A green approach to the synthesis and morphological control of high performance polyimides and their nanohybrid shish-kebabs in glycerol through reaction-induced crystallization of nylon-salt-type monomers was reporte...A green approach to the synthesis and morphological control of high performance polyimides and their nanohybrid shish-kebabs in glycerol through reaction-induced crystallization of nylon-salt-type monomers was reported. Crystalline polyimide nanoplates can be observed by direct polycondensation of pyromellitic acid with various kinds of aliphatic or aromatic diamines. With the existence of carbon nanotuhes, the polyimides can be successfully decorated on the surface of CNTs through a reaction-induced hetero-epitaxial crystallization process, and resulted in novel polyimide/CNT nanohybrid shish-kebabs （NHSKs） structures. The morphologies of the NHSKs can be fine-tuned through changing the concentration of monomers or the reaction temperature, especially through the introduction of dynamic imine chemistry, the formation process of NHSKs can be attributed to a soft epitaxy mechanism. Thus a green approach for the synthesis of high performance polyimides and their CNT based nanohybrid structures was explored, which should be of great value for their applications in high performance reinforced nanocomposites.展开更多
A series of fluorocarbon chain terminated polyetherimide is added to epoxy resin,and the effect of molecular weight on the process of phase separation is studied by time-resolved light scattering(TRLS),differential sc...A series of fluorocarbon chain terminated polyetherimide is added to epoxy resin,and the effect of molecular weight on the process of phase separation is studied by time-resolved light scattering(TRLS),differential scanning calorimeter(DSC),scanning microscopy(SEM).The results indicate that the phase separation rate decreases due to the preventing effect in-duced by low surface energy of fluorocarbon chain terminated polyetherimide.In addition,evolu-tion time of morphology is shortened and the domain size decreases with the introduction of fluorocarbon chain terminated polyetherimide.Furthermore,when the molecular weight of fluorocarbon chain terminated polyetherimide increases,the morphology can change from dis-persed phase to co-continuous phase.Thus,changing the molecular weight of fluorocarbon chain terminated polyetherimide can control the morphology of the epoxy/polyetherimide blend,which is of great significance in many industries.展开更多
Special proton-gradient-transfer acid complexes （PGTACs） in which the bonded protons are not equivalent and have gradients in transfer ability, acidity, and reactivity were reported. The acidity gradient of the prot...Special proton-gradient-transfer acid complexes （PGTACs） in which the bonded protons are not equivalent and have gradients in transfer ability, acidity, and reactivity were reported. The acidity gradient of the protons gave the PGTACs excellent catalytic activity and selectivity in the esterifica- tion of terpenols. These PGTACs are ＂reaction-induced self-separation catalysts＂ and can be easily reused. The kinetics with PGTACs as catalyst in the esterification of geraniol were also studied for use in engineering design.展开更多
The roles of reaction inhomogeneity in phase separation of polymer mixtures were described and summarized via two examples:photocross-link of polymer mixtures in the bulk state and photopolymerization of monomer in th...The roles of reaction inhomogeneity in phase separation of polymer mixtures were described and summarized via two examples:photocross-link of polymer mixtures in the bulk state and photopolymerization of monomer in the liquid state. The reaction kinetics,the reaction-induced elastic strain and the phase separation kinetics were monitored respectively by UV-Vis spectroscopy,Mach-Zehnder interferometry and laser-scanning confocal microscopy.It was found that phase separation in the bulk state was strongly inf...展开更多
A series of mixed, random cylindrical brush copolymers bearing polystyrene（PS） and poly（ε-caprolactone）（PCL） side chains were synthesized via the combination of ring-opening polymerization（ROP） and atom trans...A series of mixed, random cylindrical brush copolymers bearing polystyrene（PS） and poly（ε-caprolactone）（PCL） side chains were synthesized via the combination of ring-opening polymerization（ROP） and atom transfer radical polymerization（ATRP）. These novel cylindrical brush copolymers have been characterized by means of nuclear magnetic resonance（NMR） spectroscopy, gel permeation chromatography（GPC） and differential scanning calorimetry（DSC）. It was found that the mikto-armed cylindrical brush copolymers were microphase-separated in bulks and that the morphologies were dependent on the mass ratios of PS to PCL side chains. One of the cylindrical brush copolymers was employed to incorporate into epoxy thermoset to investigate effect of the mikto-armed cylindrical brush architecture on the reaction-induced microphase separation behavior. Depending on the concentration of the cylindrical brush in epoxy, the thermosets can display the morphologies with the spherical, worm-like and lamellar PS microdomains dispersing in continuous thermosetting matrices.展开更多
Laser ablation in liquids has emerged as a new branch of nanoscience for developing various nanomaterials with different shapes.However, how to design and control nanomaterial growth is still a challenge due to the un...Laser ablation in liquids has emerged as a new branch of nanoscience for developing various nanomaterials with different shapes.However, how to design and control nanomaterial growth is still a challenge due to the unique chemical-physical process chain correlated with nanomaterial nucleation and growth, including plasma phase(generation and rapid quenching), gas(bubble) phase,and liquid phase. In this review, through summarizing the literature about this topic and comparing with the well-established particle growth mechanisms of the conventional wet chemistry technique, our perspective on the possible nanoparticle growth mechanisms or routes is presented, aiming at shedding light on how laser-ablated particles grow in liquids. From the microscopic viewpoint, the nanoparticle growth contains six mechanisms, including LaMer-like growth, coalescence, Ostwald ripening, particle(oriented) attachment, adsorbate-induced growth and reaction-induced growth. For each microscopic growth mechanism, the vivid growth scenes of some representative nanomaterials recorded by TEM and SEM measurements are displayed. Afterwards,the scenes from the macroscopic viewpoint for the large submicro-and micro-scale nanospheres and anisotropic nanostructures formation and evolution from one nanostructure into another one are presented. The panorama of how diverse nanomaterials grow during and after laser ablation in liquids shown in this review is intended to offer a overview for researchers to search for the possible mechanisms correlated to their synthesized nanomaterials, and more expectation is desired to better design and tailor the morphology of the nanocrystals synthesized by LAL technique.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.20974069,21174089)the Ministry of Education(No.JS20091210507067)Sichuan University(No.0082204121012)
文摘A green approach to the synthesis and morphological control of high performance polyimides and their nanohybrid shish-kebabs in glycerol through reaction-induced crystallization of nylon-salt-type monomers was reported. Crystalline polyimide nanoplates can be observed by direct polycondensation of pyromellitic acid with various kinds of aliphatic or aromatic diamines. With the existence of carbon nanotuhes, the polyimides can be successfully decorated on the surface of CNTs through a reaction-induced hetero-epitaxial crystallization process, and resulted in novel polyimide/CNT nanohybrid shish-kebabs （NHSKs） structures. The morphologies of the NHSKs can be fine-tuned through changing the concentration of monomers or the reaction temperature, especially through the introduction of dynamic imine chemistry, the formation process of NHSKs can be attributed to a soft epitaxy mechanism. Thus a green approach for the synthesis of high performance polyimides and their CNT based nanohybrid structures was explored, which should be of great value for their applications in high performance reinforced nanocomposites.
文摘A series of fluorocarbon chain terminated polyetherimide is added to epoxy resin,and the effect of molecular weight on the process of phase separation is studied by time-resolved light scattering(TRLS),differential scanning calorimeter(DSC),scanning microscopy(SEM).The results indicate that the phase separation rate decreases due to the preventing effect in-duced by low surface energy of fluorocarbon chain terminated polyetherimide.In addition,evolu-tion time of morphology is shortened and the domain size decreases with the introduction of fluorocarbon chain terminated polyetherimide.Furthermore,when the molecular weight of fluorocarbon chain terminated polyetherimide increases,the morphology can change from dis-persed phase to co-continuous phase.Thus,changing the molecular weight of fluorocarbon chain terminated polyetherimide can control the morphology of the epoxy/polyetherimide blend,which is of great significance in many industries.
基金supported by the National Natural Science Foundation of China (21376115, 21576129)~~
文摘Special proton-gradient-transfer acid complexes （PGTACs） in which the bonded protons are not equivalent and have gradients in transfer ability, acidity, and reactivity were reported. The acidity gradient of the protons gave the PGTACs excellent catalytic activity and selectivity in the esterifica- tion of terpenols. These PGTACs are ＂reaction-induced self-separation catalysts＂ and can be easily reused. The kinetics with PGTACs as catalyst in the esterification of geraniol were also studied for use in engineering design.
基金supported by the Ministry of Education (MONKASHO),Japan through the Grant-in-Aid on the Priority-Research-Area"Molecular Nanodynamics"and"Soft Matter Physics".The Grant-in-Aid for Scientific Research (No.20350107) is also gratefully acknowledged.
文摘The roles of reaction inhomogeneity in phase separation of polymer mixtures were described and summarized via two examples:photocross-link of polymer mixtures in the bulk state and photopolymerization of monomer in the liquid state. The reaction kinetics,the reaction-induced elastic strain and the phase separation kinetics were monitored respectively by UV-Vis spectroscopy,Mach-Zehnder interferometry and laser-scanning confocal microscopy.It was found that phase separation in the bulk state was strongly inf...
基金financially supported by the National Natural Science Foundation of China(Nos.51133003,21274091 and 21774078)the Shanghai Synchrotron Radiation Facility under the projects(Nos.10sr0260 and 10sr0126)
文摘A series of mixed, random cylindrical brush copolymers bearing polystyrene（PS） and poly（ε-caprolactone）（PCL） side chains were synthesized via the combination of ring-opening polymerization（ROP） and atom transfer radical polymerization（ATRP）. These novel cylindrical brush copolymers have been characterized by means of nuclear magnetic resonance（NMR） spectroscopy, gel permeation chromatography（GPC） and differential scanning calorimetry（DSC）. It was found that the mikto-armed cylindrical brush copolymers were microphase-separated in bulks and that the morphologies were dependent on the mass ratios of PS to PCL side chains. One of the cylindrical brush copolymers was employed to incorporate into epoxy thermoset to investigate effect of the mikto-armed cylindrical brush architecture on the reaction-induced microphase separation behavior. Depending on the concentration of the cylindrical brush in epoxy, the thermosets can display the morphologies with the spherical, worm-like and lamellar PS microdomains dispersing in continuous thermosetting matrices.
基金supported by the National Key Basic Research Program of China (Grant No. 2014CB931704)the National Natural Science Foundation of China (Grant No. 11304315, 51401206, 11404338, 51371166, 51571186, and 11504375)the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs (CAS/SAFEA) International Partnership Program for Creative Research Teams
文摘Laser ablation in liquids has emerged as a new branch of nanoscience for developing various nanomaterials with different shapes.However, how to design and control nanomaterial growth is still a challenge due to the unique chemical-physical process chain correlated with nanomaterial nucleation and growth, including plasma phase(generation and rapid quenching), gas(bubble) phase,and liquid phase. In this review, through summarizing the literature about this topic and comparing with the well-established particle growth mechanisms of the conventional wet chemistry technique, our perspective on the possible nanoparticle growth mechanisms or routes is presented, aiming at shedding light on how laser-ablated particles grow in liquids. From the microscopic viewpoint, the nanoparticle growth contains six mechanisms, including LaMer-like growth, coalescence, Ostwald ripening, particle(oriented) attachment, adsorbate-induced growth and reaction-induced growth. For each microscopic growth mechanism, the vivid growth scenes of some representative nanomaterials recorded by TEM and SEM measurements are displayed. Afterwards,the scenes from the macroscopic viewpoint for the large submicro-and micro-scale nanospheres and anisotropic nanostructures formation and evolution from one nanostructure into another one are presented. The panorama of how diverse nanomaterials grow during and after laser ablation in liquids shown in this review is intended to offer a overview for researchers to search for the possible mechanisms correlated to their synthesized nanomaterials, and more expectation is desired to better design and tailor the morphology of the nanocrystals synthesized by LAL technique.
