A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhi...A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry （DSC） and thermogravimetric analyses （TGA）. Scanning electron microscope （SEM） was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.展开更多
CIDNP techniques were applied to study the mechanism of photocycloadditions of 2-chloro-5-methoxybenzoquinone 1 with arylacetylenes 2-5 in benzene-d6 and acetonitrile-d6 respectively.
Nanocomposites（PMSEPE/Q8M8^H） were prepared via solution blending of octakis（dimethylsiloxy）octasilsesquoixane（Q8M8^H） into poly（dimethylsilyleneethynylenephenyleneethynyle ne）（PMSEPE）. PMSEPE/Q8M8^H nanocom...Nanocomposites（PMSEPE/Q8M8^H） were prepared via solution blending of octakis（dimethylsiloxy）octasilsesquoixane（Q8M8^H） into poly（dimethylsilyleneethynylenephenyleneethynyle ne）（PMSEPE）. PMSEPE/Q8M8^H nanocomposites were characterized by Fourier transform infrared（FT-IR） spectroscopy, rheological measurement, differential scanning calorimetry（DSC）, scanning electron microscopy（SEM） and thermal gravimetric analysis（TGA）. The experimental results show that the hydrosilylation reaction in PMSEPE/Q8M8^H nanocomposites occurs slowly exceeding 180 ℃. PMSEPE/Q8M8^H nanocomposites can be cured at temperatures less than 260 ℃ and the cube structure of Q8M8^H keeps stable during the curing process. POSS domains are evenly dispersed in the cured nanocomposite. However, serious aggregation of POSS occurs at 15% Q8M8^H content. The thermal and thermooxidative stabilities of PMSEPE/Q8M8^H nanocomposites obviously depend on the content of Q8M8^H. The incorporation of Q8M8^H can effectively enhance the thermal and thermooxidative stabilities of cured PMSEPE. PMSEPE/Q8M8^H nanocomposites can be the candidates for applications in high temperature environment.展开更多
Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers...Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers while maintaining heat resistance is a challenge in engineering applications.Here,poly(diethynylbenzene-methylsilyl-3-benzonitrile)(DEB-CN) and poly(diethynylbenzene-methylsilyl-3,6-diethynylcarbazole-3-benzonitrile)(DEC-CN) were synthesized via an isopropylmagnesium chloride lithium-chloride complex (i-PrMgCl·LiCl),overcoming the compatibility problem between cyano groups and Grignard reagents.The cyano and alkyne groups in the resin underwent cyclization to form pyridine,catalyzed by the-NH-moiety in DEC-CN,resulting in extremely high thermal stability (5%weight loss temperature:669.3°C,glass transition temperature>650°C).The combination of cyano dipole-dipole pairing and hydrogen bonding greatly enhanced the resin-fiber interface properties,while the generated pyridine promoted stress relief in the crosslinked network,substantially improving the mechanical properties of the cyano-silicon-containing arylacetylene resin composites.The flexural strength of quartz fiber cloth/DEC-CN composites was 298.2 MPa at room temperature and 145.9 MPa at 500°C,corresponding to 84.0%and 127.6%enhancements,respectively,over the cyano-free counterpart.These cyano-silicon-containing arylacetylene resins exhibited a dual reinforcement mechanism involving physical interfacial interactions and chemical crosslinking,achieving a good balance between thermal stability and mechanical properties.展开更多
A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with （trimethylsilyl）acetylene catalyzed by MCM-41-supported mercapto palladium...A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with （trimethylsilyl）acetylene catalyzed by MCM-41-supported mercapto palladium（0） complex, followed by desilylation under mild conditions. This polymeric palladium catalyst can be reused many times without any decrease in activity.展开更多
Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs...Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs);we here report on synthesis of a homologous series of thermoresponsive dendronized poly(arylacetylene)s with either poly(phenyl acetylene)or poly(naphthalene acetylene)as the backbones;and investigate tunability of their helical conformations.These polymers carry dendritic OEG pendants with either methoxyl-or ethoxyl-terminals to tune their unprecedent thermoresponsive behaviors;and at the same time;dendritic shielding plays an important role in mediating their thermal phase transition temperatures.Helicity of these polymers is originated from the chiral alanine or phenylalanine moieties within the dendritic pendants;which can be tailored through manipulating solvation in different organic solvents or via thermal dehydration and collapse in water.Furthermore;achiral additives such as linear or dendritic OEGs and benzene derivatives can act similarly as thermal dehydration to induce chirality transitions of these polymers in aqueous phase through interplay competitions between the additives and the polymers against their hydration.展开更多
A series of poly[（methylsilylene ethynylenephenyleneethynylene）-co-（dimethylsilylene ethynylenephenyleneethynylene）]s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene u...A series of poly[（methylsilylene ethynylenephenyleneethynylene）-co-（dimethylsilylene ethynylenephenyleneethynylene）]s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene units into the polymer chain backbone. The resultant copolymers were soluble in a variety of common organic solvents at room temperature. The copolymers were characterized by FT-IR, ^1H-NMR, GPC, rheological analysis, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The results showed that the copolymers exhibited good processability and cured at low temperatures like 200℃. The curing reactions involved in hydrosilylation of Si-H and alkyne groups and the polymerization of alkynes. Td5 （5% weight loss） of the cured copolymers ranged from 629℃ to 686℃, and the decomposition residues of cured copolymers at 1000℃ ranged from 88.1% to 90.9% under nitrogen. Thermal stability of the copolymers increased with the introduction of methylsilylene traits into polymer chains. The cured copolymers were sintered at 1450℃, and the results of X-ray diffraction analysis showed that β-SIC was formed in the sintered products.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
文摘A modified silicon-containing arylacetylene resin with a well-defined organic-inorganic POSS functionality was successfully synthesized by Huisgen azide-alkyne 1,3-dipolar cycloaddition. The POSS hybridized resin exhibits excellent thermal properties which were characterized by differential scanning calorimetry （DSC） and thermogravimetric analyses （TGA）. Scanning electron microscope （SEM） was used to characterize fracture surface of the hybridized polymer. The results show that phase separation occurs. The POSS moieties are aggregated each other in the polymer to form 200-400 nm domains.
基金Financial support from the National Natural Science Foundation of China (No: 29975002) is gratefully acknowledged.
文摘CIDNP techniques were applied to study the mechanism of photocycloadditions of 2-chloro-5-methoxybenzoquinone 1 with arylacetylenes 2-5 in benzene-d6 and acetonitrile-d6 respectively.
基金Funded by the Shanghai Leading Academic Discipline Project(B502)the Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application(Soochow University)
文摘Nanocomposites（PMSEPE/Q8M8^H） were prepared via solution blending of octakis（dimethylsiloxy）octasilsesquoixane（Q8M8^H） into poly（dimethylsilyleneethynylenephenyleneethynyle ne）（PMSEPE）. PMSEPE/Q8M8^H nanocomposites were characterized by Fourier transform infrared（FT-IR） spectroscopy, rheological measurement, differential scanning calorimetry（DSC）, scanning electron microscopy（SEM） and thermal gravimetric analysis（TGA）. The experimental results show that the hydrosilylation reaction in PMSEPE/Q8M8^H nanocomposites occurs slowly exceeding 180 ℃. PMSEPE/Q8M8^H nanocomposites can be cured at temperatures less than 260 ℃ and the cube structure of Q8M8^H keeps stable during the curing process. POSS domains are evenly dispersed in the cured nanocomposite. However, serious aggregation of POSS occurs at 15% Q8M8^H content. The thermal and thermooxidative stabilities of PMSEPE/Q8M8^H nanocomposites obviously depend on the content of Q8M8^H. The incorporation of Q8M8^H can effectively enhance the thermal and thermooxidative stabilities of cured PMSEPE. PMSEPE/Q8M8^H nanocomposites can be the candidates for applications in high temperature environment.
基金financially supported by the Key Laboratory of Specially Functional Polymeric Materials and Related Technology of Ministry of Education, East China University of Science & Technology, and the Fundamental Research Funds for the Central Universities (Nos. 50321041918013 and 50321041917001)。
文摘Silicon-containing arylacetylene (PSA) resins have broad application prospects because of their excellent heat resistance.However,improving their mechanical properties and interfacial bonding with reinforcement fibers while maintaining heat resistance is a challenge in engineering applications.Here,poly(diethynylbenzene-methylsilyl-3-benzonitrile)(DEB-CN) and poly(diethynylbenzene-methylsilyl-3,6-diethynylcarbazole-3-benzonitrile)(DEC-CN) were synthesized via an isopropylmagnesium chloride lithium-chloride complex (i-PrMgCl·LiCl),overcoming the compatibility problem between cyano groups and Grignard reagents.The cyano and alkyne groups in the resin underwent cyclization to form pyridine,catalyzed by the-NH-moiety in DEC-CN,resulting in extremely high thermal stability (5%weight loss temperature:669.3°C,glass transition temperature>650°C).The combination of cyano dipole-dipole pairing and hydrogen bonding greatly enhanced the resin-fiber interface properties,while the generated pyridine promoted stress relief in the crosslinked network,substantially improving the mechanical properties of the cyano-silicon-containing arylacetylene resin composites.The flexural strength of quartz fiber cloth/DEC-CN composites was 298.2 MPa at room temperature and 145.9 MPa at 500°C,corresponding to 84.0%and 127.6%enhancements,respectively,over the cyano-free counterpart.These cyano-silicon-containing arylacetylene resins exhibited a dual reinforcement mechanism involving physical interfacial interactions and chemical crosslinking,achieving a good balance between thermal stability and mechanical properties.
基金the National Natural Science Foundation of China (No.20462002)Natural Science Foundation of Jiangxi Province (No.0420015)for financial support.
文摘A variety of terminal arylacetylenes have been conveniently synthesized in good to high yields via Sonogashira coupling of aryl iodides with （trimethylsilyl）acetylene catalyzed by MCM-41-supported mercapto palladium（0） complex, followed by desilylation under mild conditions. This polymeric palladium catalyst can be reused many times without any decrease in activity.
基金supported by the National Natural Science Foundation of China(22271183,22371179,21971160).
文摘Helical poly(arylacetylene)s have formed an intriguing class of polymers;whose chiralities are dynamic and liable to external stimuli.By combining dendronized polymer topology with dendritic oligoethylene glycols(OEGs);we here report on synthesis of a homologous series of thermoresponsive dendronized poly(arylacetylene)s with either poly(phenyl acetylene)or poly(naphthalene acetylene)as the backbones;and investigate tunability of their helical conformations.These polymers carry dendritic OEG pendants with either methoxyl-or ethoxyl-terminals to tune their unprecedent thermoresponsive behaviors;and at the same time;dendritic shielding plays an important role in mediating their thermal phase transition temperatures.Helicity of these polymers is originated from the chiral alanine or phenylalanine moieties within the dendritic pendants;which can be tailored through manipulating solvation in different organic solvents or via thermal dehydration and collapse in water.Furthermore;achiral additives such as linear or dendritic OEGs and benzene derivatives can act similarly as thermal dehydration to induce chirality transitions of these polymers in aqueous phase through interplay competitions between the additives and the polymers against their hydration.
基金supported by the National High Technology Research and Development Program of China (No.2002-305205)the Special Material Project Program of China(No.51312)Key Project of Science and Technology Foundation of China(9140-12011308)
文摘A series of poly[（methylsilylene ethynylenephenyleneethynylene）-co-（dimethylsilylene ethynylenephenyleneethynylene）]s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene units into the polymer chain backbone. The resultant copolymers were soluble in a variety of common organic solvents at room temperature. The copolymers were characterized by FT-IR, ^1H-NMR, GPC, rheological analysis, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The results showed that the copolymers exhibited good processability and cured at low temperatures like 200℃. The curing reactions involved in hydrosilylation of Si-H and alkyne groups and the polymerization of alkynes. Td5 （5% weight loss） of the cured copolymers ranged from 629℃ to 686℃, and the decomposition residues of cured copolymers at 1000℃ ranged from 88.1% to 90.9% under nitrogen. Thermal stability of the copolymers increased with the introduction of methylsilylene traits into polymer chains. The cured copolymers were sintered at 1450℃, and the results of X-ray diffraction analysis showed that β-SIC was formed in the sintered products.
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.
