Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors....Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors.This dynamic color-changing capability is crucial for applications that require adaptable optical properties,positioning CLCs as key materials in advanced photonic technologies.This review focuses on the mechanisms of dynamic color tuning in CLCs across various forms,including small molecules,cholesteric liquid crystal elastomers(CLCEs),and cholesteric liquid crystal networks(CLCNs),and emphasizes the distinct responsive coloration each structure provides.Key developments in photochromic mechanisms based on azobenzene,dithienylethene,and molecular motor switches,are discussed for their roles in enhancing the stability and tuning range of CLCs.We examine the color-changing behaviors of CLCEs under mechanical stimuli and CLCNs under swelling,highlighting the advantages of each form.Following this,applications of dynamic color-tuning CLCs in information encryption,adaptive camouflage,and smart sensing technologies are explored.The review concludes with an outlook on current challenges and future directions in CLC research,particularly in biomimetic systems and dynamic photonic devices,aiming to broaden their functional applications and impact.展开更多
Photonic fibrous soft actuators that can modulate light and produce responsive deformation would have broad technological implications in areas,ranging from smart textiles and intelligent artificial muscles to medical...Photonic fibrous soft actuators that can modulate light and produce responsive deformation would have broad technological implications in areas,ranging from smart textiles and intelligent artificial muscles to medical devices.However,creating such multifunctional soft actuators has proved tremendously challenging.Here,we report novel cholesteric liquid crystal elastomer(CLCE)based photonic fibrous soft actuators(PFSAs).CLCE can serve as chiral photonic soft active material and allow for multiresponse in shapes and colors.We leveraged a tubularmold-based processing technology to prepare fibrous CLCE actuators,and the prepared actuators exhibit the capabilities to dynamically switch structural colors and geometrical shapes by mechanical,temperature,or light stimuli.CLCE-based PFSAs demonstrate diverse functionalities,including visual weight feedback,optically driven object manipulation,and light driven locomotion.It is anticipated that our PFSAs would offer many new possibilities for developing advanced soft actuators.展开更多
Smart chiral liquid crystal elastomers are a class of soft photonic crystals with periodic nanostructures.There are two kinds of chiral liquid crystal elastomers with structural colors:cholesteric liquid crystal elast...Smart chiral liquid crystal elastomers are a class of soft photonic crystals with periodic nanostructures.There are two kinds of chiral liquid crystal elastomers with structural colors:cholesteric liquid crystal elastomers with a one-dimensional helical nanostructure and blue-phase liquid crystal elastomers with a three-dimensional photonic crystal nanostructure.The self-assembled nanostructure of chiral liquid crystal elastomers can be dynamically controlled under external stimulation,and the reflected color can be adjusted throughout the visible light range.Along with the development of innovative material systems and cutting-edge manufacturing technologies,researchers have proposed diverse strategies to design and synthesize chiral liquid crystal elastomers and have thoroughly investigated their properties and potential applications.Here,we provide a systematic review of the progress in the design and fabrication of smart chiral liquid crystal elastomers,focusing on the cholesteric liquid crystal elastomers via surface-enforced alignment,bar coating,3D printing,anisotropic deswelling methods as well as the three-dimensional selfassembly of blue-phase liquid crystal elastomers without additional alignment.Smart chiral liquid crystal elastomers are able to respond quickly to external stimuli and have a wide range of applications in areas such as adaptive optics,color-changing camouflage,soft robotics,and information encryption.This review concludes with a perspective on the opportunities and challenges for the future development of smart chiral liquid crystal elastomers.展开更多
In the exploration of circularly polarized luminescence(CPL)materials,doping cholesteric liquid crystals(CLCs)with achiral dyes is a common strategy.Conjugated polymers are favored as achiral dyes for their superior l...In the exploration of circularly polarized luminescence(CPL)materials,doping cholesteric liquid crystals(CLCs)with achiral dyes is a common strategy.Conjugated polymers are favored as achiral dyes for their superior luminescent properties.In this study,a series of oligomers(M1-M3)and the conjugated polymer F8BT were synthesized to systematically assess the impact of the length of the conjugated backbone on CPL signals of CLCs doped with conjugated polymers.As the length rose from M1 to M3,CPL intensity concurrently increased(|g_(lum)|increased from 0.35 to 0.84),attributable to enhanced dichroism(order parameter,SFincreased from 0.20 to 0.56).In contrast,F8BT polymer resulted in diminished CPL intensity(|g_(lum)|=0.64)due to the reduced compatibility.Achieving a balance between dichroism and compatibility is crucial for optimizing CPL in conjugated polymer-doped CLCs.The guiding principle established here may have broad applicability in other CPL assemblies,offering a strategic avenue to engineer highperformance CPL materials with conjugated polymer.展开更多
The formation and physico-chemical properties of biomaterial, based on double-stranded (ds) DNA molecules and bearing high concentration of gadolinium, is described. This “rigid” biomaterial demonstrate a few unique...The formation and physico-chemical properties of biomaterial, based on double-stranded (ds) DNA molecules and bearing high concentration of gadolinium, is described. This “rigid” biomaterial demonstrate a few unique properties: (i) the ds DNA molecules forming complexes with gadolinium are fixed in the spatial structure of “rigid” particles, (ii) an abnormal negative band in the circular dichroism spectrum permits to follow the formation of this biomaterial;(iii) local concentration gadolinium in the content of biomaterial can reach 40%. These properties show that we are dealing with a novel type of biomaterial strongly enriched by gadolinium. This opens a gateway for practical application of this biomaterial for neutron-capture reactions. A first attempt to apply this material for neutron-capture reaction in combination with neutron generator of thermal neutron flux was performed. Positive result obtained at destruction of CHO cells allows one to state that the advantages of this biomaterial are a simple manipulation with it, a possibility to adjust its gadolinium content, long-term stability of its physico-chemical properties, as well as a reduced cost of neutron-capture experiment.展开更多
Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable struc...Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable structures and synergistic properties is still on the way. Herein, we propose a simple and effective approach to create the multi-functional stimuli-responsive biomimetic devices with independently pre-programmable colorful visual patterns, complex geometries and morphable modes. The metal organic framework(MOF)-based composite film acts as a rigidity actuation substrate to support and mechanically guide the spatial configuration of the soft chiral nematic liquid crystal elastomer(CLCE) sheet. We can directly program the structural color of the CLCE sheet by adjusting the thickness distribution without tedious chemical modification. By using this coordination strategy, we fabricate an artificial flower, which exhibits a synergistic effect of both shape transformation and color change like paeonia ‘Coral Sunset’at different flowering stages, and can even perform different flowering behaviors by bending, twisting and curling petals. The assembled bionic flower is innovatively demonstrated to respond to local stimuli of humidity, heat or ultraviolet irradiation. Therefore, the spatial assembly of CLCE combined with functional MOF materials has a wide range of potential application in multi-functional integrated artificial systems.展开更多
Liquid crystals （LCs） and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopan...Liquid crystals （LCs） and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopant and monomer concentrations on the electro-optical properties, such as contrast ratio, driving voltage, hysteresis width and response time, are investigated. The reasons of electro-optical properties influenced by the concentrations of the materials are discussed. Through the proper material recipe, the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.展开更多
In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a c...In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.展开更多
Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) becomes a cholesteric liquid crystalline solution withvivid colors when the (E-CE)C concentration is 42 wt%～52 wt%. (E-CE)C/polyacrylic acid (PAA) composites wit...Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) becomes a cholesteric liquid crystalline solution withvivid colors when the (E-CE)C concentration is 42 wt%～52 wt%. (E-CE)C/polyacrylic acid (PAA) composites withcholesteric structure were prepared by polymerzing AA in (E-CE)C/AA liquid crystalline solutions. The layers of orderedpolymer chains in the cholesteric phase were inclined during polymerization and the degree of the inclination depended onthe polymerization temperature and the concentration of the solution before polymerization. The cholesteric structure in thecomposites could not be changed when temperature was lower than 100℃. Cross-linking of the PAA in compositesimproved their water-resistance. The cholesteric order of the composites without cross-linking was destroyed when theywhere immersed in water. The color derived from the selective reflection of the cholesteric phase of the cross-linkedcomposites turned from blue to red after the composites absorbed water. The color of the composites could be returned to theoriginal one when the absorbed water was removed from the swollen composites.展开更多
In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough...In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough and merge with each other with increasing concentration. The band-like texture is composed of parallel equidistant bright and dark alternative strips which are about 0.2-2.0 μm in width. In the band-like texture, the layers of ordered polymer chains are perpendicular to the solution film and the axes of helicoids are parallel to it. The width of the strips is different in different zones. Under the effect of an external magnetic field, the strips in the band-like texture first become wider and then narrower gradually.Moreover, the axes of helicoids in the (E-CE) C/DCA mesomorphic solution change from the direction normal to the magnetic field to the agreement with the magnetic field direction.展开更多
The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional c...The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.展开更多
Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architec...Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.展开更多
The concentration of 26 elements in biles and gallstones from Chi-nese patients and the concentration of 10 elements from Japanese patients withgallstones were determined by inductively coupled plasma atomic emission ...The concentration of 26 elements in biles and gallstones from Chi-nese patients and the concentration of 10 elements from Japanese patients withgallstones were determined by inductively coupled plasma atomic emission spec-trometry (ICAP). Comparison of the level of elements between cholesterol andpigment gallstones revealed that Ca, Na, Fe, Cu, S, and Zn were higher inpigment gallstones than those in the cholesterol gallstones. Cholesterol stones aredivided into three subtypes: pure, mixed and combinated cholesterol stone.There were no significant difference among element contents. The levels of Ca,P, S, Li, and Ba in gallbladder biles were obviously higher in control groupthan in gallstone group. The element composition in gallbladder bile were similarto those in common bile duct bile. The former were 2～3 time high than the lat-ter.展开更多
The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surface techniques. A periodical lamellar-like structure was observed in the permanganic acid etched film surfac...The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surface techniques. A periodical lamellar-like structure was observed in the permanganic acid etched film surface by both scanning electron microscopy (SEM) and atomic force microscopy (AFM), instead of the thumb-print texture which can be detected with polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etching selectivity between cholesteric layers due to different molecular arrangement on the film surface. Four kinds of perpendicular disclinations, i.e. chi --> tau (-) + lambda (+), chi --> lambda (-) + tau (+), chi --> tau (-) + tau (+) and chi --> lambda (-) + lambda (+) were found in the composite films from SEM observations. The smallest periodicity of lamellar-like structure (equals to half pitch) is 20 similar to 40 nm measured with AFM.展开更多
The dimesogenic compound consisting of cholesterol and cyanobiphenyl mesogens interlinked by ω-oxyalkanoyl spacer was synthesized. The mesomorphic properties were investigated by differential scanning calorimetry （...The dimesogenic compound consisting of cholesterol and cyanobiphenyl mesogens interlinked by ω-oxyalkanoyl spacer was synthesized. The mesomorphic properties were investigated by differential scanning calorimetry （DSC）, polarizing optical microscopy （POM）, and X-ray diffraction （XRD）. The experimental results indicated that this compound exhibited mesophase over a much wider temperature range and a new mesophase blue phase （BP）. Focal conic domains （FCDs） and droplets texture to the smectic A phase （SA）, oily streaks typical to the chiral nematic （N＊） phase were found in the liquid crystalline state, respectively. Besides, it exhibited a smectic layer spacing about 1.0 time to the length of the molecule, which indicated a monolayer type of SA ordering. 2009 Hal Quan Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The kinetics of mesophase formation of a thermotropic hydroxyethyl cellulose acetate from isotropic phase to cholesteric mesophase has been studied by means of depolarizing transmittance method. Avrami type analysis o...The kinetics of mesophase formation of a thermotropic hydroxyethyl cellulose acetate from isotropic phase to cholesteric mesophase has been studied by means of depolarizing transmittance method. Avrami type analysis of the data gives an exponent n close to 1, which suggests the nucleation followed by rod-like growth. It means that the kinetic behavior of phase transition from isotropic to cholesteric mesophase is very similar to that of the mesophase formation from isotropic to nematic mesophase.展开更多
N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to pr...N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.展开更多
Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usuall...Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usually used as the exter nal stimulus source,which is not envir on ment-frie ndly enough.On the other hand,the mecha nical properties of CLCs are not strong eno ugh for these practical applications.Therefore,it still remains a challenge to endow the CLCs with visible light response and high mechanical properties at the same time.Herein,an axially chiral tetra-fluorinated binaphthyl azobenzene gelator(S-4F-AG)is synthesized.Upon 550 and 450 nm light irradiations,S-4F-AG exhibits excellent photo-switchable behaviors.Notably,the maximum con tent of c/s-isomer and its half-life are as high as 35%and 89 h in acet on itrile,respectively.A self-supporting CLC physical gel with a storage modulus around 104 Pa can be obtained when 3wt%S-4F-AG and 12wt%binaphthyl azobenzene derivative(dopant 2)are co-doped into a nematic LC host P0616A.This CLC physical gel exhibits a temperature-driven blue,green,and red reflection colors reversibly.Importantly,such three primary RGB colors can also be realized by adjusting the exposure time of 550 nm green light.This work lays a solid foundation for the applications ranging from information storage to high-tech anticounterfeit.展开更多
Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The typ...Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The type of cholesteric mesomorphic azacrown ether have not been reported so far.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52233001,51927805,and 52173110)the Innovation Program of Shanghai Municipal Education Commission(No.2023ZKZD07)the Shanghai Rising-Star Program(No.22QA1401200)。
文摘Cholesteric liquid crystals(CLCs)exhibit unique helical superstructures that selectively reflect circularly polarized light,enabling them to dynamically respond to environmental changes with tunable structural colors.This dynamic color-changing capability is crucial for applications that require adaptable optical properties,positioning CLCs as key materials in advanced photonic technologies.This review focuses on the mechanisms of dynamic color tuning in CLCs across various forms,including small molecules,cholesteric liquid crystal elastomers(CLCEs),and cholesteric liquid crystal networks(CLCNs),and emphasizes the distinct responsive coloration each structure provides.Key developments in photochromic mechanisms based on azobenzene,dithienylethene,and molecular motor switches,are discussed for their roles in enhancing the stability and tuning range of CLCs.We examine the color-changing behaviors of CLCEs under mechanical stimuli and CLCNs under swelling,highlighting the advantages of each form.Following this,applications of dynamic color-tuning CLCs in information encryption,adaptive camouflage,and smart sensing technologies are explored.The review concludes with an outlook on current challenges and future directions in CLC research,particularly in biomimetic systems and dynamic photonic devices,aiming to broaden their functional applications and impact.
基金financially supported by the National Natural Science Foundation of China(Nos.52273111 and 51873197)the Natural Science Foundation of Zhejiang Province of China(No.LR22E030004)the Foundation of Westlake University。
文摘Photonic fibrous soft actuators that can modulate light and produce responsive deformation would have broad technological implications in areas,ranging from smart textiles and intelligent artificial muscles to medical devices.However,creating such multifunctional soft actuators has proved tremendously challenging.Here,we report novel cholesteric liquid crystal elastomer(CLCE)based photonic fibrous soft actuators(PFSAs).CLCE can serve as chiral photonic soft active material and allow for multiresponse in shapes and colors.We leveraged a tubularmold-based processing technology to prepare fibrous CLCE actuators,and the prepared actuators exhibit the capabilities to dynamically switch structural colors and geometrical shapes by mechanical,temperature,or light stimuli.CLCE-based PFSAs demonstrate diverse functionalities,including visual weight feedback,optically driven object manipulation,and light driven locomotion.It is anticipated that our PFSAs would offer many new possibilities for developing advanced soft actuators.
基金supported by the National Key R&D Program of China(2023YFB3812800 and 2022YFB3805702)the National Natural Science Foundation of China(No.52173181,51973155 and 52203143)+1 种基金Key Program of the National Natural Science Foundation of China(No.52130303)Tianjin Science Fund for Distinguished Young Scholars(22JCJQJC00060).
文摘Smart chiral liquid crystal elastomers are a class of soft photonic crystals with periodic nanostructures.There are two kinds of chiral liquid crystal elastomers with structural colors:cholesteric liquid crystal elastomers with a one-dimensional helical nanostructure and blue-phase liquid crystal elastomers with a three-dimensional photonic crystal nanostructure.The self-assembled nanostructure of chiral liquid crystal elastomers can be dynamically controlled under external stimulation,and the reflected color can be adjusted throughout the visible light range.Along with the development of innovative material systems and cutting-edge manufacturing technologies,researchers have proposed diverse strategies to design and synthesize chiral liquid crystal elastomers and have thoroughly investigated their properties and potential applications.Here,we provide a systematic review of the progress in the design and fabrication of smart chiral liquid crystal elastomers,focusing on the cholesteric liquid crystal elastomers via surface-enforced alignment,bar coating,3D printing,anisotropic deswelling methods as well as the three-dimensional selfassembly of blue-phase liquid crystal elastomers without additional alignment.Smart chiral liquid crystal elastomers are able to respond quickly to external stimuli and have a wide range of applications in areas such as adaptive optics,color-changing camouflage,soft robotics,and information encryption.This review concludes with a perspective on the opportunities and challenges for the future development of smart chiral liquid crystal elastomers.
基金supported by the National Natural Science Foundation of China(Nos.21975118,92156014,52373188)。
文摘In the exploration of circularly polarized luminescence(CPL)materials,doping cholesteric liquid crystals(CLCs)with achiral dyes is a common strategy.Conjugated polymers are favored as achiral dyes for their superior luminescent properties.In this study,a series of oligomers(M1-M3)and the conjugated polymer F8BT were synthesized to systematically assess the impact of the length of the conjugated backbone on CPL signals of CLCs doped with conjugated polymers.As the length rose from M1 to M3,CPL intensity concurrently increased(|g_(lum)|increased from 0.35 to 0.84),attributable to enhanced dichroism(order parameter,SFincreased from 0.20 to 0.56).In contrast,F8BT polymer resulted in diminished CPL intensity(|g_(lum)|=0.64)due to the reduced compatibility.Achieving a balance between dichroism and compatibility is crucial for optimizing CPL in conjugated polymer-doped CLCs.The guiding principle established here may have broad applicability in other CPL assemblies,offering a strategic avenue to engineer highperformance CPL materials with conjugated polymer.
文摘The formation and physico-chemical properties of biomaterial, based on double-stranded (ds) DNA molecules and bearing high concentration of gadolinium, is described. This “rigid” biomaterial demonstrate a few unique properties: (i) the ds DNA molecules forming complexes with gadolinium are fixed in the spatial structure of “rigid” particles, (ii) an abnormal negative band in the circular dichroism spectrum permits to follow the formation of this biomaterial;(iii) local concentration gadolinium in the content of biomaterial can reach 40%. These properties show that we are dealing with a novel type of biomaterial strongly enriched by gadolinium. This opens a gateway for practical application of this biomaterial for neutron-capture reactions. A first attempt to apply this material for neutron-capture reaction in combination with neutron generator of thermal neutron flux was performed. Positive result obtained at destruction of CHO cells allows one to state that the advantages of this biomaterial are a simple manipulation with it, a possibility to adjust its gadolinium content, long-term stability of its physico-chemical properties, as well as a reduced cost of neutron-capture experiment.
基金The financial support of this work by the Natural Science Foundation of Hebei province of China (No. F2020202015)。
文摘Simulating the structures and behaviors of living organisms are of great significance to develop novel multi-functional intelligent devices. However, the development of biomimetic devices with complex deformable structures and synergistic properties is still on the way. Herein, we propose a simple and effective approach to create the multi-functional stimuli-responsive biomimetic devices with independently pre-programmable colorful visual patterns, complex geometries and morphable modes. The metal organic framework(MOF)-based composite film acts as a rigidity actuation substrate to support and mechanically guide the spatial configuration of the soft chiral nematic liquid crystal elastomer(CLCE) sheet. We can directly program the structural color of the CLCE sheet by adjusting the thickness distribution without tedious chemical modification. By using this coordination strategy, we fabricate an artificial flower, which exhibits a synergistic effect of both shape transformation and color change like paeonia ‘Coral Sunset’at different flowering stages, and can even perform different flowering behaviors by bending, twisting and curling petals. The assembled bionic flower is innovatively demonstrated to respond to local stimuli of humidity, heat or ultraviolet irradiation. Therefore, the spatial assembly of CLCE combined with functional MOF materials has a wide range of potential application in multi-functional integrated artificial systems.
基金Project partially supported by the National Natural Science Foundation of China （Grant Nos. 60736042, 60578035 and 50703039） and the Science Foundation of Jilin Province of China （Grant Nos. 20050520 and 20050321-2）.
文摘Liquid crystals （LCs） and polymers are extensively used in various electro-optical applications. In this paper, normal mode polymer stabilized cholesteric LC film is prepared and studied. The effects of chiral dopant and monomer concentrations on the electro-optical properties, such as contrast ratio, driving voltage, hysteresis width and response time, are investigated. The reasons of electro-optical properties influenced by the concentrations of the materials are discussed. Through the proper material recipe, the electro-optical properties of polymer stabilized cholesteric LC film can be optimized.
基金supported by the National Natural Science Foundation of China (No. 50903004)
文摘In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.
基金The financial support from the National Natural Science Foundation of China and the National Key Projects of Basic Research-Macromolecular Condensed State is gratefully appreciated.
文摘Ethyl-cyanoethyl cellulose [(E-CE)C]/acrylic acid (AA) becomes a cholesteric liquid crystalline solution withvivid colors when the (E-CE)C concentration is 42 wt%～52 wt%. (E-CE)C/polyacrylic acid (PAA) composites withcholesteric structure were prepared by polymerzing AA in (E-CE)C/AA liquid crystalline solutions. The layers of orderedpolymer chains in the cholesteric phase were inclined during polymerization and the degree of the inclination depended onthe polymerization temperature and the concentration of the solution before polymerization. The cholesteric structure in thecomposites could not be changed when temperature was lower than 100℃. Cross-linking of the PAA in compositesimproved their water-resistance. The cholesteric order of the composites without cross-linking was destroyed when theywhere immersed in water. The color derived from the selective reflection of the cholesteric phase of the cross-linkedcomposites turned from blue to red after the composites absorbed water. The color of the composites could be returned to theoriginal one when the absorbed water was removed from the swollen composites.
基金This work was supported by Academia Sinica Selected Research Program.
文摘In the ethyl-cyanoethylcellulose ((E-CE)C)/dichloroacetic acid (DCA) cholesteric liquid crystalline solution, the hand-like texture is formed when the mesophase aggregates with the disk-like texture grow to big enough and merge with each other with increasing concentration. The band-like texture is composed of parallel equidistant bright and dark alternative strips which are about 0.2-2.0 μm in width. In the band-like texture, the layers of ordered polymer chains are perpendicular to the solution film and the axes of helicoids are parallel to it. The width of the strips is different in different zones. Under the effect of an external magnetic field, the strips in the band-like texture first become wider and then narrower gradually.Moreover, the axes of helicoids in the (E-CE) C/DCA mesomorphic solution change from the direction normal to the magnetic field to the agreement with the magnetic field direction.
基金This work was financially supported by the National High-Tech Research and Development Program of China (No. 2003AA327050).
文摘The planar texture of glassy cholesteric siloxane cyclic side-chain liquid crystals was fixed by quenching initially. Then the polymer network formed by the optically active polymerizable monomers imposed additional constraints on the motion of chain segments of the glassy liquid crystal and then further stabilized the molecule arrangement. A cholesteric liquid crystal film with stable optical properties was developed by this method.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51573006,51573003,51203003,51303008,51302006,51402006,51272026,and 51273022)the Major Project of Beijing Science and Technology Program,China(Grant Nos.Z151100003315023 and Z141100003814011)the Fok Ying Tung Education Foundation,China(Grant No.142009)
文摘Cholesteric liquid crystals（CLCs） have recently sparked an enormous amount of interest in the development of soft matter materials due to their unique ability to self-organize into a helical supra-molecular architecture and their excellent selective reflection of light based on the Bragg relationship.Nowadays,by the virtue of building the self-organized nanostructures with pitch gradient or non-uniform pitch distribution,extensive work has already been performed to obtain CLC films with a broad reflection band.Based on authors＇ many years＇ research experience,this critical review systematically summarizes the physical and optical background of the CLCs with broadband reflection characteristics,methods to obtain broadband reflection of CLCs,as well as the application in the field of intelligent optical modulation materials.Combined with the research status and the advantages in the field,the important basic and applied scientific problems in the research direction are also introduced.
文摘The concentration of 26 elements in biles and gallstones from Chi-nese patients and the concentration of 10 elements from Japanese patients withgallstones were determined by inductively coupled plasma atomic emission spec-trometry (ICAP). Comparison of the level of elements between cholesterol andpigment gallstones revealed that Ca, Na, Fe, Cu, S, and Zn were higher inpigment gallstones than those in the cholesterol gallstones. Cholesterol stones aredivided into three subtypes: pure, mixed and combinated cholesterol stone.There were no significant difference among element contents. The levels of Ca,P, S, Li, and Ba in gallbladder biles were obviously higher in control groupthan in gallstone group. The element composition in gallbladder bile were similarto those in common bile duct bile. The former were 2～3 time high than the lat-ter.
基金This work was supported by the National Natural Science Foundation of China (No. 29974023) and Natural Science Foundation of Fujian (No.29910006).
文摘The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surface techniques. A periodical lamellar-like structure was observed in the permanganic acid etched film surface by both scanning electron microscopy (SEM) and atomic force microscopy (AFM), instead of the thumb-print texture which can be detected with polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etching selectivity between cholesteric layers due to different molecular arrangement on the film surface. Four kinds of perpendicular disclinations, i.e. chi --> tau (-) + lambda (+), chi --> lambda (-) + tau (+), chi --> tau (-) + tau (+) and chi --> lambda (-) + lambda (+) were found in the composite films from SEM observations. The smallest periodicity of lamellar-like structure (equals to half pitch) is 20 similar to 40 nm measured with AFM.
基金supported by the National Natural Science Foundation(No.20674005)the Major project of Ministry Education of the People's Republic of China(No.104187)Doctoral Fund of Ministry of Education ofthe People's Republic of China(No.20050425850)
文摘The dimesogenic compound consisting of cholesterol and cyanobiphenyl mesogens interlinked by ω-oxyalkanoyl spacer was synthesized. The mesomorphic properties were investigated by differential scanning calorimetry （DSC）, polarizing optical microscopy （POM）, and X-ray diffraction （XRD）. The experimental results indicated that this compound exhibited mesophase over a much wider temperature range and a new mesophase blue phase （BP）. Focal conic domains （FCDs） and droplets texture to the smectic A phase （SA）, oily streaks typical to the chiral nematic （N＊） phase were found in the liquid crystalline state, respectively. Besides, it exhibited a smectic layer spacing about 1.0 time to the length of the molecule, which indicated a monolayer type of SA ordering. 2009 Hal Quan Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金This work supported by the National Basic Research Project-Macromolecular Condensed State
文摘The kinetics of mesophase formation of a thermotropic hydroxyethyl cellulose acetate from isotropic phase to cholesteric mesophase has been studied by means of depolarizing transmittance method. Avrami type analysis of the data gives an exponent n close to 1, which suggests the nucleation followed by rod-like growth. It means that the kinetic behavior of phase transition from isotropic to cholesteric mesophase is very similar to that of the mesophase formation from isotropic to nematic mesophase.
基金Supported by the National Natural Science Foundation of China( No. 2 9974 0 2 3)
文摘N -Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.
文摘Photo-responsive cholesteric liquid crystals(CLCs)have attracted much attention in recent years due to their wide applications in filters,tun able optical lasers,dyn amic display devices,etc.However,UV light is usually used as the exter nal stimulus source,which is not envir on ment-frie ndly enough.On the other hand,the mecha nical properties of CLCs are not strong eno ugh for these practical applications.Therefore,it still remains a challenge to endow the CLCs with visible light response and high mechanical properties at the same time.Herein,an axially chiral tetra-fluorinated binaphthyl azobenzene gelator(S-4F-AG)is synthesized.Upon 550 and 450 nm light irradiations,S-4F-AG exhibits excellent photo-switchable behaviors.Notably,the maximum con tent of c/s-isomer and its half-life are as high as 35%and 89 h in acet on itrile,respectively.A self-supporting CLC physical gel with a storage modulus around 104 Pa can be obtained when 3wt%S-4F-AG and 12wt%binaphthyl azobenzene derivative(dopant 2)are co-doped into a nematic LC host P0616A.This CLC physical gel exhibits a temperature-driven blue,green,and red reflection colors reversibly.Importantly,such three primary RGB colors can also be realized by adjusting the exposure time of 550 nm green light.This work lays a solid foundation for the applications ranging from information storage to high-tech anticounterfeit.
文摘Five aza-crown-ethers were synthesized and four of them shown to have cholesteric liquid crystalline properties. Their properties relevant to cholesteric liquid crystal were determined by DSC and the textures. The type of cholesteric mesomorphic azacrown ether have not been reported so far.
