Low dielectric constant(low-k)materials are critical for advanced packaging in high-density microelectronic devices and high-frequency communication technologies.Ladder polysiloxanes,which are characterized by their u...Low dielectric constant(low-k)materials are critical for advanced packaging in high-density microelectronic devices and high-frequency communication technologies.Ladder polysiloxanes,which are characterized by their unique double-chain structure and intrinsic microporosity,offer remarkable advantages in terms of thermal stability,oxidation resistance,and dielectric performance.However,structural defects in ladder polysiloxanes,such as cage-like and irregular oligomers,and their effects on dielectric properties remain underexplored.In this study,a series of ladder-like polysiloxanes(X-TMS)with diverse side groups weresynthesized via a one-step base-catalyzed method.The influence of the benzocyclobutene(BCB)side groups on the formation of regular ladder structures was systematically investigated.Notably,BCB incorporation disrupted the structural regularity,favoring the formation of cage-like and irregular topologies,which were extensively characterized using 29silicon nuclear magnetic resonance spectroscopy(^(29)Si-NMR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),and X-ray diffraction(XRD).These structural defects were beneficial for improving the hydrophobicity and thermal stability.Copolymerization of X-TMS with commercial DVS-BCB resins further enhanced the mechanical properties,with the elastic modulus increasing from 3.6 GPa to 4.4 GPa and water absorption reduced from 0.33 wt%to 0.06 wt%.This study establishes a clear correlation between topological structures and material properties.These findings not only advance the understanding of the structure-property relationships in ladder polysiloxanes but also provide a novel approach for designing high-performance interlayer dielectric materials for next-generation microelectronics.展开更多
Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a n...Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.展开更多
Side chain liquid crystalline golysiloxanes conta ing biphenyl and benzyl ether mesogen were synthesized by the hydrosilation of poly(methylhydrcsiloxane) with 4-(4-allyloxybenzytoxy)-4'- methoxybiphenyl(M_1),4-(4...Side chain liquid crystalline golysiloxanes conta ing biphenyl and benzyl ether mesogen were synthesized by the hydrosilation of poly(methylhydrcsiloxane) with 4-(4-allyloxybenzytoxy)-4'- methoxybiphenyl(M_1),4-(4-allyloxybenzyloxy)-4'-ethoxybiphenyl(M_2),4-(4-allyloxybenzyloxy)-4'- propoxybiphenyl(M_3),4-(4-allyloxybenzyloxy)-4'-butoxybiphenyl(M_4),4-(4-allyloxybenzyloxy)-4'- pentyloxybiphenyl(M_5).The phase behavior of monomeric and polymeric liquid crystals was chararcterized by differential scanning calorimetry and optical polarization microscopy.Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.展开更多
A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It ex...A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.展开更多
A series of stable waterborne polysiloxaneurethane （WPSUR） dispersions were prepared using amino-terminated polydimethylsiloxane （NS）, dimethylolpropionic acid （DMPA）, castor oil, polypropylene glycol and toluen...A series of stable waterborne polysiloxaneurethane （WPSUR） dispersions were prepared using amino-terminated polydimethylsiloxane （NS）, dimethylolpropionic acid （DMPA）, castor oil, polypropylene glycol and toluene diisocyanate. Meanwhile, NS with different molecular weights was synthesized and used as the soft co-segment. Effects of types and contents of soft co-segments as well as chain extenders on the thermal degradation and stability for WPSUR films were examined. Results reveal that WPSUR films exhibit excellent water resistance and mechanical properties as compared with pure polyurethane （PU） films, and the NS soft co-segment possesses a remarkable effect on the second stage （stage Ⅱ）, while the content of the hard segment is propitious to the initial stage （stage Ⅰ）. Moreover, the highest temperature of stage Ⅱ （T2m） for WPSUR films using NS as soft co-segment is 413℃, approximately being 30℃ higher than that of those typical PUs using HDA and APDMS as the chain extenders, respectively.展开更多
The film morphology of dodecyl/carboxyl modified polysiloxane(RCAS) on cotton fabric or the silicon wafer was investigated and characterized by field emission scanning electron microscopy(FESEM),atomic force microscop...The film morphology of dodecyl/carboxyl modified polysiloxane(RCAS) on cotton fabric or the silicon wafer was investigated and characterized by field emission scanning electron microscopy(FESEM),atomic force microscope(AFM),and Fourier transform infrared spectrometer(FTIR).Experimental results indicate that RCAS is a good film forming material on different substrates.Relatively smooth film was formed on cotton fabric surface,on which the grooves disappeared.In addition,RCAS formed a micromorphology inhomogeneous and unsmooth film on the silicon wafer.Many high or low bright peaks distributed randomly on the film surface,especially as the field was 2μm×2 μm and the date scale was 5 nm in AFM observation.Then RCAS was emulsified with nonionic surfactant alkyl polyoxyethylene ether in order to achieve a transparent organosilicon emulsion-RCAS emulsion(RCSE),which possessed good stability.The properties of RCSE and its application performance on cotton fabrics were investigated and characterized by transmission electron microscope(TEM),particle size analysis,and voltage test instrument.The results show that the average particle size of RCAS emulsion is 28.32 nm,while the ζ voltage is-37.88 mV.Compared with untreatd cotton fabric,the softness of treated fabric can be improved with RCSE to a certain extent.At the same time,the fabric treated with RCSE acquires unique fluffy and soft handle.展开更多
Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU p...Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.展开更多
In this paper, a new polymer of polysiloxane modified polyurethane was synthesized by using H-containing silicone oil, toluene diisocyanate（TDI）, 1,4-butanediol and unsaturated polyether.
In this study, a UV-curable polysiloxane methacrylate （PSMA） was synthesized by a one-step method. The reaction was catalyzed by chloroplatinic acid between polymethylhydrosiloxane （PMHS） and hydroxyethyl methacry...In this study, a UV-curable polysiloxane methacrylate （PSMA） was synthesized by a one-step method. The reaction was catalyzed by chloroplatinic acid between polymethylhydrosiloxane （PMHS） and hydroxyethyl methacrylate （HEMA）, as proved by FTIR and ^1H-NMR. The preliminary results indicate that the obtained UV-cured PSMA film has very good thermal stability, excellent transparency and satisfactory tensile strength. Our work provides a simple but efficient way to prepare UV-curable PSMA, which may find potential applications in UV-curing optical fiber, metal and glass coating and other fields.展开更多
We put forward a large-area and cost-effective method to fabricate superhydrophobic coating by introducing in-situ functionalized nano-SiO2 into side-amino modified hydroxy-terminated polydimethylsiloxane （SA-HTPDMS...We put forward a large-area and cost-effective method to fabricate superhydrophobic coating by introducing in-situ functionalized nano-SiO2 into side-amino modified hydroxy-terminated polydimethylsiloxane （SA-HTPDMS） curing system. With the characterization using water contact angle （WCA） tester, Fourier transform infrared spectroscopy （FTIR）, scanning electron microscope （SEM）, atomic force microscopy （AFM） and simultaneous thermal analysis, the as-prepared coating displayed a tremendous WCA of 154.8±1°, sliding angle （SA） about 3.5° and stable self-cleaning property range from -10 to 80 ℃. It was also found that the synergistic effect of surface micro-nano hierarchical structure and chemical hydrophobicity, stability from matrix had made contributions to the superhydrophobicity and excellent heat resistance up to 300 ℃.展开更多
Polydimethylsiloxane/ polymethylacrylate （ PDMS/ PMA ） interpenetratrating polymer networks （IPNs） was fabricated by simultaneous synthesis and characterized by thermogravimetry （ TG ）. The kinetics of the therm...Polydimethylsiloxane/ polymethylacrylate （ PDMS/ PMA ） interpenetratrating polymer networks （IPNs） was fabricated by simultaneous synthesis and characterized by thermogravimetry （ TG ）. The kinetics of the thermal decomposition of polysiloxane/ polymethylacrylate IPNs in N2 and air was studied at different heating rates. It was observed that there were two decomposition peaks both in N2 and air, which showed that thermal decomposition process obeyed two-step pyrolysis mechanism and accorded with the two compositions of IPN. Kinetic parameters were determined during simultaneous integration of the Doyle equation and the IPN/ s kinetics equation was one-order equation in N2 and Air. The decomposition activation energy in N2 and air were 147. 405 kJ· monl^-1 and 192.656 kJ·monl^-1 respectively.展开更多
A series of novel polysiloxane polyurea-urethane blockcopolymers based on methylene bis(p-phenylisocyanate (MDI), sodium-s-1,2-dihydroxy propyl sulphonate (SDPS) and aminopropyl-terminated polydimethylsiloxane (ATPS) ...A series of novel polysiloxane polyurea-urethane blockcopolymers based on methylene bis(p-phenylisocyanate (MDI), sodium-s-1,2-dihydroxy propyl sulphonate (SDPS) and aminopropyl-terminated polydimethylsiloxane (ATPS) was synthesized with varying length of soft segments and neutralizing cation. The effect of the chemical composition and the cation on the morphology and mechanical properties of the samples were studied. It was found that the SDPS chain extender based samples have definite chemical structure (-MDI-SDPS-MDI-ATPS-). As the length of the soft segment increases, an improvement of phase separation was observed. In addition, when SO3Na was translated into SO3H or the sulphonic acid groups were neutralized with different charge cations (Na+, Zn2+ and Al3+), the morphology and mechanical properties changed greatly.展开更多
We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTI...We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetty, polarized optical microscopy and small-angle X-ray scattering. These obtained alkenylsilane linked novel LCPs exhibit higher glass transition temperatures and clearing points, and especially display the tendency of forming smectic phases, in strong contrast with the nematic phases of their comparative conventional alkylsilane linked analogues, which manifests more rigid features of the alkenylsilane linkages and their significant influence on the mesomorphic properties.展开更多
A new ionic liquids grafted polysiloxane used as stationary phase for capillary gas chromatography （CGC） is described. The stationary phase of 1-vinyl-3-hexylimidazolium hexafluorophosphate anchored to polysiloxane ...A new ionic liquids grafted polysiloxane used as stationary phase for capillary gas chromatography （CGC） is described. The stationary phase of 1-vinyl-3-hexylimidazolium hexafluorophosphate anchored to polysiloxane （PMHS-[VHIm][PF6]） was synthe- sized, characterized and coated onto capillary columns by static coating. The results show that the present stationary phase exhibits a very good chromatographic resolution and selectivity for Grob test mixture and alcohols with baseline resolution and symmetry peaks. The present work suggests that novel stationary phase has a great potential for further development and application. 2009 Mei Ling Qi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
A series of side chain liquid crystalline polysiloxanes containing either cholesteryl or cyanobiphenyl mesogenic groups were synthesized by the hydrosilylation reaction of a polysiloxane containing Si H group with a v...A series of side chain liquid crystalline polysiloxanes containing either cholesteryl or cyanobiphenyl mesogenic groups were synthesized by the hydrosilylation reaction of a polysiloxane containing Si H group with a vinyl terminated compound containing the mesogenic group. Their chemical structures were confirmed by IR, 1H NMR, and elemental analysis, Their phase behaviors were investigated by differential scanning calorimetry, optical polarizing microscope, and X ray diffraction techniques. The results show that all these polysiloxanes except PⅤ display smectic or nematic mesonorphism or both. The dependence of phase transition temperature on the rigidity of mesogenic unit. the length of spacer group, and the flexibility of Si(CH 3) 2O chain is also described.展开更多
Two kinds of side chain liquid crystalline polysiloxanes containing crown ether and benzyl ether were synthesized and characterized by optical polarization microscopy. Both the monomeric liquid crystals and polymeric ...Two kinds of side chain liquid crystalline polysiloxanes containing crown ether and benzyl ether were synthesized and characterized by optical polarization microscopy. Both the monomeric liquid crystals and polymeric liquid crystals show smectic phases.展开更多
Thermosetting resin matrix is the key component of advaneed wave-tra nsparent composites,where low dielectric constant,excellent processability,high thermal stability,as well as good bonding ability are required for r...Thermosetting resin matrix is the key component of advaneed wave-tra nsparent composites,where low dielectric constant,excellent processability,high thermal stability,as well as good bonding ability are required for resins.Herein,we prepared a series of phenylethynyl terminated polyimide(PI)resins by grafting amine-functi onalized hyperbra nched polysiloxane(HBPSi)to PI chains during the in situ polymerization.The effects of HBPSi on the processability of oligomers,molecular packing,thermal stability,dielectric property and bonding ability to reinforce Kevlar fibers of the cured PI/HBPSi composite resins have been examined in detail.The dielectric constants of the cured composite resins were greatly reduced from 3.29 to 2.19 without compromising its processability and thermal stability.Meanwhile,the 10 wt%HBPSi-containing PI resin demonstrated better bonding ability to reinforce fibers with the in terfacial shear strength(IFSS)of 37.64 MPa,compared with that of neat PI-6 matrix(27.34 MPa),and better adhesion to metal with the lap shear strength of 10.48 MPa,50%higher than that of neat resin PI-6(6.98 MPa).These resultant PI/HBPSi composite resins exhibit excellent comprehensive properties,indicating their great potential as low-dielectric constant resin matrix in radar radome.展开更多
Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reduce the internal stress owing to the mismatch in coefficient of thermal expansion (CTE). Polysiloxane-epoxy resin block copolymers w...Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reduce the internal stress owing to the mismatch in coefficient of thermal expansion (CTE). Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to the curing. In the cured resin, the domain size of the polysiloxane phase depended on the structure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus of the cured resin depended largely on the level of the modifier, while the CTE was affected greatly by the structure of the polysiloxane. By means of incorporating a few percent of methylphenylsiloxane unit into the polydimethylsiloxane chain, or by introducing; more compatible end-capping groups, the compounds of more effective low stress modifiers were synthesized.展开更多
A new serial chiral side-chain liquid crystal polysiloxanes containing L-Tyr structures were synthesized at room temperature. Both of them exhibited Sc phase at room temperature.
基金financially supported by the National Natural Science Foundation of China(Nos.52373316,22075298,and52373020)the Beijing Municipal Natural Science Foundation(No.2212053)。
文摘Low dielectric constant(low-k)materials are critical for advanced packaging in high-density microelectronic devices and high-frequency communication technologies.Ladder polysiloxanes,which are characterized by their unique double-chain structure and intrinsic microporosity,offer remarkable advantages in terms of thermal stability,oxidation resistance,and dielectric performance.However,structural defects in ladder polysiloxanes,such as cage-like and irregular oligomers,and their effects on dielectric properties remain underexplored.In this study,a series of ladder-like polysiloxanes(X-TMS)with diverse side groups weresynthesized via a one-step base-catalyzed method.The influence of the benzocyclobutene(BCB)side groups on the formation of regular ladder structures was systematically investigated.Notably,BCB incorporation disrupted the structural regularity,favoring the formation of cage-like and irregular topologies,which were extensively characterized using 29silicon nuclear magnetic resonance spectroscopy(^(29)Si-NMR),Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),and X-ray diffraction(XRD).These structural defects were beneficial for improving the hydrophobicity and thermal stability.Copolymerization of X-TMS with commercial DVS-BCB resins further enhanced the mechanical properties,with the elastic modulus increasing from 3.6 GPa to 4.4 GPa and water absorption reduced from 0.33 wt%to 0.06 wt%.This study establishes a clear correlation between topological structures and material properties.These findings not only advance the understanding of the structure-property relationships in ladder polysiloxanes but also provide a novel approach for designing high-performance interlayer dielectric materials for next-generation microelectronics.
基金support from the National Nat-ural Science Foundation of China(No.52403114)the Technolog-ical Base Scientific Research Projects(Highly Thermally Conduc-tive Nonmetal Materials)+3 种基金the Innovation Capability Support Pro-gram of Shaanxi(No.2024RS-CXTD-57)the Natural Science Foun-dation of Chongqing(No.2023NSCQ-MSX2547)the Fundamental Research Funds for the Central Universities(No.D5000240077)the Shaanxi Coal Chemical Industry Technology Research In-stitute Co.,Ltd.(No.2023YJY-Y-HZ-XS-NX003).
文摘Polysiloxane-based thermally conductive composites are essential for electronic heat management,but they face challenges such as limited thermal conductivity enhancement and low improvement efficiency.In this work,a novel liquid crystal crosslinker(LCC)based on biphenyl liquid crystal moieties was synthe-sized.Liquid crystal polydimethylsiloxane(LC-PDMS)with intrinsic highλwas prepared by crosslinking vinyl/methyl-hydrogen functionalized PDMS by LCC at its liquid crystal transition temperature,and boron nitride nanosheets(BNNs)with different particle sizes were used to prepare BNNs/LC-PDMS composites.When the mass ratio of LCC to vinyl-terminated PDMS is 2:1,the LC-PDMS exhibitsa well-ordered liquid crystal phase,and itsλ_(Ⅱ)reachesthe maximum value of 0.34 W(m K)^(-1),approximately 1.7 times that of general PDMS(0.20 W(m K)^(-1)).Theλ_(Ⅱ)of BNNs/LC-PDMS composites increases with the addition of BNNs,and when the mass fraction of BNNs reaches 30 wt%,with a 1:9 mass ratio of small BNNs(1μm)to large BNNs(10μm),the composite achieves the highestλ_(Ⅱ)of 12.50 W(m K)^(-1),a 68.5%increase com-pared to BNNs/PMDS composites containing the same amount of BNNs(7.42 W(m K)^(-1)).Additionally,BNNs/LC-PDMS composites also demonstrate excellent electrical insulation properties and low density,making them promising candidates for applications in highly integrated electronics fields.
基金The project supported by the National Natural Science Foundationthe Doctoral Programme Foundation of Institution of Higher Education of China
文摘Side chain liquid crystalline golysiloxanes conta ing biphenyl and benzyl ether mesogen were synthesized by the hydrosilation of poly(methylhydrcsiloxane) with 4-(4-allyloxybenzytoxy)-4'- methoxybiphenyl(M_1),4-(4-allyloxybenzyloxy)-4'-ethoxybiphenyl(M_2),4-(4-allyloxybenzyloxy)-4'- propoxybiphenyl(M_3),4-(4-allyloxybenzyloxy)-4'-butoxybiphenyl(M_4),4-(4-allyloxybenzyloxy)-4'- pentyloxybiphenyl(M_5).The phase behavior of monomeric and polymeric liquid crystals was chararcterized by differential scanning calorimetry and optical polarization microscopy.Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.
文摘A new capillary gas chromatography stationary phase, monokis (2,6 di O benzyl 3 O propyl (3’)) hexakis(2,6 di O benzyl 3 O methyl) β CD bonded polysiloxane, was synthesized. It exhibited separation abilities to disubstituted benzene isomers and some chiral solutes. It was also found that the polarity of CD derivatives can be lowered both by chemically bonding it to polysiloxane and by diluting it in polysiloxane. The separation abilities of the polysiloxane anchored CDs (SP CD) are higher than that of the unbonded CDs (S CD) and the diluted S CD at lower column temperature. Hydrosilylation reaction is one of the best methods to lower the operating temperature of CDs.
基金supported by the Science and Technology Department of Zhejiang Province(No.2006C11050)
文摘A series of stable waterborne polysiloxaneurethane （WPSUR） dispersions were prepared using amino-terminated polydimethylsiloxane （NS）, dimethylolpropionic acid （DMPA）, castor oil, polypropylene glycol and toluene diisocyanate. Meanwhile, NS with different molecular weights was synthesized and used as the soft co-segment. Effects of types and contents of soft co-segments as well as chain extenders on the thermal degradation and stability for WPSUR films were examined. Results reveal that WPSUR films exhibit excellent water resistance and mechanical properties as compared with pure polyurethane （PU） films, and the NS soft co-segment possesses a remarkable effect on the second stage （stage Ⅱ）, while the content of the hard segment is propitious to the initial stage （stage Ⅰ）. Moreover, the highest temperature of stage Ⅱ （T2m） for WPSUR films using NS as soft co-segment is 413℃, approximately being 30℃ higher than that of those typical PUs using HDA and APDMS as the chain extenders, respectively.
基金National Natural Science Foundation of China (No. 50373025)Doctoral Fund of the Ministry of Education of China (No.200807080002)Postgraduate Innovation Foundation of Shaanxi University of Science & Technology,China
文摘The film morphology of dodecyl/carboxyl modified polysiloxane(RCAS) on cotton fabric or the silicon wafer was investigated and characterized by field emission scanning electron microscopy(FESEM),atomic force microscope(AFM),and Fourier transform infrared spectrometer(FTIR).Experimental results indicate that RCAS is a good film forming material on different substrates.Relatively smooth film was formed on cotton fabric surface,on which the grooves disappeared.In addition,RCAS formed a micromorphology inhomogeneous and unsmooth film on the silicon wafer.Many high or low bright peaks distributed randomly on the film surface,especially as the field was 2μm×2 μm and the date scale was 5 nm in AFM observation.Then RCAS was emulsified with nonionic surfactant alkyl polyoxyethylene ether in order to achieve a transparent organosilicon emulsion-RCAS emulsion(RCSE),which possessed good stability.The properties of RCSE and its application performance on cotton fabrics were investigated and characterized by transmission electron microscope(TEM),particle size analysis,and voltage test instrument.The results show that the average particle size of RCAS emulsion is 28.32 nm,while the ζ voltage is-37.88 mV.Compared with untreatd cotton fabric,the softness of treated fabric can be improved with RCSE to a certain extent.At the same time,the fabric treated with RCSE acquires unique fluffy and soft handle.
基金supported by the National Natural Science Foundation of China(No.20874040)Research Funds from University of Jinan(XKY0721)
文摘Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.
文摘In this paper, a new polymer of polysiloxane modified polyurethane was synthesized by using H-containing silicone oil, toluene diisocyanate（TDI）, 1,4-butanediol and unsaturated polyether.
文摘In this study, a UV-curable polysiloxane methacrylate （PSMA） was synthesized by a one-step method. The reaction was catalyzed by chloroplatinic acid between polymethylhydrosiloxane （PMHS） and hydroxyethyl methacrylate （HEMA）, as proved by FTIR and ^1H-NMR. The preliminary results indicate that the obtained UV-cured PSMA film has very good thermal stability, excellent transparency and satisfactory tensile strength. Our work provides a simple but efficient way to prepare UV-curable PSMA, which may find potential applications in UV-curing optical fiber, metal and glass coating and other fields.
基金Supported by National High Technology Research and Development ProgramofChina(863Program)(No.2003AA305920)
文摘We put forward a large-area and cost-effective method to fabricate superhydrophobic coating by introducing in-situ functionalized nano-SiO2 into side-amino modified hydroxy-terminated polydimethylsiloxane （SA-HTPDMS） curing system. With the characterization using water contact angle （WCA） tester, Fourier transform infrared spectroscopy （FTIR）, scanning electron microscope （SEM）, atomic force microscopy （AFM） and simultaneous thermal analysis, the as-prepared coating displayed a tremendous WCA of 154.8±1°, sliding angle （SA） about 3.5° and stable self-cleaning property range from -10 to 80 ℃. It was also found that the synergistic effect of surface micro-nano hierarchical structure and chemical hydrophobicity, stability from matrix had made contributions to the superhydrophobicity and excellent heat resistance up to 300 ℃.
文摘Polydimethylsiloxane/ polymethylacrylate （ PDMS/ PMA ） interpenetratrating polymer networks （IPNs） was fabricated by simultaneous synthesis and characterized by thermogravimetry （ TG ）. The kinetics of the thermal decomposition of polysiloxane/ polymethylacrylate IPNs in N2 and air was studied at different heating rates. It was observed that there were two decomposition peaks both in N2 and air, which showed that thermal decomposition process obeyed two-step pyrolysis mechanism and accorded with the two compositions of IPN. Kinetic parameters were determined during simultaneous integration of the Doyle equation and the IPN/ s kinetics equation was one-order equation in N2 and Air. The decomposition activation energy in N2 and air were 147. 405 kJ· monl^-1 and 192.656 kJ·monl^-1 respectively.
文摘A series of novel polysiloxane polyurea-urethane blockcopolymers based on methylene bis(p-phenylisocyanate (MDI), sodium-s-1,2-dihydroxy propyl sulphonate (SDPS) and aminopropyl-terminated polydimethylsiloxane (ATPS) was synthesized with varying length of soft segments and neutralizing cation. The effect of the chemical composition and the cation on the morphology and mechanical properties of the samples were studied. It was found that the SDPS chain extender based samples have definite chemical structure (-MDI-SDPS-MDI-ATPS-). As the length of the soft segment increases, an improvement of phase separation was observed. In addition, when SO3Na was translated into SO3H or the sulphonic acid groups were neutralized with different charge cations (Na+, Zn2+ and Al3+), the morphology and mechanical properties changed greatly.
基金financially supported by the National Natural Science Foundation of China(No.21374016)
文摘We describe in this work an alkyne-hydrosilylation approach to synthesize a series of novel polysiloxane sidechain LCPs attaching end-on or side-on mesogenic side groups. Their properties are characterized by NMR, FTIR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetty, polarized optical microscopy and small-angle X-ray scattering. These obtained alkenylsilane linked novel LCPs exhibit higher glass transition temperatures and clearing points, and especially display the tendency of forming smectic phases, in strong contrast with the nematic phases of their comparative conventional alkylsilane linked analogues, which manifests more rigid features of the alkenylsilane linkages and their significant influence on the mesomorphic properties.
基金the National Natural Science Foundation of China for the funding(No.20675007)
文摘A new ionic liquids grafted polysiloxane used as stationary phase for capillary gas chromatography （CGC） is described. The stationary phase of 1-vinyl-3-hexylimidazolium hexafluorophosphate anchored to polysiloxane （PMHS-[VHIm][PF6]） was synthe- sized, characterized and coated onto capillary columns by static coating. The results show that the present stationary phase exhibits a very good chromatographic resolution and selectivity for Grob test mixture and alcohols with baseline resolution and symmetry peaks. The present work suggests that novel stationary phase has a great potential for further development and application. 2009 Mei Ling Qi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘A series of side chain liquid crystalline polysiloxanes containing either cholesteryl or cyanobiphenyl mesogenic groups were synthesized by the hydrosilylation reaction of a polysiloxane containing Si H group with a vinyl terminated compound containing the mesogenic group. Their chemical structures were confirmed by IR, 1H NMR, and elemental analysis, Their phase behaviors were investigated by differential scanning calorimetry, optical polarizing microscope, and X ray diffraction techniques. The results show that all these polysiloxanes except PⅤ display smectic or nematic mesonorphism or both. The dependence of phase transition temperature on the rigidity of mesogenic unit. the length of spacer group, and the flexibility of Si(CH 3) 2O chain is also described.
基金This project was financially supported by the National Natural Science Foundation of China(Approved No.29775006)
文摘Two kinds of side chain liquid crystalline polysiloxanes containing crown ether and benzyl ether were synthesized and characterized by optical polarization microscopy. Both the monomeric liquid crystals and polymeric liquid crystals show smectic phases.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51903038,21774019 and 21975040)the Program of Shanghai Academic Research Leader(No.18XD1400100)+1 种基金the Scientific Research Innovation Plan of Shanghai Education Commission(No.2019-01-07-00-03-E00001)the Fundamental Research Funds for the Central Universities and Graduate Innovation Fund of Donghua University(No.CUSF-DH-D-2019009).
文摘Thermosetting resin matrix is the key component of advaneed wave-tra nsparent composites,where low dielectric constant,excellent processability,high thermal stability,as well as good bonding ability are required for resins.Herein,we prepared a series of phenylethynyl terminated polyimide(PI)resins by grafting amine-functi onalized hyperbra nched polysiloxane(HBPSi)to PI chains during the in situ polymerization.The effects of HBPSi on the processability of oligomers,molecular packing,thermal stability,dielectric property and bonding ability to reinforce Kevlar fibers of the cured PI/HBPSi composite resins have been examined in detail.The dielectric constants of the cured composite resins were greatly reduced from 3.29 to 2.19 without compromising its processability and thermal stability.Meanwhile,the 10 wt%HBPSi-containing PI resin demonstrated better bonding ability to reinforce fibers with the in terfacial shear strength(IFSS)of 37.64 MPa,compared with that of neat PI-6 matrix(27.34 MPa),and better adhesion to metal with the lap shear strength of 10.48 MPa,50%higher than that of neat resin PI-6(6.98 MPa).These resultant PI/HBPSi composite resins exhibit excellent comprehensive properties,indicating their great potential as low-dielectric constant resin matrix in radar radome.
文摘Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reduce the internal stress owing to the mismatch in coefficient of thermal expansion (CTE). Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to the curing. In the cured resin, the domain size of the polysiloxane phase depended on the structure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus of the cured resin depended largely on the level of the modifier, while the CTE was affected greatly by the structure of the polysiloxane. By means of incorporating a few percent of methylphenylsiloxane unit into the polydimethylsiloxane chain, or by introducing; more compatible end-capping groups, the compounds of more effective low stress modifiers were synthesized.
文摘A new serial chiral side-chain liquid crystal polysiloxanes containing L-Tyr structures were synthesized at room temperature. Both of them exhibited Sc phase at room temperature.
