A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.Whe...A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.When used as the sole hardener,5 wt%PA-DAO increased the tensile,flexural,and impact strengths by 165%,81%,and 455%,respectively,over the parent amine system,whereas the tensile and flexural toughness increased by 1387% and 775%,respectively.At 25 wt% loading,the resin attained a UL-94 V-0 rating and a limiting oxygen index of 28.1%,accompanied by a 71% reduction in the peak heat-release rate and a 53%suppression of total smoke production.This facile,green protocol provides scalable access to ultra-tough,intrinsically flame-retardant epoxy networks without external plasticizers or additives.展开更多
Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain...Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain high-molecular-weight copolymers with narrow molecular weight distributions.Herein,we prepared a novel biodegradable material,poly(butylene succinate-co-glycolide)(PBSGL),through ring-opening copolymerization using glycolide,succinic anhydride,and 1,4-butanediol as raw materials,providing a new solution strategy for marine pollution.GL could be polymerized according to the pre-designed composition by 1H-nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)results,indicating controlled polymerization with the synthesized PBSGLs having a weight-average molecular weight of up to 12.30×10^(4) g/mol and a narrow molecular weight distribution(1.33–1.65).Differential scanning calorimeter(DSC)and thermogravimetric analysis(TGA)results showed that T_(g) of PBSGLs increased from−32.5°C to−26.5°C with the increase of GL content from 0%to 40%,while T_(m)(>76°C)was much lower than T_(d,5%)(>314°C),which indicated that PBSGLs had good thermal stability and expanded the processing window and application range of the original poly(butylene succinate)(PBS)materials.Under simulated difficult conditions,PBSGL copolyesters could degrade faster with increasing GL content,where PBSGL40 degraded by 22.6%in 12 days,showing good biodegradability.Currently,most biodegradable polyesters with good performance slowly degrade in seawater.In a 30-day artificial seawater degradation test,the amorphous PBSGL40 copolyester showed a about 15-fold(2.33%weight loss)improvement in degradation ability compared to pure PBS,demonstrating rapid seawater degradation capability.展开更多
This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement...This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement and polyester fibers.This study varies the content of admixed cement(1%–20%)and polyester fibers(0–20%),including the curing time(3–28 d)for preparing 360 samples.Moreover,this study uses the Michaelis-Menten kinetics concept to model cement hydration saturation.From the study,it is concluded as follows.The modelled results reveals that at least 10%cement and 1%polyester fiber are recommended to attain the 28-d UCS standards(294 kPa)for highway subgrade materials in Thailand.This also fulfils sustainable construction due to reducing normal-use cement from 20%to 10%.Unfortunately,the addition of polyester fibers into the Bangkok clay with at least 5%cement reduces shear modulus by 1.12–1.32 times.The Abram's relationship between shear modulus and the mixing-water-to-cement ratio is found time-dependent.From the composite theory,the BE detects the polyester fiber zone as a defect in the Bangkok clay(matrix)with 5%–20%cement.So,the 28-d shear modulus in the polyester fiber zone is negative(up to0.034 MPa for 20%fiber),similar to softening phenomenon in concrete cracking(negative stiffness).For the 28-d shear modulus of fiber zone,the optimum cement content is around 2%for the positive influences of polyester fibers.Experimentally,the timedependent normalized UCS for 10%and 20%cement is compatible with other studies,and its development rate increases with the cement content as 0.3017,0.3172 and 0.3204 for 5%,10%and 20%cement,respectively.The 28-d relationship between shear modulus and UCS shows that low-cement soft clay requires high polyester fiber content(5%–20%)to activate UCS improvement.However,the soft clay with enough cement(20%)causes the uniformly distributed UCS improvement.展开更多
Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-r...Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-retardant performance and excellent formability.Due to the high Ca content,the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy does not burn at 1065℃.The formability of the alloys is measured using a three-point bending test,and the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy shows excellent formability,with a significant increase in bending displacement from 7.1 mm to 23.8 mm compared to the Mg-6Al-3Ca-0.4Mn(wt%)alloy.The combined effect of the weakened basal texture,the reduction of twins and the plastically deformable Al2Ca phase particles ensures good formability of the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The dynamic recrystallization mechanisms of the alloys have been analyzed,and the promotion of dynamic recrystallization by the PSN mechanism is responsible for the weakened basal texture and the reduction of twins in the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The new Mg alloy is attractive for industrial applications due to its excellent flame-retardant performance and formability.展开更多
Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,p...Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,phosphorous-containing 1-vinylimidazole salts(called VIDHP and VIDPP)were synthesized through the facile neutralization of the acid and 1-vinylimidazole.VIDHP and VIDPP were then applied as flame-retardant crosslinking agents of VERs,by which phosphorus-containing groups could be incorporated into the resin chain via ionic bonds.VIDHP/VER and VIDPP/VER showed a high curing activity and can be well cured in moderate temperatures.With 20 wt.%additions of VIDHP and VIDPP,VIDHP20/VER,and VIDPP20/VER presented a limiting oxygen index value of 29.7%and 28.4%,respectively,with the latter achieving a UL 94 V0 rating.In the cone calorimetric test,compared to the unmodified VERs,VIDPP20/VER exhibited large reductions in the peak heat release rate,total heat release rate,and total smoke release rate while VIDHP20/VER demonstrated comparatively inferior performance in terms of the heat release.VIDHP20/VER and VIDPP20/VER showed good thermal stability and presented a little lower glass transition temperature than the control sample.VIDPP with a low phosphorus oxidation state(+1)demonstrated high flame-retardant activities in the gaseous phase,whereas VIDHP with a high phosphorus oxidation state(+5)primarily exhibited efficacy in the condensed phase.展开更多
The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)an...The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)and 6-hydroxy-2-naphthoic acid(HNA)as comonomers at a molar ratio of 7∶3.The structure of TLCP was confirmed by the Fourier transform infrared(FTIR)spectrometer and nuclear magnetic resonance(NMR)spectrometer.The thermal and rheological properties of TLCP before and after heat treatment were analyzed systematically by the differential scanning calorimeter(DSC),dynamic mechanical analyzer(DMA)and high-temperature rotational rheometer.The results revealed that the melting temperature,glass transition temperature and melt viscosity of the TLCP increased significantly after heat treatment.It indicates that the crystallization of the TLCP is perfect,and solid-phase condensation occurs during heat treatment,which increases its molecular mass.In conclusion,heat treatment at a temperature below but close to the melting temperature can effectively regulate the structure and properties of the TLCP,and the results of this study can provide a reference for the high strengthening of TLCP fibers.展开更多
The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-...The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-sourced polycarbonates due to their lack of functionality has hindered field development. We successfully demonstrated the flame retardancy of poly(chloropropylene carbonate) (PCPC), a perfectly alternating copolymer of epichlorohydrin (ECH) and CO_(2). This was prepared at a 200-gram scale using a high-efficacy tetranuclear organoborane catalyst. PCPC’s excellent flame-retardant performance has been proven by both the vertical combustion test (UL94 V-0) and the limiting oxygen index (LOI) value (29.1%). The underlaid flame-retardant mechanism of PCPC was clearly elucidated. As a result, we confirmed that the generated cyclic carbonates and concurrently released flame-retardant chlorine radicals, hydrogen chloride, and CO_(2) during combustion render PCPC an excellent flame retardant. Furthermore, we investigated the practicability of PCPC as a halogen-rich polymeric flame retardant by blending it with commercial bisphenol A polycarbonate (BPA-PC). PCPC upgraded the flame retardancy rating of BPA polycarbonate from V-2 to V-0 even with a mere 1 wt% addition. It is our hope that this result will prove useful in future developments of advanced CO_(2)-sourced polymeric materials.展开更多
Chemical modification of polymers represents a pivotal method for achieving functionalized polymer materials.However,due to the lack of post-functional handle,the chemical modification of polyester materials remains a...Chemical modification of polymers represents a pivotal method for achieving functionalized polymer materials.However,due to the lack of post-functional handle,the chemical modification of polyester materials remains a significant challenge.Ring-opening copolymerization of cyclic anhydride and epoxides is a powerful approach to synthesize polyesters.In this work,we for the first time demonstrate the functionalizability of polyesters synthesized with brominated anhydride monomers.The post-functionalization is amenable to a wide variety of reactive groups and reactions with high yields.With multiple well-established functionalization pathways of brominated polyester materials and optimized the conditions for the modification reactions,a series of functionalized polyester materials can be obtained with high yields,providing new insights for the research about functionalization of polymers.展开更多
The low lithium transference number of conventional dual-ion polymer electrolytes will lead to concentration polarization and lithium dendrite growth,thereby affecting the safety and cycling performance of lithium bat...The low lithium transference number of conventional dual-ion polymer electrolytes will lead to concentration polarization and lithium dendrite growth,thereby affecting the safety and cycling performance of lithium batteries.Herein,we report a flame-retardant polycarbonate-based single-ion conducting polymer electrolyte(PAGEC-B/PFN).Due to the immobilization of anions within the polycarbonate crosslinking network,PAGEC-B/PFN exhibits a high lithium transference number(0.86),which is beneficial for alleviating concentration polarization and suppressing the growth of lithium dendrite.With the assistance of the TEP flame retardant and FEC,as well as LiNO_(3) additives,PAGEC-B/PFN exhibits excellent flame retardancy,high ionic conductivity,and outstanding interfacial compatibility with the lithium metal anode.As expected,PAGEC-B/PFN achieves a high critical current density of up to 2.0 mA cm^(-2)and stable cycling of Li‖Li cell for over 2200 h.Meanwhile,LFP‖PAGEC-B/PFN‖Li cell delivers a specific capacity of 147.8 mA h g^(-1)at 0.5 C and exhibits excellent cycling performance over 600 cycles.This work provides a strategy for designing solid-state lithium batteries with high safety and high performance.展开更多
The effect of extrusion temperature on the dynamic recrystallization behavior and mechanical properties of the flame-retardant Mg−6Al−3Ca−1Zn−1Sn−Mn(wt.%)alloy was investigated.The observed dynamic recrystallization m...The effect of extrusion temperature on the dynamic recrystallization behavior and mechanical properties of the flame-retardant Mg−6Al−3Ca−1Zn−1Sn−Mn(wt.%)alloy was investigated.The observed dynamic recrystallization mechanisms in the alloy include continuous dynamic recrystallization(CDRX)and particle simulated nucleation(PSN)during hot extrusion.A significant increase in yield strength,from 218 to 358 MPa,representing a 140 MPa increase,is achieved by decreasing the extrusion temperature.The strengthening mechanisms were analyzed quantitatively,with the enhanced strength primarily attributed to grain boundary and dislocation strengthening.The plasticity mechanism was analyzed qualitatively,and the increase in the volume fraction of unDRXed grains caused by the decrease in extrusion temperature leads to an increase in the number of{1012}tensile twins during the tensile deformation,resulting in a reduction in plasticity.展开更多
The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from ep...The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.展开更多
Single ion gel polymer electrolyte has the advantages of high Li^(+)conductivity and dendrite mitigation.However,the addition of organic solvent makes the electrolyte flammable,posing serious safety hazards.Herein,we ...Single ion gel polymer electrolyte has the advantages of high Li^(+)conductivity and dendrite mitigation.However,the addition of organic solvent makes the electrolyte flammable,posing serious safety hazards.Herein,we report a flame-retard ant cross-linked sp^(3)boron-based single-ion gel polymer electrolyte(BSIPE).BSIPE was prepared by a simple one-step photoinitiated in situ thiol-ene click reaction.Due to the boron-based anions being immobilized in the cross-linking network,the developed BSIPE/PFN exhibits a high t_(Li^(+))(0.87),which can mitigate concentration polarization phenomenon and suppress the growth of lithium dendrites.BSIPE/PFN plasticized with triethyl phosphate(TEP),fluoroethylene carbonate(FEC)and LiNO_(3)exhibits enhanced ionic conductivity of 4.25×10^(-4)S cm^(-1)at 30℃ and flame retardancy.FEC and LiNO_(3) are conducive to form a stable solid electrolyte interphase(SEI)rich in Li_(3)N and LiF to improve interface stability.As expected,the dendrite-free Li‖BSIPE/PFN‖Li symmetric cell exhibits considerable cycling life over 1500 h.BSIPE/PFN significantly boosts the performance of LFP‖Li cell,which displays a capacity retention of 84.6%after 500 cycles.The BSIPE/PFN has promising applications in highsafety and high-performance lithium metal batteries.展开更多
To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via ...To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via melt polycondensation.Diester monomers M and N were synthesized via the Williamson reaction,using lignin-derived 2-methoxyhydroquinone,methyl 4-chloromethylbenzoate,and methyl chloroacetate as starting materials.Hydroquinone bis(2-hydroxyethyl)ether(HQEE)and 1,4-cyclohexanedimethanol(CHDM)were employed as cyclic segments,while 1,4-butanediol(BDO)and 1,6-hexanediol(HDO)served as alkyl segments within the copolymer structures.The novel copolyesters exhibited molecular weights(Mw)in the range of 5.25×10^(4)–5.87×10^(4) g/mol,with polydispersity indices spanning from 2.50–2.66.Evaluation of the structural and thermomechanical properties indicated that the inclusion of alkyl segments induced a reduction in both crystallinity and molecular weight,while significantly improving the flexibility,whereas cyclic segments enhanced the processability of the copolyesters.Copolyesters P_(1) and P_(2),due to the presence of rigid segments(HQEE and CHDM),displayed relatively high glass transition temperatures(Tg>80℃)and melting temperatures(Tm>170℃).Notably,P_(2),incorporating CHDM,exhibited superior elongation properties(272%),attributed to the enhanced chain mobility resulting from its trans-conformation,while P_(1) was found to be likely brittle owing to excessive chain stiffness.Biodegradability assessment using earthworms as bioindicators revealed that the copolyesters demonstrated moderate degradation profiles,with P_(2) exhibiting a degradation rate of 4.82%,followed by P_(4) at 4.07%,P_(3) at 3.65%,and P_(1) at 3.17%.The higher degradation rate of P_(2) was attributed to its relatively larger d-spacing and lower toxicity,which facilitated enzymatic hydrolytic attack by microorganisms.These findings highlight the significance of optimizing the structural chain segments within aliphatic-aromatic copolyesters.By doing so,it is possible to significantly enhance their properties and performance,offering viable bio-based alternatives to petroleum-based polyesters such as polyethylene terephthalate(PET).展开更多
Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic p...Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.展开更多
The polycarbonate(bisphenol A)/acrylonitrile—butadiene—styrene(PC/ABS)features excellent mechanical properties,but its high flammability poses a potential safety hazard in practical applications.Although the incorpo...The polycarbonate(bisphenol A)/acrylonitrile—butadiene—styrene(PC/ABS)features excellent mechanical properties,but its high flammability poses a potential safety hazard in practical applications.Although the incorporation of halogen-free additives enhances flame retardancy,it often leads to substantial smoke emission and compromises the mechanical properties of PC/ABS alloy.Therefore,simultaneous enhancement of both flame retardancy with low smoke and mechanical properties holds significant practical value for material development.Herein,a low-smoke PC/ABS composite with balanced flame retardancy and mechanical properties was achieved through an efficient ternary flame retardant system containing bisphenol A bis(diphenyl phosphate)(BDP),potassium-4-(phenylsulfonyl)benzenesulfonate(KSS),and 3-glycidyloxypropyltrimethoxysilane-modified boehmite(m-BM).PC/ABS/BDP6/KSS2/m-BM2 can achieve the same flame retardant level(V-0)as PC/ABS/BDP14,and the limiting oxygen index is increased to 26.8%.Meanwhile,the tensile strength and impact strength are increased by 16.1%and 81.4%respectively.The ternary system can significantly inhibit the release of smoke and heat,under the same flame retardant load(10%(mass)),the total heat release and total smoke production of PC/ABS loaded with ternary flame-retardant system decreased by 18.1%and 21.9%respectively compared to only BDP loaded.This ternary flame-retardant system provides a practical solution for developing high-performance,low-smoke flame-retardant PC/ABS composites.展开更多
Renewable 2,5-furandicarboxylic acid-based polyesters are one of the most promising materials for achieving plastic replacement in the age of energy and environmental crisis.However,their properties still cannot compe...Renewable 2,5-furandicarboxylic acid-based polyesters are one of the most promising materials for achieving plastic replacement in the age of energy and environmental crisis.However,their properties still cannot compete with those of petrochemical-based plastics,owing to insufficient molecular and/or microstructure designs.Herein,we utilize the Ti_(3)C_(2)T_(x)-based MXene nanosheets for decorating carbon nanotube(CNT)and obtaining the structurally stable and highly dispersed dendritic heterostructured MXene@CNT,that can act as multi-roles,i.e.,polycondensation catalyst,crystal nucleator,and interface enhancer of polyester.The biobased MXene@CNT/polybutylene furandicarboxylate(PBF)(denoted as MCP)nanocomposites are synthesized by the strategy of“in situ catalytic polymerization and hot-pressing”.Benefiting from the multi-scale interactions(i.e.,covalent bonds,hydrogen bonds,and physical interlocks)in hybrid structure,the MCP presents exceptional mechanical strength(≈101 MPa),stiffness(≈3.1 GPa),toughness(≈130 MJ m^(-3)),and barrier properties(e.g.,O_(2)0.0187 barrer,CO_(2)0.0264 barrer,and H2O 1.57×10^(-14) g cm cm^(-2) s Pa)that are higher than most reported bio-based materials and engineering plastics.Moreover,it also displays satisfactory multifunctionality with high reprocessability(90%strength retention after 5 recycling),UV resistance(blocking 85%UVA rays),and solvent-resistant properties.As a state-of-art high-performance and multifunctional material,the novel bio-based MCP nanocomposite offers a more sustainable alternative to petrochemical-based plastics in packaging and engineering material fields.More importantly,our catalysis-interfacial strengthening integration strategy opens a door for designing and constructing high-performance bio-based polyester materials in future.展开更多
A series of novel thermotropic liquid crystalline polyesters bearing nonlinear optical azobenzene side group were synthesized by high temperature solution polycondensation and their structures,thermal stability, phas...A series of novel thermotropic liquid crystalline polyesters bearing nonlinear optical azobenzene side group were synthesized by high temperature solution polycondensation and their structures,thermal stability, phase transition behavior and crystallinity were characterized by IR,elemental analysis, TG-DTA, polarizing optical microscope (POM) equipped with a hot stage and X-ray diffraction techniques. The results demonstrate that all the synthesized polyesters exhibit nematic liquid crystalline phases and show relatively high glass transition temperatures and good thermal stability.展开更多
The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/M...The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.展开更多
基金financially supported by Zhejiang Provincial"Leading Force"and"Leading Bird"R&D Key Project(No.2022C03128)Basic Public Welfare Research Plan of Zhejiang Province(No.LY21C160003)+1 种基金National Natural Science Foundation(No.51991355)Zhejiang A&F University Scientific Research Start-up Fund(No.2023LFR134)。
文摘A simultaneous boost in toughness and fire safety of epoxy(EP)is achieved through solvent-free one-step neutralization of phytic acid with 1,8-diaminooctane to yield a multifunctional bio-based curing agent,PA-DAO.When used as the sole hardener,5 wt%PA-DAO increased the tensile,flexural,and impact strengths by 165%,81%,and 455%,respectively,over the parent amine system,whereas the tensile and flexural toughness increased by 1387% and 775%,respectively.At 25 wt% loading,the resin attained a UL-94 V-0 rating and a limiting oxygen index of 28.1%,accompanied by a 71% reduction in the peak heat-release rate and a 53%suppression of total smoke production.This facile,green protocol provides scalable access to ultra-tough,intrinsically flame-retardant epoxy networks without external plasticizers or additives.
基金financially supported by the National Natural Science Foundation of China (No. 52203012)Shanghai Rising-Star Program (No. 23QC1400900).
文摘Ocean-degradable polyesters incorporating hydrophilic and rapidly degradable glycolide(GL)units into the polymer chain are the most promising for addressing marine plastic pollution,however,it is challenging to obtain high-molecular-weight copolymers with narrow molecular weight distributions.Herein,we prepared a novel biodegradable material,poly(butylene succinate-co-glycolide)(PBSGL),through ring-opening copolymerization using glycolide,succinic anhydride,and 1,4-butanediol as raw materials,providing a new solution strategy for marine pollution.GL could be polymerized according to the pre-designed composition by 1H-nuclear magnetic resonance(1H-NMR)and gel permeation chromatography(GPC)results,indicating controlled polymerization with the synthesized PBSGLs having a weight-average molecular weight of up to 12.30×10^(4) g/mol and a narrow molecular weight distribution(1.33–1.65).Differential scanning calorimeter(DSC)and thermogravimetric analysis(TGA)results showed that T_(g) of PBSGLs increased from−32.5°C to−26.5°C with the increase of GL content from 0%to 40%,while T_(m)(>76°C)was much lower than T_(d,5%)(>314°C),which indicated that PBSGLs had good thermal stability and expanded the processing window and application range of the original poly(butylene succinate)(PBS)materials.Under simulated difficult conditions,PBSGL copolyesters could degrade faster with increasing GL content,where PBSGL40 degraded by 22.6%in 12 days,showing good biodegradability.Currently,most biodegradable polyesters with good performance slowly degrade in seawater.In a 30-day artificial seawater degradation test,the amorphous PBSGL40 copolyester showed a about 15-fold(2.33%weight loss)improvement in degradation ability compared to pure PBS,demonstrating rapid seawater degradation capability.
基金allocated by National Science,Research and Innovation Fund(NSRF)King Mongkut's University of Technology North Bangkok(project no.KMUTNB-FF-67-B-44 and KMUTNB-FF-67-B-45)supported by the NSRF through the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(grant no.B40G660036).
文摘This study proposes to use the unconfined compressive strength(UCS)and the bender element(BE)tests for determining the strength and the initial small-strain shear modulus of Bangkok soft marine clay improved by cement and polyester fibers.This study varies the content of admixed cement(1%–20%)and polyester fibers(0–20%),including the curing time(3–28 d)for preparing 360 samples.Moreover,this study uses the Michaelis-Menten kinetics concept to model cement hydration saturation.From the study,it is concluded as follows.The modelled results reveals that at least 10%cement and 1%polyester fiber are recommended to attain the 28-d UCS standards(294 kPa)for highway subgrade materials in Thailand.This also fulfils sustainable construction due to reducing normal-use cement from 20%to 10%.Unfortunately,the addition of polyester fibers into the Bangkok clay with at least 5%cement reduces shear modulus by 1.12–1.32 times.The Abram's relationship between shear modulus and the mixing-water-to-cement ratio is found time-dependent.From the composite theory,the BE detects the polyester fiber zone as a defect in the Bangkok clay(matrix)with 5%–20%cement.So,the 28-d shear modulus in the polyester fiber zone is negative(up to0.034 MPa for 20%fiber),similar to softening phenomenon in concrete cracking(negative stiffness).For the 28-d shear modulus of fiber zone,the optimum cement content is around 2%for the positive influences of polyester fibers.Experimentally,the timedependent normalized UCS for 10%and 20%cement is compatible with other studies,and its development rate increases with the cement content as 0.3017,0.3172 and 0.3204 for 5%,10%and 20%cement,respectively.The 28-d relationship between shear modulus and UCS shows that low-cement soft clay requires high polyester fiber content(5%–20%)to activate UCS improvement.However,the soft clay with enough cement(20%)causes the uniformly distributed UCS improvement.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701100)the Applied Basic Research Program Project of Liaoning Province of China(No.2023020253-JH2/1016)the Key Research and Development Plan of Shanxi Province(No.202102050201005)。
文摘Poor formability is a key problem that limits the application of flame-retardant Mg-Al-Ca based alloys at room temperature.In this study,we present a new Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy which exhibits excellent flame-retardant performance and excellent formability.Due to the high Ca content,the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy does not burn at 1065℃.The formability of the alloys is measured using a three-point bending test,and the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy shows excellent formability,with a significant increase in bending displacement from 7.1 mm to 23.8 mm compared to the Mg-6Al-3Ca-0.4Mn(wt%)alloy.The combined effect of the weakened basal texture,the reduction of twins and the plastically deformable Al2Ca phase particles ensures good formability of the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The dynamic recrystallization mechanisms of the alloys have been analyzed,and the promotion of dynamic recrystallization by the PSN mechanism is responsible for the weakened basal texture and the reduction of twins in the Mg-6Al-3Ca-0.4Mn-2Zn(wt%)alloy.The new Mg alloy is attractive for industrial applications due to its excellent flame-retardant performance and formability.
基金supported by the National Natural Science Foundation of China(Grant Nos.51991351 and51903132)the Young Elite Scientist Sponsorship Program by CAST(No.2022QNRC001).
文摘Different reactive flame retardants have been extensively developed for vinyl ester resins(VERs),but very few of them can yield a flame-retardant resin that meets defined standards(e.g.UL-94 V-0 rating).In this work,phosphorous-containing 1-vinylimidazole salts(called VIDHP and VIDPP)were synthesized through the facile neutralization of the acid and 1-vinylimidazole.VIDHP and VIDPP were then applied as flame-retardant crosslinking agents of VERs,by which phosphorus-containing groups could be incorporated into the resin chain via ionic bonds.VIDHP/VER and VIDPP/VER showed a high curing activity and can be well cured in moderate temperatures.With 20 wt.%additions of VIDHP and VIDPP,VIDHP20/VER,and VIDPP20/VER presented a limiting oxygen index value of 29.7%and 28.4%,respectively,with the latter achieving a UL 94 V0 rating.In the cone calorimetric test,compared to the unmodified VERs,VIDPP20/VER exhibited large reductions in the peak heat release rate,total heat release rate,and total smoke release rate while VIDHP20/VER demonstrated comparatively inferior performance in terms of the heat release.VIDHP20/VER and VIDPP20/VER showed good thermal stability and presented a little lower glass transition temperature than the control sample.VIDPP with a low phosphorus oxidation state(+1)demonstrated high flame-retardant activities in the gaseous phase,whereas VIDHP with a high phosphorus oxidation state(+5)primarily exhibited efficacy in the condensed phase.
基金National Key Research and Development Program of China (No.2021YFB3700105)。
文摘The thermotropic liquid crystal polyester(TLCP)fiber is an increasingly important strategic high-performance fiber.In this paper,the TLCP was prepared by two-step melt polymerization using 4-hydroxybenzoic acid(HBA)and 6-hydroxy-2-naphthoic acid(HNA)as comonomers at a molar ratio of 7∶3.The structure of TLCP was confirmed by the Fourier transform infrared(FTIR)spectrometer and nuclear magnetic resonance(NMR)spectrometer.The thermal and rheological properties of TLCP before and after heat treatment were analyzed systematically by the differential scanning calorimeter(DSC),dynamic mechanical analyzer(DMA)and high-temperature rotational rheometer.The results revealed that the melting temperature,glass transition temperature and melt viscosity of the TLCP increased significantly after heat treatment.It indicates that the crystallization of the TLCP is perfect,and solid-phase condensation occurs during heat treatment,which increases its molecular mass.In conclusion,heat treatment at a temperature below but close to the melting temperature can effectively regulate the structure and properties of the TLCP,and the results of this study can provide a reference for the high strengthening of TLCP fibers.
基金supported by the National Science Fund for Distinguished Young Scholars(No.T2225004)National Natural Science Foundation of China(No.52373092)Shccig-Qinling Program.
文摘The alternating copolymer of CO_(2) with epoxide is a green plastic that can efficiently transform CO_(2) into valuable chemicals. Despite the significant advances made, the restricted practical application of CO_(2)-sourced polycarbonates due to their lack of functionality has hindered field development. We successfully demonstrated the flame retardancy of poly(chloropropylene carbonate) (PCPC), a perfectly alternating copolymer of epichlorohydrin (ECH) and CO_(2). This was prepared at a 200-gram scale using a high-efficacy tetranuclear organoborane catalyst. PCPC’s excellent flame-retardant performance has been proven by both the vertical combustion test (UL94 V-0) and the limiting oxygen index (LOI) value (29.1%). The underlaid flame-retardant mechanism of PCPC was clearly elucidated. As a result, we confirmed that the generated cyclic carbonates and concurrently released flame-retardant chlorine radicals, hydrogen chloride, and CO_(2) during combustion render PCPC an excellent flame retardant. Furthermore, we investigated the practicability of PCPC as a halogen-rich polymeric flame retardant by blending it with commercial bisphenol A polycarbonate (BPA-PC). PCPC upgraded the flame retardancy rating of BPA polycarbonate from V-2 to V-0 even with a mere 1 wt% addition. It is our hope that this result will prove useful in future developments of advanced CO_(2)-sourced polymeric materials.
基金financially supported by the National Key R&D Program of China(No.2021YFA1501700)the Science and Technology Development Plan of Jilin Province(Nos.20230101042JC and 20210201059GX)+1 种基金the National Natural Science Foundation of China,Basic Science Center Program(No.51988102)the National Natural Science Foundation of China(Nos.52203017 and 52073272)。
文摘Chemical modification of polymers represents a pivotal method for achieving functionalized polymer materials.However,due to the lack of post-functional handle,the chemical modification of polyester materials remains a significant challenge.Ring-opening copolymerization of cyclic anhydride and epoxides is a powerful approach to synthesize polyesters.In this work,we for the first time demonstrate the functionalizability of polyesters synthesized with brominated anhydride monomers.The post-functionalization is amenable to a wide variety of reactive groups and reactions with high yields.With multiple well-established functionalization pathways of brominated polyester materials and optimized the conditions for the modification reactions,a series of functionalized polyester materials can be obtained with high yields,providing new insights for the research about functionalization of polymers.
基金supported by the National Natural Science Foundation of China(22179149,22075329,51573215,and 21978332)Guangzhou Municipal Science and Technology Program(2025B01J2007,2025A03J4025,2025A03J4026)Fundamental Research Fund of Henan Academy of Sciences(232018002)。
文摘The low lithium transference number of conventional dual-ion polymer electrolytes will lead to concentration polarization and lithium dendrite growth,thereby affecting the safety and cycling performance of lithium batteries.Herein,we report a flame-retardant polycarbonate-based single-ion conducting polymer electrolyte(PAGEC-B/PFN).Due to the immobilization of anions within the polycarbonate crosslinking network,PAGEC-B/PFN exhibits a high lithium transference number(0.86),which is beneficial for alleviating concentration polarization and suppressing the growth of lithium dendrite.With the assistance of the TEP flame retardant and FEC,as well as LiNO_(3) additives,PAGEC-B/PFN exhibits excellent flame retardancy,high ionic conductivity,and outstanding interfacial compatibility with the lithium metal anode.As expected,PAGEC-B/PFN achieves a high critical current density of up to 2.0 mA cm^(-2)and stable cycling of Li‖Li cell for over 2200 h.Meanwhile,LFP‖PAGEC-B/PFN‖Li cell delivers a specific capacity of 147.8 mA h g^(-1)at 0.5 C and exhibits excellent cycling performance over 600 cycles.This work provides a strategy for designing solid-state lithium batteries with high safety and high performance.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701100)the Applied Basic Research Program Project of Liaoning Province,China(No.2023020253-JH2/1016)the Key Research and Development Plan of Shanxi Province,China(No.202102050201005).
文摘The effect of extrusion temperature on the dynamic recrystallization behavior and mechanical properties of the flame-retardant Mg−6Al−3Ca−1Zn−1Sn−Mn(wt.%)alloy was investigated.The observed dynamic recrystallization mechanisms in the alloy include continuous dynamic recrystallization(CDRX)and particle simulated nucleation(PSN)during hot extrusion.A significant increase in yield strength,from 218 to 358 MPa,representing a 140 MPa increase,is achieved by decreasing the extrusion temperature.The strengthening mechanisms were analyzed quantitatively,with the enhanced strength primarily attributed to grain boundary and dislocation strengthening.The plasticity mechanism was analyzed qualitatively,and the increase in the volume fraction of unDRXed grains caused by the decrease in extrusion temperature leads to an increase in the number of{1012}tensile twins during the tensile deformation,resulting in a reduction in plasticity.
基金financially supported by the National Natural Science Foundation of China(Nos.22071016 and 21920102006)。
文摘The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.
基金supported by the National Natural Science Foundation of China(22179149,22075329,51573215,and 21978332)Research and Development Project of Henan Academy Sciences China(232018002)。
文摘Single ion gel polymer electrolyte has the advantages of high Li^(+)conductivity and dendrite mitigation.However,the addition of organic solvent makes the electrolyte flammable,posing serious safety hazards.Herein,we report a flame-retard ant cross-linked sp^(3)boron-based single-ion gel polymer electrolyte(BSIPE).BSIPE was prepared by a simple one-step photoinitiated in situ thiol-ene click reaction.Due to the boron-based anions being immobilized in the cross-linking network,the developed BSIPE/PFN exhibits a high t_(Li^(+))(0.87),which can mitigate concentration polarization phenomenon and suppress the growth of lithium dendrites.BSIPE/PFN plasticized with triethyl phosphate(TEP),fluoroethylene carbonate(FEC)and LiNO_(3)exhibits enhanced ionic conductivity of 4.25×10^(-4)S cm^(-1)at 30℃ and flame retardancy.FEC and LiNO_(3) are conducive to form a stable solid electrolyte interphase(SEI)rich in Li_(3)N and LiF to improve interface stability.As expected,the dendrite-free Li‖BSIPE/PFN‖Li symmetric cell exhibits considerable cycling life over 1500 h.BSIPE/PFN significantly boosts the performance of LFP‖Li cell,which displays a capacity retention of 84.6%after 500 cycles.The BSIPE/PFN has promising applications in highsafety and high-performance lithium metal batteries.
基金financially supported by State Administration of Foreign Experts Affairs(SAFEA)through the High-End Foreign Expert Program(No.BG2021227001)postdoctoral funding from Wuhan University of Science and Technology(No.105008701)。
文摘To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via melt polycondensation.Diester monomers M and N were synthesized via the Williamson reaction,using lignin-derived 2-methoxyhydroquinone,methyl 4-chloromethylbenzoate,and methyl chloroacetate as starting materials.Hydroquinone bis(2-hydroxyethyl)ether(HQEE)and 1,4-cyclohexanedimethanol(CHDM)were employed as cyclic segments,while 1,4-butanediol(BDO)and 1,6-hexanediol(HDO)served as alkyl segments within the copolymer structures.The novel copolyesters exhibited molecular weights(Mw)in the range of 5.25×10^(4)–5.87×10^(4) g/mol,with polydispersity indices spanning from 2.50–2.66.Evaluation of the structural and thermomechanical properties indicated that the inclusion of alkyl segments induced a reduction in both crystallinity and molecular weight,while significantly improving the flexibility,whereas cyclic segments enhanced the processability of the copolyesters.Copolyesters P_(1) and P_(2),due to the presence of rigid segments(HQEE and CHDM),displayed relatively high glass transition temperatures(Tg>80℃)and melting temperatures(Tm>170℃).Notably,P_(2),incorporating CHDM,exhibited superior elongation properties(272%),attributed to the enhanced chain mobility resulting from its trans-conformation,while P_(1) was found to be likely brittle owing to excessive chain stiffness.Biodegradability assessment using earthworms as bioindicators revealed that the copolyesters demonstrated moderate degradation profiles,with P_(2) exhibiting a degradation rate of 4.82%,followed by P_(4) at 4.07%,P_(3) at 3.65%,and P_(1) at 3.17%.The higher degradation rate of P_(2) was attributed to its relatively larger d-spacing and lower toxicity,which facilitated enzymatic hydrolytic attack by microorganisms.These findings highlight the significance of optimizing the structural chain segments within aliphatic-aromatic copolyesters.By doing so,it is possible to significantly enhance their properties and performance,offering viable bio-based alternatives to petroleum-based polyesters such as polyethylene terephthalate(PET).
基金supported by the National Natural Science Foundation of China,Fund for Distinguished Young Scholars(No.52325301)CAS Project for Young Scientists in Basic Research(YSBR-094)the National Natural Science Foundation of China,Basic Science Center Program(No.51988102).
文摘Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.
基金supported by the National Natural Science Foundation of China(22278140,U22B20143)the Science and Technology Commission of Shanghai Municipality(22DZ1205900)Project supported by Shanghai Municipal Science and Technology Major Project,the Fundamental Research Funds for the Central Universities。
文摘The polycarbonate(bisphenol A)/acrylonitrile—butadiene—styrene(PC/ABS)features excellent mechanical properties,but its high flammability poses a potential safety hazard in practical applications.Although the incorporation of halogen-free additives enhances flame retardancy,it often leads to substantial smoke emission and compromises the mechanical properties of PC/ABS alloy.Therefore,simultaneous enhancement of both flame retardancy with low smoke and mechanical properties holds significant practical value for material development.Herein,a low-smoke PC/ABS composite with balanced flame retardancy and mechanical properties was achieved through an efficient ternary flame retardant system containing bisphenol A bis(diphenyl phosphate)(BDP),potassium-4-(phenylsulfonyl)benzenesulfonate(KSS),and 3-glycidyloxypropyltrimethoxysilane-modified boehmite(m-BM).PC/ABS/BDP6/KSS2/m-BM2 can achieve the same flame retardant level(V-0)as PC/ABS/BDP14,and the limiting oxygen index is increased to 26.8%.Meanwhile,the tensile strength and impact strength are increased by 16.1%and 81.4%respectively.The ternary system can significantly inhibit the release of smoke and heat,under the same flame retardant load(10%(mass)),the total heat release and total smoke production of PC/ABS loaded with ternary flame-retardant system decreased by 18.1%and 21.9%respectively compared to only BDP loaded.This ternary flame-retardant system provides a practical solution for developing high-performance,low-smoke flame-retardant PC/ABS composites.
基金financial supports from the National Natural Science Foundation of China(Grant No.NSFC52473104)National Key R&D Program of China(Grant No.2022YFC2104500)+3 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.Y24B040002)Ningbo 2025 Key Scientific Research Programs(Grant No.2022Z160)the China Postdoctoral Science Foundation(Grant No.2023M733601)the Ningbo Natural Science Foundation(Grant No.2023I333&2023J409).
文摘Renewable 2,5-furandicarboxylic acid-based polyesters are one of the most promising materials for achieving plastic replacement in the age of energy and environmental crisis.However,their properties still cannot compete with those of petrochemical-based plastics,owing to insufficient molecular and/or microstructure designs.Herein,we utilize the Ti_(3)C_(2)T_(x)-based MXene nanosheets for decorating carbon nanotube(CNT)and obtaining the structurally stable and highly dispersed dendritic heterostructured MXene@CNT,that can act as multi-roles,i.e.,polycondensation catalyst,crystal nucleator,and interface enhancer of polyester.The biobased MXene@CNT/polybutylene furandicarboxylate(PBF)(denoted as MCP)nanocomposites are synthesized by the strategy of“in situ catalytic polymerization and hot-pressing”.Benefiting from the multi-scale interactions(i.e.,covalent bonds,hydrogen bonds,and physical interlocks)in hybrid structure,the MCP presents exceptional mechanical strength(≈101 MPa),stiffness(≈3.1 GPa),toughness(≈130 MJ m^(-3)),and barrier properties(e.g.,O_(2)0.0187 barrer,CO_(2)0.0264 barrer,and H2O 1.57×10^(-14) g cm cm^(-2) s Pa)that are higher than most reported bio-based materials and engineering plastics.Moreover,it also displays satisfactory multifunctionality with high reprocessability(90%strength retention after 5 recycling),UV resistance(blocking 85%UVA rays),and solvent-resistant properties.As a state-of-art high-performance and multifunctional material,the novel bio-based MCP nanocomposite offers a more sustainable alternative to petrochemical-based plastics in packaging and engineering material fields.More importantly,our catalysis-interfacial strengthening integration strategy opens a door for designing and constructing high-performance bio-based polyester materials in future.
文摘A series of novel thermotropic liquid crystalline polyesters bearing nonlinear optical azobenzene side group were synthesized by high temperature solution polycondensation and their structures,thermal stability, phase transition behavior and crystallinity were characterized by IR,elemental analysis, TG-DTA, polarizing optical microscope (POM) equipped with a hot stage and X-ray diffraction techniques. The results demonstrate that all the synthesized polyesters exhibit nematic liquid crystalline phases and show relatively high glass transition temperatures and good thermal stability.
文摘The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.
