A series of“half-sandwich”bis(imino)pyridyl iron complexes with a substituted 8-(p-Xphenyl)naphthylamine(X=OMe,Me,CF3)was designed and synthesized by combining weakπ-πinteraction with steric and electronic tunings...A series of“half-sandwich”bis(imino)pyridyl iron complexes with a substituted 8-(p-Xphenyl)naphthylamine(X=OMe,Me,CF3)was designed and synthesized by combining weakπ-πinteraction with steric and electronic tunings.The weak noncovalentπ-πinteraction as well as the steric and electronic effects of bis(imino)pyridyl iron complexes were identified by experimental analyses and calculations.The roles of weakπ-πinteraction,steric bulk,and electronic tuning on the ethylene polymerization performance of bis(imino)pyridyl iron catalysts were studied in detail.The combination ofπ-πinteraction with steric and electronic tunings can access to thermally stable bis(imino)pyridyl iron at 130°C.展开更多
A series of unsymmetrical a-diimine nickel complexes with various backbones and substituted aniline moieties were synthesized and characterized. The crystallographic analysis of the nickel complexes confirmed the exis...A series of unsymmetrical a-diimine nickel complexes with various backbones and substituted aniline moieties were synthesized and characterized. The crystallographic analysis of the nickel complexes confirmed the existence of meso-and rac-configuration in solid structure. Nickel complexes after activation by MAO were screened for ethylene polymerization to evaluate backbone substituent effect on synthesis of bimodal PE. Acenaphthyl nickel complex with planar backbone afforded a bimodal PE with a broad polydispersity, whereas camphyl nickel complex with rigid and bulky backbone afforded a monomodal PE with a narrow polydispersity. Steric effect of aniline moiety for acenaphthyl nickel complex was also examined, and bimodal PE with dominant high-molecular-weight fraction was obtained by modifying substituents on aniline moiety.展开更多
To improve creep resistance of directional polytetrafluoroethylene （PTFE） films, epoxy grafted nano-SiO2 is mixed with PTFE powder before sintering and calender rolling. The aligned macromolecular chains （especiall...To improve creep resistance of directional polytetrafluoroethylene （PTFE） films, epoxy grafted nano-SiO2 is mixed with PTFE powder before sintering and calender rolling. The aligned macromolecular chains （especially those in amorphous region） of the composite films can be bundled up by the nanoparticles to share the applied stress together. In addition, incorporation of silica nanoparticles increases crystallinity of PTFE and favors microfibrillation of PTFE in the course of large deformation. As result, PTFE films exhibit lower creep strain and creep rate, and higher tensile strength and hardness. The work is believed to open an avenue for manufacturing high performance fluoropolymers by nano-inclusions.展开更多
Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only sh...Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only show good ORR activity in alkaline medium,and become less effective in acidic environment.We believe that an appropriate combination of both ionic and electronic transport path,and well dopant distribution of doped carbon-based materials would help to realize high ORR performance un-der both acidic and alkaline cond让ions.Accordingly,a nitrogen and sulfur co-doped carbon framework with hierarchical through-hole structure is fabricated by morphology-controlled solid-state pyrolysis of poly(aniline-co-2-ami no thiophenol)foam.The uniform high concentrations of nitrogen and sulfur,high intrinsic conductivity,and integrated three dimensional ionic and electronic transfer passageways of the 3D porous structure lead to synergistic effects in catalyzing ORR.As a result,the limiting current density of the carbonized poly(aniline-co-2-aminothiophenol)foam is equivalent to commercial Pt/C in acidic environment,and twice the latter in alkaline medium.展开更多
A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was chara...A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum （lH-NMR） and thermogravimetric analysis （TGA）. The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared （ATR- FTIR）, contact-angle measurements （CDA） and scanning electron microscopy （SEM）. The results indicated that poly（ethylene glycol） methyl methacrylate-co-lauryl methacrylate （PEGMA-co-LMA） could diffuse preferably onto the surface of the polyethylene （PE） film, and thus can be used as an efficient surface modifier for PE.展开更多
Poly（N-isopropylacrylamide-co-N-vinylpyrrolidone） [P（NIPAM-co-NVP）] copolymers with different content of N-vinylpyrrolidone （NVP） were synthesized, and reversible aggregation kinetics of the copolymers in aqueou...Poly（N-isopropylacrylamide-co-N-vinylpyrrolidone） [P（NIPAM-co-NVP）] copolymers with different content of N-vinylpyrrolidone （NVP） were synthesized, and reversible aggregation kinetics of the copolymers in aqueous solutions was investigated with elastic light scattering （ELS） spectra. The results indicated that the apparent activation energy of aggregation process during heating and dissociation process during cooling increased with the NVP content increasing. The phase transition temperature also increased as the content of NVP increased, suggesting that the hydrophilic nature of NVP strongly affected the phase behavior of the copolymer solutions. The higher the content of NVP, the higher the temperature required to break the balance between the hydrophilic and hydrophobie interaction. Besides, during heating and cooling process, the phase transition hysteresis of P（NIPAM-co-NVP） chains decreased when the hydrophilic comonomer increased.展开更多
Thioxanthone-based N-phthalimidoamino acid ammonium salt（thioxanthen-DBU） as a photocaged base was synthesized and characterized. The photochemical properties and initiation mechanism were analyzed. It was found tha...Thioxanthone-based N-phthalimidoamino acid ammonium salt（thioxanthen-DBU） as a photocaged base was synthesized and characterized. The photochemical properties and initiation mechanism were analyzed. It was found that the compound absorbs over the UV and visible region with relatively high absorption coefficients. Furthermore, the covalent binding of N-phthalimidoamino acid and type II chromophores（thioxanthone, TX） remarkably improved the photoreactivity. Specifically, in combination with a benzoyl peroxide initiator, thioxanthen-DBU was able to initiate the amine-mediated redox photopolymerization of trimethylol propane triacrylate（TMPTA）, and an excellent photopolymerization profile was obtained.展开更多
Herein we demonstrate crystallization-driven self-assembly ofisotactic polystyrene （iPS） with high isotacticity and narrow molecular weight distribution and crystallization-induced switching of the morphology of iPS...Herein we demonstrate crystallization-driven self-assembly ofisotactic polystyrene （iPS） with high isotacticity and narrow molecular weight distribution and crystallization-induced switching of the morphology of iPS aggregates in N, N-dimethylformamide （DMF）. The formation and morphology switching of the self-assembled aggregates of iPS are investigated by means of dynamic light scattering （DLS）, scanning electron microscopy （SEM）, differential scanning calorimetry （DSC） and wide angle X-ray diffraction （WXRD）. The results reveal that cooling DMF solution of iPS promotes iPS chains to self-assemble into spherical aggregates with a gelled core cross-linked by microcrystals, which is surrounded by solvent-swollen corona. Furthermore, crystallization induces the deformation of iPS aggregates from spherical to plate-like or nest-like.展开更多
Benzoylfonnamide（BFA） derivatives are proposed as new photocagcd bases with good solubility in epoxy resin.Initially their structures were confirmed by ~1H NMR,^（13）C NMR,and elemental analysis.Next,we detail thei...Benzoylfonnamide（BFA） derivatives are proposed as new photocagcd bases with good solubility in epoxy resin.Initially their structures were confirmed by ~1H NMR,^（13）C NMR,and elemental analysis.Next,we detail their thermal stability,solubility behavior,and photolysis products.Furthermore,the model photo-latent anion polymerization（AP） of epoxide system in the presence of BFA-dBA（N,N-dibenzyl-2-oxo-2-phenylacetamide） as a photocaged base has been investigated,and excellent photopolymerization profile is obtained.展开更多
Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clea...Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.展开更多
基金supported by the State Key Research Development Program of China(No.2021YFB3800701)National Natural Science Foundation of China(NSFC,No.52173016)+2 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2024A1515012784,2024A1515011102,and 2023A1515110549)Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.24qnpy047)PetroChina Scientific and Technological Projects(No.2022DJ6308).
文摘A series of“half-sandwich”bis(imino)pyridyl iron complexes with a substituted 8-(p-Xphenyl)naphthylamine(X=OMe,Me,CF3)was designed and synthesized by combining weakπ-πinteraction with steric and electronic tunings.The weak noncovalentπ-πinteraction as well as the steric and electronic effects of bis(imino)pyridyl iron complexes were identified by experimental analyses and calculations.The roles of weakπ-πinteraction,steric bulk,and electronic tuning on the ethylene polymerization performance of bis(imino)pyridyl iron catalysts were studied in detail.The combination ofπ-πinteraction with steric and electronic tunings can access to thermally stable bis(imino)pyridyl iron at 130°C.
基金supported by NSFC (Nos. 21274167, 51173209 and 21174164)CNPC Innovation Foundationthe Fundamental Research Funds for the Central Universities (Project 10lgpy10)
文摘A series of unsymmetrical a-diimine nickel complexes with various backbones and substituted aniline moieties were synthesized and characterized. The crystallographic analysis of the nickel complexes confirmed the existence of meso-and rac-configuration in solid structure. Nickel complexes after activation by MAO were screened for ethylene polymerization to evaluate backbone substituent effect on synthesis of bimodal PE. Acenaphthyl nickel complex with planar backbone afforded a bimodal PE with a broad polydispersity, whereas camphyl nickel complex with rigid and bulky backbone afforded a monomodal PE with a narrow polydispersity. Steric effect of aniline moiety for acenaphthyl nickel complex was also examined, and bimodal PE with dominant high-molecular-weight fraction was obtained by modifying substituents on aniline moiety.
基金financially supported by the National Natural Science Foundation of China (No.51173207)Sino-Hungarian Scientific and Technological Cooperation Project (No.2009DFA52660)+1 种基金Key projects of Guangdong Education Office (No.cxzd1101)Natural Science Foundation of Guangdong (Nos.2010B010800020,2011B090500004,2011BZ100051)
文摘To improve creep resistance of directional polytetrafluoroethylene （PTFE） films, epoxy grafted nano-SiO2 is mixed with PTFE powder before sintering and calender rolling. The aligned macromolecular chains （especially those in amorphous region） of the composite films can be bundled up by the nanoparticles to share the applied stress together. In addition, incorporation of silica nanoparticles increases crystallinity of PTFE and favors microfibrillation of PTFE in the course of large deformation. As result, PTFE films exhibit lower creep strain and creep rate, and higher tensile strength and hardness. The work is believed to open an avenue for manufacturing high performance fluoropolymers by nano-inclusions.
基金financial support by the National Natural Science Foundation of China (Grant: 51333008)Young Teacher Training Program of Sun Yat-sen University (Grant: 17lgpy86)
文摘Developing high-performance non-precious metal electrocatalysts for oxygen reduction reaction(ORR)is crucial for the commercialization of fuel cells and metal-air batteries.However,doped carbon-based materials only show good ORR activity in alkaline medium,and become less effective in acidic environment.We believe that an appropriate combination of both ionic and electronic transport path,and well dopant distribution of doped carbon-based materials would help to realize high ORR performance un-der both acidic and alkaline cond让ions.Accordingly,a nitrogen and sulfur co-doped carbon framework with hierarchical through-hole structure is fabricated by morphology-controlled solid-state pyrolysis of poly(aniline-co-2-ami no thiophenol)foam.The uniform high concentrations of nitrogen and sulfur,high intrinsic conductivity,and integrated three dimensional ionic and electronic transfer passageways of the 3D porous structure lead to synergistic effects in catalyzing ORR.As a result,the limiting current density of the carbonized poly(aniline-co-2-aminothiophenol)foam is equivalent to commercial Pt/C in acidic environment,and twice the latter in alkaline medium.
基金supported by the National Natural Science Foundation of China (Nos. 51173214, J1103305)Department of Education of Guangdong Province (2012KJCX0005)Science and Technology Bureau of Guangzhou
文摘A new macromolecular surface modifier, a copolymer of lauryl methacrylate （LMA） and poly（ethylene glycol） methyl methacrylate （PEGMA）, was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum （lH-NMR） and thermogravimetric analysis （TGA）. The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared （ATR- FTIR）, contact-angle measurements （CDA） and scanning electron microscopy （SEM）. The results indicated that poly（ethylene glycol） methyl methacrylate-co-lauryl methacrylate （PEGMA-co-LMA） could diffuse preferably onto the surface of the polyethylene （PE） film, and thus can be used as an efficient surface modifier for PE.
基金Funded by the National Natural Science Foundation of China(50973129,51273048)the National Natural Science Foundation of Guangdong Province(S2012010009743)
文摘Poly（N-isopropylacrylamide-co-N-vinylpyrrolidone） [P（NIPAM-co-NVP）] copolymers with different content of N-vinylpyrrolidone （NVP） were synthesized, and reversible aggregation kinetics of the copolymers in aqueous solutions was investigated with elastic light scattering （ELS） spectra. The results indicated that the apparent activation energy of aggregation process during heating and dissociation process during cooling increased with the NVP content increasing. The phase transition temperature also increased as the content of NVP increased, suggesting that the hydrophilic nature of NVP strongly affected the phase behavior of the copolymer solutions. The higher the content of NVP, the higher the temperature required to break the balance between the hydrophilic and hydrophobie interaction. Besides, during heating and cooling process, the phase transition hysteresis of P（NIPAM-co-NVP） chains decreased when the hydrophilic comonomer increased.
基金financially supported by National Natural Science Foundation of China(No.20974127,21374135)China Postdoctoral Science Foundation(No.2013M542178)+1 种基金the Open Foundation of the State Key Laboratory of Pulp and Paper Engineering in South China University of Technology(No.C713043z)the Fundamental Research Funds for the Central Universities(No.2013ZB0025)
文摘Thioxanthone-based N-phthalimidoamino acid ammonium salt（thioxanthen-DBU） as a photocaged base was synthesized and characterized. The photochemical properties and initiation mechanism were analyzed. It was found that the compound absorbs over the UV and visible region with relatively high absorption coefficients. Furthermore, the covalent binding of N-phthalimidoamino acid and type II chromophores（thioxanthone, TX） remarkably improved the photoreactivity. Specifically, in combination with a benzoyl peroxide initiator, thioxanthen-DBU was able to initiate the amine-mediated redox photopolymerization of trimethylol propane triacrylate（TMPTA）, and an excellent photopolymerization profile was obtained.
基金financially supported by the National Natural Science Foundation of China(Nos.21174167 and 20974123)the Guangdong Province Higher School Science and Technology Innovation Key Project and the Natural Science Foundation of Guangdong Province(No.S2013030013474)
文摘Herein we demonstrate crystallization-driven self-assembly ofisotactic polystyrene （iPS） with high isotacticity and narrow molecular weight distribution and crystallization-induced switching of the morphology of iPS aggregates in N, N-dimethylformamide （DMF）. The formation and morphology switching of the self-assembled aggregates of iPS are investigated by means of dynamic light scattering （DLS）, scanning electron microscopy （SEM）, differential scanning calorimetry （DSC） and wide angle X-ray diffraction （WXRD）. The results reveal that cooling DMF solution of iPS promotes iPS chains to self-assemble into spherical aggregates with a gelled core cross-linked by microcrystals, which is surrounded by solvent-swollen corona. Furthermore, crystallization induces the deformation of iPS aggregates from spherical to plate-like or nest-like.
基金financially supported by National Natural Science Foundation of China(No.21374135)China Postdoctoral Science Foundation(Nos.2013M542178 and 2014M562183)+1 种基金the Open Foundation of the State Key Laboratory of Pulp and Paper Engineering in South China University of Technology(No.C713043z)the Fundamental Research Funds for the Central Universities (No.2013ZB0025)
文摘Benzoylfonnamide（BFA） derivatives are proposed as new photocagcd bases with good solubility in epoxy resin.Initially their structures were confirmed by ~1H NMR,^（13）C NMR,and elemental analysis.Next,we detail their thermal stability,solubility behavior,and photolysis products.Furthermore,the model photo-latent anion polymerization（AP） of epoxide system in the presence of BFA-dBA（N,N-dibenzyl-2-oxo-2-phenylacetamide） as a photocaged base has been investigated,and excellent photopolymerization profile is obtained.
基金supported by the National Natural Science Foundation of China (20874117, 50903095, 51073176 and U0634001)Doctoral Fund of Ministry of Education of China (20090171110026)the Science and Technology Program of Guangdong Province (2010B010800021)
文摘Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.
