Ethylene glycol(EG)is a biomass derivative of polyethylene terephthalate(PET),and its electrocatalytic conversion into high-value chemicals has sparked widespread interest.This study reviews the most recent research d...Ethylene glycol(EG)is a biomass derivative of polyethylene terephthalate(PET),and its electrocatalytic conversion into high-value chemicals has sparked widespread interest.This study reviews the most recent research development in electrocatalysis-based EG to glycolic acid(GA)conversion.Firstly,the strategies and research results of modulating the electronic structure of catalysts for efficient selective GA production from EG are reviewed.Second,by reviewing the data of in-situ Fourier transform infrared spectroscopy and in-situ electrochemically attenuated total reflection surface enhanced infrared absorption spectroscopy,the reaction pathway and catalytic mechanism of EG partial oxidation to GA were clarified.Finally,the design and regulation of catalysts for selective oxidation of EG by electrocatalysis in the future are prospected.展开更多
Ethylene glycol oxidation reaction(EGOR)is important to address the environmental issues caused by the increased production of polyethylene terephthalate(PET).Metal organic frameworks(MOFs)with superior stability,high...Ethylene glycol oxidation reaction(EGOR)is important to address the environmental issues caused by the increased production of polyethylene terephthalate(PET).Metal organic frameworks(MOFs)with superior stability,high specific surface area and excellent catalytic performance can convert PET into valuable products through EGOR and hydrogen evolution reaction(HER).Herein,a microbial template strategy was adopted to prepare carbon sphere-supported orthogonal nanosheet bimetallic MOF catalysts.The prepared catalyst needs only 1.42 V,307 mV,and 1.83 V at a current density of 100 mA cm^(-2) for EGOR,HER,and EGOR//HER,respectively.More importantly,it can stably perform for at least 160 h at a current density of 500 mA cm^(-2).The high specific surface area of bimetallic MOF and the synergistic effect of yeast carbon shell increase the contact area between the intrinsic active sites and*OH and EG,thus improving the EGOR and HER catalytic activity and stability.This work provides a novel strategy to construct bimetallic orthogonal electrocatalysts with efficient HER//EGOR performance,which is of great significance for achieving sustainable energy conversion and environmental purification.展开更多
Traditional photo-electcatalyst structures of small noble metal nanoparticles assembling into large-scale photoactive semiconductors still suffer from agglomeration of noble metal nanoparticles,insufficient charge tra...Traditional photo-electcatalyst structures of small noble metal nanoparticles assembling into large-scale photoactive semiconductors still suffer from agglomeration of noble metal nanoparticles,insufficient charge transfer,undesirable photoresponse ability that restricted the photo-electrocatalytic performance.To this end,a novel design strategy is proposed in this work,namely integrating small-scale photoactive materials(doped graphene quantum dots,S,N-GQDs)with large-sized noble metal(Pd P)nanoflowers to form novel photo-electrocatalysts for high-efficient alcohol oxidation reaction.As expected,superior electrocatalytic performance of Pd P/S,N-GQDs for ethylene glycol oxidation is acquired,thanks to the nanoflower structure with larger specific surface area and abundant active sites.Furthermore,nonmetal P are demonstrated,especially optimizing the adsorption strength,enhancing the interfacial contact,reducing metal agglomeration,ensuring uniform and efficient doping of S,N-GQDs,and ultimately significantly boost the catalytic activity of photo-electrocatalysts.展开更多
The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution...The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.展开更多
The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of po...The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.展开更多
Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal ...Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal sites in the state-of-the-art metal single-atom catalysts(M-SACs)hinders their further industrial applications,and the high potential and valueless oxygen product of the conventional anodic oxygen evolution reaction(OER)further limit the economic efficiency of this technology.To address this,a dynamically local structure reconstruction strategy is proposed to in situ transfer the active sites from unstable metal sites to the stable surrounding carbon sites for efficient and durable 2e^(-)ORR electrocatalysis.For the as-designed Mn-N_(3)O-C catalyst,by reconstructing Mn sites into Mn(^(*)OH),the Mn sites were passivated and carbon sites adjacent to the O atom were verified to be the actual active sites by in situ characterization and theoretical calculation.Consequently,Mn-N_(3)O-C exhibited>80%Faradaic efficiency and superior long-term durability over 100 h for H_(2)O_(2)electrosynthesis at~120 mA cm^(-2).In addition,coupling anodic ethylene glycol oxidation reaction(EGOR)further improves the efficiency and economic viability of the H_(2)O_(2)electrosynthesis system.This two-pronged strategy thus opens up a new opportunity for the development of stable H_(2)O_(2)electrosynthesis with low energy consumption and superior economic performance.展开更多
Gaining in-depth insights into the effects of particle shapes and packing style on ethylene oxidation reaction is of paramount industrial importance.In this work,reactor models of five packing structures with differen...Gaining in-depth insights into the effects of particle shapes and packing style on ethylene oxidation reaction is of paramount industrial importance.In this work,reactor models of five packing structures with different particle shapes and three packing structures with different packing styles are established by employing software Blender and COMSOL Multiphysics to explore how the reaction-diffusion behaviors affect ethylene oxidation process.The reliabilities of rigid body dynamics model and particle-resolved reactor model are verified by comparing simulated and experimental pressure drops and ethylene conversions.In all the five packing structures with laminar flow conditions,the high bed porosity and low total particle surface area for the trilobe packing structure give rise to the lowest pressure drop of 27.8 Pa/m,while the internal voids cutting mode provides the excellent heat transfer capacity for the Raschig ring packing structure and the highest ethylene conversion and thereby the highest bed temperature rise of 25.1 K for the four-hole cylinder packing structure.Based on these analyses,changing the packing style to the bottom-up Raschig ring-four hole cylinder packing structure would be a good strategy for the effectively lowered reactor temperature rise by 4.8 K together with the slightly reduced ethylene conversion.展开更多
For future clean energy demand,it is essential to develop highly efficient and durable materials for use in renewable energy conversion devices.Herein,we report an electrocatalyst loaded with Pd-Pb-Bi nanoalloys on re...For future clean energy demand,it is essential to develop highly efficient and durable materials for use in renewable energy conversion devices.Herein,we report an electrocatalyst loaded with Pd-Pb-Bi nanoalloys on reduced graphene(rGO)-wrapped In_(2)O_(3)(PdPbBi@rGO/In_(2)O_(3))prepared by a hydrothermal method.PdPbBi@rGO/In_(2)O_(3)exhibits higher forward current density(229.12 mA·cm^(-2)),larger electrochemical active surface area(ECSA)(85.87 m^(2)·g^(-1)Pd),smaller impedance(12.68Ω)and lower E_(onset)(-0.56 V)than commercial Pd/C.Specifically,the current density and ECS A are 8.46 and3.38 times higher than those of commercial Pd/C(27.07 mA·cm^(-2),25.41 m^(2)·g^(-1)Pd),respectively.Furthermore,the oxidation mechanism of ethylene glycol and the removal of carbon monoxide[CO]_(ads)from the surface of Pd are also discussed in detail.The columnar support structure wrapped by rGO provides a huge active surface area for catalysis.Moreover,the electronic effect of Pd-PbBi nanoalloys can accelerate the removal of CO intermediate species,obtain more Pd active sites and improve the electrocatalytic performance.Our first synthesis of this highly electrocatalyst offers promising value for commercial application in direct fuel cells.展开更多
The research of poly(ethylene oxide)(PEO)-based solid composite electrolyte with high ionic conductivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion batteries(ASSLI...The research of poly(ethylene oxide)(PEO)-based solid composite electrolyte with high ionic conductivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion batteries(ASSLIBs). Herein, uniform nanorod structured CeO_(2) fillers were controllably synthesized by electrospinning, which were subsequently filled into PEO polymer to prepare CeO_(2)/PEO solid composite electrolyte. The addition of CeO_(2) nanorods can reduce both the glass transition temperature and the melting point of PEO polymer, and also interact with PEO and lithium bis(trifluoromethanesulphonyl)imide(LITFSI) by Lewis acid—base reaction. Therefore, the solid composite electrolyte exhibits a high ionic conductivity of 4.52 × 10^(-4)S/cm, a wide electrochemical stability window of about 4.8 V, and a good interfacial stability with Li at 55℃. Moreover, the LiFePO_4/Li ASSLIB divulges the discharging specific capacity of 165, 162, 156 and 146 mA,h/g at 0.2, 0.5, 1 and 2 C, respectively, and achieves the capacity retention of 90.3% after 150 cycles at 0.5 C. Consequently, one dimensional CeO_(2) nanorods can be considered as an alternative filler for polymeric solid electrolyte.展开更多
Recently,poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been attracting great attention,and efforts are currently underway to develop PEO-based composite electrolytes for next generation high performa...Recently,poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been attracting great attention,and efforts are currently underway to develop PEO-based composite electrolytes for next generation high performance all-solid-state lithium metal batteries.In this article,a novel sandwich structured solid-state PEO composite electrolyte is developed for high performance all-solid-state lithium metal batteries.The PEO-based composite electrolyte is fabricated by hot-pressing PEO,LiTFSI and Ti_(3)C_(2)T_(x) MXene nanosheets into glass fiber cloth(GFC).The as-prepared GFC@PEO-MXene electrolyte shows high mechanical properties,good electrochemical stability,and high lithium-ion migration number,which indicates an obvious synergistic effect from the microscale GFC and the nanoscale MXene.Such as,the GFC@PEO-1 wt%MXene electrolyte shows a high tensile strength of 43.43 MPa and an impressive Young's modulus of 496 MPa,which are increased by 1205%and 6048%over those of PEO.Meanwhile,the ionic conductivity of GFC@PEO-1 wt%MXene at 60℃ reaches 5.01×10^(-2) S m^(-1),which is increased by around 200%compared with that of GFC@PEO electrolyte.In addition,the Li/Li symmetric battery based on GFC@PEO-1 wt%MXene electrolyte shows an excellent cycling stability over 800 h(0.3 mA cm^(-2),0.3 mAh cm^(-2)),which is obviously longer than that based on PEO and GFC@PEO electrolytes due to the better compatibility of GFC@PEO-1 wt%MXene electrolyte with Li anode.Furthermore,the solid-state Li/LiFePO_(4) battery with GFC@PEO-1 wt%MXene as electrolyte demonstrates a high capacity of 110.2–166.1 mAh g^(-1) in a wide temperature range of 25–60C,and an excellent capacity retention rate.The developed sandwich structured GFC@PEO-1 wt%MXene electrolyte with the excellent overall performance is promising for next generation high performance all-solid-state lithium metal batteries.展开更多
The mechanism of the oxide extraction reaction between singlet germylene carbene and its derivatives X2Ge=C： （X=H, F, Cl, CH3） and ethylene oxide has been investigated with B3LYP/6-311G（d,p） method. The results s...The mechanism of the oxide extraction reaction between singlet germylene carbene and its derivatives X2Ge=C： （X=H, F, Cl, CH3） and ethylene oxide has been investigated with B3LYP/6-311G（d,p） method. The results show that this kind of reaction has similar mechanism, the shift of 2p lone electron pair of O in ethylene oxide to the 2p unoccupied orbital of C in X2Ge=C： gives a p→p donor-acceptor bond, thereby leading to the formation of intermediate. As the p→p donor-acceptor bond continues to strengthen, that is the C-O bond continues to shorten, the intermediate generates product （P＋C2H4） via transition state. It is the substituent electronegativity that mainly affect the extraction reactions. When the substituent electronegativity is greater, the energy barrier is lower, and the reaction rate is greater.展开更多
Low ionic conductivity is a major obstacle for polymer solid-state electrolytes.In response to this issue,a design concept of enhanced regional electric potential difference(EREPD)is proposed to modulate the interacti...Low ionic conductivity is a major obstacle for polymer solid-state electrolytes.In response to this issue,a design concept of enhanced regional electric potential difference(EREPD)is proposed to modulate the interaction of nanofillers with other components in the composite polymer solid-state electrolytes(CPSEs).While ensuring the periodic structure of the graphdiyne(GDY)backbone,methoxysubstituted GDY(OGDY)is prepared by an asymmetric substitution strategy,which increases the electric potential differences within each repeating unit of GDY.The staggered distributed electron-rich regions and electron-deficient regions on the two-dimensional plane of OGDY increase the free Li^(+)concentration through Lewis acid-base pair interaction.The adjacent ERRs and EDRs form uniformly distributed EREPDs,creating a continuous potential gradient that synergistically facilitates the efficient migration of Li^(+).Impressively,the OGDY/poly(ethylene oxide)(PEO)exhibits a high ionic conductivity(1.1×10^(-3)S cm^(−1))and ion mobility number(0.71).In addition,the accelerated Li^(+)migration promotes the formation of uniform and dense SEI layers and inhibits the growth of lithium dendrites.As a proof of concept,Li||Li symmetric cell and Li||LiFePO_(4)full cell and pouch cell assembled with OGDY/PEO exhibit good performance,highlighting the effectiveness of our EREPD design strategy for improving CPSEs performance.展开更多
At present,replacing the liquid electrolyte in a lithium metal battery with a solid electrolyte is considered to be one of the most powerful strategies to avoid potential safety hazards.Composite solid electrolytes(CP...At present,replacing the liquid electrolyte in a lithium metal battery with a solid electrolyte is considered to be one of the most powerful strategies to avoid potential safety hazards.Composite solid electrolytes(CPEs)have excellent ionic conductivity and flexibility owing to the combination of functional inorganic materials and polymer solid electrolytes(SPEs).Nevertheless,the ionic conductivity of CPEs is still lower than those of commercial liquid electrolytes,so the development of high-performance CPEs has important practical significance.Herein,a novel fast lithium-ion conductor material LiTa_(2)PO_(8) was first filled into poly(ethylene oxide)(PEO)-based SPE,and the optimal ionic conductivity was achieved by filling different concentrations(the ionic conductivity is 4.61×10^(-4)S/cm with a filling content of 15 wt%at 60℃).The enhancement in ionic conductivity is due to the improvement of PEO chain movement and the promotion of LiTFSI dissociation by LiTa_(2)PO_(8).In addition,LiTa_(2)PO_(8) also takes the key in enhancing the mechanical strength and thermal stability of CPEs.The assembled LiFePO_(4) solid-state lithium metal battery displays better rate performance(the specific capacities are as high as 157.3,152,142.6,105 and 53.1 mAh/g under0.1,0.2,0.5,1 and 2 C at 60℃,respectively)and higher cycle performance(the capacity retention rate is86.5%after 200 cycles at 0.5 C and 60℃).This research demonstrates the feasibility of LiTa_(2)PO_(8) as a filler to improve the performance of CPEs,which may provide a fresh platform for developing more advanced solid-state electrolytes.展开更多
Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (e...Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.展开更多
Triethylene glycol monoethyl ether(CH_(3)CH_(2)O-(CH_(2)CH_(2)O)_(3)H,EtO(EO)_(3)H)is a valuable finechemical material.Its unique physical properties andchemical characteristics make it a major component ofthe super b...Triethylene glycol monoethyl ether(CH_(3)CH_(2)O-(CH_(2)CH_(2)O)_(3)H,EtO(EO)_(3)H)is a valuable finechemical material.Its unique physical properties andchemical characteristics make it a major component ofthe super brake fluid for automobiles[1,2].In general,EtO(EO)_(3)H is synthesized from the ethoxylation re-action of ethanol with ethylene oxide(EO)in thepresence of the KOH catalyst.展开更多
Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid el...Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.展开更多
The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).L...The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).Li-ion can transfer along the PEO chain or across the layer of TpPa-SO_(3) Li within the nanochannels,resulting in a high Li-ion conductivity of3.01×10^(-4)S/cm at 60℃.When the CPE with 0.75 wt.%TpPa-SO_(3) Li was used in the LiFePO_(4)‖Li solid-state battery,the cell delivered a stable capacity of 125 mA·h/g after 250 cycles at 0.5 C,60℃.In comparison,the cell using the CPE without TpPa-SO_(3) Li exhibited a capacity of only 118 mA·h/g.展开更多
Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic ac...Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.展开更多
Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ ...Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ AlR_3-H_2O (R=ethyl, iso-butyl) catalysts gavehigher molecular weight (M_w～10~4), while Al(OR)_3 catalysts gave the higher alternatingcopolymer structure with slightly lower molecular weight. The in-situ AlR_3-H_2O systemshave been evaluated in more detail for the reaction which showed the optimum H_2O/Almolar ratio to be 0.5. The copolymers with different composition (F_(SA)/F_(EO)= 36/64to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melt-ing point (T_m), glass transition temperature (T_g) and enthalpy of fusion (ΔH_f) of thesecopolymers are depended on the copolymer composition and in the range of 87～102℃,-12～-18℃, and 37～66J/g, respectively. The second heating scan of DSC also in-dicated that the higher alternating copolymer was more easily recrystallized. The onsetdecomposition temperature was more than 300℃ under nitrogen and influenced by thecopolymer composition.展开更多
Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H...Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H-1-NMR analysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecular weight copolymers with various EO content were obtained and their values of molecular weight distribution (MWD) fell in the range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used, The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.展开更多
文摘Ethylene glycol(EG)is a biomass derivative of polyethylene terephthalate(PET),and its electrocatalytic conversion into high-value chemicals has sparked widespread interest.This study reviews the most recent research development in electrocatalysis-based EG to glycolic acid(GA)conversion.Firstly,the strategies and research results of modulating the electronic structure of catalysts for efficient selective GA production from EG are reviewed.Second,by reviewing the data of in-situ Fourier transform infrared spectroscopy and in-situ electrochemically attenuated total reflection surface enhanced infrared absorption spectroscopy,the reaction pathway and catalytic mechanism of EG partial oxidation to GA were clarified.Finally,the design and regulation of catalysts for selective oxidation of EG by electrocatalysis in the future are prospected.
基金the financial support of the Hubei Key Laboratory for Processing and Application of Catalytic Materials(202440704)the National Natural Science Foundation of China(22102125)The financial support of the Open Research Fund(2024JYBKF06)of Key Laboratory of Material Chemistry for Energy Conversion and Storage,Ministry of Education is also acknowledged.
文摘Ethylene glycol oxidation reaction(EGOR)is important to address the environmental issues caused by the increased production of polyethylene terephthalate(PET).Metal organic frameworks(MOFs)with superior stability,high specific surface area and excellent catalytic performance can convert PET into valuable products through EGOR and hydrogen evolution reaction(HER).Herein,a microbial template strategy was adopted to prepare carbon sphere-supported orthogonal nanosheet bimetallic MOF catalysts.The prepared catalyst needs only 1.42 V,307 mV,and 1.83 V at a current density of 100 mA cm^(-2) for EGOR,HER,and EGOR//HER,respectively.More importantly,it can stably perform for at least 160 h at a current density of 500 mA cm^(-2).The high specific surface area of bimetallic MOF and the synergistic effect of yeast carbon shell increase the contact area between the intrinsic active sites and*OH and EG,thus improving the EGOR and HER catalytic activity and stability.This work provides a novel strategy to construct bimetallic orthogonal electrocatalysts with efficient HER//EGOR performance,which is of great significance for achieving sustainable energy conversion and environmental purification.
基金supported by Zhejiang Provincial Natural Science Foundation of China(No.LTGS23B030002)the National Natural Science Foundation of China(Nos.21978111 and 22278175)。
文摘Traditional photo-electcatalyst structures of small noble metal nanoparticles assembling into large-scale photoactive semiconductors still suffer from agglomeration of noble metal nanoparticles,insufficient charge transfer,undesirable photoresponse ability that restricted the photo-electrocatalytic performance.To this end,a novel design strategy is proposed in this work,namely integrating small-scale photoactive materials(doped graphene quantum dots,S,N-GQDs)with large-sized noble metal(Pd P)nanoflowers to form novel photo-electrocatalysts for high-efficient alcohol oxidation reaction.As expected,superior electrocatalytic performance of Pd P/S,N-GQDs for ethylene glycol oxidation is acquired,thanks to the nanoflower structure with larger specific surface area and abundant active sites.Furthermore,nonmetal P are demonstrated,especially optimizing the adsorption strength,enhancing the interfacial contact,reducing metal agglomeration,ensuring uniform and efficient doping of S,N-GQDs,and ultimately significantly boost the catalytic activity of photo-electrocatalysts.
基金financially supported by the Maoming Science and Technology Bureau(No.2022DZXHT007)。
文摘The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.
基金supported by the Key-Area Research and Development Program of Guangdong Province(No.2023B0101200006)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011926)+1 种基金Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates,Guangzhou 510640,China(South China University of Technology)(No.2023B1212060003)State Key Laboratory of Applied Microbiology Southern China(No.SKLAM008-2022)。
文摘The dynamics of the drying process of polymer solutions are important for the development of coatings and films.In the present work,digital holographic microscopy(DHM)was performed to capture the drying dynamics of poly(ethylene oxide)(PEO)droplets using a gold nanoparticle tracer,where the heterogeneous flow field in different regions was illustrated.This demonstrates that the gold nanoparticles at either the center or the edge regions of the droplet exhibit anisotropic kinematic behavior.At early stage,Marangoni backflow causes gold nanoparticles to move towards the edge firstly,and the circles back towards the droplet center after arriving the contact line with a sudden increase in z axis for 10.4μm,indicating the scale of the upward-moving microscopic flow vortices.This phenomenon does not occur in water droplets in the absence of polymers.The gold nanoparticles underwent Brownian-like motion at the center of the PEO droplet or water droplet owing to the low perturbation of the flow field.At the late stage of pinning of the PEO droplets,the motion showed multiple reverses in the direction of the gold nanoparticles,indicating the complexity of the flow field.This study enhances the understanding of the drying dynamics of polymer solution droplets and offers valuable insights into the fabrication of surface materials.
基金supported by the National Natural Science Foundation of China(22379111 and 22179093)。
文摘Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal sites in the state-of-the-art metal single-atom catalysts(M-SACs)hinders their further industrial applications,and the high potential and valueless oxygen product of the conventional anodic oxygen evolution reaction(OER)further limit the economic efficiency of this technology.To address this,a dynamically local structure reconstruction strategy is proposed to in situ transfer the active sites from unstable metal sites to the stable surrounding carbon sites for efficient and durable 2e^(-)ORR electrocatalysis.For the as-designed Mn-N_(3)O-C catalyst,by reconstructing Mn sites into Mn(^(*)OH),the Mn sites were passivated and carbon sites adjacent to the O atom were verified to be the actual active sites by in situ characterization and theoretical calculation.Consequently,Mn-N_(3)O-C exhibited>80%Faradaic efficiency and superior long-term durability over 100 h for H_(2)O_(2)electrosynthesis at~120 mA cm^(-2).In addition,coupling anodic ethylene glycol oxidation reaction(EGOR)further improves the efficiency and economic viability of the H_(2)O_(2)electrosynthesis system.This two-pronged strategy thus opens up a new opportunity for the development of stable H_(2)O_(2)electrosynthesis with low energy consumption and superior economic performance.
基金financially supported by the National Key R&D Program of China(grant No.2022YFA1503503)the National Natural Science Foundation of China(grant No.22038003,21922803,22178100 and 22008066)+1 种基金the Innovation Program of Shanghai Municipal Education Commission,the Program of Shanghai Academic/Technology Research Leader(grant No.21XD1421000)the Shanghai Science and Technology Innovation Action Plan(grant No.22JC1403800).
文摘Gaining in-depth insights into the effects of particle shapes and packing style on ethylene oxidation reaction is of paramount industrial importance.In this work,reactor models of five packing structures with different particle shapes and three packing structures with different packing styles are established by employing software Blender and COMSOL Multiphysics to explore how the reaction-diffusion behaviors affect ethylene oxidation process.The reliabilities of rigid body dynamics model and particle-resolved reactor model are verified by comparing simulated and experimental pressure drops and ethylene conversions.In all the five packing structures with laminar flow conditions,the high bed porosity and low total particle surface area for the trilobe packing structure give rise to the lowest pressure drop of 27.8 Pa/m,while the internal voids cutting mode provides the excellent heat transfer capacity for the Raschig ring packing structure and the highest ethylene conversion and thereby the highest bed temperature rise of 25.1 K for the four-hole cylinder packing structure.Based on these analyses,changing the packing style to the bottom-up Raschig ring-four hole cylinder packing structure would be a good strategy for the effectively lowered reactor temperature rise by 4.8 K together with the slightly reduced ethylene conversion.
基金financially supported by the Key Laboratory of Organic Functional Molecule Synthesis and Applications,Ministry of Education(No.KLSAOFM1913)。
文摘For future clean energy demand,it is essential to develop highly efficient and durable materials for use in renewable energy conversion devices.Herein,we report an electrocatalyst loaded with Pd-Pb-Bi nanoalloys on reduced graphene(rGO)-wrapped In_(2)O_(3)(PdPbBi@rGO/In_(2)O_(3))prepared by a hydrothermal method.PdPbBi@rGO/In_(2)O_(3)exhibits higher forward current density(229.12 mA·cm^(-2)),larger electrochemical active surface area(ECSA)(85.87 m^(2)·g^(-1)Pd),smaller impedance(12.68Ω)and lower E_(onset)(-0.56 V)than commercial Pd/C.Specifically,the current density and ECS A are 8.46 and3.38 times higher than those of commercial Pd/C(27.07 mA·cm^(-2),25.41 m^(2)·g^(-1)Pd),respectively.Furthermore,the oxidation mechanism of ethylene glycol and the removal of carbon monoxide[CO]_(ads)from the surface of Pd are also discussed in detail.The columnar support structure wrapped by rGO provides a huge active surface area for catalysis.Moreover,the electronic effect of Pd-PbBi nanoalloys can accelerate the removal of CO intermediate species,obtain more Pd active sites and improve the electrocatalytic performance.Our first synthesis of this highly electrocatalyst offers promising value for commercial application in direct fuel cells.
基金Project supported by the Education Department of Henan Province(22A170017)the Science and Technology Department of Henan Province(232102240011)+1 种基金Henan Institute of Science and Technology(2016034)National College Students'Innovation and Entrepreneurship Training Program(202211071012)。
文摘The research of poly(ethylene oxide)(PEO)-based solid composite electrolyte with high ionic conductivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion batteries(ASSLIBs). Herein, uniform nanorod structured CeO_(2) fillers were controllably synthesized by electrospinning, which were subsequently filled into PEO polymer to prepare CeO_(2)/PEO solid composite electrolyte. The addition of CeO_(2) nanorods can reduce both the glass transition temperature and the melting point of PEO polymer, and also interact with PEO and lithium bis(trifluoromethanesulphonyl)imide(LITFSI) by Lewis acid—base reaction. Therefore, the solid composite electrolyte exhibits a high ionic conductivity of 4.52 × 10^(-4)S/cm, a wide electrochemical stability window of about 4.8 V, and a good interfacial stability with Li at 55℃. Moreover, the LiFePO_4/Li ASSLIB divulges the discharging specific capacity of 165, 162, 156 and 146 mA,h/g at 0.2, 0.5, 1 and 2 C, respectively, and achieves the capacity retention of 90.3% after 150 cycles at 0.5 C. Consequently, one dimensional CeO_(2) nanorods can be considered as an alternative filler for polymeric solid electrolyte.
基金support of the Fundamental Research Funds for the Central Universities(No.2022CDJQY-004)the Fund for Innovative Research Groups of Natural Science Foundation of Hebei Province(No.A2020202002).
文摘Recently,poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been attracting great attention,and efforts are currently underway to develop PEO-based composite electrolytes for next generation high performance all-solid-state lithium metal batteries.In this article,a novel sandwich structured solid-state PEO composite electrolyte is developed for high performance all-solid-state lithium metal batteries.The PEO-based composite electrolyte is fabricated by hot-pressing PEO,LiTFSI and Ti_(3)C_(2)T_(x) MXene nanosheets into glass fiber cloth(GFC).The as-prepared GFC@PEO-MXene electrolyte shows high mechanical properties,good electrochemical stability,and high lithium-ion migration number,which indicates an obvious synergistic effect from the microscale GFC and the nanoscale MXene.Such as,the GFC@PEO-1 wt%MXene electrolyte shows a high tensile strength of 43.43 MPa and an impressive Young's modulus of 496 MPa,which are increased by 1205%and 6048%over those of PEO.Meanwhile,the ionic conductivity of GFC@PEO-1 wt%MXene at 60℃ reaches 5.01×10^(-2) S m^(-1),which is increased by around 200%compared with that of GFC@PEO electrolyte.In addition,the Li/Li symmetric battery based on GFC@PEO-1 wt%MXene electrolyte shows an excellent cycling stability over 800 h(0.3 mA cm^(-2),0.3 mAh cm^(-2)),which is obviously longer than that based on PEO and GFC@PEO electrolytes due to the better compatibility of GFC@PEO-1 wt%MXene electrolyte with Li anode.Furthermore,the solid-state Li/LiFePO_(4) battery with GFC@PEO-1 wt%MXene as electrolyte demonstrates a high capacity of 110.2–166.1 mAh g^(-1) in a wide temperature range of 25–60C,and an excellent capacity retention rate.The developed sandwich structured GFC@PEO-1 wt%MXene electrolyte with the excellent overall performance is promising for next generation high performance all-solid-state lithium metal batteries.
文摘The mechanism of the oxide extraction reaction between singlet germylene carbene and its derivatives X2Ge=C： （X=H, F, Cl, CH3） and ethylene oxide has been investigated with B3LYP/6-311G（d,p） method. The results show that this kind of reaction has similar mechanism, the shift of 2p lone electron pair of O in ethylene oxide to the 2p unoccupied orbital of C in X2Ge=C： gives a p→p donor-acceptor bond, thereby leading to the formation of intermediate. As the p→p donor-acceptor bond continues to strengthen, that is the C-O bond continues to shorten, the intermediate generates product （P＋C2H4） via transition state. It is the substituent electronegativity that mainly affect the extraction reactions. When the substituent electronegativity is greater, the energy barrier is lower, and the reaction rate is greater.
基金supported by the National Key Research and Development Project of China(2022YFA1204500,2022YFA1204503,2018YFA0703501)the National Natural Science Foundation of China(22275115,21875274,11704024)+4 种基金the Natural Science Foundation of Shandong Province(ZR2024ZD02)Natural Science Foundation of Hebei Province(B2020201006)Hebei Province Innovation Capability Enhancement Plan Project(22567620H)Young Scholarship Funding of Shandong University.Post-graduate Innovation Fund Project of Open Laboratory Project Fund of Hebei University(HBU2025SS010)Basic Research Project of Shandong University-Xin’an Group Silicon-Based High-End New Materials Institute.
文摘Low ionic conductivity is a major obstacle for polymer solid-state electrolytes.In response to this issue,a design concept of enhanced regional electric potential difference(EREPD)is proposed to modulate the interaction of nanofillers with other components in the composite polymer solid-state electrolytes(CPSEs).While ensuring the periodic structure of the graphdiyne(GDY)backbone,methoxysubstituted GDY(OGDY)is prepared by an asymmetric substitution strategy,which increases the electric potential differences within each repeating unit of GDY.The staggered distributed electron-rich regions and electron-deficient regions on the two-dimensional plane of OGDY increase the free Li^(+)concentration through Lewis acid-base pair interaction.The adjacent ERRs and EDRs form uniformly distributed EREPDs,creating a continuous potential gradient that synergistically facilitates the efficient migration of Li^(+).Impressively,the OGDY/poly(ethylene oxide)(PEO)exhibits a high ionic conductivity(1.1×10^(-3)S cm^(−1))and ion mobility number(0.71).In addition,the accelerated Li^(+)migration promotes the formation of uniform and dense SEI layers and inhibits the growth of lithium dendrites.As a proof of concept,Li||Li symmetric cell and Li||LiFePO_(4)full cell and pouch cell assembled with OGDY/PEO exhibit good performance,highlighting the effectiveness of our EREPD design strategy for improving CPSEs performance.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.52073212,51772205,51772208)the General Program of Municipal Natural Science Foundation of Tianjin(Nos.17JCYBJC17000,17JCYBJC22700)。
文摘At present,replacing the liquid electrolyte in a lithium metal battery with a solid electrolyte is considered to be one of the most powerful strategies to avoid potential safety hazards.Composite solid electrolytes(CPEs)have excellent ionic conductivity and flexibility owing to the combination of functional inorganic materials and polymer solid electrolytes(SPEs).Nevertheless,the ionic conductivity of CPEs is still lower than those of commercial liquid electrolytes,so the development of high-performance CPEs has important practical significance.Herein,a novel fast lithium-ion conductor material LiTa_(2)PO_(8) was first filled into poly(ethylene oxide)(PEO)-based SPE,and the optimal ionic conductivity was achieved by filling different concentrations(the ionic conductivity is 4.61×10^(-4)S/cm with a filling content of 15 wt%at 60℃).The enhancement in ionic conductivity is due to the improvement of PEO chain movement and the promotion of LiTFSI dissociation by LiTa_(2)PO_(8).In addition,LiTa_(2)PO_(8) also takes the key in enhancing the mechanical strength and thermal stability of CPEs.The assembled LiFePO_(4) solid-state lithium metal battery displays better rate performance(the specific capacities are as high as 157.3,152,142.6,105 and 53.1 mAh/g under0.1,0.2,0.5,1 and 2 C at 60℃,respectively)and higher cycle performance(the capacity retention rate is86.5%after 200 cycles at 0.5 C and 60℃).This research demonstrates the feasibility of LiTa_(2)PO_(8) as a filler to improve the performance of CPEs,which may provide a fresh platform for developing more advanced solid-state electrolytes.
基金Supported by the National Natural Science Foundation of China and the State Education Committee of China
文摘Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.
文摘Triethylene glycol monoethyl ether(CH_(3)CH_(2)O-(CH_(2)CH_(2)O)_(3)H,EtO(EO)_(3)H)is a valuable finechemical material.Its unique physical properties andchemical characteristics make it a major component ofthe super brake fluid for automobiles[1,2].In general,EtO(EO)_(3)H is synthesized from the ethoxylation re-action of ethanol with ethylene oxide(EO)in thepresence of the KOH catalyst.
基金The authors would like to acknowledge the financial support from National Nat-ural Science Foundation of China (U2004199)Excellent Youth Foundation of Henan Province (202300410373)+2 种基金China Postdoctoral Science Foundation (2021T140615 and 2020M672281)Natural Science Foundation of Henan Province (212300410285)Young Talent Support Project of Henan Province(2021HYTP028).
文摘Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.
基金supported by the State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)the National Natural Science Foundation of China(Nos.21878216,22005215)+1 种基金Hebei Province Innovation Ability Promotion Project(No.20312201D)the National Key Research and Development Program of China(No.2019YFE0118800)。
文摘The lithiated covalent organic framework(named TpPa-SO_(3) Li),which was prepared by a mild chemical lithiation strategy,was introduced in poly(ethylene oxide)(PEO)to produce the composite polymer electrolytes(CPEs).Li-ion can transfer along the PEO chain or across the layer of TpPa-SO_(3) Li within the nanochannels,resulting in a high Li-ion conductivity of3.01×10^(-4)S/cm at 60℃.When the CPE with 0.75 wt.%TpPa-SO_(3) Li was used in the LiFePO_(4)‖Li solid-state battery,the cell delivered a stable capacity of 125 mA·h/g after 250 cycles at 0.5 C,60℃.In comparison,the cell using the CPE without TpPa-SO_(3) Li exhibited a capacity of only 118 mA·h/g.
文摘Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.
文摘Ring opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO)was successfully carried out by using a series of aluminum-based catalyst in 1,4-dioxane at62±2℃. The results showed that in-situ AlR_3-H_2O (R=ethyl, iso-butyl) catalysts gavehigher molecular weight (M_w～10~4), while Al(OR)_3 catalysts gave the higher alternatingcopolymer structure with slightly lower molecular weight. The in-situ AlR_3-H_2O systemshave been evaluated in more detail for the reaction which showed the optimum H_2O/Almolar ratio to be 0.5. The copolymers with different composition (F_(SA)/F_(EO)= 36/64to 45/55 mol/mol) were synthesized by using different monomer feed ratio. The melt-ing point (T_m), glass transition temperature (T_g) and enthalpy of fusion (ΔH_f) of thesecopolymers are depended on the copolymer composition and in the range of 87～102℃,-12～-18℃, and 37～66J/g, respectively. The second heating scan of DSC also in-dicated that the higher alternating copolymer was more easily recrystallized. The onsetdecomposition temperature was more than 300℃ under nitrogen and influenced by thecopolymer composition.
文摘Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complex as the catalyst was carried out. The structure of random copolymers was confirmed by C-13-NMR and IR spectra. H-1-NMR analysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecular weight copolymers with various EO content were obtained and their values of molecular weight distribution (MWD) fell in the range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used, The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.
