Although tremendous efforts have been devoted to the structural and functional tailoring of natural polyphenol-functionalized nan oparticles,preparing ultrasmall sized(<6 nm)particles with precisely-defined structu...Although tremendous efforts have been devoted to the structural and functional tailoring of natural polyphenol-functionalized nan oparticles,preparing ultrasmall sized(<6 nm)particles with precisely-defined structures has remained a grand challenge.In this work,we reported the preparation of ultra-small and precisely structured polyhedral oligomeric silsesquioxanes(POSS)-based polyphenol nanopartides(T8^-,T10^-,and T12^-GAPOSS)by accurately functionalizing the POSS surface with plant polyphenol gallic acid units via thiol-Michael"click"reactions.Those polyphenol nanoparticles exhibited strong free radical scavenging capacity,good biocompatibility and ability to resist cell oxidative damage,which dem on strated great potentials in inhibiting oxidative stress in duced pathologies.展开更多
Ladder-like polyphenylsilsesquioxanes with fairly high regularity were synthesized using an endo-template 1,2-ethylenediamine at mild temperature via direct co-hydrolysis and condensation reactions in the presence of ...Ladder-like polyphenylsilsesquioxanes with fairly high regularity were synthesized using an endo-template 1,2-ethylenediamine at mild temperature via direct co-hydrolysis and condensation reactions in the presence of acid catalysts in the mixture of 1,4-dioxane/H20. The features for synthesis of ladder-like polyphenylsilsesquioxanes were investigated in detail. The products obtained were characterized by FTIR, SEC, XRD and NMR.展开更多
Layer-by-layer (LBL) self-assembly method was used to fabricate siliceous ultrathin films by using polyhedral oligomeric silsesquioxanes as building blocks. Ammonium salt of octasilsesquioxane acid (OSi8) and poly(dia...Layer-by-layer (LBL) self-assembly method was used to fabricate siliceous ultrathin films by using polyhedral oligomeric silsesquioxanes as building blocks. Ammonium salt of octasilsesquioxane acid (OSi8) and poly(diallyldimethylammonium chloride) (PDDA) were alternately assembled onto CaF2 slide to form nanocomposite multilayers. Linear build-up of the LBL films was confirmed by UV-Vis spectroscopy. IR spectrum suggests existence of OSi8 and PDDA in the LBL films. Atomic force microscopic surface topography of the LBL films indicates the OSi8 covers the entire surface of the topmost layer and shows a granular morphology.展开更多
Two novel and well-defined polyhedral oligomeric silsesquioxanes（POSS） with two same Si_8O_（12） cores and a reactive NH group, namely bridged-POSS（2a and 2b）,have been prepared by the traditional ＇corner-cappin...Two novel and well-defined polyhedral oligomeric silsesquioxanes（POSS） with two same Si_8O_（12） cores and a reactive NH group, namely bridged-POSS（2a and 2b）,have been prepared by the traditional ＇corner-capping＇ reaction.X-ray diffraction demonstrates that those two POSS have the similar T_8 structure.From the thermo-gravimetric analysis,bridged-POSS shows the belter thermal degradation stability than the contrastive POSS.展开更多
An extended series of Mn-based cage-like phenylsilsesquioxanes were obtained via convenient selfassembly reactions and complexations with 1,10-phenanthroline.The structural features of these cage complexes such as(i)v...An extended series of Mn-based cage-like phenylsilsesquioxanes were obtained via convenient selfassembly reactions and complexations with 1,10-phenanthroline.The structural features of these cage complexes such as(i)various nuclearities and types of silsesquioxane ligands.展开更多
In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and tra...In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and trans isomers.Using such a starting material results in a subsequent mixture of isomers when hydrosilyl-ation reactions using DDSQ-Me_(2)H_(2)and hydroxyalkyl-substituted alkenes catalyzed by Karstedt catalyst are performed.We describe a procedure to sequentially crystallize the two isomers from one another,affording a protocol potentially applicable to other closely related derivatives.The ability to access pure cis and trans isomers of double-decker silsesquioxanes may result in the preparation of new materials and polymers with well-defined properties.All resulting silsesquioxanes were characterized by multinuclear(^(1)H,^(13)C,and^(29)Si)NMR spectroscopy,FT-IR,and HR-MS.Additionally,we report five crystal structures of geometrical isomers,including two cis forms described in the literature for the first time.This is a break-through in itself and sets a new strategy for obtaining such exiting organosilicon-based systems.展开更多
Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlo...Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlorosilanes.The investigation of this process allowed us to propose the possible mechanism of this transformation.The formation of all structures was confirmed by NMR,FT-IR,and X-ray(for eleven examples)techniques and their thermal stability was verified(TGA).Additionally,we revealed unusual intramolecular homocoupling product formation during the silylative coupling reaction of vinyl-DDSQ derivatives.It deserves to be emphasized that these findings are the first example of a thorough investigation of hydrolytic condensation and the silylative coupling procedures in the chemistry of DDSQs.展开更多
Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations becaus...Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations because of the formation of co-oligomers up to 20 units in a chain.Herein,we present a distinct look at known hydrosilylation reactions for forming hybrid copolymers.展开更多
A straightforward protocol for the efficient synthesis of sulfur-substituted silsesquioxanes(SQ),based on theα-hydrothiolation of terminal alkynes and catalyzed by a supersteric NHC–rhodium complex,is presented for ...A straightforward protocol for the efficient synthesis of sulfur-substituted silsesquioxanes(SQ),based on theα-hydrothiolation of terminal alkynes and catalyzed by a supersteric NHC–rhodium complex,is presented for the first time.The proposed strategy led to a novel class of nanomaterials with many potential medicinal and synthetic applications which had previously been inaccessible by other methods.As a result,twelve new mercapto-modified SQ derivatives were obtained with yields in the range from 84% to 92% and comprehensively characterized by spectroscopic methods.展开更多
Organoboranes have recently advanced ring-opening(co)polymerization(ROP)with high controllability,offering diverse polymer structures.Following the pioneering use of triethylborane(BEt_(3))in ROP,the categories of org...Organoboranes have recently advanced ring-opening(co)polymerization(ROP)with high controllability,offering diverse polymer structures.Following the pioneering use of triethylborane(BEt_(3))in ROP,the categories of organoborane have been updated to functional borane-based catalysts,borinane,multiboranes integrated into small organic scaffolds or macromolecular frameworks,which circumvent some limitations of BEt_(3)such as dilution effect,limited activity,and sensitivity to moisture and oxygen.In this study,well-defined nanoscopic polyhedral oligomeric silsesquioxanes(POSS)with eight vinyl groups serving as a substrate to create nanoscopic multiborane(POSS-B8)Lewis acid.This design offered high local density and closely positioned active sites for targeting the high-activity ROP of epoxides.Various initiators combined with POSS-B8 and chain transfer agents(CTAs)were investigated to endow diverse structures and molecular weights of polyethers.Density functional theory(DFT)calculations revealed exceptional catalytic behavior,with a turnover frequency(TOF)=3750 h^(−1)per borane of the POSS-B8.This was due to a much lowered activation energy for the chain propagation(15.0 kcal mol^(−1))and“intramolecular”propagation mode,assisted by one borane paired with three identical boranes in a concerted manner.A“self-concentrating synergistic effects”model was proposed to explain the structure-activity relationships.This work provides a newly designed strategy for creating a remarkably active and thermally robust borane catalyst for the ROP of epoxides.展开更多
The tetrameric neodymium-silsesquioxane cage complex,{[(i-C_4H_9)_7(Si_7O_(12))Nd])4NaCl},was prepared and used as precursor for the polymerization of isoprene.When activated by AlEt_3 in the presence of TMSCl,this PO...The tetrameric neodymium-silsesquioxane cage complex,{[(i-C_4H_9)_7(Si_7O_(12))Nd])4NaCl},was prepared and used as precursor for the polymerization of isoprene.When activated by AlEt_3 in the presence of TMSCl,this POSS-Nd complex (POSS=polyhedral oligomeric silsesquioxane) shows a moderate activity for the polymerization,and the effects of different ratios of Al/Nd,Cl/Nd and time on the polymerization were investigated.Moreover,The POSS-Nd complex may serve as models for the silica-supported rare earth cat...展开更多
Atomic oxygen （AO） found in low earth orbit can cause serious erosion to polyimide （PI） materials, which greatly limits their lifetime. 8-phenyl silsesquioxane （OPPOSS） was synthesized, and OPPOSS/PI composites ...Atomic oxygen （AO） found in low earth orbit can cause serious erosion to polyimide （PI） materials, which greatly limits their lifetime. 8-phenyl silsesquioxane （OPPOSS） was synthesized, and OPPOSS/PI composites were pre- pared by physical blending, followed by thermal imidization to enhance the AO erosion resistance of PI materials. The morphology, composition, and structure of the composites were analyzed before and after AO exposure in a ground sim- ulated facility of atomic oxygen. After 16 h AO exposure, the OPPOSS/PI composite with 5wt% OPPOSS addition shows an erosion rate of about 1.4×10-24 cm3/atom with only 48% mass loss of that of PI without OPPOSS addition. The mixture of OPPOSS nano molecules is assembled into a kind of regular square structure and distributed evenly in OPPOSS/PI composites. Some SiO2 particles are formed in the composites during AO exposure, which can act as ＂inert points＂ to reduce the AO erosion rate of OPPOSS/PI composites.展开更多
In the selected experimental conditions, firstly, the branched products with functional groups, N-（2-hydroxylpropylphenylether） （3-aminopropyl） triethoxysilane （APES-PGE, containing one hydroxyl group） and N-[di...In the selected experimental conditions, firstly, the branched products with functional groups, N-（2-hydroxylpropylphenylether） （3-aminopropyl） triethoxysilane （APES-PGE, containing one hydroxyl group） and N-[di（2-hydroxylpropylphenylether）]（3-aminopropyl） triethoxysilane （APES-PGE2, containing two hydroxyl groups）, were synthesized by reacting 1 mole of （3-aminopropyl）triethoxysilane （APES） with 2 mole of phenylglycidylether （PGE）. Then the hydrolytic condensation of APES-PGE and APES-PGE2 was performed by dissolving 1 g of the corresponding silane in 1.5 ml tetrahydrofuran （THF）, adding water and eventually a catalyst （molar ratios: [H2O]/Si=3, [NaOH]/Si=0.05）, and heating at 50 ℃ for 24 h, allowing continuous evaporation of volatiles. The final products with branches containing hydroxyl groups were polyhedral oligomeric silsesquioxanes （POSS）. The products from two reactions were characterized by standard spectroscopic techniques, gel partition chromatography （GPC）, Fourier-transformed infrared spectroscopy （FTIR） and matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry （UV-MALDI-TOF MS）. Additionally, a narrow mass distribution of multifunctionalized POSS was shown by UV-MALDI-TOF MS and assignments of the MS peaks.展开更多
Polyhedral oligomeric Silsesquioxanes (POSS) derived from vinyltrimethoxysilane (VMS) and modified with titanium tetrabutoxide (TTBO) (PVT) were prepared by sol-gel process catalyzed by hydrochloric acid (molar ratio:...Polyhedral oligomeric Silsesquioxanes (POSS) derived from vinyltrimethoxysilane (VMS) and modified with titanium tetrabutoxide (TTBO) (PVT) were prepared by sol-gel process catalyzed by hydrochloric acid (molar ratio: [HCl]/Si=0.05), and heating at 45 ℃ during 3 days. The PVT films (f-PVT) with different TTBO content, 5, 20 and 25wt% TTBO, were prepared by adding the stoichiometric amount of benzoyl peroxide (BPO) to PVT solutions in ethanol, dip-coating over glass substrates, and curing using an appropriate thermal cycle and time. The hardness and elastic modulus of f-PVT were tested by continuous stiffness measurement (CSM) of nanoindentation, and the tribological behaviors were comparatively investigated with a nanoscratch test. The influence of the different TTBO contents on the mechanical properties of f-PVT was discussed. The scratch and friction coefficient profiles of f-PVT were illustrated. As the results of the test, f-PVT with 20% TTBO showed the better scratch resistance and tribological behavior.展开更多
The nonlinear optical （NLO） active chromophore was prepared bv a bridging agent, glyeidyl ether （ AGE）, to connect disperse orange 3 （ DO3 ） and （ γ-Methaerylpropyl）-silsesquioxane （MP-SSO）. A freeradical p...The nonlinear optical （NLO） active chromophore was prepared bv a bridging agent, glyeidyl ether （ AGE）, to connect disperse orange 3 （ DO3 ） and （ γ-Methaerylpropyl）-silsesquioxane （MP-SSO）. A freeradical polymerization was performed to fabricate the methacrylate/Silica hybrid NLO films. Different amounts （ 5-25 wt% ） of （γ-methacrylpropyl） -polyhedral oligomeric silsesquioxanes （POSS） were added as the modifier to improve the degree of cross-linking, density and structure of the NLO matrix. As a result, the modified material properties including coating transmittance, glass transition temperature （ Tg ） , absoption spectra before and after poling, Marker stripes, etc. were presented. The hybrid film containing 15 wt% POSS exhibits the highest T, nonresonant second-order nonlinearity （d33 = 92 pro/V） and temporal stability among the others.展开更多
In membrane distillation(MD),complicated feed water with amphiphilic contaminants induces fouling/wetting of the MD membrane and can even lead to process failure.This study reports a facile approach to fabricate robus...In membrane distillation(MD),complicated feed water with amphiphilic contaminants induces fouling/wetting of the MD membrane and can even lead to process failure.This study reports a facile approach to fabricate robust and self-healing hybrid amphiphobic membranes for anti-surfactant-wetting MD based on the ultra-low surface energy of fluorinated polyhedral oligomeric silsesquioxanes(F-POSS)and its thermal induced motivation and rotation.The thermal treatment makes the membranes achieving amphiphobicity at a very low cost of F-POSS(13.04 wt.%),which is about 1/3 of without thermal treatment.The prepared membrane exhibits excellent amphiphobicity,i.e.ethanol contact angle of 120.3°,without using environmentally toxic fluorinated nanoparticles.Robust MD performance was observed for the amphiphobic membrane in concentrated sodium dodecyl sulfate(SDS)feed solutions.Furthermore,the fabricated membrane exhibited stable amphiphobicity even in extreme environments,including strong acid or alkaline solutions.In the event of a damaged or abraded membrane surface where the F-POSS can be removed,the amphiphobic membrane exhibits self-healing ability with additional thermal treatment.This simple approach without the use of nanoparticles provides an environmentally friendly way for fabrication of amphiphobic membranes for anti-surfactant-wetting membrane distillation.展开更多
Herein, we present a novel way for the production of self-healing hydrogels with stretch beyond 4200% than their initial length and relatively high tensile strength （0.1-0.25 MPa）. Furthermore, the hydrogel was inse...Herein, we present a novel way for the production of self-healing hydrogels with stretch beyond 4200% than their initial length and relatively high tensile strength （0.1-0.25 MPa）. Furthermore, the hydrogel was insensitive to notch. Even for the samples containing V-notches, a stretch of 2300% was demonstrated. The hydrogels were developed by in situ crosslinking of the self-assembled colloidal poly（acrylic acid） （PAA）/functionalized polyhedral oligomeric silsesquioxane （POSS） micelles. This was achieved by the addition of functionalized polyhedral oligomeric silsesquioxane with tertiary amines and hydroxyls （POSS-AH） into the PAA reaction solution. The POSS-AH led to micellar growth, then the dual- crosslinked network was constructed. One type of crosslink was formed by hydrogen-bonding and ionic interactions between PAA chains and POSS-AH, the other type of crosslink was formed by covalent bonds between PAA and bis（N,N＇-methylene- bis-acrylamide）.展开更多
Octa（aminophenyl）silsesquioxane （OAPS） was used as the curing agent of diglycidyl ether of bisphenol-A （DGEBA） epoxy resin. A study on comparison of DGEBA/OAPS with DGEBA/4,4＇-diaminodiphenyl sulfone （DDS） ep...Octa（aminophenyl）silsesquioxane （OAPS） was used as the curing agent of diglycidyl ether of bisphenol-A （DGEBA） epoxy resin. A study on comparison of DGEBA/OAPS with DGEBA/4,4＇-diaminodiphenyl sulfone （DDS） epoxy resins was achieved. Differential scanning calorimetry was used to investigate the curing reaction and its kinetics, and the glass transition of DGEBA/OAPS. Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins. The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy. Scanning electron microscopy was used to observe morphology of the two epoxy resins. The results indicated that OAPS had very good compatibility with DGEBA in molecular level, and could form a transparent DGEBA/OAPS resin. The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS. The DGEBA/OAPS resin didn＇t exhibit glass transition, but the DGEBA/DDS did, which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points. Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin. Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield, but its initial decomposition temperature seemed to be lowered.展开更多
4-（2-Ferrocenylethenyl）-phenyl-POSS Fc-CH=CH-C6H6-（C5H9）7Si8O12 （FEPS, Fc： ferrocene）, containing metal and C=C double bond, was firstly synthesized as a mixture of E/Z isomers by the Wittig reaction. The chemi...4-（2-Ferrocenylethenyl）-phenyl-POSS Fc-CH=CH-C6H6-（C5H9）7Si8O12 （FEPS, Fc： ferrocene）, containing metal and C=C double bond, was firstly synthesized as a mixture of E/Z isomers by the Wittig reaction. The chemical structure of FEPS was characterized by FTIR, ^1H-, ^13C and ^29Si- NMR.展开更多
基金the National Natural Science Foundation of China(Nos.51603133 and 21774079)National Key R&D Program of China(No.2019YFA0904500)+1 种基金the Program of the Science,Technology Department of Guangzhou,China(No.201803020039)the Fundamental Research Funds for Central Universities.
文摘Although tremendous efforts have been devoted to the structural and functional tailoring of natural polyphenol-functionalized nan oparticles,preparing ultrasmall sized(<6 nm)particles with precisely-defined structures has remained a grand challenge.In this work,we reported the preparation of ultra-small and precisely structured polyhedral oligomeric silsesquioxanes(POSS)-based polyphenol nanopartides(T8^-,T10^-,and T12^-GAPOSS)by accurately functionalizing the POSS surface with plant polyphenol gallic acid units via thiol-Michael"click"reactions.Those polyphenol nanoparticles exhibited strong free radical scavenging capacity,good biocompatibility and ability to resist cell oxidative damage,which dem on strated great potentials in inhibiting oxidative stress in duced pathologies.
基金financially supported by the Zhejiang Provincial Natural Science Foundation(No.LY14E030008)the Commonweal Technology Application Research Project of Zhejiang Province(No.2013C31079)+1 种基金the National Natural Science Foundation of China(No.51353003)the China Postdoctoral Science Foundation(No.2013 M531455)
文摘Ladder-like polyphenylsilsesquioxanes with fairly high regularity were synthesized using an endo-template 1,2-ethylenediamine at mild temperature via direct co-hydrolysis and condensation reactions in the presence of acid catalysts in the mixture of 1,4-dioxane/H20. The features for synthesis of ladder-like polyphenylsilsesquioxanes were investigated in detail. The products obtained were characterized by FTIR, SEC, XRD and NMR.
文摘Layer-by-layer (LBL) self-assembly method was used to fabricate siliceous ultrathin films by using polyhedral oligomeric silsesquioxanes as building blocks. Ammonium salt of octasilsesquioxane acid (OSi8) and poly(diallyldimethylammonium chloride) (PDDA) were alternately assembled onto CaF2 slide to form nanocomposite multilayers. Linear build-up of the LBL films was confirmed by UV-Vis spectroscopy. IR spectrum suggests existence of OSi8 and PDDA in the LBL films. Atomic force microscopic surface topography of the LBL films indicates the OSi8 covers the entire surface of the topmost layer and shows a granular morphology.
基金the National Natural Science Foundation of China(No20772092)the Hubei Province Natural Science Fund for Distinguished Young Scholars(No2007ABB021) for financial support
文摘Two novel and well-defined polyhedral oligomeric silsesquioxanes（POSS） with two same Si_8O_（12） cores and a reactive NH group, namely bridged-POSS（2a and 2b）,have been prepared by the traditional ＇corner-capping＇ reaction.X-ray diffraction demonstrates that those two POSS have the similar T_8 structure.From the thermo-gravimetric analysis,bridged-POSS shows the belter thermal degradation stability than the contrastive POSS.
基金financially supported by the Russian Science Foundation(project no.22-13-00250)Elemental analysis data were collected using the equipment of the Center for Molecular Composition Studies of INEOS RAS with the support from the Ministry of Science and Higher Education of the Russian Federation.D.G.acknowledges the RUDN University Scientific Projects Grant System,project no.025239-2-174+1 种基金Israel Science Foundation(ISF)grant no.370/20the Esther K.and M.Mark Watkins Chair for Synthetic Organic Chemistry.XANES experiment was supported by the Ministry of Education of the Russian Federation:No.075-15-2022-1107.We dedicate this article to the memory of our dear friend and colleague Dr.M.M.Levitsky(INEOS RAS,Moscow,Russia).
文摘An extended series of Mn-based cage-like phenylsilsesquioxanes were obtained via convenient selfassembly reactions and complexations with 1,10-phenanthroline.The structural features of these cage complexes such as(i)various nuclearities and types of silsesquioxane ligands.
基金supported by the National Science Centre,Poland(Grant No.2020/39/B/ST4/00910).
文摘In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and trans isomers.Using such a starting material results in a subsequent mixture of isomers when hydrosilyl-ation reactions using DDSQ-Me_(2)H_(2)and hydroxyalkyl-substituted alkenes catalyzed by Karstedt catalyst are performed.We describe a procedure to sequentially crystallize the two isomers from one another,affording a protocol potentially applicable to other closely related derivatives.The ability to access pure cis and trans isomers of double-decker silsesquioxanes may result in the preparation of new materials and polymers with well-defined properties.All resulting silsesquioxanes were characterized by multinuclear(^(1)H,^(13)C,and^(29)Si)NMR spectroscopy,FT-IR,and HR-MS.Additionally,we report five crystal structures of geometrical isomers,including two cis forms described in the literature for the first time.This is a break-through in itself and sets a new strategy for obtaining such exiting organosilicon-based systems.
基金funded by the National Science Centre(NCN)grant no UMO-2016/23/B/ST5/00201,UMO-2017/27/N/ST5/00175,and UMO-2020/36/T/ST5/00072 and grants no.POWR.03.02.00-00-I023/17 and POWR.03.02.00-00-I026/16 cofinanced by the European Union through the European Social Fund under the Operational Program Knowledge Education Development.
文摘Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlorosilanes.The investigation of this process allowed us to propose the possible mechanism of this transformation.The formation of all structures was confirmed by NMR,FT-IR,and X-ray(for eleven examples)techniques and their thermal stability was verified(TGA).Additionally,we revealed unusual intramolecular homocoupling product formation during the silylative coupling reaction of vinyl-DDSQ derivatives.It deserves to be emphasized that these findings are the first example of a thorough investigation of hydrolytic condensation and the silylative coupling procedures in the chemistry of DDSQs.
基金supported by the National Science Centre(Poland)Project OPUS UMO 2016/23/B/ST5/00201 and grant no.POWR.03.02.00-00-I026/16 co-financed by the European Union through the European Social Fund under the Operational Program Knowledge Education Development.
文摘Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations because of the formation of co-oligomers up to 20 units in a chain.Herein,we present a distinct look at known hydrosilylation reactions for forming hybrid copolymers.
基金the National Science Centre(Poland)(Project Sonata Bis No.2019/34/E/ST5/00103).
文摘A straightforward protocol for the efficient synthesis of sulfur-substituted silsesquioxanes(SQ),based on theα-hydrothiolation of terminal alkynes and catalyzed by a supersteric NHC–rhodium complex,is presented for the first time.The proposed strategy led to a novel class of nanomaterials with many potential medicinal and synthetic applications which had previously been inaccessible by other methods.As a result,twelve new mercapto-modified SQ derivatives were obtained with yields in the range from 84% to 92% and comprehensively characterized by spectroscopic methods.
基金supported by the National Natural Science Foundation of China(grant nos.22175105 and 22473047)the National Key R&D Program of China(grant no.2021YFA1501600)the Natural Science Foundation of Shandong Province,China(grant no.ZR2024MB019).
文摘Organoboranes have recently advanced ring-opening(co)polymerization(ROP)with high controllability,offering diverse polymer structures.Following the pioneering use of triethylborane(BEt_(3))in ROP,the categories of organoborane have been updated to functional borane-based catalysts,borinane,multiboranes integrated into small organic scaffolds or macromolecular frameworks,which circumvent some limitations of BEt_(3)such as dilution effect,limited activity,and sensitivity to moisture and oxygen.In this study,well-defined nanoscopic polyhedral oligomeric silsesquioxanes(POSS)with eight vinyl groups serving as a substrate to create nanoscopic multiborane(POSS-B8)Lewis acid.This design offered high local density and closely positioned active sites for targeting the high-activity ROP of epoxides.Various initiators combined with POSS-B8 and chain transfer agents(CTAs)were investigated to endow diverse structures and molecular weights of polyethers.Density functional theory(DFT)calculations revealed exceptional catalytic behavior,with a turnover frequency(TOF)=3750 h^(−1)per borane of the POSS-B8.This was due to a much lowered activation energy for the chain propagation(15.0 kcal mol^(−1))and“intramolecular”propagation mode,assisted by one borane paired with three identical boranes in a concerted manner.A“self-concentrating synergistic effects”model was proposed to explain the structure-activity relationships.This work provides a newly designed strategy for creating a remarkably active and thermally robust borane catalyst for the ROP of epoxides.
基金supported by the National Natural Science Foundation(No.20674071)the Special Funds for MajorState Basic Research Projects(No.2005CB623802).
文摘The tetrameric neodymium-silsesquioxane cage complex,{[(i-C_4H_9)_7(Si_7O_(12))Nd])4NaCl},was prepared and used as precursor for the polymerization of isoprene.When activated by AlEt_3 in the presence of TMSCl,this POSS-Nd complex (POSS=polyhedral oligomeric silsesquioxane) shows a moderate activity for the polymerization,and the effects of different ratios of Al/Nd,Cl/Nd and time on the polymerization were investigated.Moreover,The POSS-Nd complex may serve as models for the silica-supported rare earth cat...
基金fnancially supported by the National Natural Science Foundation of China(No.51206009)
文摘Atomic oxygen （AO） found in low earth orbit can cause serious erosion to polyimide （PI） materials, which greatly limits their lifetime. 8-phenyl silsesquioxane （OPPOSS） was synthesized, and OPPOSS/PI composites were pre- pared by physical blending, followed by thermal imidization to enhance the AO erosion resistance of PI materials. The morphology, composition, and structure of the composites were analyzed before and after AO exposure in a ground sim- ulated facility of atomic oxygen. After 16 h AO exposure, the OPPOSS/PI composite with 5wt% OPPOSS addition shows an erosion rate of about 1.4×10-24 cm3/atom with only 48% mass loss of that of PI without OPPOSS addition. The mixture of OPPOSS nano molecules is assembled into a kind of regular square structure and distributed evenly in OPPOSS/PI composites. Some SiO2 particles are formed in the composites during AO exposure, which can act as ＂inert points＂ to reduce the AO erosion rate of OPPOSS/PI composites.
文摘In the selected experimental conditions, firstly, the branched products with functional groups, N-（2-hydroxylpropylphenylether） （3-aminopropyl） triethoxysilane （APES-PGE, containing one hydroxyl group） and N-[di（2-hydroxylpropylphenylether）]（3-aminopropyl） triethoxysilane （APES-PGE2, containing two hydroxyl groups）, were synthesized by reacting 1 mole of （3-aminopropyl）triethoxysilane （APES） with 2 mole of phenylglycidylether （PGE）. Then the hydrolytic condensation of APES-PGE and APES-PGE2 was performed by dissolving 1 g of the corresponding silane in 1.5 ml tetrahydrofuran （THF）, adding water and eventually a catalyst （molar ratios: [H2O]/Si=3, [NaOH]/Si=0.05）, and heating at 50 ℃ for 24 h, allowing continuous evaporation of volatiles. The final products with branches containing hydroxyl groups were polyhedral oligomeric silsesquioxanes （POSS）. The products from two reactions were characterized by standard spectroscopic techniques, gel partition chromatography （GPC）, Fourier-transformed infrared spectroscopy （FTIR） and matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry （UV-MALDI-TOF MS）. Additionally, a narrow mass distribution of multifunctionalized POSS was shown by UV-MALDI-TOF MS and assignments of the MS peaks.
文摘Polyhedral oligomeric Silsesquioxanes (POSS) derived from vinyltrimethoxysilane (VMS) and modified with titanium tetrabutoxide (TTBO) (PVT) were prepared by sol-gel process catalyzed by hydrochloric acid (molar ratio: [HCl]/Si=0.05), and heating at 45 ℃ during 3 days. The PVT films (f-PVT) with different TTBO content, 5, 20 and 25wt% TTBO, were prepared by adding the stoichiometric amount of benzoyl peroxide (BPO) to PVT solutions in ethanol, dip-coating over glass substrates, and curing using an appropriate thermal cycle and time. The hardness and elastic modulus of f-PVT were tested by continuous stiffness measurement (CSM) of nanoindentation, and the tribological behaviors were comparatively investigated with a nanoscratch test. The influence of the different TTBO contents on the mechanical properties of f-PVT was discussed. The scratch and friction coefficient profiles of f-PVT were illustrated. As the results of the test, f-PVT with 20% TTBO showed the better scratch resistance and tribological behavior.
基金Sponsored by the Department of Science and Technology, the Government of Heilongjiang Province (Grant No.ZJG0506-02 and GB04A204).
文摘The nonlinear optical （NLO） active chromophore was prepared bv a bridging agent, glyeidyl ether （ AGE）, to connect disperse orange 3 （ DO3 ） and （ γ-Methaerylpropyl）-silsesquioxane （MP-SSO）. A freeradical polymerization was performed to fabricate the methacrylate/Silica hybrid NLO films. Different amounts （ 5-25 wt% ） of （γ-methacrylpropyl） -polyhedral oligomeric silsesquioxanes （POSS） were added as the modifier to improve the degree of cross-linking, density and structure of the NLO matrix. As a result, the modified material properties including coating transmittance, glass transition temperature （ Tg ） , absoption spectra before and after poling, Marker stripes, etc. were presented. The hybrid film containing 15 wt% POSS exhibits the highest T, nonresonant second-order nonlinearity （d33 = 92 pro/V） and temporal stability among the others.
基金the National Key Research and Development Program of China(No.2016YFB0600501)Natural Science Foundation of China(Nos.51425405 and 21377130)China Scholarship Council(No.201804910753)。
文摘In membrane distillation(MD),complicated feed water with amphiphilic contaminants induces fouling/wetting of the MD membrane and can even lead to process failure.This study reports a facile approach to fabricate robust and self-healing hybrid amphiphobic membranes for anti-surfactant-wetting MD based on the ultra-low surface energy of fluorinated polyhedral oligomeric silsesquioxanes(F-POSS)and its thermal induced motivation and rotation.The thermal treatment makes the membranes achieving amphiphobicity at a very low cost of F-POSS(13.04 wt.%),which is about 1/3 of without thermal treatment.The prepared membrane exhibits excellent amphiphobicity,i.e.ethanol contact angle of 120.3°,without using environmentally toxic fluorinated nanoparticles.Robust MD performance was observed for the amphiphobic membrane in concentrated sodium dodecyl sulfate(SDS)feed solutions.Furthermore,the fabricated membrane exhibited stable amphiphobicity even in extreme environments,including strong acid or alkaline solutions.In the event of a damaged or abraded membrane surface where the F-POSS can be removed,the amphiphobic membrane exhibits self-healing ability with additional thermal treatment.This simple approach without the use of nanoparticles provides an environmentally friendly way for fabrication of amphiphobic membranes for anti-surfactant-wetting membrane distillation.
基金financially supported by the Natural Science Foundation of Guangdong Province(No.2014A030313379)the National Natural Science Foundation of China(Nos.81171459 and 31400824)
文摘Herein, we present a novel way for the production of self-healing hydrogels with stretch beyond 4200% than their initial length and relatively high tensile strength （0.1-0.25 MPa）. Furthermore, the hydrogel was insensitive to notch. Even for the samples containing V-notches, a stretch of 2300% was demonstrated. The hydrogels were developed by in situ crosslinking of the self-assembled colloidal poly（acrylic acid） （PAA）/functionalized polyhedral oligomeric silsesquioxane （POSS） micelles. This was achieved by the addition of functionalized polyhedral oligomeric silsesquioxane with tertiary amines and hydroxyls （POSS-AH） into the PAA reaction solution. The POSS-AH led to micellar growth, then the dual- crosslinked network was constructed. One type of crosslink was formed by hydrogen-bonding and ionic interactions between PAA chains and POSS-AH, the other type of crosslink was formed by covalent bonds between PAA and bis（N,N＇-methylene- bis-acrylamide）.
文摘Octa（aminophenyl）silsesquioxane （OAPS） was used as the curing agent of diglycidyl ether of bisphenol-A （DGEBA） epoxy resin. A study on comparison of DGEBA/OAPS with DGEBA/4,4＇-diaminodiphenyl sulfone （DDS） epoxy resins was achieved. Differential scanning calorimetry was used to investigate the curing reaction and its kinetics, and the glass transition of DGEBA/OAPS. Thermogravimetric analysis was used to investigate thermal decomposition of the two kinds of epoxy resins. The reactions between amino groups and epoxy groups were investigated using Fourier transform infrared spectroscopy. Scanning electron microscopy was used to observe morphology of the two epoxy resins. The results indicated that OAPS had very good compatibility with DGEBA in molecular level, and could form a transparent DGEBA/OAPS resin. The curing reaction of the DGEBA/OAPS prepolymer could occur under low temperatures compared with DGEBA/DDS. The DGEBA/OAPS resin didn＇t exhibit glass transition, but the DGEBA/DDS did, which meant that the large cage structure of OAPS limited the motion of chains between the cross-linking points. Measurements of the contact angle indicated that the DGEBA/OAPS showed larger angles with water than the DGEBA/DDS resin. Thermogravimetric analysis indicated that the incorporation of OAPS into epoxy system resulted in low mass loss rate and high char yield, but its initial decomposition temperature seemed to be lowered.
基金We gratefully acknowledge the financial support of the National Natural Science Foundation of China(Project No.CN-20374007 and CN-50203002)Key Project of Science and Technology Foundation of Ministry of Education(03023).
文摘4-（2-Ferrocenylethenyl）-phenyl-POSS Fc-CH=CH-C6H6-（C5H9）7Si8O12 （FEPS, Fc： ferrocene）, containing metal and C=C double bond, was firstly synthesized as a mixture of E/Z isomers by the Wittig reaction. The chemical structure of FEPS was characterized by FTIR, ^1H-, ^13C and ^29Si- NMR.
