Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-san...Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.展开更多
The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with V...The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.展开更多
Liquid trimethoxy silane-functionalized cis-polybutadiene(cis-PB-Si(OMe)3),possessing number-average molecular weights of cis-PB segments(Mn,PB)ranging from 1800 g/mol to 5400 g/mol,with cis-1,4 content of ca.80%and h...Liquid trimethoxy silane-functionalized cis-polybutadiene(cis-PB-Si(OMe)3),possessing number-average molecular weights of cis-PB segments(Mn,PB)ranging from 1800 g/mol to 5400 g/mol,with cis-1,4 content of ca.80%and high functionality(>96%)could be synthesized by coordination copolymerization of living cis-PB chain ends with ethenyltrimethoxy-silane with neodymium-based catalytic system.The silicon hydroxyl-functionalized cis-polybutadiene(cis-PB-Si(OH)_(3))-based micelles in water have been achieved by in situ hydrolysis of cis-PB-Si(OMe)_(3)in hexane/water mixture(pH=6.8)at 70℃and by sequential removal of residue hexane.The size of the above micelles with soft elastic cis-PB cores could be remarkably enlarged by loading SiO_(2)nanoparticles on their surfaces via hydrogen bonding interaction.Giant supramolecular long chain aggregates or networks formed by hydrogen bonding interaction and possible O—Si—O chemical bonds between cis-PB-Si(OH)3-based micellar surfaces had relatively large size and thus precipitated from water after several months of storage,leading to production of cis-PB-Si(OH)_(3)solid elastomer with extremely low T_(g)at−107.0℃.The left cis-PB-Si(OH)_(3)-based micelles in water with relatively small size gradually formed the water-insoluble cis-PB-Si(OH)_(3)-based supramolecular aggregates or networks.The cis-PB-Si(OH)_(3)-based supramolecular elastomer exhibited excellent self-healing property within 60 s at 25℃.The elastomer(20 mg)in a joint of 25 mm×30 mm(2.7 mg/cm^(2))provided very strong adhesion for two pieces of glass and the bound glass keep unchanged at room temperature for 98 h even hung with 100 g of steel column below.The cis-PB-Si(OH)3-based supramolecular elastomer would have potential applications in adhesives,self-healing materials,damping materials and elastic materials.展开更多
Synthesizing orientated liquid crystal elastomers(LCEs)via the two-stage thiol-acrylate Michael addition and photopolymerization(TAMAP)reaction is extensively used.However,excess acrylates,initiators,and strong stimul...Synthesizing orientated liquid crystal elastomers(LCEs)via the two-stage thiol-acrylate Michael addition and photopolymerization(TAMAP)reaction is extensively used.However,excess acrylates,initiators,and strong stimuli are inevitably involved in the second stage crosslinking.Herein,we simplify the strategy through taking advantage of a volatile alkaline(originally added to catalyze the thiol-acrylate addition in the first crosslinking stage).Without excess functional groups,the residual catalyst after annealing is still enough to trigger reactions of dynamic covalent bonds at a relatively mild temperature(80℃)to program the alignment of LCEs.The reversible reaction switches off by itself after this process since the catalyst gradually but totally evaporates upon heating.The obtained soft actuators exhibit robust actuation during repeated deformation(over 1000 times).Many shape-morphing modes can be achieved by rationally designing orientation patterns.This strategy not only facilitates the practical synthesis of LCE actuators,but also balances the intrinsic conflict between stability and reprogrammability of exchangeable LCEs.Moreover,the method of applying volatile catalysts has the potential to be extended to other dynamic covalent bonds(DCBs)applied to crosslinked polymer systems.展开更多
Donor-acceptor(D-A)conjugated polymers comprising electron-deficient aromatic dicarboximide units represent an important type of organic semiconductors,especially for electron transporting properties.Pyrene-1,5,6,10-t...Donor-acceptor(D-A)conjugated polymers comprising electron-deficient aromatic dicarboximide units represent an important type of organic semiconductors,especially for electron transporting properties.Pyrene-1,5,6,10-tetracarboxyl diimide(PyDI),a new PAH dicarboximide molecule recently reported by us,provides a fine balance between the electron-stabilizing ability andπ-stacking tendency,as compared to the naphthalenediimide(NDI)and perylenediimide(PDI)analogues.In this study,using thienylene-vinylene-thienylene(TVT)and biselenophene(BS)as the electron donating comonomer,along with PyDI as the acceptor moiety,we develop two new D-A type conjugated polymers,which exhibit impressive electron-transporting performance.Specifically,in the solution-processed OFET devices,electron mobility of 0.18 and 0.20 cm^(2)·V^(−1)·s^(−1) are achieved with these polymers,respectively.Such findings further prove the optimal potential of PyDI for application as an electron-acceptor building block in the development of polymeric n-type semiconductors among all various high-performance functional D-A polymers.展开更多
Due to their dynamic nature and strength tunability,metallo-supramolecular polymers have been introduced into various materials.The mechanical strength of the metallo-supramolecular polymers in the system directly inf...Due to their dynamic nature and strength tunability,metallo-supramolecular polymers have been introduced into various materials.The mechanical strength of the metallo-supramolecular polymers in the system directly influences the mechanical properties(e.g.,the toughness)of the materials.Therefore,it is necessary to explore the mechanical behavior of the metallo-supramolecular polymers.Herein,we present a single-molecule method to systematically explore the chain structure and mechanical properties of metallo-supramolecular polymer by using a loop protected architecture.Notably,we found that the mechanical stability of the individual chain,which is determined by the strength of terpyridine-Fe^(2+) -terpyridine(tpy-Fe^(2+)-tpy)bonds,was about 0.6–1.0 nN,depending on the pulling speed.This value is around three times higher than those measured using old methods.In addition,the unique loop protected structure further reduces the interference of non-specific polymer-AFM tip(or polymer-substrate)interactions on the quantification of the actual strength and kinetic parameter of noncovalent interactions in supramolecular polymers.Furthermore,the single chain flexibility of the metallo-supramolecular polymer was investigated and found to be comparable to the corresponding covalent analogues.Our findings provide a new way to explore the force response of supramolecular polymers composed of metal-ligand interactions and will be useful for the design of metallo-supramolecular polymer-based functional materials with tailored mechanical properties.展开更多
Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguis...Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and.supported by an International Advisory Board in which many famous active polymer scientists all over the world are included.展开更多
The power conversion efficiency(PCE)of polymer solar cells(PSCs)has exceeded 19%due to the rapid progress of photoactive organic materials,including conjugated polymer donors and the matched non-fullerene acceptors(NF...The power conversion efficiency(PCE)of polymer solar cells(PSCs)has exceeded 19%due to the rapid progress of photoactive organic materials,including conjugated polymer donors and the matched non-fullerene acceptors(NFAs).Due to the high density of oxygen vacancies and the consequent photocatalytic reactivity of ZnO,structure inverted polymer solar cells with the ZnO electron transport layer(ETL)usually suffer poor device photostability.In this work,the eco-friendly glucose(Glu)is found to simultaneously improve the efficiency and stability of polymer:NFA solar cells.Under the optimal conditions,we achieved improved PCEs from 14.77%to 15.86%for the PM6:Y6 solar cells.Such a PCE improvement was attributed to the improvement in J_(SC) and FF,which is ascribed to the smoother and more hydrophobic surface of the ZnO/Glu surface,thereby enhancing the charge extraction efficiency and inhibiting charge recombination.Besides,UV-Vis absorption spectra analysis revealed that glucose modification could significantly inhibit the photodegradation of Y6,resulting in a significant improvement in the stability of the device with 92%of its initial PCE after aging for 1250 h.The application of natural interface materials in this work brings hope for the commercial application of organic solar cells and provides new ideas for developing new interface materials.展开更多
Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this ...Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this study,stress relaxation measurements are performed after intervals of a strong flow during which the precursors form.The small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes,each of different periods.A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s,the stress can fully relax and the orientation of the subsequent crystals(formed upon quenching the sample at different stress levels)decays gradually with the relaxation.In comparison,for those precursors formed after 5 s,the stress hardly relaxes during~10^(4) s,and the orientation of the subsequent crystals hardly decays,suggesting that the precursors have been somehow stabilized during the shear.These features have been discussed with respect to the percolation of the precursors to form a reversible network.展开更多
Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst ...Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst system is rare thus far.In this contribution,by introducing different backbones,flexible and rigid axial substituents into theα-imino-ketone framework,a family of cationic nickel catalysts were synthesized and fully characterized.Without the addition of any activator,systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity,polymer molecular weight,branching density and incorporation.In particular,owing to the unique semi-opening feature of theα-imino-ketone framework,the preferred nickel catalyst exhibited high activity of 175 kg·mol^(-1)·h^(-1)to produce functionalized polyethylene with molecular weight of 13.4 kg·mol^(-1)and comonomer incorporation of 2.9 mol%.展开更多
Silica rods with homogeneous(hydrophilic or hydrophobic)and amphiphilic surface properties were synthesized and their efficiencies in suppressing the flow-induced droplet coalescence of immiscible polyisobutylene(PIB)...Silica rods with homogeneous(hydrophilic or hydrophobic)and amphiphilic surface properties were synthesized and their efficiencies in suppressing the flow-induced droplet coalescence of immiscible polyisobutylene(PIB)/polydimethylsiloxane(PDMS)blends were evaluated via in situ visualization technique.The flow-induced coalescence behavior of blends was found to strongly depend on the surface nature and concentration of silica rods added as well as the blend ratio.While a trace amount of rods promoted coalescence,all kinds of rods demonstrated a morphology refinement effect at high rod concentrations.Good compatibilization effects were obtained at high rod concentrations,especially for hydrophilic and amphiphilic rods.Based on confocal laser scanning microscopy results,these phenomena observed were interpreted reasonably in terms of the selective distribution and aggregation of silica rods,which were suggested to be decisive for the stabilization mechanism and efficiency of these rods.展开更多
Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strate...Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether,and to develop more high-performance,multi-purpose polymer materials.Herein,the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-AI complex in the presence of PPNCI for the copolymerization of epoxides and£-caprolactone(CL).Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL,affording copolymers with a gradient sequence structure.The dynamic thermomechanical analysis(DMA)study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio.This study provides a theoretical basis for the preparation of high-performance polymer materials.展开更多
High transparency and toughness are prerequisites for sustainable polymers if they are to find wide application as alternatives to petroleum-based polymers.However,the utility of sustainable polymers such as commercia...High transparency and toughness are prerequisites for sustainable polymers if they are to find wide application as alternatives to petroleum-based polymers.However,the utility of sustainable polymers such as commercially available polylactide(PLA)is limited by their inherent brittleness and high cost.Unfortunately,toughening PLA-based materials via cost-effective blending strategies without sacrificing transparency remains a challenge.Herein,we report a novel strategy involving active refractive index matching for creation of highly transparent and tough PLA blends.Specifically,we engineered the refractive index of a promising renewable poly(epichlorohydrin-co-ethylene oxide)elastomer by introducing polar ionic moieties via a simple chemical method,and we blended the resulting ionomers with PLA.The best blend showed an impact strength of>80 kJ/m2,an elongation at break of 400%,and high transparency(90%).These characteristics are of great importance for potential applications such as packaging.Our strategy offers a versatile new way to prepare high-performance sustainable polymer materials with excellent transparency.展开更多
Development of degradable polyester elastomers plays an important role in the applications of soft mateirals.Noncrystalline polymenthides(PMs)from menthol derived lactone monomers are excellent soft segments for prepa...Development of degradable polyester elastomers plays an important role in the applications of soft mateirals.Noncrystalline polymenthides(PMs)from menthol derived lactone monomers are excellent soft segments for preparing degradable polyester elastomers.By using cyclic trimeric phosphazene base(CTPB)as an organocatalyst,we succesfully synthesized PMs with different molecular weights(8.2 kDa to 100.7 kDa)in high yields via ring-opening polymerization(ROP)of menthide.When a CTPB/urea binary catalytic system was adopted,the polymerizations proceeded in a more controlled manner.Using glycerol as initiator,star shaped PMs with well.defined structure were synthesized and subsequently end-capped by acrylate.UV iradiation of the terminal acrylate groups in the star-shaped PMs resulted in formation of chemically cos-linked polyester elastomers without heat or other stimuli.The obtained polyester elastomers exhibit matched modulus(3.8-5.5 MPa),tensile strength(0.56-0.68 MPa),and strain at break(280%-320%)with soft body tssues,displaying great potential in biomedical applications.展开更多
Four truxene-based conjugated microporous polymers(Tr-CMPs)were prepared via different synthetic methods and their structure-property relationships were studied.The polymer networks have high Brunauer-Emmett-Teller(BE...Four truxene-based conjugated microporous polymers(Tr-CMPs)were prepared via different synthetic methods and their structure-property relationships were studied.The polymer networks have high Brunauer-Emmett-Teller(BET)specific surface areas ranging from 554 m^2·g^–1to 1024 m^2·g^–1.Pore sizes of the CMPs with different linkers are mainly located between 0.60 and 1.96 nm.Among all the Tr-CMPs,TrCMP4 has the highest BET surface area of 1024 m^2·g^–1and exhibits the highest H2 uptake of 0.88 wt%.Tr-CMP2 prepared by Suzuki-Miyaura coupling reaction has the highest photoluminescence quantum yields(PLQYs)of 13.06% and CO2 uptake of 6.25 wt%.展开更多
Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguis...Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and supported by an International Advisory Board in which many famous active polymer scientists all over the world are included.The journal was first published in 1983 under the title Polymer Communications and has the current name since 1985.展开更多
Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by sim...Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic initiator.The performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction condition.Urea-derived catalysts are generally superior to thiourea-derived ones.Provided with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction time.In addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.展开更多
Binuclear and hexanuclear titanium complexes stabilized by tetradentate [OOOO]^(4–)-type ligand were active in ethylene polymerization in the presence of Et2 AlCl/Bu2 Mg binary co-catalyst, giving high molecular weig...Binuclear and hexanuclear titanium complexes stabilized by tetradentate [OOOO]^(4–)-type ligand were active in ethylene polymerization in the presence of Et2 AlCl/Bu2 Mg binary co-catalyst, giving high molecular weight polyethylene. The binuclear complex showed significantly higher catalytic activity and thermal stability in comparison to mononuclear analogue. Ultra high molecular weight polyethylene(UHMWPE) samples were processed by a solid-state uniaxial deformation into high-strength(up to 2.5 GPa) and highmodulus(over 100 GPa) oriented film tapes, which indirectly indicates a low degree of entanglements between the macromolecular chains.展开更多
By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and cryst...By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.展开更多
A series of triblock copolymers, containing a CO_2-switchable block poly(2-(dimethylamino)ethyl methacrylate)(PDM) block and two symmetrical hydrophilic blocks polyacrylamide(PAM), were synthesized using atom transfer...A series of triblock copolymers, containing a CO_2-switchable block poly(2-(dimethylamino)ethyl methacrylate)(PDM) block and two symmetrical hydrophilic blocks polyacrylamide(PAM), were synthesized using atom transfer radical polymerization(ATRP) method. The p H and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO_2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO_2, and the triblock copolymer aqueous solution displayed a CO_2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1 H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar vesicle-network aggregate structure transition. The release of rhodamine B from the vesicles with and without CO_2 stimuli showed the potential application in drug delivery domains; after CO_2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO_2-switchable morphology changes and CO_2-induced drug release was proposed.展开更多
基金financially supported by the open research fund program of Science and Technology on Aerospace Chemical Power Laboratory (No. STACPL120221B03)the National Natural Science Foundation of China (Nos. s22175059,52073275 and U21A20279)。
文摘Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.
基金financially supported by the National Natural Science Foundation of China (Nos.21774006 and 21634002)。
文摘The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.
基金the National Natural Science Foundation of China(NSFC)(Nos.21634002,51790501 and 51521062)the Fundamental Research Funds for the Central Universities(Nos.XK1802-2 and XK1802-1).
文摘Liquid trimethoxy silane-functionalized cis-polybutadiene(cis-PB-Si(OMe)3),possessing number-average molecular weights of cis-PB segments(Mn,PB)ranging from 1800 g/mol to 5400 g/mol,with cis-1,4 content of ca.80%and high functionality(>96%)could be synthesized by coordination copolymerization of living cis-PB chain ends with ethenyltrimethoxy-silane with neodymium-based catalytic system.The silicon hydroxyl-functionalized cis-polybutadiene(cis-PB-Si(OH)_(3))-based micelles in water have been achieved by in situ hydrolysis of cis-PB-Si(OMe)_(3)in hexane/water mixture(pH=6.8)at 70℃and by sequential removal of residue hexane.The size of the above micelles with soft elastic cis-PB cores could be remarkably enlarged by loading SiO_(2)nanoparticles on their surfaces via hydrogen bonding interaction.Giant supramolecular long chain aggregates or networks formed by hydrogen bonding interaction and possible O—Si—O chemical bonds between cis-PB-Si(OH)3-based micellar surfaces had relatively large size and thus precipitated from water after several months of storage,leading to production of cis-PB-Si(OH)_(3)solid elastomer with extremely low T_(g)at−107.0℃.The left cis-PB-Si(OH)_(3)-based micelles in water with relatively small size gradually formed the water-insoluble cis-PB-Si(OH)_(3)-based supramolecular aggregates or networks.The cis-PB-Si(OH)_(3)-based supramolecular elastomer exhibited excellent self-healing property within 60 s at 25℃.The elastomer(20 mg)in a joint of 25 mm×30 mm(2.7 mg/cm^(2))provided very strong adhesion for two pieces of glass and the bound glass keep unchanged at room temperature for 98 h even hung with 100 g of steel column below.The cis-PB-Si(OH)3-based supramolecular elastomer would have potential applications in adhesives,self-healing materials,damping materials and elastic materials.
基金supported by the National Natural Science Foundation of China(Nos.51722303,21674057 and 21788102).
文摘Synthesizing orientated liquid crystal elastomers(LCEs)via the two-stage thiol-acrylate Michael addition and photopolymerization(TAMAP)reaction is extensively used.However,excess acrylates,initiators,and strong stimuli are inevitably involved in the second stage crosslinking.Herein,we simplify the strategy through taking advantage of a volatile alkaline(originally added to catalyze the thiol-acrylate addition in the first crosslinking stage).Without excess functional groups,the residual catalyst after annealing is still enough to trigger reactions of dynamic covalent bonds at a relatively mild temperature(80℃)to program the alignment of LCEs.The reversible reaction switches off by itself after this process since the catalyst gradually but totally evaporates upon heating.The obtained soft actuators exhibit robust actuation during repeated deformation(over 1000 times).Many shape-morphing modes can be achieved by rationally designing orientation patterns.This strategy not only facilitates the practical synthesis of LCE actuators,but also balances the intrinsic conflict between stability and reprogrammability of exchangeable LCEs.Moreover,the method of applying volatile catalysts has the potential to be extended to other dynamic covalent bonds(DCBs)applied to crosslinked polymer systems.
基金financially supported by the National Natural Science Foundation of China (Nos. 21925501, 22175004 and 22020102001)the Beijing National Laboratory for Molecular Sciences (No. BNLMS-CXXM-201902)
文摘Donor-acceptor(D-A)conjugated polymers comprising electron-deficient aromatic dicarboximide units represent an important type of organic semiconductors,especially for electron transporting properties.Pyrene-1,5,6,10-tetracarboxyl diimide(PyDI),a new PAH dicarboximide molecule recently reported by us,provides a fine balance between the electron-stabilizing ability andπ-stacking tendency,as compared to the naphthalenediimide(NDI)and perylenediimide(PDI)analogues.In this study,using thienylene-vinylene-thienylene(TVT)and biselenophene(BS)as the electron donating comonomer,along with PyDI as the acceptor moiety,we develop two new D-A type conjugated polymers,which exhibit impressive electron-transporting performance.Specifically,in the solution-processed OFET devices,electron mobility of 0.18 and 0.20 cm^(2)·V^(−1)·s^(−1) are achieved with these polymers,respectively.Such findings further prove the optimal potential of PyDI for application as an electron-acceptor building block in the development of polymeric n-type semiconductors among all various high-performance functional D-A polymers.
基金financially supported by the National Natural Science Foundation of China (Nos.21827805 and 21525418 for W.Z.) and (No.22071079 for M.W)。
文摘Due to their dynamic nature and strength tunability,metallo-supramolecular polymers have been introduced into various materials.The mechanical strength of the metallo-supramolecular polymers in the system directly influences the mechanical properties(e.g.,the toughness)of the materials.Therefore,it is necessary to explore the mechanical behavior of the metallo-supramolecular polymers.Herein,we present a single-molecule method to systematically explore the chain structure and mechanical properties of metallo-supramolecular polymer by using a loop protected architecture.Notably,we found that the mechanical stability of the individual chain,which is determined by the strength of terpyridine-Fe^(2+) -terpyridine(tpy-Fe^(2+)-tpy)bonds,was about 0.6–1.0 nN,depending on the pulling speed.This value is around three times higher than those measured using old methods.In addition,the unique loop protected structure further reduces the interference of non-specific polymer-AFM tip(or polymer-substrate)interactions on the quantification of the actual strength and kinetic parameter of noncovalent interactions in supramolecular polymers.Furthermore,the single chain flexibility of the metallo-supramolecular polymer was investigated and found to be comparable to the corresponding covalent analogues.Our findings provide a new way to explore the force response of supramolecular polymers composed of metal-ligand interactions and will be useful for the design of metallo-supramolecular polymer-based functional materials with tailored mechanical properties.
文摘Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and.supported by an International Advisory Board in which many famous active polymer scientists all over the world are included.
基金financially supported by the National Natural Science Foundation of China (No.22075315)the Chinese Academy of Science (Nos.YJKYYQ20180029 and GJHZ2092-019)the Youth Innovation Promotion Association,CAS (No.2019317)。
文摘The power conversion efficiency(PCE)of polymer solar cells(PSCs)has exceeded 19%due to the rapid progress of photoactive organic materials,including conjugated polymer donors and the matched non-fullerene acceptors(NFAs).Due to the high density of oxygen vacancies and the consequent photocatalytic reactivity of ZnO,structure inverted polymer solar cells with the ZnO electron transport layer(ETL)usually suffer poor device photostability.In this work,the eco-friendly glucose(Glu)is found to simultaneously improve the efficiency and stability of polymer:NFA solar cells.Under the optimal conditions,we achieved improved PCEs from 14.77%to 15.86%for the PM6:Y6 solar cells.Such a PCE improvement was attributed to the improvement in J_(SC) and FF,which is ascribed to the smoother and more hydrophobic surface of the ZnO/Glu surface,thereby enhancing the charge extraction efficiency and inhibiting charge recombination.Besides,UV-Vis absorption spectra analysis revealed that glucose modification could significantly inhibit the photodegradation of Y6,resulting in a significant improvement in the stability of the device with 92%of its initial PCE after aging for 1250 h.The application of natural interface materials in this work brings hope for the commercial application of organic solar cells and provides new ideas for developing new interface materials.
基金financially supported by the National Natural Science Foundation of China(No.21790343).
文摘Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar crystals.The formation leads to further growth of shear/normal stress after the stress reaches the steady state.In this study,stress relaxation measurements are performed after intervals of a strong flow during which the precursors form.The small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes,each of different periods.A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s,the stress can fully relax and the orientation of the subsequent crystals(formed upon quenching the sample at different stress levels)decays gradually with the relaxation.In comparison,for those precursors formed after 5 s,the stress hardly relaxes during~10^(4) s,and the orientation of the subsequent crystals hardly decays,suggesting that the precursors have been somehow stabilized during the shear.These features have been discussed with respect to the percolation of the precursors to form a reversible network.
基金financially supported by the National Natural Science Foundation of China(Nos.22122110,21871250 and 22001244)the Jilin Provincial Science and Technology Department Program(No.20200801009GH)。
文摘Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst system is rare thus far.In this contribution,by introducing different backbones,flexible and rigid axial substituents into theα-imino-ketone framework,a family of cationic nickel catalysts were synthesized and fully characterized.Without the addition of any activator,systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity,polymer molecular weight,branching density and incorporation.In particular,owing to the unique semi-opening feature of theα-imino-ketone framework,the preferred nickel catalyst exhibited high activity of 175 kg·mol^(-1)·h^(-1)to produce functionalized polyethylene with molecular weight of 13.4 kg·mol^(-1)and comonomer incorporation of 2.9 mol%.
基金supported by the National Natural Science Foundation of China(Nos.51873111,51721091)the Scientific Research Foundation of Sichuan Province(No.2018HH0001)+1 种基金the Programme of Introducing Talents of Discipline to Universities(No.B13040)the Graduate Innovation Foundation of Sichuan University(No.2018YJSY088).
文摘Silica rods with homogeneous(hydrophilic or hydrophobic)and amphiphilic surface properties were synthesized and their efficiencies in suppressing the flow-induced droplet coalescence of immiscible polyisobutylene(PIB)/polydimethylsiloxane(PDMS)blends were evaluated via in situ visualization technique.The flow-induced coalescence behavior of blends was found to strongly depend on the surface nature and concentration of silica rods added as well as the blend ratio.While a trace amount of rods promoted coalescence,all kinds of rods demonstrated a morphology refinement effect at high rod concentrations.Good compatibilization effects were obtained at high rod concentrations,especially for hydrophilic and amphiphilic rods.Based on confocal laser scanning microscopy results,these phenomena observed were interpreted reasonably in terms of the selective distribution and aggregation of silica rods,which were suggested to be decisive for the stabilization mechanism and efficiency of these rods.
基金the National Natural Science Foundation of China(Nos.21722402 and 21674015).
文摘Copolymerization is a commonly employed method for optimizing the properties of polymer materials.Incorporating ether segments into polyesters main chain to obtain polyether-polyester copolymers is an effective strategy to realize the integration of multiple properties of polyester and polyether,and to develop more high-performance,multi-purpose polymer materials.Herein,the synthesis of poly(ether-ester)s is accessible by employing the biphenyl-linked heterodinuclear salen Cr-AI complex in the presence of PPNCI for the copolymerization of epoxides and£-caprolactone(CL).Monitoring the copolymerization process reveals that catalyst 1 exhibited good performance for the copolymerization of epoxides and CL,affording copolymers with a gradient sequence structure.The dynamic thermomechanical analysis(DMA)study indicates the obtained poly(ether-ester)s possess enhanced flexibility compared with the block copolymers or blend of PPO and PCL homopolymers with the same ratio.This study provides a theoretical basis for the preparation of high-performance polymer materials.
基金supported by the National Natural Science Foundation of China(No.51573130)。
文摘High transparency and toughness are prerequisites for sustainable polymers if they are to find wide application as alternatives to petroleum-based polymers.However,the utility of sustainable polymers such as commercially available polylactide(PLA)is limited by their inherent brittleness and high cost.Unfortunately,toughening PLA-based materials via cost-effective blending strategies without sacrificing transparency remains a challenge.Herein,we report a novel strategy involving active refractive index matching for creation of highly transparent and tough PLA blends.Specifically,we engineered the refractive index of a promising renewable poly(epichlorohydrin-co-ethylene oxide)elastomer by introducing polar ionic moieties via a simple chemical method,and we blended the resulting ionomers with PLA.The best blend showed an impact strength of>80 kJ/m2,an elongation at break of 400%,and high transparency(90%).These characteristics are of great importance for potential applications such as packaging.Our strategy offers a versatile new way to prepare high-performance sustainable polymer materials with excellent transparency.
基金This work was financially supported by the National Natural Science Foundation of China(No.21704048)the 111 Project(No.D17004)the Taishan Scholars Constructive Engineering Foundation(No.tsqn20161031).
文摘Development of degradable polyester elastomers plays an important role in the applications of soft mateirals.Noncrystalline polymenthides(PMs)from menthol derived lactone monomers are excellent soft segments for preparing degradable polyester elastomers.By using cyclic trimeric phosphazene base(CTPB)as an organocatalyst,we succesfully synthesized PMs with different molecular weights(8.2 kDa to 100.7 kDa)in high yields via ring-opening polymerization(ROP)of menthide.When a CTPB/urea binary catalytic system was adopted,the polymerizations proceeded in a more controlled manner.Using glycerol as initiator,star shaped PMs with well.defined structure were synthesized and subsequently end-capped by acrylate.UV iradiation of the terminal acrylate groups in the star-shaped PMs resulted in formation of chemically cos-linked polyester elastomers without heat or other stimuli.The obtained polyester elastomers exhibit matched modulus(3.8-5.5 MPa),tensile strength(0.56-0.68 MPa),and strain at break(280%-320%)with soft body tssues,displaying great potential in biomedical applications.
基金financially supported by the the National Natural Science Foundation of China (Nos. 21574087 and 21404074)Science and Technology Department of Sichuan Province (Nos. 2019YJ0128 and 2019YFG0277)
文摘Four truxene-based conjugated microporous polymers(Tr-CMPs)were prepared via different synthetic methods and their structure-property relationships were studied.The polymer networks have high Brunauer-Emmett-Teller(BET)specific surface areas ranging from 554 m^2·g^–1to 1024 m^2·g^–1.Pore sizes of the CMPs with different linkers are mainly located between 0.60 and 1.96 nm.Among all the Tr-CMPs,TrCMP4 has the highest BET surface area of 1024 m^2·g^–1and exhibits the highest H2 uptake of 0.88 wt%.Tr-CMP2 prepared by Suzuki-Miyaura coupling reaction has the highest photoluminescence quantum yields(PLQYs)of 13.06% and CO2 uptake of 6.25 wt%.
文摘Chinese Journal of Polymer Science(CJPS)is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry,Chinese Academy of Sciences.CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and supported by an International Advisory Board in which many famous active polymer scientists all over the world are included.The journal was first published in 1983 under the title Polymer Communications and has the current name since 1985.
基金financially supported by the National Natural Science Foundation of China (Nos. 21734004 and 21674038)
文摘Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic initiator.The performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction condition.Urea-derived catalysts are generally superior to thiourea-derived ones.Provided with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction time.In addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.
基金financially supported by the Russian Science Foundation(No.16-13-10502)
文摘Binuclear and hexanuclear titanium complexes stabilized by tetradentate [OOOO]^(4–)-type ligand were active in ethylene polymerization in the presence of Et2 AlCl/Bu2 Mg binary co-catalyst, giving high molecular weight polyethylene. The binuclear complex showed significantly higher catalytic activity and thermal stability in comparison to mononuclear analogue. Ultra high molecular weight polyethylene(UHMWPE) samples were processed by a solid-state uniaxial deformation into high-strength(up to 2.5 GPa) and highmodulus(over 100 GPa) oriented film tapes, which indirectly indicates a low degree of entanglements between the macromolecular chains.
基金financially supported by the National Natural Science Foundation of China(Nos.51525305 and 21134006)the Newton Advanced Fellowship of Royal Society(No.NA150222)
文摘By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.
基金financially supported by Scientific Research Innovation Team Project of Provincial Universities in Sichuan Province (No. 13TD0025)
文摘A series of triblock copolymers, containing a CO_2-switchable block poly(2-(dimethylamino)ethyl methacrylate)(PDM) block and two symmetrical hydrophilic blocks polyacrylamide(PAM), were synthesized using atom transfer radical polymerization(ATRP) method. The p H and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO_2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO_2, and the triblock copolymer aqueous solution displayed a CO_2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1 H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the viscosity variation was the result of a unilamellar vesicle-network aggregate structure transition. The release of rhodamine B from the vesicles with and without CO_2 stimuli showed the potential application in drug delivery domains; after CO_2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO_2-switchable morphology changes and CO_2-induced drug release was proposed.
