Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline p...Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline polymorph is an intriguing phenomenon that the presence of multiple packing and aggregate architectures of the same molecular system.The studies on polymorphs for molecule-based fluorophores provide the opportunities to adjust the mode of molecular packing and photophysical properties,which will help to illustrate the structure-property relationship.In this review,we focus on the recent progress in various feasible methods of molecule-based crystalline polymorphism growth and their adjustable photofunctional properties,which will open up possibilities of variant optical applications.Firstly,several effective ways to prepare and screen polymorphs are sorted out.And then,we discuss the discrepant properties and multifunctional applications(such as sensors,laser and OFET).Finally,the development trends and future prospects of these polymorphs are also briefly introduced.展开更多
Cellulose nanocrystals(CNCs)can self-assemble in suspension to form chiral cholesteric structure of liquid crystal with unique birefringence phenomena,and the structural parameters strongly depend upon the aspect rati...Cellulose nanocrystals(CNCs)can self-assemble in suspension to form chiral cholesteric structure of liquid crystal with unique birefringence phenomena,and the structural parameters strongly depend upon the aspect ratio,surface structure,and physicochemical properties of CNC,along with suspension media.Many attempts have been carried out to keep this cholesteric structure in solid state via removing solvent,such as slower solvent-evaporation,rapid vacuum-filtration,and spin-casting under centrifugal force.The solid-state iridescence of the cholesteric CNC arrays has been used as structural color,and showed a great potential for the coding and securing of optical information.Moreover,to promote practical applications of such structural iridescence,the cholesteric CNC arrays have been embedded into many kinds of substrates via in-situ reaction of monomers or physical blending with polymers.However,this kind of structural iridescences may lead to misreading information.The uniaxial-orientation assembly of CNC has thus been proposed via regulating external force fields of CNC self-assembly,and successfully achieved nanoparticle assembly-induced solid-state monochrome emission based on enhanced inelastic collision theory of CNC dipoles and photons.This method can eliminate the chiral arrangement of CNC and the corresponding iridescence,and the structural monochromaticity can contribute to enhancing the accuracy of optical information.Overall,the CNC can be controllably assembled as the ordered arrays in solid state and presented structural color,and support optical anti-counterfeiting strategies different from the fluorescent technologies.展开更多
A reaction bonding fabrication process using various grain size of SiC powder was investigated. The properties such as mechanical, thermal and physic property were tested and analyzed. RBSiC produced using this proces...A reaction bonding fabrication process using various grain size of SiC powder was investigated. The properties such as mechanical, thermal and physic property were tested and analyzed. RBSiC produced using this process is a polycrystalline material and has high specific stiffness (density of 3.09 g/cm3 with elastic modulus of 362.39 GPa), strength (269.64 MPa) and hardness (19.43 GPa). At room temperature its low CTE (3.47×10?6/K), combined with relatively high thermal conductivity (161.14 W/mK) and specific heat capacity (593.86 J/kg.K) can minimize the bothersome thermal distortion. This advantage is outstanding even at higher temperature of test range. Two d 250 mm RBSiC mirror were polished. Surface roughness value less than 5 nm was obtained. Results prove that this reaction bonding process is a feasible method to produced high quality RBSiC optical mirror.展开更多
Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precis...Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precision machining,the process of digital ultra-precision machining and its technical contents were presented in this paper. In the conclusions,it was stated that the digitalization of ultra-precision machining will be an economical and efficient way for the production of new sorts of optical workpieces.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21771021 and 21822501)the Beijing Nova Program(No.xx2018115)+1 种基金the Fundamental Research Funds for the Central UniversitiesAnalytical and Measurements Fund of Beijing Normal University
文摘Recently,molecule-based luminescent materials have been drawing extensive attention due to their desirable properties and promising applications in the fields of sensors,lighting display and cell imaging.Crystalline polymorph is an intriguing phenomenon that the presence of multiple packing and aggregate architectures of the same molecular system.The studies on polymorphs for molecule-based fluorophores provide the opportunities to adjust the mode of molecular packing and photophysical properties,which will help to illustrate the structure-property relationship.In this review,we focus on the recent progress in various feasible methods of molecule-based crystalline polymorphism growth and their adjustable photofunctional properties,which will open up possibilities of variant optical applications.Firstly,several effective ways to prepare and screen polymorphs are sorted out.And then,we discuss the discrepant properties and multifunctional applications(such as sensors,laser and OFET).Finally,the development trends and future prospects of these polymorphs are also briefly introduced.
基金the National Natural Science Foundation of China(51603171)Fundamental Research Funds for the Central Universities(XDJK2016C032)the Talent Project of Southwest University(SWU115034)
文摘Cellulose nanocrystals(CNCs)can self-assemble in suspension to form chiral cholesteric structure of liquid crystal with unique birefringence phenomena,and the structural parameters strongly depend upon the aspect ratio,surface structure,and physicochemical properties of CNC,along with suspension media.Many attempts have been carried out to keep this cholesteric structure in solid state via removing solvent,such as slower solvent-evaporation,rapid vacuum-filtration,and spin-casting under centrifugal force.The solid-state iridescence of the cholesteric CNC arrays has been used as structural color,and showed a great potential for the coding and securing of optical information.Moreover,to promote practical applications of such structural iridescence,the cholesteric CNC arrays have been embedded into many kinds of substrates via in-situ reaction of monomers or physical blending with polymers.However,this kind of structural iridescences may lead to misreading information.The uniaxial-orientation assembly of CNC has thus been proposed via regulating external force fields of CNC self-assembly,and successfully achieved nanoparticle assembly-induced solid-state monochrome emission based on enhanced inelastic collision theory of CNC dipoles and photons.This method can eliminate the chiral arrangement of CNC and the corresponding iridescence,and the structural monochromaticity can contribute to enhancing the accuracy of optical information.Overall,the CNC can be controllably assembled as the ordered arrays in solid state and presented structural color,and support optical anti-counterfeiting strategies different from the fluorescent technologies.
基金Project(90205034) supported by the National Natural Science Foundation of China
文摘A reaction bonding fabrication process using various grain size of SiC powder was investigated. The properties such as mechanical, thermal and physic property were tested and analyzed. RBSiC produced using this process is a polycrystalline material and has high specific stiffness (density of 3.09 g/cm3 with elastic modulus of 362.39 GPa), strength (269.64 MPa) and hardness (19.43 GPa). At room temperature its low CTE (3.47×10?6/K), combined with relatively high thermal conductivity (161.14 W/mK) and specific heat capacity (593.86 J/kg.K) can minimize the bothersome thermal distortion. This advantage is outstanding even at higher temperature of test range. Two d 250 mm RBSiC mirror were polished. Surface roughness value less than 5 nm was obtained. Results prove that this reaction bonding process is a feasible method to produced high quality RBSiC optical mirror.
文摘Digital manufacturing technology can be used in optical field to solve many problems caused by traditional machining. According to the characters of digital manufacturing and the practical applications of ultra-precision machining,the process of digital ultra-precision machining and its technical contents were presented in this paper. In the conclusions,it was stated that the digitalization of ultra-precision machining will be an economical and efficient way for the production of new sorts of optical workpieces.
