundation of China(grant no.21971037)the Jiangsu Provincial Natural Science Foundation of China(grant no.BK20170024)for the support of this research project.
文摘The development of synthetic polymers that mimic the double-stranded helical structure of DNA is a fascinating topic in polymer science.In this study,we designed and synthesized two chiral norbornene monomers containing adenine and thymine,which were mixed to form a hydrogen-bonding complementary complex,by which a ring-opening metathesis polymerization(ROMP)was performed.High-resolution transmission electron microscopy(HRTEM)undoubtedly showed the self-assembly of the optically active complementary nucleobasefunctionalized polynorbornenes into a double helix.Computer simulations and a two-dimensional nuclear Overhauser effect spectroscopy(2DNOESY)experiment showed that the doublestranded helical polynorbornene was derived from a copolymer of alternating adenine and thymine units.
基金Supported by the Special Funds for Major State Basic Research Projects( No.G19990 64 80 0 ),the National NaturalScience Foundation of China( No.2 973 4141) ,and SKL EP ( 0 0 62 ) ,SINOPEC and CNPC.
文摘Polynorbornenes were synthesized in the presence of an iron based catalyst, 2,6-bis[1-(2,6-diisopropyl-phenylimino)ethyl]pyridine iron(Ⅱ) dichloride. The FTIR, 1H NMR and 13C NMR analysis results revealed that the structure of the obtained polynorbornenes consisted of vinyl addition polymer substructures without any ring-opening structures. The polymers were amorphous with a short-range order, displayed in the WAXD(wide angle X-ray diffraction) diagrams. The glass transition temperatures ranged from 200 to 400 ℃. The effects of the polymerization reaction conditions, such as Al/Fe molar ratio and toluene/CH_2Cl_2 volume ratio, on the activity, intrinsic viscosity and T_g were also studied.
文摘In order to realize a metal containing nano-structure, a block-copolymer containing alkynyl groups in one block was designed and synthesized by living ring opening metathesis polymerization (ROMP) technique. The newly developed bis-3-bromopyridine complex of Grubbs catalyst was employed in the series of polymerization and it yielded the desired polymers with great molecular weight control and narrow polydispersities. The characteristics of the block copolymers were investigated by gel permeation chromatography, H- and 13H- NMR spectroscopy. Complexation of the alkynyl group containing block copolymers by treatment with dicobalt octacarbonyl occurred smoothly in 5 min at room temperature. GPC analysis before and after cobalt complexation indicated a significant increase of the hydrodynamic volume. AFM images of the films before and after the complexation also showed a noticeable change in its morphology where grain sizes become smaller and more regular upon complexation.
文摘The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II). Both catalysts were used to synthesize random and block high molecular weight copolymers which were further hydrogenated using a Wilkinson’s catalyst. Then, the saturated copolymers were modified by reacting with sodium 4-hydroxybenzene-sulfonate dihydrate to generate new ionomers with fluoro-sulfonic acid pendant groups.
