A novel soluble regular ladder poly（benzoyl-3-aminopropyl） silsesquioxane （LPBAS） was facilely prepared under effective assistance of concerted H-bonding self-assembly of amido groups of side chains and silanol gr...A novel soluble regular ladder poly（benzoyl-3-aminopropyl） silsesquioxane （LPBAS） was facilely prepared under effective assistance of concerted H-bonding self-assembly of amido groups of side chains and silanol groups, respectively, of a new template monomer [1,3-bis（benzoyl-3-aminopropyl）-1,1,3,3-tetraethoxydisiloxane] （M）. The ordered ladder structure of LPBAS is manifested in： （1） the presence of two Bragg peaks representing the ladder width （d） and ladder thickness （t） in X-ray diffraction （XRD） pattern; （2） narrow base-line width （w = 6） of resonance absorption for -CH2SiO3/2 moiety in 29Si-NMR and （3） high glass transition temperature Tg = 1 12℃ in differential scanning calorimetry （DSC） analysis.展开更多
A novel soluble, reactive ladder-like polysilsesquioxane (L) with lateral bromophenyl groups was synthesized successfully by stepwise coupling polymerization (SCP) method including preaminolysis, hydrolysis and polyco...A novel soluble, reactive ladder-like polysilsesquioxane (L) with lateral bromophenyl groups was synthesized successfully by stepwise coupling polymerization (SCP) method including preaminolysis, hydrolysis and polycondensation steps. The monomer 3-trichlorosilylpropoxy-4-bromobenzene (M) was first prepared via hydrosilylation reaction catalyzed by dicyclopentadienylplatinum dichloride (Cp2PtCl2). The title polymer (L) was characterized by 1H-NMR, 29Si-NMR, FTIR, X-ray diffraction (XRD), DSC and vapor pressure osmometry (VPO). The experimental results indicate that the polymer (L) possesses a typical ladder-like structure.展开更多
A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polyc...A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polycondensation. The monomer, 3-trichlorosilylpropoxy 4-acetoxybenzoate (M), was synthesized by hydrosilylation of allyloxy 4-acetoxybenzoate with trichlorosilane in the presence of dicyclopentadienylplatinum (II) chloride (Cp2PtCl2) catalyst. Combination of FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, XRD, DSC, TGA and VPO methods was used to demonstrate that the polymer obtained has an ordered ladderlike structure. The synthesized Ester-T may have promising applications as a precursor of advanced functional polymers.展开更多
Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsilo...Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsiloxane chains and the ladderlike polysilsesquioxanes chains, the cyclization of the polydimethylsiloxane chains is hindered. The high thermal stability of the ladderlike polymers can improve the thermal stability of the silicone gels without sacrificing their good comprehensive properties.展开更多
Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier ...Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy. Polyimide （PI）/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix, respectively. The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy, meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films. With the increase of amino content, both the interracial interactions and the cross-linking density of hybrids enhanced, which results in the decline of surface silicon concentration, increase of Young＇s modulus and drop of elongation at break. Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.展开更多
In order to study the effect of different modification methods on polysilsesquioxane(POSS)modified cellulose,a molecular dynamics method was used to establish a pure cellulose model and a series of modified models mod...In order to study the effect of different modification methods on polysilsesquioxane(POSS)modified cellulose,a molecular dynamics method was used to establish a pure cellulose model and a series of modified models modified by polysilsesquioxane in different ways.And their thermodynamic properties were calculated.The results showed that the performance of cellulose models was better than that of unmodified model,and the modified effect was the best when two cellulose chains were grafted onto polysilsesquioxane by chemical bond(M2 model).Compared with pure cellulose model,the cohesive energy density and solubility parameters of M2 model are increased by 9%,and the values of tensile modulus,bulk modulus,shear modulus and Cauchy pressure increased by 38.6%,29.5%,41.1% and 29.5%,respectively.In addition,the free volume fraction and mean square displacement of each model were calculated and analyzed in this work.Compared with the pure cellulose model,the molecular chain entanglement of cellulose was increased due to the existence of the chemical bonds in the M2 model,which made the cellulose molecular chains occupy more free volume,so that the system had a smaller free volume fraction,inhibited the chain movement of cellulose chains,and thus improved the thermal stability of cellulose.展开更多
基金This work was financially supported by NSFC (Nos. 50073028, 29974036 and 20174047).
文摘A novel soluble regular ladder poly（benzoyl-3-aminopropyl） silsesquioxane （LPBAS） was facilely prepared under effective assistance of concerted H-bonding self-assembly of amido groups of side chains and silanol groups, respectively, of a new template monomer [1,3-bis（benzoyl-3-aminopropyl）-1,1,3,3-tetraethoxydisiloxane] （M）. The ordered ladder structure of LPBAS is manifested in： （1） the presence of two Bragg peaks representing the ladder width （d） and ladder thickness （t） in X-ray diffraction （XRD） pattern; （2） narrow base-line width （w = 6） of resonance absorption for -CH2SiO3/2 moiety in 29Si-NMR and （3） high glass transition temperature Tg = 1 12℃ in differential scanning calorimetry （DSC） analysis.
基金This work was supported by the National Natural Science Foundation of China (No. 20174047, 20204016, 50273043) andDow Corning Corporation, USA.
文摘A novel soluble, reactive ladder-like polysilsesquioxane (L) with lateral bromophenyl groups was synthesized successfully by stepwise coupling polymerization (SCP) method including preaminolysis, hydrolysis and polycondensation steps. The monomer 3-trichlorosilylpropoxy-4-bromobenzene (M) was first prepared via hydrosilylation reaction catalyzed by dicyclopentadienylplatinum dichloride (Cp2PtCl2). The title polymer (L) was characterized by 1H-NMR, 29Si-NMR, FTIR, X-ray diffraction (XRD), DSC and vapor pressure osmometry (VPO). The experimental results indicate that the polymer (L) possesses a typical ladder-like structure.
基金The authors are grateful to the National Natural Science Foundation of China(No.29874034),Dow Coming Corporation and Institute of Materials Research and Engineering,National University of Singapore for their financial supports.
文摘A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polycondensation. The monomer, 3-trichlorosilylpropoxy 4-acetoxybenzoate (M), was synthesized by hydrosilylation of allyloxy 4-acetoxybenzoate with trichlorosilane in the presence of dicyclopentadienylplatinum (II) chloride (Cp2PtCl2) catalyst. Combination of FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, XRD, DSC, TGA and VPO methods was used to demonstrate that the polymer obtained has an ordered ladderlike structure. The synthesized Ester-T may have promising applications as a precursor of advanced functional polymers.
基金This project is financially supported by Institute of Materials Research and Engineering, Singapore.
文摘Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsiloxane chains and the ladderlike polysilsesquioxanes chains, the cyclization of the polydimethylsiloxane chains is hindered. The high thermal stability of the ladderlike polymers can improve the thermal stability of the silicone gels without sacrificing their good comprehensive properties.
基金financially supported by the National Natural Science Foundation of China (No.51073020)
文摘Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy. Polyimide （PI）/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix, respectively. The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy, meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films. With the increase of amino content, both the interracial interactions and the cross-linking density of hybrids enhanced, which results in the decline of surface silicon concentration, increase of Young＇s modulus and drop of elongation at break. Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.
基金supported by the the National Key Research and Development Program of China(No.2017YFB0902700 and No.2017YBF0902702)the National Natural Science Foundation of China(No.51977179)Fundamental Research Funds for the Central Universities(No.XDJK2020D018).
文摘In order to study the effect of different modification methods on polysilsesquioxane(POSS)modified cellulose,a molecular dynamics method was used to establish a pure cellulose model and a series of modified models modified by polysilsesquioxane in different ways.And their thermodynamic properties were calculated.The results showed that the performance of cellulose models was better than that of unmodified model,and the modified effect was the best when two cellulose chains were grafted onto polysilsesquioxane by chemical bond(M2 model).Compared with pure cellulose model,the cohesive energy density and solubility parameters of M2 model are increased by 9%,and the values of tensile modulus,bulk modulus,shear modulus and Cauchy pressure increased by 38.6%,29.5%,41.1% and 29.5%,respectively.In addition,the free volume fraction and mean square displacement of each model were calculated and analyzed in this work.Compared with the pure cellulose model,the molecular chain entanglement of cellulose was increased due to the existence of the chemical bonds in the M2 model,which made the cellulose molecular chains occupy more free volume,so that the system had a smaller free volume fraction,inhibited the chain movement of cellulose chains,and thus improved the thermal stability of cellulose.
基金The financial support from the National Nature Science Foundation of China （No. 10835008） and State Key Laboratory of Coal Conversion （SKLCC） in-house project （No. 2008BWZ011） were highly acknowledged.
文摘以2-氨基噻唑和异氰酸酯丙基三乙氧基硅烷为原料,合成了γ-(2-噻唑脲基)丙基三乙氧基硅烷(TUPTES),并采用溶胶-凝胶工艺制备了其过渡金属配合物(PTUPTES-Cu,PTUPTES-Ni).用红外光谱、核磁共振谱、扫描电镜和能谱等分析手段进行了表征.磁性测试结果表明,两种配合物在低温下都是较好的软铁磁体,其居里-外斯温度分别为119和75 K.
