Machine learning(ML)has emerged as a powerful tool for predicting polymer properties,including glass transition temperature(Tg),which is a critical factor influencing polymer applications.In this study,a dataset of po...Machine learning(ML)has emerged as a powerful tool for predicting polymer properties,including glass transition temperature(Tg),which is a critical factor influencing polymer applications.In this study,a dataset of polymer structures and their Tg values were created and represented as adjacency matrices based on molecular graph theory.Four key structural descriptors,flexibility,side chain occupancy length,polarity,and hydrogen bonding capacity,were extracted and used as inputs for ML models:Extra Trees(ET),Random Forest(RF),Gaussian Process Regression(GPR),and Gradient Boosting(GB).Among these,ET and GPR achieved the highest predictive performance,with R2 values of 0.97,and mean absolute errors(MAE)of approximately 7–7.5 K.The use of these extracted features significantly improved the prediction accuracy compared to previous studies.Feature importance analysis revealed that flexibility had the strongest influence on Tg,followed by side-chain occupancy length,hydrogen bonding,and polarity.This work demonstrates the potential of data-driven approaches in polymer science,providing a fast and reliable method for Tg prediction that does not require experimental inputs.展开更多
Advancing the integration of artificial intelligence and polymer science requires high-quality,open-source,and large-scale datasets.However,existing polymer databases often suffer from data sparsity,lack of polymer-pr...Advancing the integration of artificial intelligence and polymer science requires high-quality,open-source,and large-scale datasets.However,existing polymer databases often suffer from data sparsity,lack of polymer-property labels,and limited accessibility,hindering system-atic modeling across property prediction tasks.Here,we present OpenPoly,a curated experimental polymer database derived from extensive lit-erature mining and manual validation,comprising 3985 unique polymer-property data points spanning 26 key properties.We further develop a multi-task benchmarking framework that evaluates property prediction using four encoding methods and eight representative models.Our re-sults highlight that the optimized degree-of-polymerization encoding coupled with Morgan fingerprints achieves an optimal trade-off between computational cost and accuracy.In data-scarce condition,XGBoost outperforms deep learning models on key properties such as dielectric con-stant,glass transition temperature,melting point,and mechanical strength,achieving R2 scores of 0.65-0.87.To further showcase the practical utility of the database,we propose potential polymers for two energy-relevant applications:high temperature polymer dielectrics and fuel cell membranes.By offering a consistent and accessible benchmark and database,OpenPoly paves the way for more accurate polymer-property modeling and fosters data-driven advances in polymer genome engineering.展开更多
The article describes ethylene polymerization reactions with transition metal catalysts based on complexes of CoCl_(2) and FeCl_(2) with an N,N,N-tridentate ligand 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridine. Th...The article describes ethylene polymerization reactions with transition metal catalysts based on complexes of CoCl_(2) and FeCl_(2) with an N,N,N-tridentate ligand 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridine. The complexes are converted into polymerization catalysts by reacting them either with polymethylalumoxane (MAO) or with a combination of Al(C2H5)2Cl and Mg(C4H9)2 at an [Al]:[Mg] ratio of ~3. Both MAO-activated complexes readily polymerize ethylene at 35 ℃ with the formation of linear, low molecular weight polymers with a narrow molecular weight distribution. The same complexes, when activated with the Al(C2H5)2Cl-Mg(C4H9)2 combination, form multi-center catalysts and generate polyethylenes with a broad molecular weight distribution.展开更多
In this work, we synthesized a new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（1,4-NDC）（L）]（1）, by using mixed 1,4-naphthalenedicarboxylic acid（1,4-H2NDC） and typical chelating N-donor ligands 2-（2-chl...In this work, we synthesized a new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（1,4-NDC）（L）]（1）, by using mixed 1,4-naphthalenedicarboxylic acid（1,4-H2NDC） and typical chelating N-donor ligands 2-（2-chloro-6-fluorophenyl）-1H-imidazo[4,5-f][1,10]phenanthroline ligand（L）. Compound 1 crystallizes in monoclinic, space group P21/n with a = 12.936（5）, b = 15.245（5）, c = 13.499（5） ？, β = 105.456（5）o, V = 2565.9（16） A^3, Z = 4, C（31）H（16）CdClFN4O4, Mr = 675.33, Dc = 1.748 g/cm^3, F（000） = 1344, μ（MoKa） = 1.011 mm^-1, R = 0.0350 and wR = 0.0926. In 1, each 1,4-NDC anion bridges three adjacent Cd（Ⅱ） atoms to give a two-dimensional layer structure. The L ligands are attached on both sides of the layer in chelating coordination modes. In addition, the N–H···O hydrogen bond between L and 1,4-NDC further stabilizes the layer structure of 1. Moreover, the solid state luminescent property of 1 was also investigated at room temperature.展开更多
A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） an...A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） and Zn（NO3）2. The colorless block crystals of complex 1 （C30H22N408Zn2） belong to the triclinic system, space group P1 with a = 10.213（2）, b = 12.052（2）, c = 12.392（3） A, a = 82.97（3）, β = 76.04（3）, y = 78.02（3）°, V= 1443.8（5） A3, Z = 2, Dc = 1.604 g/cm3, Mr = 697.26, F（000） = 708, R = 0.0403 and wR = 0.0907 for 4886 observed reflections （1 〉 2σ（I））. In 1, the tetrahedral Zn11 cations are linked by [p-bdc]2- anions into 2D sql networks, which are further connected by bix ligands forming an interesting 2-fold 4,4-connected mog-type 3D network with a point symbol of {4·6^4·8}^2{4^2·6^2·8^2}. Complex 1 was characterized by elemental, IR spectroscopy, powder X-ray diffractions and thermalgravimetric analysis. In addition, complex 1 exhibits coordination induced photoluminescent property.展开更多
An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer ad...An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.展开更多
The reaction of flexible bis（imidazole） ligand and 1,2-bis（imidazol-l＇-yl）methane （bimm） with Co（Ⅱ） salt under ionothermal method resulted in the formation of a new coordination polymer {[Co（bimm）3]·...The reaction of flexible bis（imidazole） ligand and 1,2-bis（imidazol-l＇-yl）methane （bimm） with Co（Ⅱ） salt under ionothermal method resulted in the formation of a new coordination polymer {[Co（bimm）3]·（PF6）2}n （1）. X-ray single-crystal diffraction determination reveals that 1 crystallizes in the triclinic Pi space group, with α = 8.647（6）, b = 12.092（9）, c = 14.967（1 l） A, α = 88.912（8）, β = 81.199（8）, ）, = 89.395（8）°, V= 1546 （2） A3, Z = 2, Mr = 793.39, Dc= 1.704 Mg/m3,μ = 0.768 mm-1 F（000） = 798, the final R = 0.0626 and wR = 0.1634 for 4319 observed reflections with I〉 2σ（I）. In compound 1, the Co（lI） ion is connected to another Co（ll） by two bimm ligands to form 1D double chains which are further linked by bimm ligands to form a 2D wavelike layer. Topologically, the structure of 1 represents a uninodal 2D 4-connected sq1/Shubnikov tetragonal plane net. Moreover, thermogravimetric analyses and photocatalytic property for 1 have also been investigated.展开更多
5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold inter...5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2（HIA）1/2（DPEE）1/2]n （1）, was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2＋ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118（5）, b = 17.1698（7）, c =14.9922（7） ？, V = 2113.82（18） ？3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction （PXRD）, thermogravimetry analyses （TGA） and photoluminescent properties, were also investigated.展开更多
A one-dimensional chain-like coordination polymer [Mn（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized from 2,4,6-trimethylbenzoic acid, 1,10-phenanthroline and anhydrous manganese（Ⅱ ） sulfate and then characte...A one-dimensional chain-like coordination polymer [Mn（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized from 2,4,6-trimethylbenzoic acid, 1,10-phenanthroline and anhydrous manganese（Ⅱ ） sulfate and then characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.05643（16）, b = 2.05643（16）, c = 1.3939（2） nm, V = 5.8946（11） nm^3, Mr = 579.54, Z = 8, Dc = 1.306 g/cm^3, μ（MoKα） = 0.490 mm^-1, F（000） = 2424, S = 0.985, the final R = 0.0411 and wR = 0.0950. The Flack factor is -0.01（2）. The crystal structure shows that two neighboring man- ganese（Ⅱ ） ions are linked together by one bridge-chelating 2,4,6-trimethylbenzoic group, forming a one-dimensional chain structure. The manganese（Ⅱ ） ion is coordinated with two nitrogen atoms of one 1,10-phenanthroline, three oxygen atoms from three 2,4,6-trimethylbenzoic acids and one water oxygen atom, giving a distorted octahedral coordination geometry. The cyclic voltametric behavior of the complex was also investigated.展开更多
A new Pb（Ⅱ） coordination polymer, [Pb（1,4-chdc）（L）]_n·nH_2O（1）, was synthesized under hydrothermal condition（1,4-H2 chdc = 1,4-cyclohexanedicarboxylic acid and L = 2-（3-fluorophenyl）-1H-imidazo[4,5-f]...A new Pb（Ⅱ） coordination polymer, [Pb（1,4-chdc）（L）]_n·nH_2O（1）, was synthesized under hydrothermal condition（1,4-H2 chdc = 1,4-cyclohexanedicarboxylic acid and L = 2-（3-fluorophenyl）-1H-imidazo[4,5-f][1,10]phenanthroline）. Its crystal structure was determined by singlecrystal X-ray diffraction. Compound 1 crystallizes in triclinic, space group P1 with a = 9.1182（8）, b = 11.3249（10）, c = 12.7326（12） A, α = 77.897（2）, β = 81.644（2）, γ = 84.491（2）°, V = 1269.0（2） A^3, Z = 2, C_（27）H_（24）FN_4O_5Pb, M_r = 710.69, D_c = 1.860 g/cm^3, F（000） = 690, μ（MoKa） = 6.701 mm^（-1）, R = 0.0349 and wR = 0.0746. In 1, each 1,4-chdc anion bridges two neighboring Pb（Ⅱ） atoms in a bidentate chelating coordination mode to give a chain structure. The L ligands are attached on one side of the chain through chelating the Pb（Ⅱ） atoms, and are stacked with those of an adjacent chain through π-π interactions, yielding a layer structure. The O-H···O and N-H···O hydrogen bonding interactions further stabilize the supramolecular layer structure of 1. Moreover, solid state luminescent property of 1 was also studied.展开更多
Polypeptide brushes are attractive platforms to generate functional and responsive interfaces that are of potential interest due to their possible biodegradability, biocompatibility and tunable secondary structures. S...Polypeptide brushes are attractive platforms to generate functional and responsive interfaces that are of potential interest due to their possible biodegradability, biocompatibility and tunable secondary structures. Surface-initiated ringopening polymerization（SI-ROP） of α-amino acid N-carboxyanhydrides represents a powerful and versatile strategy to generate polypeptide brushes. This review is an attempt to capture the state-of-the-art in this field and highlights the latest developments in several selected areas. In addition to presenting an overview of the synthetic methods that have been used to generate polypeptide brushes via SI-ROP, this article will discuss the preparation of patterned polypeptide brushes, the conformational properties of surface-tethered polypeptides, ways to control chain orientation at surfaces as well as properties and applications of these thin polymer films.展开更多
A novel Cd（Ⅱ） coordination polymer with diacylhydrazide ligand N,N？-bis（3-methoxysalicyl）-2,6-pyridinedicarbohydrazide（H_6msphz）,[Cd_2（H_2msphz）（Py）_4]_n（1,Py = pyridine） has been synthesized through sol...A novel Cd（Ⅱ） coordination polymer with diacylhydrazide ligand N,N？-bis（3-methoxysalicyl）-2,6-pyridinedicarbohydrazide（H_6msphz）,[Cd_2（H_2msphz）（Py）_4]_n（1,Py = pyridine） has been synthesized through solvothermal reaction and structurally characterized by single-crystal X-ray diffraction,IR,TGA and PXRD investigations. It crystallizes in triclinic system,space group P1,with a = 11.0230（11）,b = 11.7264（15）,c = 17.3395（14） ？,α = 70.520（9）,β = 84.806（7）,γ = 81.965（9）°,V = 2089.9（4） ？~3,Dc = 1.638 gcm^（–3）,μ = 1.083 mm^（-1）,F（000） = 1032,Z = 2 and S = 1.040. In complex 1,the H_2msphz4-ligand uses not only its coordinated pocket to catch one Cd（Ⅱ） ion,but also its two terminal groups to chelate other two Cd（Ⅱ） ions,leading to the formation of a chain structure. The adjacent chains are further assembled together by two kinds of π-π interactions between the Py rings,resulting in the finial double layered supramolecular structure. In addition,complex 1 is found to show photoluminescence in the solid state at room temperature,which can be ascribed to the intraligand π→π＊ transitions.展开更多
In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H...In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H_2ATA） and 4,4￠-biphenyldicarboxylic acid（H_2BPDC）, are employed as the secondary auxiliary ligands. Two new complexes [Cd_2L_2（ATA）]（1） and [Cd_2L_2（BPDC）·2MeO H· 4H_2O]（2） with distinct 3D frameworks were obtained. In complex 1, ligands ATA bridge the 1D Cd（Ⅱ）-L infinite chains into a 3D polymeric coordination network. Complex 2 is a 3D porous framework, in which adjacent 2D Cd（Ⅱ）-L coordination layers were linked together by the coor- dinated BPDC ligands. The variant structures of two complexes indicate that the skeleton of dicarboxylate anions plays a great role in the assembly of such different frameworks. In addition, the photoluminescent properties（fluorescent emission, lifetime, and quantum yield） of polymers 1 and 2 were also investigated in the solid state.展开更多
A new carbon bridged cyclopentadienyl chromium complex of the type [（C5H4）C（CH3）2 CH2（C5H4N）]CrCl2 was prepared by treatment of CrCl3·（THF）3 in THF solution with the lithium salt of ligand containing cycl...A new carbon bridged cyclopentadienyl chromium complex of the type [（C5H4）C（CH3）2 CH2（C5H4N）]CrCl2 was prepared by treatment of CrCl3·（THF）3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis（EA）, and the crystal structure was determined by X-ray diffraction analysis. Activated by Al（i-Bu）3, the chromium complex displayed a very high activity for methyl methacrylate（MMA） polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate（PMMA） with a viscosity average molecular weight（Wη） of 416000 g·mol-1 at 60 ℃ for MMA/ Al（i-Bu）3 /chromium catalyst molar ratio of up to 2000：20：1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.展开更多
The title complex bis{1-{[（6-ethyl-2-pyridinyl）imino]methylenyl}-2-naphthale- nolato-N,O}-nickel（lI） （C36H32NnO2Ni） has been synthesized by the reaction of l-{[（6-ethyl-2- pyridinyl）imino]methylenyl}-2-naphtha...The title complex bis{1-{[（6-ethyl-2-pyridinyl）imino]methylenyl}-2-naphthale- nolato-N,O}-nickel（lI） （C36H32NnO2Ni） has been synthesized by the reaction of l-{[（6-ethyl-2- pyridinyl）imino]methylenyl}-2-naphthalenol with Ni（CH3COO）2·4H2O, and characterized by IR spectrum, elemental analysis and TG. The complicated space structure has been confirmed by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 11.410（4）, b = 14.382（4）, c = 18.121（6） ,A, β = 97.147（6）% V= 2950.5（16）A3, C36H32N4O2Ni, Mr = 611.37, Z = 4, Dc = 1.376 g/cm3, μ = 0.698 mm-1 F（000） = 1280, the final R = 0.0519 and wR = 0.1493 （1 〉2σ（I））. This title compound was used as precatalysts for the polymerisation of norbornene. When activated with MAO, the complex exhibited excellent catalytic activity up to 1.98 × 107 g ofPNB （mol of Ni）-1 h-1 with high monomer conversion.展开更多
Two cobalt coordination polymers with the same 2D structure have been hydrothermally synthesized based on two bifunctional ligands with tetrazole and phosphonate（phosphonic acid） groups,namely,diethyl 4-（2H-1,2,3,4...Two cobalt coordination polymers with the same 2D structure have been hydrothermally synthesized based on two bifunctional ligands with tetrazole and phosphonate（phosphonic acid） groups,namely,diethyl 4-（2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（C_2H_5-L1） and 4-（2H-1,2,3,4-tetrazol-5-yl）benzylphosphonic acid（H_2L2）. The structures of the two complexes are characterized by elemental analysis,IR,TGA and X-ray single-crystal/powder diffraction. The pink block crystals of complex [Co（L1）（H_2O）]·H_2O（1） belong to the monoclinic system,space group C2/m with a = 20.8390（11）,b = 7.2695（3）,c = 10.0156（6） A,β = 109.773（7）°,V = 1427.80（13） A^3,Z = 4,D_c = 1.680 mg/cm^-3,M_r = 361.16,F（000） = 740,R = 0.0316 and wR = 0.0826 for 1702 observed reflections（I 〉 2σ（I））. The purple block crystals of complex [Co（L2）（H_2O）]·2H_2O（2） also belong to the monoclinic system,space group C2/c with a = 25.5382（16）,b = 7.3844（3）,c = 15.1925（11） A,β = 124.238（9）°,V = 2368.6（2） A^3,Z = 8,D_c = 1.969 mg/cm^-3,M_r = 351.12,F（000） = 1432,R = 0.0475,wR = 0.1617 for 2088 observed reflections（I 〉 2σ（I））. Both the nitrogen atoms of tetrazole group and oxygen atoms of phosphonate（phosphonic acid） groups in the ligands coordinated with the metal cobalt. The magnetic property of complex 1 is also investigated.展开更多
Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tarta...Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly（styrene）-b-poly（ethylene oxide） using small-angle X-ray scattering,transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods： for poly（ethylene oxide） segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.展开更多
A novel phenoxyimine-based Schiff base ligand and its mononuclear complex [C（58）H（52）N2NiO2]（L = 2-benzhydryl-4-dimethoxy-3,5-dimethyl-salicylaldehyde） has been synthesized and characterized by IR spectrum, elem...A novel phenoxyimine-based Schiff base ligand and its mononuclear complex [C（58）H（52）N2NiO2]（L = 2-benzhydryl-4-dimethoxy-3,5-dimethyl-salicylaldehyde） has been synthesized and characterized by IR spectrum, elemental analysis, TG, WAXD spectra, ^1H NMR and ^（13）C NMR. In addition, the molecular structure has been measured by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 14.510（6）, b = 18.573（7）, c = 20.961（6） A, β = 123.453（19）°, V = 4713（3）A^3, Mr = 867.73, Z = 4, Dc = 1.223 g/cm^3, μ = 0.456 mm^-1, F（000） = 1832, the final R = 0.0685 and wR = 0.1758（I 〉 2σ（I））. The complex was used as homogeneous catalysis of polymerization of norbornene, and the MAO as cocatalyst. The nickel complex exhibited good catalytic activity up to 1.913 × 10^7 g of PNB（mol of Ni）^-1h^-1,and the yields of these reactions depend on the nature of the substituent in the aromatic ring.展开更多
The syntheses, structures and catalytic activities of two yttrium complexes supported by pyrrolide ligands are reported. Treatment of Y（N（Si Me3）2）3 with one equivalent of H3bptd（H3bptd = 1,9-bis（2-pyrrolyl）-2,...The syntheses, structures and catalytic activities of two yttrium complexes supported by pyrrolide ligands are reported. Treatment of Y（N（Si Me3）2）3 with one equivalent of H3bptd（H3bptd = 1,9-bis（2-pyrrolyl）-2,5,8-triazanona-1,8-diene） in THF gave a complex of composition [Y（bptd）（THF）]2（1）. Reaction of Y（N（Si Me3）2）3 with one equivalent of H3tpa（H3tpa = tris（pyrrolyl-α-methyl）amine） in THF generated [Y（tpa）（THF）3]（2） in good yield. Complexes 1and 2 have been characterized by single-crystal X-ray diffraction, elemental analyses and NMR spectroscopy. Complex 1 is dinuclear. The two metal centers are doubly bridged by two amine nitrogen atoms to form a Y–N–Y–N four-membered rhombus ring. The geometries of Y^3＋ ions in 1and 2 are well described as pentagonal bipyramid and capped octahedron, respectively. The ring-opening polymerization reactions of ε-caprolactone initiated by 1 and 2, respectively, were investigated. They both exhibited good catalytic activity for the polymerization of ε-caprolactone. All of the obtained polymers have high molecular weights and relatively narrower PDIs. The polymers generated by 2 possessed polydispersity close to 1.1. The good catalytic activities of 1 and 2 reveal their potential applications in polymer industry.展开更多
The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN micr...The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.展开更多
文摘Machine learning(ML)has emerged as a powerful tool for predicting polymer properties,including glass transition temperature(Tg),which is a critical factor influencing polymer applications.In this study,a dataset of polymer structures and their Tg values were created and represented as adjacency matrices based on molecular graph theory.Four key structural descriptors,flexibility,side chain occupancy length,polarity,and hydrogen bonding capacity,were extracted and used as inputs for ML models:Extra Trees(ET),Random Forest(RF),Gaussian Process Regression(GPR),and Gradient Boosting(GB).Among these,ET and GPR achieved the highest predictive performance,with R2 values of 0.97,and mean absolute errors(MAE)of approximately 7–7.5 K.The use of these extracted features significantly improved the prediction accuracy compared to previous studies.Feature importance analysis revealed that flexibility had the strongest influence on Tg,followed by side-chain occupancy length,hydrogen bonding,and polarity.This work demonstrates the potential of data-driven approaches in polymer science,providing a fast and reliable method for Tg prediction that does not require experimental inputs.
基金financially supported by the National Natural Science Foundation of China (Nos. 92372126,52373203)the Excellent Young Scientists Fund Program
文摘Advancing the integration of artificial intelligence and polymer science requires high-quality,open-source,and large-scale datasets.However,existing polymer databases often suffer from data sparsity,lack of polymer-property labels,and limited accessibility,hindering system-atic modeling across property prediction tasks.Here,we present OpenPoly,a curated experimental polymer database derived from extensive lit-erature mining and manual validation,comprising 3985 unique polymer-property data points spanning 26 key properties.We further develop a multi-task benchmarking framework that evaluates property prediction using four encoding methods and eight representative models.Our re-sults highlight that the optimized degree-of-polymerization encoding coupled with Morgan fingerprints achieves an optimal trade-off between computational cost and accuracy.In data-scarce condition,XGBoost outperforms deep learning models on key properties such as dielectric con-stant,glass transition temperature,melting point,and mechanical strength,achieving R2 scores of 0.65-0.87.To further showcase the practical utility of the database,we propose potential polymers for two energy-relevant applications:high temperature polymer dielectrics and fuel cell membranes.By offering a consistent and accessible benchmark and database,OpenPoly paves the way for more accurate polymer-property modeling and fosters data-driven advances in polymer genome engineering.
基金carried out according to the program of Fundamental Scientific Research of the Russian Federation
文摘The article describes ethylene polymerization reactions with transition metal catalysts based on complexes of CoCl_(2) and FeCl_(2) with an N,N,N-tridentate ligand 2,6-bis[1-(2,6-dimethylphenylimino)ethyl]pyridine. The complexes are converted into polymerization catalysts by reacting them either with polymethylalumoxane (MAO) or with a combination of Al(C2H5)2Cl and Mg(C4H9)2 at an [Al]:[Mg] ratio of ~3. Both MAO-activated complexes readily polymerize ethylene at 35 ℃ with the formation of linear, low molecular weight polymers with a narrow molecular weight distribution. The same complexes, when activated with the Al(C2H5)2Cl-Mg(C4H9)2 combination, form multi-center catalysts and generate polyethylenes with a broad molecular weight distribution.
基金Supported by Science and Technology Development Projects of Jilin Province(No.20150101007JC)
文摘In this work, we synthesized a new two-dimensional Cd（Ⅱ） coordination polymer, [Cd（1,4-NDC）（L）]（1）, by using mixed 1,4-naphthalenedicarboxylic acid（1,4-H2NDC） and typical chelating N-donor ligands 2-（2-chloro-6-fluorophenyl）-1H-imidazo[4,5-f][1,10]phenanthroline ligand（L）. Compound 1 crystallizes in monoclinic, space group P21/n with a = 12.936（5）, b = 15.245（5）, c = 13.499（5） ？, β = 105.456（5）o, V = 2565.9（16） A^3, Z = 4, C（31）H（16）CdClFN4O4, Mr = 675.33, Dc = 1.748 g/cm^3, F（000） = 1344, μ（MoKa） = 1.011 mm^-1, R = 0.0350 and wR = 0.0926. In 1, each 1,4-NDC anion bridges three adjacent Cd（Ⅱ） atoms to give a two-dimensional layer structure. The L ligands are attached on both sides of the layer in chelating coordination modes. In addition, the N–H···O hydrogen bond between L and 1,4-NDC further stabilizes the layer structure of 1. Moreover, the solid state luminescent property of 1 was also investigated at room temperature.
基金Support by the National Natural Science Foundation of China(21371052)
文摘A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） and Zn（NO3）2. The colorless block crystals of complex 1 （C30H22N408Zn2） belong to the triclinic system, space group P1 with a = 10.213（2）, b = 12.052（2）, c = 12.392（3） A, a = 82.97（3）, β = 76.04（3）, y = 78.02（3）°, V= 1443.8（5） A3, Z = 2, Dc = 1.604 g/cm3, Mr = 697.26, F（000） = 708, R = 0.0403 and wR = 0.0907 for 4886 observed reflections （1 〉 2σ（I））. In 1, the tetrahedral Zn11 cations are linked by [p-bdc]2- anions into 2D sql networks, which are further connected by bix ligands forming an interesting 2-fold 4,4-connected mog-type 3D network with a point symbol of {4·6^4·8}^2{4^2·6^2·8^2}. Complex 1 was characterized by elemental, IR spectroscopy, powder X-ray diffractions and thermalgravimetric analysis. In addition, complex 1 exhibits coordination induced photoluminescent property.
基金supported by the National Natural Science Foundation of China(11272233)National Key Basic Research and Development Program(2012CB720101)2012 opening subjects of The State Key Laboratory of Nonlinear Mechanics(LNM),Institute of Mechanics,Chinese Academy of Sciences
文摘An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.
基金supported by the Natural Science Foundation of Henan Province(132300410326)the Foundation of the Education Department of Henan Province(13A150801 and 14A150040)
文摘The reaction of flexible bis（imidazole） ligand and 1,2-bis（imidazol-l＇-yl）methane （bimm） with Co（Ⅱ） salt under ionothermal method resulted in the formation of a new coordination polymer {[Co（bimm）3]·（PF6）2}n （1）. X-ray single-crystal diffraction determination reveals that 1 crystallizes in the triclinic Pi space group, with α = 8.647（6）, b = 12.092（9）, c = 14.967（1 l） A, α = 88.912（8）, β = 81.199（8）, ）, = 89.395（8）°, V= 1546 （2） A3, Z = 2, Mr = 793.39, Dc= 1.704 Mg/m3,μ = 0.768 mm-1 F（000） = 798, the final R = 0.0626 and wR = 0.1634 for 4319 observed reflections with I〉 2σ（I）. In compound 1, the Co（lI） ion is connected to another Co（ll） by two bimm ligands to form 1D double chains which are further linked by bimm ligands to form a 2D wavelike layer. Topologically, the structure of 1 represents a uninodal 2D 4-connected sq1/Shubnikov tetragonal plane net. Moreover, thermogravimetric analyses and photocatalytic property for 1 have also been investigated.
基金supported by the Natural Science Foundation of Guizhou Province(20122344)125 program of Guizhou Education Department(2012015)the Doctoral Scientific Fund of Zunyi Normal College(2012BSJJ12)
文摘5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2（HIA）1/2（DPEE）1/2]n （1）, was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2＋ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118（5）, b = 17.1698（7）, c =14.9922（7） ？, V = 2113.82（18） ？3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction （PXRD）, thermogravimetry analyses （TGA） and photoluminescent properties, were also investigated.
基金Supported by the Construct Program of the Key Discipline in Hunan Province and the Foundation of Education Committee of Hunan Province (06C195)
文摘A one-dimensional chain-like coordination polymer [Mn（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized from 2,4,6-trimethylbenzoic acid, 1,10-phenanthroline and anhydrous manganese（Ⅱ ） sulfate and then characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.05643（16）, b = 2.05643（16）, c = 1.3939（2） nm, V = 5.8946（11） nm^3, Mr = 579.54, Z = 8, Dc = 1.306 g/cm^3, μ（MoKα） = 0.490 mm^-1, F（000） = 2424, S = 0.985, the final R = 0.0411 and wR = 0.0950. The Flack factor is -0.01（2）. The crystal structure shows that two neighboring man- ganese（Ⅱ ） ions are linked together by one bridge-chelating 2,4,6-trimethylbenzoic group, forming a one-dimensional chain structure. The manganese（Ⅱ ） ion is coordinated with two nitrogen atoms of one 1,10-phenanthroline, three oxygen atoms from three 2,4,6-trimethylbenzoic acids and one water oxygen atom, giving a distorted octahedral coordination geometry. The cyclic voltametric behavior of the complex was also investigated.
文摘A new Pb（Ⅱ） coordination polymer, [Pb（1,4-chdc）（L）]_n·nH_2O（1）, was synthesized under hydrothermal condition（1,4-H2 chdc = 1,4-cyclohexanedicarboxylic acid and L = 2-（3-fluorophenyl）-1H-imidazo[4,5-f][1,10]phenanthroline）. Its crystal structure was determined by singlecrystal X-ray diffraction. Compound 1 crystallizes in triclinic, space group P1 with a = 9.1182（8）, b = 11.3249（10）, c = 12.7326（12） A, α = 77.897（2）, β = 81.644（2）, γ = 84.491（2）°, V = 1269.0（2） A^3, Z = 2, C_（27）H_（24）FN_4O_5Pb, M_r = 710.69, D_c = 1.860 g/cm^3, F（000） = 690, μ（MoKa） = 6.701 mm^（-1）, R = 0.0349 and wR = 0.0746. In 1, each 1,4-chdc anion bridges two neighboring Pb（Ⅱ） atoms in a bidentate chelating coordination mode to give a chain structure. The L ligands are attached on one side of the chain through chelating the Pb（Ⅱ） atoms, and are stacked with those of an adjacent chain through π-π interactions, yielding a layer structure. The O-H···O and N-H···O hydrogen bonding interactions further stabilize the supramolecular layer structure of 1. Moreover, solid state luminescent property of 1 was also studied.
基金financially supported by the Sino-Swiss Science and Technology Cooperation(No.EG41-092011)as well as the Chinese Academy of Sciences(Visiting Professorship for Senior International Scientists to H.A.K.)
文摘Polypeptide brushes are attractive platforms to generate functional and responsive interfaces that are of potential interest due to their possible biodegradability, biocompatibility and tunable secondary structures. Surface-initiated ringopening polymerization（SI-ROP） of α-amino acid N-carboxyanhydrides represents a powerful and versatile strategy to generate polypeptide brushes. This review is an attempt to capture the state-of-the-art in this field and highlights the latest developments in several selected areas. In addition to presenting an overview of the synthetic methods that have been used to generate polypeptide brushes via SI-ROP, this article will discuss the preparation of patterned polypeptide brushes, the conformational properties of surface-tethered polypeptides, ways to control chain orientation at surfaces as well as properties and applications of these thin polymer films.
基金Supported by the National Natural Science Foundation of China(Nos.51572050,21271050 and 21261004)the Guangxi Natural Science Foundation(Nos.2015GXNSFDA139007,2014GXNSFBA118055 and 2013GXNSFGA019008)
文摘A novel Cd（Ⅱ） coordination polymer with diacylhydrazide ligand N,N？-bis（3-methoxysalicyl）-2,6-pyridinedicarbohydrazide（H_6msphz）,[Cd_2（H_2msphz）（Py）_4]_n（1,Py = pyridine） has been synthesized through solvothermal reaction and structurally characterized by single-crystal X-ray diffraction,IR,TGA and PXRD investigations. It crystallizes in triclinic system,space group P1,with a = 11.0230（11）,b = 11.7264（15）,c = 17.3395（14） ？,α = 70.520（9）,β = 84.806（7）,γ = 81.965（9）°,V = 2089.9（4） ？~3,Dc = 1.638 gcm^（–3）,μ = 1.083 mm^（-1）,F（000） = 1032,Z = 2 and S = 1.040. In complex 1,the H_2msphz4-ligand uses not only its coordinated pocket to catch one Cd（Ⅱ） ion,but also its two terminal groups to chelate other two Cd（Ⅱ） ions,leading to the formation of a chain structure. The adjacent chains are further assembled together by two kinds of π-π interactions between the Py rings,resulting in the finial double layered supramolecular structure. In addition,complex 1 is found to show photoluminescence in the solid state at room temperature,which can be ascribed to the intraligand π→π＊ transitions.
基金supported by the National Natural Science Foundation of China(No.21201002)the Foundation of State Key Laboratory of Structural Chemistry(20130016)+1 种基金Anhui Provincial Natural Science Foundation(1308085QB22)Training Programs of Innovation and Entrepreneurship for Undergraduates(201410360023 and 201410360157)
文摘In order to perform a study on the structural modulation in the Cd（Ⅱ）-L architecture（HL =（E）-2-[2-（3-pyridyl）ethenyl]-8-hydroxyquinoline）, two different dicarboxylic acids, namely, 2-aminoterephthalic acid（H_2ATA） and 4,4￠-biphenyldicarboxylic acid（H_2BPDC）, are employed as the secondary auxiliary ligands. Two new complexes [Cd_2L_2（ATA）]（1） and [Cd_2L_2（BPDC）·2MeO H· 4H_2O]（2） with distinct 3D frameworks were obtained. In complex 1, ligands ATA bridge the 1D Cd（Ⅱ）-L infinite chains into a 3D polymeric coordination network. Complex 2 is a 3D porous framework, in which adjacent 2D Cd（Ⅱ）-L coordination layers were linked together by the coor- dinated BPDC ligands. The variant structures of two complexes indicate that the skeleton of dicarboxylate anions plays a great role in the assembly of such different frameworks. In addition, the photoluminescent properties（fluorescent emission, lifetime, and quantum yield） of polymers 1 and 2 were also investigated in the solid state.
基金Funded by the National Natural Science Foundation of China(No.51204125)the Natural Science Foundation of Hubei Province(Nos.2014CFB812 and 2014CFB810)the Open Fund Project Funded by the Key Laboratory of Coal Conversion and New Carbon Materials of Hubei Province in China(No.WKDM201302)
文摘A new carbon bridged cyclopentadienyl chromium complex of the type [（C5H4）C（CH3）2 CH2（C5H4N）]CrCl2 was prepared by treatment of CrCl3·（THF）3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis（EA）, and the crystal structure was determined by X-ray diffraction analysis. Activated by Al（i-Bu）3, the chromium complex displayed a very high activity for methyl methacrylate（MMA） polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate（PMMA） with a viscosity average molecular weight（Wη） of 416000 g·mol-1 at 60 ℃ for MMA/ Al（i-Bu）3 /chromium catalyst molar ratio of up to 2000：20：1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.
基金Supported by the Natural Science Foundation of Fujian Province(2010J01026)the Ministry of Education of China(No.208066)+1 种基金the Education Department of Fujian Province(JA07029)the State Key Laboratory of Structural Chemistry(No.20130013)
文摘The title complex bis{1-{[（6-ethyl-2-pyridinyl）imino]methylenyl}-2-naphthale- nolato-N,O}-nickel（lI） （C36H32NnO2Ni） has been synthesized by the reaction of l-{[（6-ethyl-2- pyridinyl）imino]methylenyl}-2-naphthalenol with Ni（CH3COO）2·4H2O, and characterized by IR spectrum, elemental analysis and TG. The complicated space structure has been confirmed by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 11.410（4）, b = 14.382（4）, c = 18.121（6） ,A, β = 97.147（6）% V= 2950.5（16）A3, C36H32N4O2Ni, Mr = 611.37, Z = 4, Dc = 1.376 g/cm3, μ = 0.698 mm-1 F（000） = 1280, the final R = 0.0519 and wR = 0.1493 （1 〉2σ（I））. This title compound was used as precatalysts for the polymerisation of norbornene. When activated with MAO, the complex exhibited excellent catalytic activity up to 1.98 × 107 g ofPNB （mol of Ni）-1 h-1 with high monomer conversion.
基金Supported by the National Natural Science Foundation of China(21371052)the Scientific Research Fund of Heilongjiang Provincial Education Department(12531512)
文摘Two cobalt coordination polymers with the same 2D structure have been hydrothermally synthesized based on two bifunctional ligands with tetrazole and phosphonate（phosphonic acid） groups,namely,diethyl 4-（2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（C_2H_5-L1） and 4-（2H-1,2,3,4-tetrazol-5-yl）benzylphosphonic acid（H_2L2）. The structures of the two complexes are characterized by elemental analysis,IR,TGA and X-ray single-crystal/powder diffraction. The pink block crystals of complex [Co（L1）（H_2O）]·H_2O（1） belong to the monoclinic system,space group C2/m with a = 20.8390（11）,b = 7.2695（3）,c = 10.0156（6） A,β = 109.773（7）°,V = 1427.80（13） A^3,Z = 4,D_c = 1.680 mg/cm^-3,M_r = 361.16,F（000） = 740,R = 0.0316 and wR = 0.0826 for 1702 observed reflections（I 〉 2σ（I））. The purple block crystals of complex [Co（L2）（H_2O）]·2H_2O（2） also belong to the monoclinic system,space group C2/c with a = 25.5382（16）,b = 7.3844（3）,c = 15.1925（11） A,β = 124.238（9）°,V = 2368.6（2） A^3,Z = 8,D_c = 1.969 mg/cm^-3,M_r = 351.12,F（000） = 1432,R = 0.0475,wR = 0.1617 for 2088 observed reflections（I 〉 2σ（I））. Both the nitrogen atoms of tetrazole group and oxygen atoms of phosphonate（phosphonic acid） groups in the ligands coordinated with the metal cobalt. The magnetic property of complex 1 is also investigated.
基金supported by National Natural Science foundation of China(Nos.21374060 and 21574081)
文摘Chiral supramolecules prepared by the additive-driven self-assembly of block copolymers provide a facile method to construct helical nanostructures. In this study, we investigated the chiral transfer from chiral tartaric acid to poly（styrene）-b-poly（ethylene oxide） using small-angle X-ray scattering,transmission electron microscopy, circular dichroism, and vibrational circular dichroism. The results showed that the chirality was transferred to both the segments of block copolymer irrespective of the interaction with the chiral additives and formation of helical phase structure. However, the chirality transfer was carried out using different methods： for poly（ethylene oxide） segments, the chirality transfer was carried out via direct hydrogen bond formation; for polystyrene segments, the chirality transfer was carried out via the cooperative motion of block copolymers during the thermal annealing.
基金Supported by the Ministry of Education of China(No.208066)the Education Department of Fujian Province(JA07029)the State Key Laboratory of Structural Chemistry(No.20130013)
文摘A novel phenoxyimine-based Schiff base ligand and its mononuclear complex [C（58）H（52）N2NiO2]（L = 2-benzhydryl-4-dimethoxy-3,5-dimethyl-salicylaldehyde） has been synthesized and characterized by IR spectrum, elemental analysis, TG, WAXD spectra, ^1H NMR and ^（13）C NMR. In addition, the molecular structure has been measured by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21/c with a = 14.510（6）, b = 18.573（7）, c = 20.961（6） A, β = 123.453（19）°, V = 4713（3）A^3, Mr = 867.73, Z = 4, Dc = 1.223 g/cm^3, μ = 0.456 mm^-1, F（000） = 1832, the final R = 0.0685 and wR = 0.1758（I 〉 2σ（I））. The complex was used as homogeneous catalysis of polymerization of norbornene, and the MAO as cocatalyst. The nickel complex exhibited good catalytic activity up to 1.913 × 10^7 g of PNB（mol of Ni）^-1h^-1,and the yields of these reactions depend on the nature of the substituent in the aromatic ring.
基金Supported by NNSFC(21272167)the Priority Academic Program Development of Jiangsu Higher Education Institution,and KLSLRC(KLSLRC-KF-13-HX-1)
文摘The syntheses, structures and catalytic activities of two yttrium complexes supported by pyrrolide ligands are reported. Treatment of Y（N（Si Me3）2）3 with one equivalent of H3bptd（H3bptd = 1,9-bis（2-pyrrolyl）-2,5,8-triazanona-1,8-diene） in THF gave a complex of composition [Y（bptd）（THF）]2（1）. Reaction of Y（N（Si Me3）2）3 with one equivalent of H3tpa（H3tpa = tris（pyrrolyl-α-methyl）amine） in THF generated [Y（tpa）（THF）3]（2） in good yield. Complexes 1and 2 have been characterized by single-crystal X-ray diffraction, elemental analyses and NMR spectroscopy. Complex 1 is dinuclear. The two metal centers are doubly bridged by two amine nitrogen atoms to form a Y–N–Y–N four-membered rhombus ring. The geometries of Y^3＋ ions in 1and 2 are well described as pentagonal bipyramid and capped octahedron, respectively. The ring-opening polymerization reactions of ε-caprolactone initiated by 1 and 2, respectively, were investigated. They both exhibited good catalytic activity for the polymerization of ε-caprolactone. All of the obtained polymers have high molecular weights and relatively narrower PDIs. The polymers generated by 2 possessed polydispersity close to 1.1. The good catalytic activities of 1 and 2 reveal their potential applications in polymer industry.
基金National Natural Science Foundations of China(Nos.51073033,51373030)the Fundamental Research Funds for the Central Universities,China(No.2232014D3-43)
文摘The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.
