We developed flame retarded polyimine type vitrimers and carbon fibre reinforced composites using two additive and a reactive flame retardant containing phosphorus:ammonium polyphosphate(APP),resorcinol bis(diphenyl p...We developed flame retarded polyimine type vitrimers and carbon fibre reinforced composites using two additive and a reactive flame retardant containing phosphorus:ammonium polyphosphate(APP),resorcinol bis(diphenyl phosphate)(RDP);and N,N’,N’’-tris(2-aminoethyl)-phosphoric acid triamide(TEDAP).We characterised the vitrimer matrix materials by differential scanning calorimetry(DSC),thermal analysis(TGA),limiting oxygen index(LOI),UL-94 test and mass loss calorimetry(MLC),while the vitrimer composites by LOI,UL-94 test,MLC and dynamic mechanical analysis(DMA).We compared the performance of the vitrimer systems to a benchmark pentaerythritol-based aliphatic epoxy resin system(PER).The vitrimer reference had higher thermal stability but lower fire performance than the PER aliphatic reference epoxy.At lower phosphorus content,the vitrimer systems exhibited a melting above their vitrimer transition temperature,which negatively affected their LOI and UL-94 results.From 2%phosphorus content,rapid charring and extinguishing of vitrimers prevented the softening and deforming.The superior performance of these same flame retardants in vitrimer systems could be attributed to the high nitrogen content of imine-based vitrimers in combination with phosphorus flame retardants,exploiting nitrogen-phosphorus synergism.In both matrices,flame retardants with solid phase action lead to better fire performance,while in composites,the lowest peak heat release rates(152 kW/m2 in vitrimer composite)were achieved with RDP acting predominantly in the gas phase,as carbon fibres hindered the intumescent phenomenon.展开更多
Graphene-polymer composites have attracted great attention as sensing materials due to their tailorable electrical conductivity, physicochemical properties, and sensitivity to geometric and functional changes.Herein, ...Graphene-polymer composites have attracted great attention as sensing materials due to their tailorable electrical conductivity, physicochemical properties, and sensitivity to geometric and functional changes.Herein, we report the first example of cylindrical monolithic polyimine vitrimer/graphene composites with excellent mechanical, compressive, rehealable and recyclable, and piezoresistive properties via simple infiltration of polymer monomers into the pores of graphene aerogel followed by thermal curing. The composites exhibit excellent durable compressibility(negligible reduction in the compression properties even after 3000 consecutive compression cycles), rapid recovery to the original size upon stress released,high compressive strength(up to 1.2 MPa), and high conductivity(up to 79 S/m). Excellent piezoresistive properties were observed, displaying consistent and reliable change of the electrical resistance with the compression ratio. Furthermore, rehealing with ~100% recovery of the compressive strength and electric conductivity was achieved under mild rehealing conditions, which is highly desired but has rarely been reported for electronic materials. The facile strategy for fabrication of rehealable monolithic polymer/GAs can open new possibilities for the sustainable development of composites with high electrical conductivity for various applications such as sensing, health monitoring, and movement detection.展开更多
Fluorenone-based polyamines, as novel light-emitting polymers, were synthesized by the condensation polymerization of 3,6-dibromo-9-fluorenone with different aromatic diamines by palladiumcatalyzed aryl amination reac...Fluorenone-based polyamines, as novel light-emitting polymers, were synthesized by the condensation polymerization of 3,6-dibromo-9-fluorenone with different aromatic diamines by palladiumcatalyzed aryl amination reaction. The structures of the polymers were characterized by means of FT-IR, 1H NMR spectroscopy and elemental analysis. The experimental results show a good agreement with the proposed structures. TGA measurement exhibits that the polymers possess good thermal stabilities with high decomposition temperatures（T5 400 ℃）. Due to the photo-induced intramolecular charge-transfer（ICT） of fluorenone-based polyimines, these polymers show significantly strong photonic luminescence in N,Ndimethylacetamide.展开更多
Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace,defense,and opto-electronics,but polyimides are difficult to be reprocessed and recycled at the end of thei...Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace,defense,and opto-electronics,but polyimides are difficult to be reprocessed and recycled at the end of their service life,resulting in a significant waste of resources.Hence,it is of great significance to develop recyclable polyimides with comparable properties to the commercial products.Herein,we report a novel polymer-to-monomers chemically recyclable poly(imide-imine)(PtM-CR-PII)plastic,synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine bonds.The PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial polyimides.The PtM-CR-PII plastic possesses a high Young’s modulus of≈3.2 GPa and a tensile strength as high as≈108 MPa,which also exhibits high thermal stability with a glass transition temperature of≈220℃.Moreover,the PtM-CR-PII plastic exhibits outstanding waterproofness,acid/alkali-resistance,and solvent-resistance,its appearance and mechanical properties can be well maintained after long-term soaking in water,highly concentrated acid and base,and various organic solvents.Furthermore,the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame retardancy.The PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index(LOI)value of 45.5%.Importantly,the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature,allowing easy separation and recovery of both monomers in high purity.The recovered pure monomers can be used to regenerate new PtM-CR-PII plastics,enabling sustainable polymer-monomers-polymer circulation.展开更多
Covalent adaptable network(CAN)polymers doped with conductive nanoparticles are an ideal candidate to create reshapeable,rehealable,and fully recyclable electronics.On the other hand,3D printing as a deterministic man...Covalent adaptable network(CAN)polymers doped with conductive nanoparticles are an ideal candidate to create reshapeable,rehealable,and fully recyclable electronics.On the other hand,3D printing as a deterministic manufacturing method has a significant potential to fabricate electronics with low cost and high design freedom.In this paper,we incorporate a conductive composite consisting of polyimine CAN and multi-wall carbon nanotubes into direct-ink-writing 3D printing to create polymeric sensors with outstanding reshaping,repairing,and recycling capabilities.The developed printable ink exhibits good printability,conductivity,and recyclability.The conductivity of printed polyimine composites is investigated at different temperatures and deformation strain levels.Their shape-reforming and Joule heating-induced interfacial welding effects are demonstrated and characterized.Finally,a temperature sensor is 3D printed with defined patterns of conductive pathways,which can be easily mounted onto 3D surfaces,repaired after damage,and recycled using solvents.The sensing capability of printed sensors is maintained after the repairing and recycling.Overall,the 3D printed reshapeable,rehealable,and recyclable sensors possess complex geometry and extend service life,which assist in the development of polymer-based electronics toward broad and sustainable applications.展开更多
Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,...Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,the pioneering polyimine materials are relatively soft and not suitable for certain applications that require high mechanical performance.Recent studies have demonstrated the possibility of significantly improving polyimine properties by varying its monomer building blocks,but such component variations are usually not straightforward and can be potentially challenging and costly.Herein,we report an in situ oxidation polymerization strategy for preparation of mechanically strong poly(imine-amide)(PIA)hybrid CANs from simple amine and aldehyde monomers.By converting a portion of reversible imine bonds into high-strength amide linkages in situ,the obtained hybrid materials exhibit gradually improved Young’s modulus and ultimate tensile strength as the oxidation level increased.Meanwhile,the PIAs remain reprocessable and can be depolymerized into small molecules and oligomers similar as polyimine.This work demonstrates the great potential of the in situ transformation strategy as a new approach for development of various mechanically tunable CANs from the same starting building blocks.展开更多
The search of biomass-based substitutes for fossil-based plastics has become a pressing task due to the severe long-term threats of plastic wastes to the ecosystem.However,the development in this area is strongly impe...The search of biomass-based substitutes for fossil-based plastics has become a pressing task due to the severe long-term threats of plastic wastes to the ecosystem.However,the development in this area is strongly impeded by the high cost of biomass separation and the poor processability of unseparated biomass.Herein,we demonstrate,for the first time,an efficient and scalable method to generate greener plastics by directly integrating unseparated biomass waste(i.e.,wood powder)with crosslinked covalent adaptable networks.Through a simple compression molding process,the wood biomass and polymer particles can be fused together to form a continuous material,which is endowed with repairability,reprocessibility,and closed-loop full recyclability.The method demonstrated in this work paves the way for largescale industrial production of environmentally friendly biomass-based plastics.展开更多
基金Project no.TKP-6-6/PALY-2021 has been implemented with the support provided by the Ministry of CultureInnovation of Hungary from the National Research,Development and Innovation Fund,financed under the TKP2021-NVA funding scheme+4 种基金funded by the National Research,Development and In-novation Office(NKFIH K142517)This research has been imple-mented with the support of the 2021-1.2.4-TÉT-2021-00050,which encourages scientific and technological cooperation between USA and HungarySupport from theÚNKP-23-3-II-BME-227,ÚNKP-23-5-BME-409 andÚNKP-23-5-BME-417 New National Excellence Pro-gram of the Ministry for Culture and Innovation from the source of the National Research,Development and Innovation Fund is acknowledgedsupported by the János Bolyai Research Scholarship of the Hungarian Academy of Sci-ences No.BO/00508/22/6 and No BO/00980/23/7support of Bertalan Papp in preparation works.
文摘We developed flame retarded polyimine type vitrimers and carbon fibre reinforced composites using two additive and a reactive flame retardant containing phosphorus:ammonium polyphosphate(APP),resorcinol bis(diphenyl phosphate)(RDP);and N,N’,N’’-tris(2-aminoethyl)-phosphoric acid triamide(TEDAP).We characterised the vitrimer matrix materials by differential scanning calorimetry(DSC),thermal analysis(TGA),limiting oxygen index(LOI),UL-94 test and mass loss calorimetry(MLC),while the vitrimer composites by LOI,UL-94 test,MLC and dynamic mechanical analysis(DMA).We compared the performance of the vitrimer systems to a benchmark pentaerythritol-based aliphatic epoxy resin system(PER).The vitrimer reference had higher thermal stability but lower fire performance than the PER aliphatic reference epoxy.At lower phosphorus content,the vitrimer systems exhibited a melting above their vitrimer transition temperature,which negatively affected their LOI and UL-94 results.From 2%phosphorus content,rapid charring and extinguishing of vitrimers prevented the softening and deforming.The superior performance of these same flame retardants in vitrimer systems could be attributed to the high nitrogen content of imine-based vitrimers in combination with phosphorus flame retardants,exploiting nitrogen-phosphorus synergism.In both matrices,flame retardants with solid phase action lead to better fire performance,while in composites,the lowest peak heat release rates(152 kW/m2 in vitrimer composite)were achieved with RDP acting predominantly in the gas phase,as carbon fibres hindered the intumescent phenomenon.
基金financially supported by National Natural Science Foundation of China (No. 21875208)Yunnan University (Nos. WX160117, C176220100005)+3 种基金University of Colorado Boulder, HighLevel Talents Introduction in Yunnan Province (No. C619300A025)the Key Project of Natural Science Foundation of Yunnan (No. 202201AS070011)Major Science and Technology Project of Precious Metal Materials Genetic Engineering in Yunnan Province (Nos. 2019ZE001-1, 202002AB080001)International Joint Research Center for Advanced Energy Materials of Yunnan Province (No. 202003AE140001)。
文摘Graphene-polymer composites have attracted great attention as sensing materials due to their tailorable electrical conductivity, physicochemical properties, and sensitivity to geometric and functional changes.Herein, we report the first example of cylindrical monolithic polyimine vitrimer/graphene composites with excellent mechanical, compressive, rehealable and recyclable, and piezoresistive properties via simple infiltration of polymer monomers into the pores of graphene aerogel followed by thermal curing. The composites exhibit excellent durable compressibility(negligible reduction in the compression properties even after 3000 consecutive compression cycles), rapid recovery to the original size upon stress released,high compressive strength(up to 1.2 MPa), and high conductivity(up to 79 S/m). Excellent piezoresistive properties were observed, displaying consistent and reliable change of the electrical resistance with the compression ratio. Furthermore, rehealing with ~100% recovery of the compressive strength and electric conductivity was achieved under mild rehealing conditions, which is highly desired but has rarely been reported for electronic materials. The facile strategy for fabrication of rehealable monolithic polymer/GAs can open new possibilities for the sustainable development of composites with high electrical conductivity for various applications such as sensing, health monitoring, and movement detection.
基金Funded by the Science and Technology Development Foundation of China Academy of Engineering Physics(Nos.2012A0302015,2012B0302050 and 2013B0302051)
文摘Fluorenone-based polyamines, as novel light-emitting polymers, were synthesized by the condensation polymerization of 3,6-dibromo-9-fluorenone with different aromatic diamines by palladiumcatalyzed aryl amination reaction. The structures of the polymers were characterized by means of FT-IR, 1H NMR spectroscopy and elemental analysis. The experimental results show a good agreement with the proposed structures. TGA measurement exhibits that the polymers possess good thermal stabilities with high decomposition temperatures（T5 400 ℃）. Due to the photo-induced intramolecular charge-transfer（ICT） of fluorenone-based polyimines, these polymers show significantly strong photonic luminescence in N,Ndimethylacetamide.
基金supported by Natural Science Foundation of Jilin Province(No.***202302003)the National Natural Science Foundation of China(No.22275069)National Key R&D Program of China(No.2023YFA1008804)。
文摘Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace,defense,and opto-electronics,but polyimides are difficult to be reprocessed and recycled at the end of their service life,resulting in a significant waste of resources.Hence,it is of great significance to develop recyclable polyimides with comparable properties to the commercial products.Herein,we report a novel polymer-to-monomers chemically recyclable poly(imide-imine)(PtM-CR-PII)plastic,synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine bonds.The PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial polyimides.The PtM-CR-PII plastic possesses a high Young’s modulus of≈3.2 GPa and a tensile strength as high as≈108 MPa,which also exhibits high thermal stability with a glass transition temperature of≈220℃.Moreover,the PtM-CR-PII plastic exhibits outstanding waterproofness,acid/alkali-resistance,and solvent-resistance,its appearance and mechanical properties can be well maintained after long-term soaking in water,highly concentrated acid and base,and various organic solvents.Furthermore,the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame retardancy.The PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index(LOI)value of 45.5%.Importantly,the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature,allowing easy separation and recovery of both monomers in high purity.The recovered pure monomers can be used to regenerate new PtM-CR-PII plastics,enabling sustainable polymer-monomers-polymer circulation.
基金support from the National Science Foundation(Grant CMMI-1901807)。
文摘Covalent adaptable network(CAN)polymers doped with conductive nanoparticles are an ideal candidate to create reshapeable,rehealable,and fully recyclable electronics.On the other hand,3D printing as a deterministic manufacturing method has a significant potential to fabricate electronics with low cost and high design freedom.In this paper,we incorporate a conductive composite consisting of polyimine CAN and multi-wall carbon nanotubes into direct-ink-writing 3D printing to create polymeric sensors with outstanding reshaping,repairing,and recycling capabilities.The developed printable ink exhibits good printability,conductivity,and recyclability.The conductivity of printed polyimine composites is investigated at different temperatures and deformation strain levels.Their shape-reforming and Joule heating-induced interfacial welding effects are demonstrated and characterized.Finally,a temperature sensor is 3D printed with defined patterns of conductive pathways,which can be easily mounted onto 3D surfaces,repaired after damage,and recycled using solvents.The sensing capability of printed sensors is maintained after the repairing and recycling.Overall,the 3D printed reshapeable,rehealable,and recyclable sensors possess complex geometry and extend service life,which assist in the development of polymer-based electronics toward broad and sustainable applications.
基金the University of Colorado Boulder and the National Science Foundation (No. 49100423C0008, Y.J.) for financial support
文摘Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks(CANs)that have been extensively studied in the past few years.While being highly malleable and recyclable,the pioneering polyimine materials are relatively soft and not suitable for certain applications that require high mechanical performance.Recent studies have demonstrated the possibility of significantly improving polyimine properties by varying its monomer building blocks,but such component variations are usually not straightforward and can be potentially challenging and costly.Herein,we report an in situ oxidation polymerization strategy for preparation of mechanically strong poly(imine-amide)(PIA)hybrid CANs from simple amine and aldehyde monomers.By converting a portion of reversible imine bonds into high-strength amide linkages in situ,the obtained hybrid materials exhibit gradually improved Young’s modulus and ultimate tensile strength as the oxidation level increased.Meanwhile,the PIAs remain reprocessable and can be depolymerized into small molecules and oligomers similar as polyimine.This work demonstrates the great potential of the in situ transformation strategy as a new approach for development of various mechanically tunable CANs from the same starting building blocks.
基金The authors would like to acknowledge Prof.Yifu Ding of the University of Colorado Boulder for the instrumentation support with DMA.This work was supported by the University of Colorado Boulder,Wong KC Education Foundation,and the National Natural Science Foundation of China(51673072).Su Z would like to thank China Scholarship Council(CSC)for financial support.
文摘The search of biomass-based substitutes for fossil-based plastics has become a pressing task due to the severe long-term threats of plastic wastes to the ecosystem.However,the development in this area is strongly impeded by the high cost of biomass separation and the poor processability of unseparated biomass.Herein,we demonstrate,for the first time,an efficient and scalable method to generate greener plastics by directly integrating unseparated biomass waste(i.e.,wood powder)with crosslinked covalent adaptable networks.Through a simple compression molding process,the wood biomass and polymer particles can be fused together to form a continuous material,which is endowed with repairability,reprocessibility,and closed-loop full recyclability.The method demonstrated in this work paves the way for largescale industrial production of environmentally friendly biomass-based plastics.
