The liquid crystalline behavior of anisotropic solutions in 100% sulphuric acid of aromatic copolyamide obtained by low-temperature solution copolycondensation of terephthalic acid chloride (TPC), p-phenylene diamine ...The liquid crystalline behavior of anisotropic solutions in 100% sulphuric acid of aromatic copolyamide obtained by low-temperature solution copolycondensation of terephthalic acid chloride (TPC), p-phenylene diamine (PPD) and 4, 4'-diamino-diphenylether (DAPE) has been studied by optical microscopy and X-ray diffraction. The effects of inherent viscosity, concentration of copolyamide in sulphuric acid, the content of the third monomer (DAPE) and sequence distribution of copolyamide on the critical concentration, isotropic temperature, phase diagram and texture of liquid crystal were investigated. The schlieren texture was observed and the results of X-ray diffraction indicate that the concentrated solutions of copolyamide exhibit nematic liquid crystalline behavior.展开更多
The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron contain...The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1873 K. The Mn distribution ratio L-Mn increases with increasing FetO content and decreasing the basicity ((%CaO + %MgO)/(%SiO2 + %Al2O3 + %P2O5)) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of L-Mn and L-p decrease by the addition of Al2O3 into slag. The expression of the dependence of L-Mn and L-p on the basicity and FetO content in slag was obtained.展开更多
The anodic behavior of cerium （Ce） in A1C13-1-ethyl-3-methyl-imidazolium chloride （A1CI3-EMIC） ionic liquid has been investigated. Linear sweep voltammetry （LSV）, electrochemical impedance spectra （EIS）, Raman...The anodic behavior of cerium （Ce） in A1C13-1-ethyl-3-methyl-imidazolium chloride （A1CI3-EMIC） ionic liquid has been investigated. Linear sweep voltammetry （LSV）, electrochemical impedance spectra （EIS）, Raman spectra, scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS） were carried out to state the process and mechanism during anodic reaction. The results show that Ce can be electrochemically oxidized and dissolved in the ionic liquid. The oxide film of Ce markedly affects its anodic behavior by blocking the dissolution of the underlying metal. Moreover. the dissolution of metal surface brings about the stripping of the oxide film on Ce, thus leading to an oxide free surface. This work demonstrates a theoretical foundation for electrolytic etching of Ce in ionic liquids,展开更多
The synthesis and phase behavior of a series of 4'-alkyloxy -4-hydroxy biphenyls were discribed.The effects of reaction conditions on the yields of products were investigated.The characterizations of thermotropic ...The synthesis and phase behavior of a series of 4'-alkyloxy -4-hydroxy biphenyls were discribed.The effects of reaction conditions on the yields of products were investigated.The characterizations of thermotropic liquid crystalline products for the type and thermal properties are discussed through the use of differential scanning calorimetry,polarizing microscopy.展开更多
In the Ruhrstahl-Heraeus （RH） refining process, liquid steel flow pattern in a ladle is controlled by the fluid flow behavior in the vacuum chamber. Potassium chloride solution and NaOH solution saturated with CO2 w...In the Ruhrstahl-Heraeus （RH） refining process, liquid steel flow pattern in a ladle is controlled by the fluid flow behavior in the vacuum chamber. Potassium chloride solution and NaOH solution saturated with CO2 were respectively used as a tracer to investigate the liquid and gas flow behaviors in the vacuum chamber. Principal compo nent and comparative analysis were made to show the factors controlling mixing and circulation flow rate. The liquid level and bubble behavior in the vacuum chamber greatly affect fluid flow in RH process. Experiments were performed to investigate the effects of liquid steel level, gas flow rate, bubble residence time, and gas injection mode on mixing, decarburization, and void fraction. The results indicate that the mixing process can be divided into three regions： the flow rate affected zone, the concentration gradient-affected zone, and their combination. The liquid steel level in the vacuum chamber of 300 mm is a critical point in the decarburization transition. For liquid level lower than 300 mm, liquid steel circulation controls decarburization, while for liquid level higher than 300mm, bubble behavior is the main controlling factor. During the RH process, it is recommended to use the concentrated bubble injection mode for low gas flow rates and the uniform bubble injection mode for high gas flow rates.展开更多
Corrosion behavior of four oxide dispersion strengthened(ODS) ferritic alloys exposed in thermal convective liquid sodium loop for 4 000 h was examined.Surface observation results reveal that coral-like surfaces with ...Corrosion behavior of four oxide dispersion strengthened(ODS) ferritic alloys exposed in thermal convective liquid sodium loop for 4 000 h was examined.Surface observation results reveal that coral-like surfaces with deposit initially formed on surfaces of all exposed specimens.In tested alloy S2,χ-phase precipitated in specimen center,and a depleted χ- phase zone formed near the specimen surface.There is a transition area between the surface and center.In the other tested alloys,no notable change on microstructure was observed.Grain boundary attack was not found in any of the tested specimens.Tensile test results indicate that sodium corrosion of the four ODS ferritic alloys for 3 000 h had no notable effect on their tensile properties.展开更多
A series of side chain liquid crystalline polymers （SCLCPs） containing triphenylene （Tp） units in the side chains, denoted as PMTS （without spacer） and PMTnS （n = 2, 3, 4, 6, which is the number of the methylen...A series of side chain liquid crystalline polymers （SCLCPs） containing triphenylene （Tp） units in the side chains, denoted as PMTS （without spacer） and PMTnS （n = 2, 3, 4, 6, which is the number of the methylene units between the main chain and Tp moieties in the side chains）, with different lengths of spacers were synthesized through conventional free radical polymerization. The chemical structures of the monomers were confirmed by 1H/IaC-NMR, and the phase behaviors were examined by differential scanning calorimetry （DSC）, polarized optical microscopy （POM） and wide-angle X-ray diffraction （1D and 2D WAXD）. The molecular characterization of the polymers was performed with 1H-NMR, gel permeation chromatography （GPC） and thermogravimetric analysis （TGA）. The phase behaviors of the polymers have been investigated by a combination of techniques including DSC, POM, 1D and 2D WAXD. The results showed that the length of spacer has significant effects on the LC phase behavior of polymers. For PMTS and PMT2S, they displayed the columnar phase developed by the Tp moieties and the main chain as a whole due to the strong coupling effect of the Tp moieties and the main chain. For the PMT3S, PMT4S and PMT6S, they formed the symmetry hexagonal columnar （~n） phase owing to the decoupling effect. All of these indicated that the ＂decoupling effect＂ or ＂coupling effect＂ depended on the length of spacers, leading to the different LC phase formation mechanism.展开更多
The lytropic liquid crystals in dodecanic acid diethanolamine (DAD) /n-butanol (C4OH) /octane (n-C8H18) /deuteron (D2O) system were studied to determine the phase regions and were investigated by 2H-NMR spectroscopy,o...The lytropic liquid crystals in dodecanic acid diethanolamine (DAD) /n-butanol (C4OH) /octane (n-C8H18) /deuteron (D2O) system were studied to determine the phase regions and were investigated by 2H-NMR spectroscopy,optical polarizing microscope and small-angle X-ray diffraction (SAXD) methods.The results indicate that the lamellar,hexagonal and cubic liquid crystals all exist in the above system.Keeping the weight ratio of DAD and C4OH constant,the microphase Structure,2H quadruple splitting and the interlayer spacing are all changed with the addition of deuteron.展开更多
Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation aftercessation of shear flow was used to study the rheological behavior and internal structure of thermot...Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation aftercessation of shear flow was used to study the rheological behavior and internal structure of thermotropic liquid crystallinepolymer(TLCP).There are two kinds of intermittent shear flow:all start-up flows are in the same direction(intermittent flowforward:IFF)and start-up flows change their directions alternately(intermittent flow reversal:IFR).The results show thatthe stress of start-up flow of IFF and IFR in the test process is not superposed,indicating different changes of internalstructure of thermotropic LCP(TLCP).Two main factors affect structure changes in the experimental time scale.One relatesto long-term texture relaxation process,the other is an interchain reaction that becomes important after 30 min.The twofactors raise the stress of IFF,but express complex effects for the stress of IFR.The latter factor becomes very important atlong time annealing process.The relaxation behavior was also studied by the application of wide range relaxation spectrumcalculated from the combined dynamic modulus,which gave three characteristic relaxation times(0.3,10 and 600 s)ascribable to the relaxations of less-phase orientation,domain orientation,and domain deformation,respectively.The resultalso shows that the domain coalescence(texture relaxation),a long relaxation time,is a much slow process and lasts beyond2400 s of the test time.展开更多
Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 w...Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144 similar to 146 degrees C. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.展开更多
We present a coarse-grained molecular dynamics simulation study of phase behavior of amphiphilic monolayers at the liquid crystal （LC）/water interface. The results revealed that LCs at interface can influence the la...We present a coarse-grained molecular dynamics simulation study of phase behavior of amphiphilic monolayers at the liquid crystal （LC）/water interface. The results revealed that LCs at interface can influence the lateral ordering of amphiphiles. Particularly, the amphiphile tails along with perpendicularly penetrated LCs between tails undergo a two-dimension phase transition from liquid-expanded into a liquid-condensed phase as their area density at interface reaches 0.93. While, the liquid-condensed phase of the monolayer never appears at oil/water interface with isotropic shape oil particles. These findings reveal the penetration of anisotropic LC can promote ordered lateral organization of amphiphiles. Moreover, we find the phase transition point is shifted to lower surface coverage of amphiphiles when the LCs have larger affinity to the amphiphile tails.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
Four new organosilane compounds containing cholesteryl group were synthesized by esterification of 3,3,5,5-tetramethyl-3,5-disila-4-oxa-cyclohexane-1-carboxylic acid and ω-hydroxyalkyl, cholesteryl carbonate in the p...Four new organosilane compounds containing cholesteryl group were synthesized by esterification of 3,3,5,5-tetramethyl-3,5-disila-4-oxa-cyclohexane-1-carboxylic acid and ω-hydroxyalkyl, cholesteryl carbonate in the presence of DCC and DMAP. Their structures were characterized by1H-NMR, IR and elemental analysis. Their phase behaviors were investigated by differential scanning calorimetry (DSC) and polarized microscopy. Results showed that these four organosilane compounds were all liquid crystalline and longer spacer was advantageous to orientation of organosilane heterocycle and cholesteryl group.展开更多
To investigate the performance of graphene(Gra) modified with ethoxycarbonyl ionic liquid(IL), chain mobility and crystallization kinetics of poly(L-lactic acid)(PLLA), a series of PLLA nanocomposites have been prepar...To investigate the performance of graphene(Gra) modified with ethoxycarbonyl ionic liquid(IL), chain mobility and crystallization kinetics of poly(L-lactic acid)(PLLA), a series of PLLA nanocomposites have been prepared using solution-cast method.IL can improve the dispersion of Gra in PLLA matrix and the samples containing IL have higher growth rate of PLLA spherulite than neat PLLA does. PLLA/IL/Gra and PLLA/2 Gra exhibit the same relaxation strength and time of αN relaxation that corresponds to the longest normal mode motion at 110-140 °C. PLLA/IL/Gra shows a faster crystallization rate than PLLA/2 Gra does, which might be attributed to the Gra-imidazolium cation interaction in IL modified Gra, the significant dispersion effect of IL at Gra surface, and the increase of nuclei density of PLLA/IL/Gra.展开更多
The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are det...The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are determined by infrared absorption spectroscopy (IR),nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing opticalmicroscope (POM) and differential scanning calorimetry (DSC).展开更多
We study the iron atomic aggregates deposited on silicone oil surfaces by using atomic force microscopy. The aggregates are composed of disk-shaped nanoparticles with the mean diameter Φc≈31.7 nm and height Hc≈4.5 ...We study the iron atomic aggregates deposited on silicone oil surfaces by using atomic force microscopy. The aggregates are composed of disk-shaped nanoparticles with the mean diameter Φc≈31.7 nm and height Hc≈4.5 nm, which are nearly independent of the nominal film thickness. The experiment shows that a material condensation process must occur in the nanoparticles during the growth period. The anomalous phenomenon is explained.展开更多
Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, di...Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, differential scanning calorimetry, polarized optical microscopic and X-ray diffraction analysis. Synthesized polymer possessed liquid crystalline (LC) properties. Spin coated PEI8M film showed out-of-plane molecular orientation on annealing and non-polarized visible light irradiation. PEI8M in solid film exhibited photoresponsive properties upon irradiation of UV and visible light. PEI8M film also exhibited reversible molecular orientation from random state to out-of-plane and from out-of-plane to random state on annealing, non-polarized UV and visible light irradiation.展开更多
The mechanical behavior of LC 4 alloy in the semisolid state at high volume fractions of solid has been studied through unconstrictive compressing test. The results show that peak stress mainly depends on grain bound...The mechanical behavior of LC 4 alloy in the semisolid state at high volume fractions of solid has been studied through unconstrictive compressing test. The results show that peak stress mainly depends on grain boundary’s cohesion and instantaneous strain rate sensitivity in the semisolid state, which is similar to that in the solid state. Analyses on microstructures and status of compressive stress of specimen demonstrate that segregation of liquid solid phase is mainly affected by strain rate and deformation temperature. There are mainly two kinds of flow in liquid phase: either from the region with relatively large hydrostatic compressive stress to the region with relatively small hydrostatic compressive stress or from the grain boundaries perpendicular to the compression axis to the grain boundaries with a certain directional angle to the compression direction. Based on the above results, compressive deformation mechanism mainly depends on deformation temperature, strain rate and stress state.展开更多
文摘The liquid crystalline behavior of anisotropic solutions in 100% sulphuric acid of aromatic copolyamide obtained by low-temperature solution copolycondensation of terephthalic acid chloride (TPC), p-phenylene diamine (PPD) and 4, 4'-diamino-diphenylether (DAPE) has been studied by optical microscopy and X-ray diffraction. The effects of inherent viscosity, concentration of copolyamide in sulphuric acid, the content of the third monomer (DAPE) and sequence distribution of copolyamide on the critical concentration, isotropic temperature, phase diagram and texture of liquid crystal were investigated. The schlieren texture was observed and the results of X-ray diffraction indicate that the concentrated solutions of copolyamide exhibit nematic liquid crystalline behavior.
文摘The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1873 K. The Mn distribution ratio L-Mn increases with increasing FetO content and decreasing the basicity ((%CaO + %MgO)/(%SiO2 + %Al2O3 + %P2O5)) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of L-Mn and L-p decrease by the addition of Al2O3 into slag. The expression of the dependence of L-Mn and L-p on the basicity and FetO content in slag was obtained.
基金Project supproted by Discipline Development Foundation of China Academy of Engineering and Physics(2015B0301065)
文摘The anodic behavior of cerium （Ce） in A1C13-1-ethyl-3-methyl-imidazolium chloride （A1CI3-EMIC） ionic liquid has been investigated. Linear sweep voltammetry （LSV）, electrochemical impedance spectra （EIS）, Raman spectra, scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS） were carried out to state the process and mechanism during anodic reaction. The results show that Ce can be electrochemically oxidized and dissolved in the ionic liquid. The oxide film of Ce markedly affects its anodic behavior by blocking the dissolution of the underlying metal. Moreover. the dissolution of metal surface brings about the stripping of the oxide film on Ce, thus leading to an oxide free surface. This work demonstrates a theoretical foundation for electrolytic etching of Ce in ionic liquids,
文摘The synthesis and phase behavior of a series of 4'-alkyloxy -4-hydroxy biphenyls were discribed.The effects of reaction conditions on the yields of products were investigated.The characterizations of thermotropic liquid crystalline products for the type and thermal properties are discussed through the use of differential scanning calorimetry,polarizing microscopy.
基金Item Sponsored by National Natural Science Foundation of China(51404022)Doctoral Fund of Ministry of Education of China(20130006110023)Ph.D Early Development Program of Taiyuan University of Science and Technology of China(20152008,20142001)
文摘In the Ruhrstahl-Heraeus （RH） refining process, liquid steel flow pattern in a ladle is controlled by the fluid flow behavior in the vacuum chamber. Potassium chloride solution and NaOH solution saturated with CO2 were respectively used as a tracer to investigate the liquid and gas flow behaviors in the vacuum chamber. Principal compo nent and comparative analysis were made to show the factors controlling mixing and circulation flow rate. The liquid level and bubble behavior in the vacuum chamber greatly affect fluid flow in RH process. Experiments were performed to investigate the effects of liquid steel level, gas flow rate, bubble residence time, and gas injection mode on mixing, decarburization, and void fraction. The results indicate that the mixing process can be divided into three regions： the flow rate affected zone, the concentration gradient-affected zone, and their combination. The liquid steel level in the vacuum chamber of 300 mm is a critical point in the decarburization transition. For liquid level lower than 300 mm, liquid steel circulation controls decarburization, while for liquid level higher than 300mm, bubble behavior is the main controlling factor. During the RH process, it is recommended to use the concentrated bubble injection mode for low gas flow rates and the uniform bubble injection mode for high gas flow rates.
文摘Corrosion behavior of four oxide dispersion strengthened(ODS) ferritic alloys exposed in thermal convective liquid sodium loop for 4 000 h was examined.Surface observation results reveal that coral-like surfaces with deposit initially formed on surfaces of all exposed specimens.In tested alloy S2,χ-phase precipitated in specimen center,and a depleted χ- phase zone formed near the specimen surface.There is a transition area between the surface and center.In the other tested alloys,no notable change on microstructure was observed.Grain boundary attack was not found in any of the tested specimens.Tensile test results indicate that sodium corrosion of the four ODS ferritic alloys for 3 000 h had no notable effect on their tensile properties.
基金financially supported by the National Natural Science Foundation of China(No.51373148)the Innovation Platform Open Foundation of University of Hunan Province(No.CX2013B265)
文摘A series of side chain liquid crystalline polymers （SCLCPs） containing triphenylene （Tp） units in the side chains, denoted as PMTS （without spacer） and PMTnS （n = 2, 3, 4, 6, which is the number of the methylene units between the main chain and Tp moieties in the side chains）, with different lengths of spacers were synthesized through conventional free radical polymerization. The chemical structures of the monomers were confirmed by 1H/IaC-NMR, and the phase behaviors were examined by differential scanning calorimetry （DSC）, polarized optical microscopy （POM） and wide-angle X-ray diffraction （1D and 2D WAXD）. The molecular characterization of the polymers was performed with 1H-NMR, gel permeation chromatography （GPC） and thermogravimetric analysis （TGA）. The phase behaviors of the polymers have been investigated by a combination of techniques including DSC, POM, 1D and 2D WAXD. The results showed that the length of spacer has significant effects on the LC phase behavior of polymers. For PMTS and PMT2S, they displayed the columnar phase developed by the Tp moieties and the main chain as a whole due to the strong coupling effect of the Tp moieties and the main chain. For the PMT3S, PMT4S and PMT6S, they formed the symmetry hexagonal columnar （~n） phase owing to the decoupling effect. All of these indicated that the ＂decoupling effect＂ or ＂coupling effect＂ depended on the length of spacers, leading to the different LC phase formation mechanism.
文摘The lytropic liquid crystals in dodecanic acid diethanolamine (DAD) /n-butanol (C4OH) /octane (n-C8H18) /deuteron (D2O) system were studied to determine the phase regions and were investigated by 2H-NMR spectroscopy,optical polarizing microscope and small-angle X-ray diffraction (SAXD) methods.The results indicate that the lamellar,hexagonal and cubic liquid crystals all exist in the above system.Keeping the weight ratio of DAD and C4OH constant,the microphase Structure,2H quadruple splitting and the interlayer spacing are all changed with the addition of deuteron.
基金This work was supported by the National Natural Science Foundation of China(Nos.201740242020400750290090).
文摘Intermittent shear flow including start-up flow and small oscillatory amplitude time sweep or stress relaxation aftercessation of shear flow was used to study the rheological behavior and internal structure of thermotropic liquid crystallinepolymer(TLCP).There are two kinds of intermittent shear flow:all start-up flows are in the same direction(intermittent flowforward:IFF)and start-up flows change their directions alternately(intermittent flow reversal:IFR).The results show thatthe stress of start-up flow of IFF and IFR in the test process is not superposed,indicating different changes of internalstructure of thermotropic LCP(TLCP).Two main factors affect structure changes in the experimental time scale.One relatesto long-term texture relaxation process,the other is an interchain reaction that becomes important after 30 min.The twofactors raise the stress of IFF,but express complex effects for the stress of IFR.The latter factor becomes very important atlong time annealing process.The relaxation behavior was also studied by the application of wide range relaxation spectrumcalculated from the combined dynamic modulus,which gave three characteristic relaxation times(0.3,10 and 600 s)ascribable to the relaxations of less-phase orientation,domain orientation,and domain deformation,respectively.The resultalso shows that the domain coalescence(texture relaxation),a long relaxation time,is a much slow process and lasts beyond2400 s of the test time.
文摘Liquid crystalline multi-block copolymers poly[1,6-bis(4-oxybenzoyl-oxy)hexane terephthalate]-b-bisphenol A polycarbonate (PHTH-6-b-PC) with different segments of polycarbonate (PC) and thermotropic polyester PHTH-6 were synthesized in tetrachloroethane at 144 similar to 146 degrees C. The influence of segment length on the resulting phase structure and thermal behavior of block copolymers was also discussed. It is demonstrated by TEM and DMA that the resulting block copolymers show a considerable microphase separation. The degree of phase separation and the thermal behavior of the block copolymers are strongly dependent on the molecular weight of the segments incorporated.
基金financially supported by the Naional Natural Science Foundation of China(Nos.21174154,50930002 and 20874110)the Supercomputer Center of Chinese Academy of Sciences
文摘We present a coarse-grained molecular dynamics simulation study of phase behavior of amphiphilic monolayers at the liquid crystal （LC）/water interface. The results revealed that LCs at interface can influence the lateral ordering of amphiphiles. Particularly, the amphiphile tails along with perpendicularly penetrated LCs between tails undergo a two-dimension phase transition from liquid-expanded into a liquid-condensed phase as their area density at interface reaches 0.93. While, the liquid-condensed phase of the monolayer never appears at oil/water interface with isotropic shape oil particles. These findings reveal the penetration of anisotropic LC can promote ordered lateral organization of amphiphiles. Moreover, we find the phase transition point is shifted to lower surface coverage of amphiphiles when the LCs have larger affinity to the amphiphile tails.
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.
文摘Four new organosilane compounds containing cholesteryl group were synthesized by esterification of 3,3,5,5-tetramethyl-3,5-disila-4-oxa-cyclohexane-1-carboxylic acid and ω-hydroxyalkyl, cholesteryl carbonate in the presence of DCC and DMAP. Their structures were characterized by1H-NMR, IR and elemental analysis. Their phase behaviors were investigated by differential scanning calorimetry (DSC) and polarized microscopy. Results showed that these four organosilane compounds were all liquid crystalline and longer spacer was advantageous to orientation of organosilane heterocycle and cholesteryl group.
基金financially supported by the National Natural Science Foundation of China(No.51603060)the Fundamental Research Funds for the Central Universities(No.JZ2017YYPY0250)
文摘To investigate the performance of graphene(Gra) modified with ethoxycarbonyl ionic liquid(IL), chain mobility and crystallization kinetics of poly(L-lactic acid)(PLLA), a series of PLLA nanocomposites have been prepared using solution-cast method.IL can improve the dispersion of Gra in PLLA matrix and the samples containing IL have higher growth rate of PLLA spherulite than neat PLLA does. PLLA/IL/Gra and PLLA/2 Gra exhibit the same relaxation strength and time of αN relaxation that corresponds to the longest normal mode motion at 110-140 °C. PLLA/IL/Gra shows a faster crystallization rate than PLLA/2 Gra does, which might be attributed to the Gra-imidazolium cation interaction in IL modified Gra, the significant dispersion effect of IL at Gra surface, and the increase of nuclei density of PLLA/IL/Gra.
文摘The synthesis and characterization of two new star-like liquid crystals are reported.They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirphase behaviors and the structures are determined by infrared absorption spectroscopy (IR),nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing opticalmicroscope (POM) and differential scanning calorimetry (DSC).
基金Project supported by the National Natural Science Foundation of China(Grant No.11074215)the Fundamental Research Funds for Central Universities of Ministry of Education of China(Grant No.2012QNA3010)
文摘We study the iron atomic aggregates deposited on silicone oil surfaces by using atomic force microscopy. The aggregates are composed of disk-shaped nanoparticles with the mean diameter Φc≈31.7 nm and height Hc≈4.5 nm, which are nearly independent of the nominal film thickness. The experiment shows that a material condensation process must occur in the nanoparticles during the growth period. The anomalous phenomenon is explained.
文摘Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, differential scanning calorimetry, polarized optical microscopic and X-ray diffraction analysis. Synthesized polymer possessed liquid crystalline (LC) properties. Spin coated PEI8M film showed out-of-plane molecular orientation on annealing and non-polarized visible light irradiation. PEI8M in solid film exhibited photoresponsive properties upon irradiation of UV and visible light. PEI8M film also exhibited reversible molecular orientation from random state to out-of-plane and from out-of-plane to random state on annealing, non-polarized UV and visible light irradiation.
文摘The mechanical behavior of LC 4 alloy in the semisolid state at high volume fractions of solid has been studied through unconstrictive compressing test. The results show that peak stress mainly depends on grain boundary’s cohesion and instantaneous strain rate sensitivity in the semisolid state, which is similar to that in the solid state. Analyses on microstructures and status of compressive stress of specimen demonstrate that segregation of liquid solid phase is mainly affected by strain rate and deformation temperature. There are mainly two kinds of flow in liquid phase: either from the region with relatively large hydrostatic compressive stress to the region with relatively small hydrostatic compressive stress or from the grain boundaries perpendicular to the compression axis to the grain boundaries with a certain directional angle to the compression direction. Based on the above results, compressive deformation mechanism mainly depends on deformation temperature, strain rate and stress state.
