Polyolefin vitrimers are polymer networks bearing reversible covalent crosslinking points, enabling them to be reprocessed and recycled. In this contribution, a series of polyolefin vitrimers were designed based on th...Polyolefin vitrimers are polymer networks bearing reversible covalent crosslinking points, enabling them to be reprocessed and recycled. In this contribution, a series of polyolefin vitrimers were designed based on the acetoacetate-functionalized polyolefin copolymers, which were produced through the direct copolymerization of ethylene with polar comonomers using a phosphinesulfonate palladium catalyst. The pendant acetoacetate group could mediate several characteristic reactions, such as the Michael addition reaction, ketone-amine condensation and metal coordination reaction. As such, structurally adjustable polyolefin vitrimers can be accessed by introducing various dynamic crosslinking bonds, including disulfide exchange, transamination of vinylogous urethane and labile metal coordination bond. The utilization of different crosslinking reactions and the mole ratio of crosslinkers significantly impact the material properties of the resultant polymers. Specifically, the generated polyolefin vitrimers demonstrated excellent reprocessability and closed-loop recycling properties. The study in this work provides an efficient strategy to access various polyolefin vitrimers.展开更多
The emergence of vitrimer,a new class of polymer materials can address the problem of recyclability,reprocess ability and recyclability of thermosetting plastics.Rosin,a natural product,is an ideal raw material for th...The emergence of vitrimer,a new class of polymer materials can address the problem of recyclability,reprocess ability and recyclability of thermosetting plastics.Rosin,a natural product,is an ideal raw material for the preparation of polymers in a more sustainable way.Nevertheless,due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure,the cross-link density of materials is frequently lowered.In this study,hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids,which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers.It was completely characterized by differential scanning calorimetry test,thermogravimetric analysis,shape memory test and self-healing test.The prepared vitrimers exhibited good self-healing properties,excellent heat resistance(T_(d)=352℃)as well as high mechanical properties(tensile strength of 46.75 MPa).The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton.Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy.Moreover,our work expanded the application field of rosin,increased the added value of rosin,and provided a novel method for preparing rosin-based vitrimers with ideal properties.展开更多
Interfacial welding of thermosetting polymers has been a challenge,but vitrimers with dynamic covalent networks open numerous opportunities for welding and adhesion of these materials.In this work,we performed interfa...Interfacial welding of thermosetting polymers has been a challenge,but vitrimers with dynamic covalent networks open numerous opportunities for welding and adhesion of these materials.In this work,we performed interfacial welding between epoxy-based vitrimers and an epoxy vitrimer and a thermoplastic polyurethane(TPU).Catalyst-controlled interfacial mechanical properties for both the vitrimer/vitrimer and vitrimer/TPU are observed,that is,the more efficient the catalyst for the transesterification reactions,the larger the interfacial fracture energy is,and the better the welding strength will be.The interfacial mechanical properties are also found to be independent of the original mechanical properties of the vitrimers.Even for a vitrimer with poor mechanical properties,both the welded vitrimer/vitrimer and vitrimer/TPU exhibit larger interfacial fracture energy than the one with better mechanical properties as long as the former uses more efficient catalyst.展开更多
Vitrimer is a new type of material that combine the advantages of thermoplastic and thermoset materials.The rapid dynamic exchange reactions at high temperature allow the topology of cross-linked networks to change an...Vitrimer is a new type of material that combine the advantages of thermoplastic and thermoset materials.The rapid dynamic exchange reactions at high temperature allow the topology of cross-linked networks to change and rearrange while keeping material structures and properties intact.The concept of vitrimer has emerged to provide a viable strategy for the recycling of highperformance polymer materials,and lots of research works have been carried out for the development of various types of vitrimers.In addition,the recycling strategies for vitrimers are particularly important to determine the performance and potential applications of the recovered materials.Therefore,it is an innovative and valu-able perspective to discuss vitrimer materials according to their different recycling strategies.In this review,we start with a brief overview of vitrimers,and then,focus on recycling strategies for vitrimers.Specifically,we highlight the advantages and disadvan-tages of the two different recycling strategies:physical and chemi-cal recycling methods,and then explore the feasibility of upcycling vitrimers using 3D printing technology.Finally,the impact of recy-cling strategies on vitrimer materials and the prospects for max-imizing the use of vitrimer materials are discussed.展开更多
It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer...It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer(MSMEV),which exhibits high mechanical properties,multi-shape memory property and malleability.The triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F(DGEBF)with 4-aminophenyl disulfide,γ-aminopropyltriethoxysilane(APTS)and poly(propylene glycol)bis(2-aminopropyl ether)(D2000).The triple crosslinking manifests triple functions:the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network;the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region,leading to multi-shape memory property;a small amount of D2000 increases the modulus difference between the glassy and rubbery states,thereby improving the shape fixity ratio.Meanwhile,the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s modulus.Moreover,integrating carbon fibers and MSMEV results in shape memory composites.The superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.展开更多
In this contribution,we reported the preparation of vitrimers by using commodity thermoplastics via post crosslinking with hindered urea bonds(HUBs).First,three hindered urea diisocyanates(HUDIs)were synthesized via t...In this contribution,we reported the preparation of vitrimers by using commodity thermoplastics via post crosslinking with hindered urea bonds(HUBs).First,three hindered urea diisocyanates(HUDIs)were synthesized via the reactions of N,N'-di-tert-butylethylenediamine,N,N'-diethylethylenediamine,and piperazine with isophorone diisocyanate(IPDI).Thereafter,these HUDIs were used as the crosslinking agents to crosslink poly(hydroxyether of bisphenol A)(PH),a commodity thermoplastics.Fourier transform infrared(FTIR)spectroscopy and dynamic mechanical thermal analyses(DMTA)indicated that the PH thermosets were successfully obtained.It was found that the thermosets displayed the behavior of vitrimers.The PH thermosets can be reprocessed at elevated temperature without using catalyst and the mechanical strengths of vitrimers were recovered as high as 95%.The reprocessing properties are attributable to dynamic exchange reaction of hindered urea bonds,contingent on types of hindered urea bonds.展开更多
Adhesives play an important role in modern society's production and daily life.Developing robust and sustainable adhesives remains a great challenge.Here we report a sustainable epoxy-vitrimer adhesive with high a...Adhesives play an important role in modern society's production and daily life.Developing robust and sustainable adhesives remains a great challenge.Here we report a sustainable epoxy-vitrimer adhesive with high adhesive strength(about 10 MPa)and reusability(82%strength after 3 times).This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of solvents.The adhesive process is also simple,requiring only 30 min at 180℃.In addition,the vitrimer adhesive has the advantages of both erasability for reuse and excellent water resistance.This work provides a facile strategy to fabricate high-strength adhesive that ensures reusability,recyclability,low cost of raw materials,and simple processing technology.Simultaneously,it expands the range of potential applications for epoxy vitrimers.展开更多
In this study,we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct.The vitrimer samples thus pr...In this study,we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct.The vitrimer samples thus prepared exhibit linear viscoelasticity dependent on the length of A moiety as well as the content of the crosslinks.When the average number of A monomers per end moiety m=1.1,the crosslinker can only extend the chain but not crosslink the chain.When m becomes 2.8 or higher,introducing a crosslinker first leads to the gelation,whereas excess in crosslinker molecules leads opening of the crosslinking sites and accordingly reentry into the sol regime.Surprisingly,a further increase in the length of the A moieties increases the relaxation time much weaker than the exponential increase seen for the physically crosslinked ABAtype ionomers.We attribute this difference to the distinct relaxation mechanisms:the relaxation of the vitrimer samples is based on relatively independent exchange reactions,which contrasts with the ABA-type ionomers that relax through the collective hopping of connected ionic groups from one ion aggregate to another.展开更多
基金supported by the National Natural Science Foundation of China (21971230, U19B6001)the Natural Science Foundation of Anhui Province (2308085Y35, 2023AH030002)+1 种基金the Hefei Natural Science Foundation (202304)the strong support from Professor Changle Chen (University of Science and Technology of China)。
文摘Polyolefin vitrimers are polymer networks bearing reversible covalent crosslinking points, enabling them to be reprocessed and recycled. In this contribution, a series of polyolefin vitrimers were designed based on the acetoacetate-functionalized polyolefin copolymers, which were produced through the direct copolymerization of ethylene with polar comonomers using a phosphinesulfonate palladium catalyst. The pendant acetoacetate group could mediate several characteristic reactions, such as the Michael addition reaction, ketone-amine condensation and metal coordination reaction. As such, structurally adjustable polyolefin vitrimers can be accessed by introducing various dynamic crosslinking bonds, including disulfide exchange, transamination of vinylogous urethane and labile metal coordination bond. The utilization of different crosslinking reactions and the mole ratio of crosslinkers significantly impact the material properties of the resultant polymers. Specifically, the generated polyolefin vitrimers demonstrated excellent reprocessability and closed-loop recycling properties. The study in this work provides an efficient strategy to access various polyolefin vitrimers.
基金This research was supported by the National Natural Science Foundation of China(Grant No.32171734)the Scientific Research Funds of Huaqiao University(Grant No.20BS201).
文摘The emergence of vitrimer,a new class of polymer materials can address the problem of recyclability,reprocess ability and recyclability of thermosetting plastics.Rosin,a natural product,is an ideal raw material for the preparation of polymers in a more sustainable way.Nevertheless,due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure,the cross-link density of materials is frequently lowered.In this study,hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids,which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers.It was completely characterized by differential scanning calorimetry test,thermogravimetric analysis,shape memory test and self-healing test.The prepared vitrimers exhibited good self-healing properties,excellent heat resistance(T_(d)=352℃)as well as high mechanical properties(tensile strength of 46.75 MPa).The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton.Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy.Moreover,our work expanded the application field of rosin,increased the added value of rosin,and provided a novel method for preparing rosin-based vitrimers with ideal properties.
基金financially supported by the National Natural Science Foundation of China(No.52173017).
文摘Interfacial welding of thermosetting polymers has been a challenge,but vitrimers with dynamic covalent networks open numerous opportunities for welding and adhesion of these materials.In this work,we performed interfacial welding between epoxy-based vitrimers and an epoxy vitrimer and a thermoplastic polyurethane(TPU).Catalyst-controlled interfacial mechanical properties for both the vitrimer/vitrimer and vitrimer/TPU are observed,that is,the more efficient the catalyst for the transesterification reactions,the larger the interfacial fracture energy is,and the better the welding strength will be.The interfacial mechanical properties are also found to be independent of the original mechanical properties of the vitrimers.Even for a vitrimer with poor mechanical properties,both the welded vitrimer/vitrimer and vitrimer/TPU exhibit larger interfacial fracture energy than the one with better mechanical properties as long as the former uses more efficient catalyst.
基金This work was supported by the Natural National Science Foundation of China[51903210]the Ningbo Natural Science Foundation[202003N4061]Innovation and Entrepreneurship Training Program for College Students of Northwestern Polytechnical University[S202110699694].
文摘Vitrimer is a new type of material that combine the advantages of thermoplastic and thermoset materials.The rapid dynamic exchange reactions at high temperature allow the topology of cross-linked networks to change and rearrange while keeping material structures and properties intact.The concept of vitrimer has emerged to provide a viable strategy for the recycling of highperformance polymer materials,and lots of research works have been carried out for the development of various types of vitrimers.In addition,the recycling strategies for vitrimers are particularly important to determine the performance and potential applications of the recovered materials.Therefore,it is an innovative and valu-able perspective to discuss vitrimer materials according to their different recycling strategies.In this review,we start with a brief overview of vitrimers,and then,focus on recycling strategies for vitrimers.Specifically,we highlight the advantages and disadvan-tages of the two different recycling strategies:physical and chemi-cal recycling methods,and then explore the feasibility of upcycling vitrimers using 3D printing technology.Finally,the impact of recy-cling strategies on vitrimer materials and the prospects for max-imizing the use of vitrimer materials are discussed.
基金by the State Key Scientific Special Project of China(No.2016ZX05017-002)the National Natural Science Foundation of China(No.51873110).
文摘It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances.Here,we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer(MSMEV),which exhibits high mechanical properties,multi-shape memory property and malleability.The triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F(DGEBF)with 4-aminophenyl disulfide,γ-aminopropyltriethoxysilane(APTS)and poly(propylene glycol)bis(2-aminopropyl ether)(D2000).The triple crosslinking manifests triple functions:the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network;the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region,leading to multi-shape memory property;a small amount of D2000 increases the modulus difference between the glassy and rubbery states,thereby improving the shape fixity ratio.Meanwhile,the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s modulus.Moreover,integrating carbon fibers and MSMEV results in shape memory composites.The superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.
基金the National Natural Science Foundation of China(Nos.51973113,51133003,and 21774078).
文摘In this contribution,we reported the preparation of vitrimers by using commodity thermoplastics via post crosslinking with hindered urea bonds(HUBs).First,three hindered urea diisocyanates(HUDIs)were synthesized via the reactions of N,N'-di-tert-butylethylenediamine,N,N'-diethylethylenediamine,and piperazine with isophorone diisocyanate(IPDI).Thereafter,these HUDIs were used as the crosslinking agents to crosslink poly(hydroxyether of bisphenol A)(PH),a commodity thermoplastics.Fourier transform infrared(FTIR)spectroscopy and dynamic mechanical thermal analyses(DMTA)indicated that the PH thermosets were successfully obtained.It was found that the thermosets displayed the behavior of vitrimers.The PH thermosets can be reprocessed at elevated temperature without using catalyst and the mechanical strengths of vitrimers were recovered as high as 95%.The reprocessing properties are attributable to dynamic exchange reaction of hindered urea bonds,contingent on types of hindered urea bonds.
基金supported by the National Natural Science Foundation of China(No.22175106)the Beijing Nova Program(No.20220484126)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230470)。
文摘Adhesives play an important role in modern society's production and daily life.Developing robust and sustainable adhesives remains a great challenge.Here we report a sustainable epoxy-vitrimer adhesive with high adhesive strength(about 10 MPa)and reusability(82%strength after 3 times).This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of solvents.The adhesive process is also simple,requiring only 30 min at 180℃.In addition,the vitrimer adhesive has the advantages of both erasability for reuse and excellent water resistance.This work provides a facile strategy to fabricate high-strength adhesive that ensures reusability,recyclability,low cost of raw materials,and simple processing technology.Simultaneously,it expands the range of potential applications for epoxy vitrimers.
基金financially supported by the National Natural Science Foundation of China(Nos.22173095 and 52103021)。
文摘In this study,we synthesized a series of ABA-type vitrimers by crosslinking the short A moieties of precursors with a bifunctional crosslinker and evaporating the small molecular byproduct.The vitrimer samples thus prepared exhibit linear viscoelasticity dependent on the length of A moiety as well as the content of the crosslinks.When the average number of A monomers per end moiety m=1.1,the crosslinker can only extend the chain but not crosslink the chain.When m becomes 2.8 or higher,introducing a crosslinker first leads to the gelation,whereas excess in crosslinker molecules leads opening of the crosslinking sites and accordingly reentry into the sol regime.Surprisingly,a further increase in the length of the A moieties increases the relaxation time much weaker than the exponential increase seen for the physically crosslinked ABAtype ionomers.We attribute this difference to the distinct relaxation mechanisms:the relaxation of the vitrimer samples is based on relatively independent exchange reactions,which contrasts with the ABA-type ionomers that relax through the collective hopping of connected ionic groups from one ion aggregate to another.
