Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environme...Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environmental pollution globally.Recognized as very persistent and very bioaccumulative(vPvB),compounds such as octamethylcyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5),and dodecamethylcyclohexasiloxane(D6)are regulated in the European Union[2]and are monitored worldwide.展开更多
Biogas can be used as an alternative energy source for producing heat and electricity;however, volatile methylsiloxanes(VOSiC) present in biogas can severely damage heat exchangers, turbines and gas engines. Consequen...Biogas can be used as an alternative energy source for producing heat and electricity;however, volatile methylsiloxanes(VOSiC) present in biogas can severely damage heat exchangers, turbines and gas engines. Consequently, e cient removal of VOSiC from biogas that is used as a biofuel is required. In this work, acetylated silica gel(Ac@SG) was synthesized,via treatment of microporous silica gel(SG) with acetic anhydride as an adsorbent, for removal of VOSiC from biogas,and characterized with XRD, SEM–EDS, N2-BET and FT-IR. This Ac@SG adsorbent exhibited a meso-/microporous structure and hydrophobic surface, indicating it was a more e cient adsorbent for removing hexamethyldisiloxane(L2) and octamethylcyclotetrasiloxane(D4) from biogas samples than conventional SG. It was found that the adsorption capacities of Ac@SG reached 304 mg L2/g for hexamethyldisiloxane and 916 mg D4/g for octamethylcyclotetrasiloxane at lower temperatures in the experimental range, and water had no significant e ect on its absorption e ciency. The used Ac@SG could be easily regenerated by heating it at 110 °C, and the adsorption capacity of recycled Ac@SG for hexamethyldisiloxane and octamethylcyclotetrasiloxane was kept constant in four recycle adsorption experiments.展开更多
Landfill biogas is a potential alternative for fossil fuel,but the containing impurities,volatile methyl siloxanes(simplified as siloxanes),often cause serious problems in gas turbines when applied to generate electri...Landfill biogas is a potential alternative for fossil fuel,but the containing impurities,volatile methyl siloxanes(simplified as siloxanes),often cause serious problems in gas turbines when applied to generate electricity.In this research,a collecting and analyzing method based on solvent adsorption and purge and trap-gas chromatography-mass spectrometry was established to determine the siloxanes in biogas from a landfill in Jinan,China,and adjacent ambient samples,such as soil,air,and leachate of the landfill.The results showed that,octamethylcyclotetrasiloxane(D4)and decamethylcyclopentasiloxane(D5)accounted for 63%of total siloxanes;and without considering D4 and D5,the order of detected siloxanes in concentration was found relating to Gibbs free energies of molecules,namely that higher abundant siloxane(except for D4 and D5)usually had lower Gibbs free energy.Additionally,the mass ratio between D4 and octamethyltrisiloxane(L3)in the bio gas varied with different garbage age in landfills,possibly revealing the breaking-down of larger siloxane molecules with time.The samples,which were collected from environmental samples adjacent to the landfill,such as soil,water,and air,presented much higher siloxane level than urban or rural area away from landfills.The current H2 S scrubber of the landfill biogas could decrease the total siloxanes from 10.7 to 5.75 mg/m^3 due to Fe2 O3 and a refrigerant drier in a purification system and cyclic siloxanes were more easily removed than linear ones.展开更多
In this study,we introduce a method for directly synthesizing various siloxanes from hydrosilanes and silanols under ambient conditions.This process relies on the use of Stryker’s reagent([(PPh_(3))CuH]_(6))as the fi...In this study,we introduce a method for directly synthesizing various siloxanes from hydrosilanes and silanols under ambient conditions.This process relies on the use of Stryker’s reagent([(PPh_(3))CuH]_(6))as the first copper catalyst,enabling this specific cross-dehydrogenative coupling.This method stands out for its exceptional chemoselectivity,making it a superb alternative to established catalytic systems.It operates under mild conditions yet maintains high process efficiency.Throughout the investigation,we demonstrated the potential for modifying the resulting hydrosiloxanes through alcoholysis to produce silyl ethers and via hydrosilylation to yield functionalized siloxanes.展开更多
Apart from some specific synthetic solutions,a dehydrogenative coupling of silanols with hydrosilanes seems to be the most atom-economical and practical method for the formation of unsymmetrical silox-anes.This goal w...Apart from some specific synthetic solutions,a dehydrogenative coupling of silanols with hydrosilanes seems to be the most atom-economical and practical method for the formation of unsymmetrical silox-anes.This goal was accomplished by simple main-group catalysis,utilizing commercially available reagents under mild conditions.展开更多
In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into ...In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into D_(n) cyclosiloxane frameworks(D=(SiMe_(2)O),n=5–8),employing appropriate cation–anion combinations.Starting with the Li^(+)cation we were able to observe the coordination of D_(5) with Li^(+)based on a suitable X-ray structure after reacting D_(5) with LiI and GaI_(3).Due to template effects,the dinuclear coordination compound[Li2(D_(5))(D_(6))(GaI_(4))_(2)](1)was obtained.The direct reaction of D_(6) with LiI and GaI_(3) yields[Li(D_(6))GaI_(4)](2)in quantitative yield.Na^(+)ions could be trapped in D_(6) and D_(7) ligand moieties after the conversion of NaI,GaI_(3),and the respective siloxane.The molecular structure of[Na(D_(6))GaI_(4)](3)reveals a six-fold coordinated Na^(+)ion,which is located on top of the siloxane D_(6).In the case of[Na(D_(7))(DCM)GaI_(4)](4),the larger ligand D_(7) provides 15-crown-5-like geometry in which the sodium ion is coordinated by the ligand in a coplanar fashion and further saturated by the solvent DCM(DCM=dichloromethane).The K^(+)ion was bound within the D_(7) ligand in a similar manner and[K(D_(7))(DCM)GaI_(4)](5)could be characterized.Due to the resemblance of NH_(4)^(+)to K^(+),this cation was also employed for complex formation.Counterintuitively,we were able to synthesize and characterize the first ever non-metal-cyclosiloxane coordination compound.After the conversion of D_(6) with NH_(4)I and GaI_(3),the compound[NH_(4)(D_(7))][Ga_(2)I_(7)](6)was obtained.The ammonium cation favors D_(7) coordination over D_(6),and the willing formation of hydrogen bonding in such a siloxane moiety was realized.As these compounds could be obtained,we also tested the limits of silyl-ether bonding.Therefore,we reacted D_(8) with in situ generated Rb[GaI_(4)]and Cs[GaI_(4)].In the case of Rb^(+),we could cumbersomely characterize[Rb(D_(8))(DCM)GaI_(4)](7)via an X-ray structure,as well as by means of mass spectrometry,but the compound starts decomposing readily in solution.The reaction with the Cs^(+)salt failed.To obtain meaningful spectroscopic data from a Rb^(+)compound and to somehow obtain a Cs^(+)complex,we employed the weakly coordinating anion[Al_(F)]^(−)(Al_(F)^(−)=[Al{OC(CF_(3))_(3)}_(4)]^(−)).The conversion of M[Al_(F)]then yielded 11[M(D_(8))AL_(F)](M=Rb:8;M=Cs^(+):9)in the solid state.Both compounds 8 and 9 were fully characterized.Finally,we aimed at synthesizing 2:1 complexes of such siloxanes.The reactions of excess D_(5) with K[Al_(F)]and D_(6) with Cs[Al_(F)]turned out to be expedient and,in the forms of[K(D_(5))_(2)][Al_(F)](10)and[Cs(D_(6))_(2)][Al_(F)](12),the first ever sandwich-type complexes observed bearing a cyclosiloxane ligand were characterized.展开更多
The synthesis of functionalized linear polysiloxanes has garnered considerable attentions due to their broad applicability.While the selective C−H bond functionalization of dimethylsiloxane monomers or polymers offers...The synthesis of functionalized linear polysiloxanes has garnered considerable attentions due to their broad applicability.While the selective C−H bond functionalization of dimethylsiloxane monomers or polymers offers a promising and versatile approach,it remains a significant synthetic challenge.In this study,we report a mild and efficient iron-catalyzed method for the C−H bond alkylation of both dimethylsiloxane monomers and polysiloxane using polar alkenes as coupling partners.This protocol exhibits broad substrate scope,tolerating a wide range of siloxane/silane substrates and polar alkenes.A variety of functional groups,including amide,ester,ketone,and nitrile,can be readily introduced into the siloxane framework.Functionalized polysiloxanes are accessible either through direct C−H bond functionalization or via copolymerization using the modified monomers.Notably,nitrile-functionalized polysiloxanes display significant photoluminescence properties,offering new opportunities for expanding the application scope of polysiloxane materials.Based on experimental studies,a plausible catalytic mechanism is also proposed.展开更多
Coal cinder is an abundant byproduct of the extensive consumption of coal in industrial production and daily life.Making full use of the cinder is conducive to a low-carbon economy.In this study,inspired by the burnin...Coal cinder is an abundant byproduct of the extensive consumption of coal in industrial production and daily life.Making full use of the cinder is conducive to a low-carbon economy.In this study,inspired by the burning of coal,a new method for constructing a silica-based composite porous material(SiO_(2)-CPM)was developed by combusting a siloxane-modified anthracite coal gel(CSiO_(2) gel).During this process,the combustion product was directly converted into a porous material,and the calorific value of the coal remained nearly unchanged(~98%of the original calorific value was retained),demonstrating the viability of this method for energy-efficient applications.The SiO_(2)-CPM exhibited an ultra-low thermal conductivity(0.036 W/(m·K)at room temperature),outperforming conventional insulation materials(e.g.,cotton~0.05 W/(m·K)).Additionally,it showed enhanced mechanical strength(fracture stress of 41.8 kPa)compared to the powder state of the coal cinder.Experimental results indicate that the amount of siloxane,structure-directing agent,and an acidic environment were critical for mechanical enhancement.The SiO_(2)-CPM showed good dimensional stability against thermal expansion and exhibited excellent thermal insulation and fire resistance even at 900℃.Meanwhile,the SiO_(2)-CPM with complex geometry could be easily fabricated using this method owing to the excellent shaping ability of the CSiO_(2) gel.Compared to conventional methods such as sol-gel synthesis or freeze-drying,this approach for fabricating SiO_(2)-CPM is simpler and cost-effective and allows the direct utilization of coal cinder post-combustion.展开更多
Enhancing the energy density of lithium-ion batteries through high-voltage cathodes holds great pro-mise.However,traditional carbonate-based electrolytes face significant challenges due to limited oxida-tive stability...Enhancing the energy density of lithium-ion batteries through high-voltage cathodes holds great pro-mise.However,traditional carbonate-based electrolytes face significant challenges due to limited oxida-tive stability and poor compatibility with high-nickel materials.This study introduces a novel electrolyte that combines bis(triethoxysilyl)methane(DMSP)as the sole solvent with lithium bis(fluorosulfonyl)imide(LiFSI)as the lithium salt.This formulation significantly improves the stability of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathodes and graphite anodes.The capacity retention of the NCM811 elec-trode increases from 5%to 95%after 1000 cycles at 1 C(3.0-4.5 V),while that of the graphite anode is improved from 22%to 92%after 400 cycles at 0.2 C(0.005-3.0 V).The NCM811//graphite pouch cell exhibits enhanced retention,rising from 12%to 66%at 25℃and from 3%to 65%at 60℃after 300 cycles at 0.2 C.Spectroscopic characterization and theoretical calculations reveal that the steric hindrance of the Si-O-CH_(3)groups in DMSP creates a weakly solvating structure,promoting the formation of Lit^(+)-FSI^(-)ion pairs and aggregation clusters,which enriches the electrode interphase with LiF,Li_(3)N,and Li_(2)SO_(3).Furthermore,DMSP with abundant Si-O effectively enhances the elasticity of the interphase layer,scav-enging harmful substances such as HF and suppressing gas evolution and transition metal dissolution.The simplicity of the DMSP-based electrolyte formulation,coupled with its superior performance,ensures scalability for large-scale manufacturing and practical application in the high-voltage battery.This work provides critical insights into improving interfacial chemistry and addressing compatibility issues in high-voltageNi-rich cathodes.展开更多
Traditional lithium-ion batteries(LIBs)employing liquid electrolytes face inherent safety risks,motivating the development of solid polymer electrolytes(SPEs)like polyethylene oxide(PEO).However,pure PEO suffers from ...Traditional lithium-ion batteries(LIBs)employing liquid electrolytes face inherent safety risks,motivating the development of solid polymer electrolytes(SPEs)like polyethylene oxide(PEO).However,pure PEO suffers from low room-temperature ionic conductivity and poor mechanical strength.Composite solid electrolytes(CSEs)incorporating inorganic filler offer promise but are hindered by poor interfacial compatibility.This study addresses this critical issue through surface engineering.Mercaptopropyl trimethoxysilane(MPTMS)is used to modify garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)particles,introducing thiol groups(-SH)onto their surface.Subsequently,thiol-functionalized LLZTO(LLZTO@MPTMS)participate in the insitu copolymerization of polyethylene glycol methyl methacrylate(PEGMEMA)and crosslinker polyethylene glycol dimethacrylate(PEGDMA),yielding a novel PEO-based CSE(PCSE).The effects of PEGMEMA molecular weight,PEGMEMA/PEGDMA ratio,and LLZTO@MPTMS content have been systematically examined to optimize the electrolyte.The resulting PCSE exhibits an ionic conductivity of 1.20×10^(-4)S·cm^(-1)at 30℃,a lithium-ion transference number of 0.36,and a wide electrochemical stability window up to 5.1 V(vs.Li^(+)/Li).Li/PCSE/Li symmetric cells demonstrate stable cycling for nearly 240 h at 0.05 mA·cm^(-2),indicating enhanced interface compatibility with lithium metal and effective dendrite suppression.Furthermore,LiFePO_(4)/PCSE/Li full cells deliver a high initial discharge capacity of 155.0 mAh·g^(-1)at 0.1 C and retain 76.0%capacity after 100 cycles,alongside excellent rate capability.These results confirm that the combined strategy of LLZTO surface modification with MPTMS and in-situ copolymerization effectively mitigates interfacial issues,presenting a promising material system for high-performance solid-state LIBs.展开更多
Three novel flame retardants containing both phosphorus and silicon elements in their structures,including[（1,1,3,3- tetramethyl-1,3-disiloxanediyl）di-2,1-ethanediyl]bis（diphenylphosphine oxide）（FR-1）,[（2,4,6,8...Three novel flame retardants containing both phosphorus and silicon elements in their structures,including[（1,1,3,3- tetramethyl-1,3-disiloxanediyl）di-2,1-ethanediyl]bis（diphenylphosphine oxide）（FR-1）,[（2,4,6,8-tetramethylcyclotetra-siloxane -2,4,6,8-tetrayl）tetra-2,1-ethanediyl]tetrakis[diphenylphosphine oxide]（FR-2） and 1,3,5,7,9,11,13,15-octakis（di-phenylphosphine oxide-2,1-ethanediyl）pentacyclo[9.5.1.1^（3,9）.l^（5,15）.1^（7,13）]octasiloxane（FR-3） were synthesized by a convenient pathway from the reaction of diphenylphosphine oxide（DPPO） and vinyl-terminated siloxanes under the catalysis of triethylborane. The chemical structures of the target compounds were confirmed by nuclear magnetic resonance（^1H NMR,^13C NMR,^29Si NMR and ^31P NMR）,matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF-MS） and Fourier transform infrared（FT IR） measurements.Thermogravimetric analysis（TGA） results indicated that the new flame retardants possessed good thermal stability both in nitrogen and in air.FR-3 containing polyhedral oligosilsesquioxanes（POSS） moiety exhibited the best thermal properties with a 10%weight loss temperature〉400℃ and a residual weight ratio〉39%at 700℃ .展开更多
Siliconated polyurethane （Si-PU） was synthesized using isophorone diisocyanate （IPDI）, hydroxybutyl-terminated polydimethylsiloxane （PDMS）, polytetramethylene ether glycol （PTMG）, polypropylene glycol （PPG）,...Siliconated polyurethane （Si-PU） was synthesized using isophorone diisocyanate （IPDI）, hydroxybutyl-terminated polydimethylsiloxane （PDMS）, polytetramethylene ether glycol （PTMG）, polypropylene glycol （PPG）, 1,6-hexanediol （HDO）, dimethylol propionic acid （DMPA） and triethylamine （TEA）. Based on butyl acrylate （BA）, 2, 2, 2-trifluoroethylmethacrylate （TFEMA） and Si-PU as a seed emulsion, a novel core-shell type acrylic-polyurethane hybrid emulsion, containing siloxane and fluorine （F-Si-PU）, was prepared by seeded emulsion polymerization. The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy （FTIR） was used to identify the chain structures of Si-PU and F-Si-PU. Investigation of transmission electron microscopy （TEM） confirmed the core-shell structure of F-Si-PU emulsion. Measurement results of water contact angle and the swelling ratio in water and n-octane for cured film showed that the water and the oil resistances for F-Si-PU had been significantly improved at a suitable content of fluorine and siloxane.展开更多
Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emu...Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emulsifiers at (78±2) ℃. The effects of different factors, such as the emulsifier, C-1706 monomer and its feeding manner on the properties of acrylate latex modified by C-1706 were investigated. The particle size distribution and the structure, the configuration, the weather durability and stain resistance of copolymer latex were characterized by particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM) and ultraviolet aging instrument respectively. The results show that SDS to OP-10 as multiple emulsifiers can lead to coordinated efficiency, the optimal emulsifier dosage is 2.4%?3.2%(mass fraction), and the mass ratio of SDS to OP-10 is 1?1? 1?2. The seeded emulsion polymerization can effectively introduce a organic-siloxane bonding in a macromolecule inter polymer, and the obtained acrylate latex modified by organic-siloxane possesses narrow distribution of particle size with mean diameter of 51.8?76.6 nm and has the excellent properties in weather durability and stain-resistance especially.展开更多
In order to inhibit and remove the thin ice and extend the lifetime of the damaged bridge, the self-healing mechanism and hydrophobic performance of asphalt modified by siloxane and polyurethane (ASP) were studied by ...In order to inhibit and remove the thin ice and extend the lifetime of the damaged bridge, the self-healing mechanism and hydrophobic performance of asphalt modified by siloxane and polyurethane (ASP) were studied by dynamic shear rheology (DSR), fluorescence microscope (FM), atomic force microscope (AFM), the fracture-healing-re-fracture test and molecular simulations. The experimental results indicated that the selfhealing capability of ASP increased with increasing heating time and temperature. Furthermore, the addition of siloxane could improve the reaction energy barrier and complex modulus, and it is believed that the self-healing is a viscosity driven process, consisting of two parts namely crack closure and properties recovery. Contact angle of ASP increased with the increasing siloxane content and it deduced that the siloxane could improve the hydrophobic performance of ASP and the ASP molecule model could simulate well the self-healing mechanism and hydrophobic performance of ASP.展开更多
Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient relea...Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.展开更多
Poly[(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)]was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorote...Poly[(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)]was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorotetramethyldisiloxane and dichloromethylsilane.The copolymer was characterized by FT-IR,~1H NMR,differential scanning calorimetry and thermogravimetric analysis.The results show that the copolymer exhibits good processability and cures at low temperatures.The cured copolymer shows high thermal stability.展开更多
The cloudy Silwet L-77 aqueous solution on the concentration range from 0.5%to 50%was investigated by dielectric relaxation spectroscopy.The concentration dependence of phase microstructure was confirmed by means of a...The cloudy Silwet L-77 aqueous solution on the concentration range from 0.5%to 50%was investigated by dielectric relaxation spectroscopy.The concentration dependence of phase microstructure was confirmed by means of analyzing the dielectric parameters of bulk solution.The relaxation behavior was assigned to the interfacial polarization between the micelle and the medium,and the relaxation distribution parameter was used to figure the shape transition from sphere to ellipsoid with the concentration increasing.The synchronous reduction of permittivity and conductivity indicated the formation of the lamellar phase. As compensation,the quantity of the surfactant liquid phase gradually decreased,whose shape constantly kept ellipsoidal.展开更多
Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and poly-tetramethylene oxide in different weight fractions were synthesized. The phase separation ofsamples was studied using DSC and dynami...Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and poly-tetramethylene oxide in different weight fractions were synthesized. The phase separation ofsamples was studied using DSC and dynamic mechanical property analysis. The results showedthat the introduction of chloromethyl group into polysiloxane increased its polarity and henceimproved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensileproperties of these samples can be adjusted by various ratios of two soft segments.展开更多
A hybrimer based on epoxy resin and phenyl-siloxane was prepared by polymerization and a solgel condensation reaction in which Eporite-904 (807 g/eq) bisphenol-A-type epoxy resin, 3-isocyanatopropyltriethoxysilane (IP...A hybrimer based on epoxy resin and phenyl-siloxane was prepared by polymerization and a solgel condensation reaction in which Eporite-904 (807 g/eq) bisphenol-A-type epoxy resin, 3-isocyanatopropyltriethoxysilane (IPTES) and phenyltriethoxysilane (PTEOS) acted as precursors. The thermal and optical properties of the epoxy/siloxane hybrimer were studied. The thermogravimetric analysis (TGA) results implied that the hybrimer could increase the crosslink density and enhance the thermal properties. The optical properties were measured after thermal and UV aging. The refractive indexes of the epoxy/siloxane hybrimers were 1.66 - 1.70, and the transmittances of the cured hybrimers were above 90% in the visible wavelength. After a 120°C/24-h thermal aging test, the decreases in the refractive index and transmittance were less than 5% and 20% respectively. The epoxy/siloxane hybrimers also showed low discoloration upon thermal aging at 120°C for 24 h under an air atmosphere.展开更多
基金supported by the Shanghai 3-year Public Health Action Plan(grant number:GWVI-11.1-39).
文摘Cyclic volatile methyl siloxanes(cVMSs)are widely used in industrial and consumer products because of their thermal stability,low reactivity,and reduced surface tension[1].Their extensive use has resulted in environmental pollution globally.Recognized as very persistent and very bioaccumulative(vPvB),compounds such as octamethylcyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5),and dodecamethylcyclohexasiloxane(D6)are regulated in the European Union[2]and are monitored worldwide.
基金financial support from the National Natural Science Foundation of China (21677046)the Natural Science Foundation of Hebei Province (B2017205146)
文摘Biogas can be used as an alternative energy source for producing heat and electricity;however, volatile methylsiloxanes(VOSiC) present in biogas can severely damage heat exchangers, turbines and gas engines. Consequently, e cient removal of VOSiC from biogas that is used as a biofuel is required. In this work, acetylated silica gel(Ac@SG) was synthesized,via treatment of microporous silica gel(SG) with acetic anhydride as an adsorbent, for removal of VOSiC from biogas,and characterized with XRD, SEM–EDS, N2-BET and FT-IR. This Ac@SG adsorbent exhibited a meso-/microporous structure and hydrophobic surface, indicating it was a more e cient adsorbent for removing hexamethyldisiloxane(L2) and octamethylcyclotetrasiloxane(D4) from biogas samples than conventional SG. It was found that the adsorption capacities of Ac@SG reached 304 mg L2/g for hexamethyldisiloxane and 916 mg D4/g for octamethylcyclotetrasiloxane at lower temperatures in the experimental range, and water had no significant e ect on its absorption e ciency. The used Ac@SG could be easily regenerated by heating it at 110 °C, and the adsorption capacity of recycled Ac@SG for hexamethyldisiloxane and octamethylcyclotetrasiloxane was kept constant in four recycle adsorption experiments.
基金supported by the National Natural Science Foundation of China(No.21407097)Supported by Shandong Key Laboratory of Water Pollution Control and Resource Reuse(No.2019KF14)the Opening Project of Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP^3)(No.FDLAP17001)
文摘Landfill biogas is a potential alternative for fossil fuel,but the containing impurities,volatile methyl siloxanes(simplified as siloxanes),often cause serious problems in gas turbines when applied to generate electricity.In this research,a collecting and analyzing method based on solvent adsorption and purge and trap-gas chromatography-mass spectrometry was established to determine the siloxanes in biogas from a landfill in Jinan,China,and adjacent ambient samples,such as soil,air,and leachate of the landfill.The results showed that,octamethylcyclotetrasiloxane(D4)and decamethylcyclopentasiloxane(D5)accounted for 63%of total siloxanes;and without considering D4 and D5,the order of detected siloxanes in concentration was found relating to Gibbs free energies of molecules,namely that higher abundant siloxane(except for D4 and D5)usually had lower Gibbs free energy.Additionally,the mass ratio between D4 and octamethyltrisiloxane(L3)in the bio gas varied with different garbage age in landfills,possibly revealing the breaking-down of larger siloxane molecules with time.The samples,which were collected from environmental samples adjacent to the landfill,such as soil,water,and air,presented much higher siloxane level than urban or rural area away from landfills.The current H2 S scrubber of the landfill biogas could decrease the total siloxanes from 10.7 to 5.75 mg/m^3 due to Fe2 O3 and a refrigerant drier in a purification system and cyclic siloxanes were more easily removed than linear ones.
基金supported by a National Science Centre Grant UMO-2021/43/D/ST4/00132.
文摘In this study,we introduce a method for directly synthesizing various siloxanes from hydrosilanes and silanols under ambient conditions.This process relies on the use of Stryker’s reagent([(PPh_(3))CuH]_(6))as the first copper catalyst,enabling this specific cross-dehydrogenative coupling.This method stands out for its exceptional chemoselectivity,making it a superb alternative to established catalytic systems.It operates under mild conditions yet maintains high process efficiency.Throughout the investigation,we demonstrated the potential for modifying the resulting hydrosiloxanes through alcoholysis to produce silyl ethers and via hydrosilylation to yield functionalized siloxanes.
基金supported by a National Science Centre Grant UMO-2018/30/E/ST5/00045(GH).
文摘Apart from some specific synthetic solutions,a dehydrogenative coupling of silanols with hydrosilanes seems to be the most atom-economical and practical method for the formation of unsymmetrical silox-anes.This goal was accomplished by simple main-group catalysis,utilizing commercially available reagents under mild conditions.
基金financially supported by the Deutsche Forschungsgemeinschaft(DFG).
文摘In this study we present a(re-)investigation into cyclodimethylsiloxanes in relation to silyl-ether bonding towards alkali metal ions.We demonstrate that all(non-radioactive)alkali metal ions can be incorporated into D_(n) cyclosiloxane frameworks(D=(SiMe_(2)O),n=5–8),employing appropriate cation–anion combinations.Starting with the Li^(+)cation we were able to observe the coordination of D_(5) with Li^(+)based on a suitable X-ray structure after reacting D_(5) with LiI and GaI_(3).Due to template effects,the dinuclear coordination compound[Li2(D_(5))(D_(6))(GaI_(4))_(2)](1)was obtained.The direct reaction of D_(6) with LiI and GaI_(3) yields[Li(D_(6))GaI_(4)](2)in quantitative yield.Na^(+)ions could be trapped in D_(6) and D_(7) ligand moieties after the conversion of NaI,GaI_(3),and the respective siloxane.The molecular structure of[Na(D_(6))GaI_(4)](3)reveals a six-fold coordinated Na^(+)ion,which is located on top of the siloxane D_(6).In the case of[Na(D_(7))(DCM)GaI_(4)](4),the larger ligand D_(7) provides 15-crown-5-like geometry in which the sodium ion is coordinated by the ligand in a coplanar fashion and further saturated by the solvent DCM(DCM=dichloromethane).The K^(+)ion was bound within the D_(7) ligand in a similar manner and[K(D_(7))(DCM)GaI_(4)](5)could be characterized.Due to the resemblance of NH_(4)^(+)to K^(+),this cation was also employed for complex formation.Counterintuitively,we were able to synthesize and characterize the first ever non-metal-cyclosiloxane coordination compound.After the conversion of D_(6) with NH_(4)I and GaI_(3),the compound[NH_(4)(D_(7))][Ga_(2)I_(7)](6)was obtained.The ammonium cation favors D_(7) coordination over D_(6),and the willing formation of hydrogen bonding in such a siloxane moiety was realized.As these compounds could be obtained,we also tested the limits of silyl-ether bonding.Therefore,we reacted D_(8) with in situ generated Rb[GaI_(4)]and Cs[GaI_(4)].In the case of Rb^(+),we could cumbersomely characterize[Rb(D_(8))(DCM)GaI_(4)](7)via an X-ray structure,as well as by means of mass spectrometry,but the compound starts decomposing readily in solution.The reaction with the Cs^(+)salt failed.To obtain meaningful spectroscopic data from a Rb^(+)compound and to somehow obtain a Cs^(+)complex,we employed the weakly coordinating anion[Al_(F)]^(−)(Al_(F)^(−)=[Al{OC(CF_(3))_(3)}_(4)]^(−)).The conversion of M[Al_(F)]then yielded 11[M(D_(8))AL_(F)](M=Rb:8;M=Cs^(+):9)in the solid state.Both compounds 8 and 9 were fully characterized.Finally,we aimed at synthesizing 2:1 complexes of such siloxanes.The reactions of excess D_(5) with K[Al_(F)]and D_(6) with Cs[Al_(F)]turned out to be expedient and,in the forms of[K(D_(5))_(2)][Al_(F)](10)and[Cs(D_(6))_(2)][Al_(F)](12),the first ever sandwich-type complexes observed bearing a cyclosiloxane ligand were characterized.
基金the financial support from the National Natural Science Foundation of China(22371223and 52433002).
文摘The synthesis of functionalized linear polysiloxanes has garnered considerable attentions due to their broad applicability.While the selective C−H bond functionalization of dimethylsiloxane monomers or polymers offers a promising and versatile approach,it remains a significant synthetic challenge.In this study,we report a mild and efficient iron-catalyzed method for the C−H bond alkylation of both dimethylsiloxane monomers and polysiloxane using polar alkenes as coupling partners.This protocol exhibits broad substrate scope,tolerating a wide range of siloxane/silane substrates and polar alkenes.A variety of functional groups,including amide,ester,ketone,and nitrile,can be readily introduced into the siloxane framework.Functionalized polysiloxanes are accessible either through direct C−H bond functionalization or via copolymerization using the modified monomers.Notably,nitrile-functionalized polysiloxanes display significant photoluminescence properties,offering new opportunities for expanding the application scope of polysiloxane materials.Based on experimental studies,a plausible catalytic mechanism is also proposed.
基金supported by the National Natural Science Foundation of China(No.52573220)the National Key R&D Program of China(No.2023YFC3404201)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-IDRY-GD24-005)the State Key Laboratory of Solid Waste Reuse for Building Materials(No.SWR-2022-009).
文摘Coal cinder is an abundant byproduct of the extensive consumption of coal in industrial production and daily life.Making full use of the cinder is conducive to a low-carbon economy.In this study,inspired by the burning of coal,a new method for constructing a silica-based composite porous material(SiO_(2)-CPM)was developed by combusting a siloxane-modified anthracite coal gel(CSiO_(2) gel).During this process,the combustion product was directly converted into a porous material,and the calorific value of the coal remained nearly unchanged(~98%of the original calorific value was retained),demonstrating the viability of this method for energy-efficient applications.The SiO_(2)-CPM exhibited an ultra-low thermal conductivity(0.036 W/(m·K)at room temperature),outperforming conventional insulation materials(e.g.,cotton~0.05 W/(m·K)).Additionally,it showed enhanced mechanical strength(fracture stress of 41.8 kPa)compared to the powder state of the coal cinder.Experimental results indicate that the amount of siloxane,structure-directing agent,and an acidic environment were critical for mechanical enhancement.The SiO_(2)-CPM showed good dimensional stability against thermal expansion and exhibited excellent thermal insulation and fire resistance even at 900℃.Meanwhile,the SiO_(2)-CPM with complex geometry could be easily fabricated using this method owing to the excellent shaping ability of the CSiO_(2) gel.Compared to conventional methods such as sol-gel synthesis or freeze-drying,this approach for fabricating SiO_(2)-CPM is simpler and cost-effective and allows the direct utilization of coal cinder post-combustion.
基金supported by the National Natural Science Foundation of China (Grant No. 22179041)the Guangzhou Science and Technology Plan Project (Grant No. 2024A04J4354)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515010034)
文摘Enhancing the energy density of lithium-ion batteries through high-voltage cathodes holds great pro-mise.However,traditional carbonate-based electrolytes face significant challenges due to limited oxida-tive stability and poor compatibility with high-nickel materials.This study introduces a novel electrolyte that combines bis(triethoxysilyl)methane(DMSP)as the sole solvent with lithium bis(fluorosulfonyl)imide(LiFSI)as the lithium salt.This formulation significantly improves the stability of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathodes and graphite anodes.The capacity retention of the NCM811 elec-trode increases from 5%to 95%after 1000 cycles at 1 C(3.0-4.5 V),while that of the graphite anode is improved from 22%to 92%after 400 cycles at 0.2 C(0.005-3.0 V).The NCM811//graphite pouch cell exhibits enhanced retention,rising from 12%to 66%at 25℃and from 3%to 65%at 60℃after 300 cycles at 0.2 C.Spectroscopic characterization and theoretical calculations reveal that the steric hindrance of the Si-O-CH_(3)groups in DMSP creates a weakly solvating structure,promoting the formation of Lit^(+)-FSI^(-)ion pairs and aggregation clusters,which enriches the electrode interphase with LiF,Li_(3)N,and Li_(2)SO_(3).Furthermore,DMSP with abundant Si-O effectively enhances the elasticity of the interphase layer,scav-enging harmful substances such as HF and suppressing gas evolution and transition metal dissolution.The simplicity of the DMSP-based electrolyte formulation,coupled with its superior performance,ensures scalability for large-scale manufacturing and practical application in the high-voltage battery.This work provides critical insights into improving interfacial chemistry and addressing compatibility issues in high-voltageNi-rich cathodes.
基金supported by the 2024 Capital Construction Funds within the Provincial Budget of Jilin Provincial Development and Reform Commission[2024C018-2].
文摘Traditional lithium-ion batteries(LIBs)employing liquid electrolytes face inherent safety risks,motivating the development of solid polymer electrolytes(SPEs)like polyethylene oxide(PEO).However,pure PEO suffers from low room-temperature ionic conductivity and poor mechanical strength.Composite solid electrolytes(CSEs)incorporating inorganic filler offer promise but are hindered by poor interfacial compatibility.This study addresses this critical issue through surface engineering.Mercaptopropyl trimethoxysilane(MPTMS)is used to modify garnet-type Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)particles,introducing thiol groups(-SH)onto their surface.Subsequently,thiol-functionalized LLZTO(LLZTO@MPTMS)participate in the insitu copolymerization of polyethylene glycol methyl methacrylate(PEGMEMA)and crosslinker polyethylene glycol dimethacrylate(PEGDMA),yielding a novel PEO-based CSE(PCSE).The effects of PEGMEMA molecular weight,PEGMEMA/PEGDMA ratio,and LLZTO@MPTMS content have been systematically examined to optimize the electrolyte.The resulting PCSE exhibits an ionic conductivity of 1.20×10^(-4)S·cm^(-1)at 30℃,a lithium-ion transference number of 0.36,and a wide electrochemical stability window up to 5.1 V(vs.Li^(+)/Li).Li/PCSE/Li symmetric cells demonstrate stable cycling for nearly 240 h at 0.05 mA·cm^(-2),indicating enhanced interface compatibility with lithium metal and effective dendrite suppression.Furthermore,LiFePO_(4)/PCSE/Li full cells deliver a high initial discharge capacity of 155.0 mAh·g^(-1)at 0.1 C and retain 76.0%capacity after 100 cycles,alongside excellent rate capability.These results confirm that the combined strategy of LLZTO surface modification with MPTMS and in-situ copolymerization effectively mitigates interfacial issues,presenting a promising material system for high-performance solid-state LIBs.
基金the National Natural Science Foundation of China(No.51173188)
文摘Three novel flame retardants containing both phosphorus and silicon elements in their structures,including[（1,1,3,3- tetramethyl-1,3-disiloxanediyl）di-2,1-ethanediyl]bis（diphenylphosphine oxide）（FR-1）,[（2,4,6,8-tetramethylcyclotetra-siloxane -2,4,6,8-tetrayl）tetra-2,1-ethanediyl]tetrakis[diphenylphosphine oxide]（FR-2） and 1,3,5,7,9,11,13,15-octakis（di-phenylphosphine oxide-2,1-ethanediyl）pentacyclo[9.5.1.1^（3,9）.l^（5,15）.1^（7,13）]octasiloxane（FR-3） were synthesized by a convenient pathway from the reaction of diphenylphosphine oxide（DPPO） and vinyl-terminated siloxanes under the catalysis of triethylborane. The chemical structures of the target compounds were confirmed by nuclear magnetic resonance（^1H NMR,^13C NMR,^29Si NMR and ^31P NMR）,matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF-MS） and Fourier transform infrared（FT IR） measurements.Thermogravimetric analysis（TGA） results indicated that the new flame retardants possessed good thermal stability both in nitrogen and in air.FR-3 containing polyhedral oligosilsesquioxanes（POSS） moiety exhibited the best thermal properties with a 10%weight loss temperature〉400℃ and a residual weight ratio〉39%at 700℃ .
基金Financial supports from the National Natural Science Foundation of China(No.50273035)Hangzhou Zhijiang Silicone Chemical Industry Co.,Ltd.are acknowledged.
文摘Siliconated polyurethane （Si-PU） was synthesized using isophorone diisocyanate （IPDI）, hydroxybutyl-terminated polydimethylsiloxane （PDMS）, polytetramethylene ether glycol （PTMG）, polypropylene glycol （PPG）, 1,6-hexanediol （HDO）, dimethylol propionic acid （DMPA） and triethylamine （TEA）. Based on butyl acrylate （BA）, 2, 2, 2-trifluoroethylmethacrylate （TFEMA） and Si-PU as a seed emulsion, a novel core-shell type acrylic-polyurethane hybrid emulsion, containing siloxane and fluorine （F-Si-PU）, was prepared by seeded emulsion polymerization. The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy （FTIR） was used to identify the chain structures of Si-PU and F-Si-PU. Investigation of transmission electron microscopy （TEM） confirmed the core-shell structure of F-Si-PU emulsion. Measurement results of water contact angle and the swelling ratio in water and n-octane for cured film showed that the water and the oil resistances for F-Si-PU had been significantly improved at a suitable content of fluorine and siloxane.
基金Project(2003B10506) supported by Science and Technology Department of Guangdong Province, China
文摘Acrylate latex modified by vinyl triisopropoxy silane (C-1706) was synthesized by seeded emulsion polymerization with anionic emulsifier sodium dodecyl sulphonate(SDS) and nonionic emulsifier OP-10 as the multiple emulsifiers at (78±2) ℃. The effects of different factors, such as the emulsifier, C-1706 monomer and its feeding manner on the properties of acrylate latex modified by C-1706 were investigated. The particle size distribution and the structure, the configuration, the weather durability and stain resistance of copolymer latex were characterized by particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope(TEM), scanning electron microscope(SEM) and ultraviolet aging instrument respectively. The results show that SDS to OP-10 as multiple emulsifiers can lead to coordinated efficiency, the optimal emulsifier dosage is 2.4%?3.2%(mass fraction), and the mass ratio of SDS to OP-10 is 1?1? 1?2. The seeded emulsion polymerization can effectively introduce a organic-siloxane bonding in a macromolecule inter polymer, and the obtained acrylate latex modified by organic-siloxane possesses narrow distribution of particle size with mean diameter of 51.8?76.6 nm and has the excellent properties in weather durability and stain-resistance especially.
基金Funded by the National Natural Science Foundation of China(No.51808329)Science and Technology Department of Shanxi Province International Cooperation(No.201603D421027)the Special Project of Commercialization of Shanxi Province Research Foundation(No.201804D131034)
文摘In order to inhibit and remove the thin ice and extend the lifetime of the damaged bridge, the self-healing mechanism and hydrophobic performance of asphalt modified by siloxane and polyurethane (ASP) were studied by dynamic shear rheology (DSR), fluorescence microscope (FM), atomic force microscope (AFM), the fracture-healing-re-fracture test and molecular simulations. The experimental results indicated that the selfhealing capability of ASP increased with increasing heating time and temperature. Furthermore, the addition of siloxane could improve the reaction energy barrier and complex modulus, and it is believed that the self-healing is a viscosity driven process, consisting of two parts namely crack closure and properties recovery. Contact angle of ASP increased with the increasing siloxane content and it deduced that the siloxane could improve the hydrophobic performance of ASP and the ASP molecule model could simulate well the self-healing mechanism and hydrophobic performance of ASP.
基金Supported by the National 12th Five-Year Science and Technology Supporting Program(2011BAD11B01)the Research & Development Projects Cooperation Project of Chinese Academy of Sciences(YDJDBNJ-2012-023)
文摘Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.
基金support of the National High Technology Research and Development Program of China(No.2002305205)the National Basic Research Program of China(No.51320006)
文摘Poly[(methylsilylene ethynylene phenylene ethynylene)-co-(tetramethyldisiloxane ethynylene phenylene ethynylene)]was synthesized by polycondensation reaction of m-diethynylbenzene magnesium reagent with 1,3-dichlorotetramethyldisiloxane and dichloromethylsilane.The copolymer was characterized by FT-IR,~1H NMR,differential scanning calorimetry and thermogravimetric analysis.The results show that the copolymer exhibits good processability and cures at low temperatures.The cured copolymer shows high thermal stability.
基金supported by National Natural Science Foundation of China(No.21003005)Beijing Municipal Commission of Education(No.KM201010011005)Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality(No.20110890)
文摘The cloudy Silwet L-77 aqueous solution on the concentration range from 0.5%to 50%was investigated by dielectric relaxation spectroscopy.The concentration dependence of phase microstructure was confirmed by means of analyzing the dielectric parameters of bulk solution.The relaxation behavior was assigned to the interfacial polarization between the micelle and the medium,and the relaxation distribution parameter was used to figure the shape transition from sphere to ellipsoid with the concentration increasing.The synchronous reduction of permittivity and conductivity indicated the formation of the lamellar phase. As compensation,the quantity of the surfactant liquid phase gradually decreased,whose shape constantly kept ellipsoidal.
文摘Two series of polyurethanes based on mixed polychloromethyl methyl siloxane and poly-tetramethylene oxide in different weight fractions were synthesized. The phase separation ofsamples was studied using DSC and dynamic mechanical property analysis. The results showedthat the introduction of chloromethyl group into polysiloxane increased its polarity and henceimproved the miscibilities with polytetramethylene oxide and polyurethane hard segment.Particularly, in the case of N-methyldiethanolamine extended materials, the surface and tensileproperties of these samples can be adjusted by various ratios of two soft segments.
文摘A hybrimer based on epoxy resin and phenyl-siloxane was prepared by polymerization and a solgel condensation reaction in which Eporite-904 (807 g/eq) bisphenol-A-type epoxy resin, 3-isocyanatopropyltriethoxysilane (IPTES) and phenyltriethoxysilane (PTEOS) acted as precursors. The thermal and optical properties of the epoxy/siloxane hybrimer were studied. The thermogravimetric analysis (TGA) results implied that the hybrimer could increase the crosslink density and enhance the thermal properties. The optical properties were measured after thermal and UV aging. The refractive indexes of the epoxy/siloxane hybrimers were 1.66 - 1.70, and the transmittances of the cured hybrimers were above 90% in the visible wavelength. After a 120°C/24-h thermal aging test, the decreases in the refractive index and transmittance were less than 5% and 20% respectively. The epoxy/siloxane hybrimers also showed low discoloration upon thermal aging at 120°C for 24 h under an air atmosphere.
