A new series of chiral shish-kebab type liquid crystal block copolymers that form the smecticC(Sc~*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC.DSC. TG, POM. X-ray dif...A new series of chiral shish-kebab type liquid crystal block copolymers that form the smecticC(Sc~*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC.DSC. TG, POM. X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whenthey were heated to their melting temperatures (T_m) and the copolymers 8 were in liquid crystal phase at roomtemperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiralsmectic C(Sc~*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal blockcopolymers that form a chiral smectic C(Sc~*) phase. The variation of melting and isotropization temperatureswith molecular structure was also discussed.展开更多
The novel shish-kebab-type liquid crystalline poly(p-phenylene)s were synthesized through Suzuki coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,4-benzenediboronic acid bist...The novel shish-kebab-type liquid crystalline poly(p-phenylene)s were synthesized through Suzuki coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,4-benzenediboronic acid bistrimethylene cyclic ester (monomer 2). Their structure and properties were characterized by GPC, DSC, X-ray diffraction and polarizing optical microscope (POM). It was found that the polymers turned to liquid crystalline phase above their melting point. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The mesophase was identified by X-ray diffraction method. The polymers could dissolve in common organic solvents and show strong blue fluorescence. The maximum absorption bands of polymers prepared from annealed films have large red-shift due to the spontaneous orientation of the liquid crystalline side chains. The same phenomena were also observed in the fluorescence spectra.展开更多
Novel shish-kebab type liquid crystalline poly(p-phenylenevinylene) derivatives were synthesized by Stille coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]l,4-dibromobenzene (monomer 1) and 1,2-bis(tributylstan...Novel shish-kebab type liquid crystalline poly(p-phenylenevinylene) derivatives were synthesized by Stille coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]l,4-dibromobenzene (monomer 1) and 1,2-bis(tributylstannyl) ethylene (monomer 2). The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.展开更多
For the first time, a highly crystalline porous shish-kebab structure with a high degree of crystallinity was obtained by using a combination of two methods for the formation of porous polymeric materials. A treatment...For the first time, a highly crystalline porous shish-kebab structure with a high degree of crystallinity was obtained by using a combination of two methods for the formation of porous polymeric materials. A treatment procedure using supercritical carbon dioxide(sc CO_(2))was carried out for oriented ultrahigh molecular weight polyethylene(UHMWPE) films, which provided special conditions for the crystallization of dissolved UHMWPE macromolecules on the surface of oriented UHMWPE crystals. The prepared porous materials were investigated by scanning electron microscopy(SEM) and differential scanning calorimetry(DSC). The particularity of the obtained porous shish-kebab is the absence of the amorphous phase between lamellar crystals(kebabs). The obtained pores had an oval shape, and they were oriented in the orientation direction of the UHMWPE macromolecules. The pore size ranged from 0.05 μm to 4 μm. Controlling the conditions for the crystallization of the UHMWPE macromolecules using supercritical CO_(2) gives the possibility to control the size of both lamellar disks and pores formed.展开更多
Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a ...Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a polycaprolactone(PCL)scaffold with a shish-kebab structure was prepared by electrospinning and solution-induced crystallization.L929 cells were used to investigate the behavior of fibroblasts on the multi-level microfiber.The results showed that the shish-kebab fiber-based scaffold enhanced the cell proliferation when compared with the normal fiber and the fiber with a porous structure.Protein absorption,cell adhesive force,and cell modulus also increased by the shish-kebab fiber.The shish-kebab fiber-based scaffold with improved fibroblast-regulation ability can be applied in rapid wound healing.展开更多
Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish...Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish-kebabs″ is the intrinsic course for the fiber having highperformance.In this paper,the formation mechanism of the characteristic structure of PE fibershas been investigated by means of SEM,DSC,WAXD,SAXS and TEM,The experimental resultsshow that the extended-chain structure of PE fibers is formed originally from the bridged mole-cules in amorphous region and increased gradually during further drawing porcess.The″shish-kebab″ structure is formed by the combination of extended-chalnS and originalfolded-chains.展开更多
The electrospinning process was applied to fabricate the nanofibers of biodegradable poly(ε-caprolactone)(PCL) in which different contents of multiwalled carbon nanotubes(MWCNTs) were embedded. Afterward,the electros...The electrospinning process was applied to fabricate the nanofibers of biodegradable poly(ε-caprolactone)(PCL) in which different contents of multiwalled carbon nanotubes(MWCNTs) were embedded. Afterward,the electrospun nanofibers were successfully decorated with shish-kebab structure via a self-induced crystallization technique. The topographical features and the mechanical properties of the composite scaffolds were characterized,and the biocompatibility of the material was assessed by using human osteogenic sarcoma osteoblasts(MG-63 cells). The carbon nanotube(CNT) concentration is found to affect the fiber diameter and mechanical properties of electrospun nanofibers and the periodic distance of the shish-kebab architecture. Cellular attachment and proliferation assays reveal that 0.5 wt% CNT-embedded PCL scaffold shows enhanced biocompatibility with MG-63 cells than their counterparts made of neat PCL, and the collagen-like nanotopology provided by the shish-kebab structure further facilitates the cell adhesion and proliferation. The superior interactions between cells and scaffolds demonstrate that the shish-kebab-structured CNTs/PCL nanofibers may be promising candidate for tissue engineering scaffold application.展开更多
Formation of shish-kebab crystals using a bimodal polyethylene system containing high molecular weight(HMW)component with different ethyl branch contents was investigated.In situ small-angle X-ray scattering(SAXS)and ...Formation of shish-kebab crystals using a bimodal polyethylene system containing high molecular weight(HMW)component with different ethyl branch contents was investigated.In situ small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)techniques were used to monitor the formation and evolution of shish-kebab structure sheared at low temperature in simple shear mode and low rate.Only the bimodal PE with no branch formed shish-kebab crystals at the shear temperature of 129℃,and the shish length increased with the crystallization time,while bimodal PE with branch has no observable shish under the same conditions.The degree of crystallization for bimodal PE with no branch increased with time up to above 7%,while those with ethyl branch increased continually up to above 23%.Furthermore,bimodal PE's Hermans orientation factor with no branch increased to 0.60,while those with ethyl branch only increased to a value below 0.15.This study indicated that the shish-kebab crystal formed at the low temperature of 129℃is due to the stretch of entangled chains under shear for the bimodal PE with no branch.Only partly oriented lamellar crystals were formed for the bimodal PE with ethyl branch.All the results at the shear temperatures higher,closed to,and lower than the melting point,the modulation of shish crystals formation owing to different mechanisms of the coil-stretch transition and the stretched network by changing shear temperature was achieved in the bimodal PE samples.展开更多
In recent years,the hybrid shish-kebab structure with excellent physical properties and functionalities has attracted much attention because it provides a way of blending nanofibers with different properties into poly...In recent years,the hybrid shish-kebab structure with excellent physical properties and functionalities has attracted much attention because it provides a way of blending nanofibers with different properties into polymer matrix in a regular arrangement.It is often not easy to induce the formation of the hierarchically ordered structure for the semi-crystalline polymer in heterogeneous shish-kebab structure.A poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL)heterogeneous shish-kebab structure,i.e.,the PCL crystals periodically crystallized onto PLA nanofibers,was successfully created and the interfacial crystal morphology of the PLA/PCL heterogeneous shish-kebab structure was observed using scanning electron microscopy and atomic force microscopy.NaOH aqueous solution was applied to modify the surface of the PLA nanofibers to produce adsorption sites and carboxyl groups.The total reflectance Fourier transform infrared spectroscopy(ATR-FTIR)and X-ray diffraction(XRD)results demonstrated that the formation of the heterogeneous shish-kebab structure was mainly due to the hydrogen bonding interaction between the kebab and shish interface,and the growth process of the kebab crystals also promoted the crystallization of the shish fibers.This heterogeneous nanostructure of biodegradable polymers will have great applications in tissue engineering and regenerative medicine.展开更多
The role of mold temperature on the morphology and properties of rotational shearing polyethylene(PE)pipes was studied via a self-.developed rotational shear system(RSS).The result indicated that when the mold tempera...The role of mold temperature on the morphology and properties of rotational shearing polyethylene(PE)pipes was studied via a self-.developed rotational shear system(RSS).The result indicated that when the mold temperature was 150℃,the hoop tensile strength and Vicat softening temperature were enhanced rapidly,which were 383.6%and 137.9%higher than those of the conventional PE pipes,respectively.Morphology and crystal structure studies by SEM and DSC revealed that once the rotational shear was applied,the shish-kebab structure began to appear.With the increase of the mold temperature,due to the relaxation of most of the oriented molecular chains,the preservation of shish-kebab structure became difficult.When the mold temperature was 190℃,only the inner layer of the pipes,where the cooling rate was the largest,could preserve the shish-kebab structure.According to WAXD,there was less shish structure,and the growth of kebab was distorted in the inner layer of the pipes at 210℃.The result of SAXS suggested that the length of shish changed most within the temperature range from 170℃to 190。C.The results of DSC and WAXD showed less change in crystallinity and degree of orientation between the two temperatures.It can be concluded that the reduction of shish length leads to a decrease in mechanical properties and heat-resistance.展开更多
One-dimensional carbon nano-materials,in particular carbon nanotubes (CNTs) and carbon nanofibers (CNFs),are of scientific and technological interest due to their satisfactory properties and ability to serve as templa...One-dimensional carbon nano-materials,in particular carbon nanotubes (CNTs) and carbon nanofibers (CNFs),are of scientific and technological interest due to their satisfactory properties and ability to serve as templates for directed assembly.In this work,linear high density polyethylene (PE) was periodically decorated on CNTs and CNFs using a supercritical carbon dioxide (scCO_(2))antisolvent-induced polymer epitaxy (SAIPE) method,leading to nano-hybrid shish-kebab (NHSK) structures.The formation mechanism of different morphologies of PE lamellae on CNTs and CNFs has been discussed.Palladium nanoparticles were synthesized and immobilized on the PE/CNF NHSK structure with the assistance of scCO_(2).The obtained hierarchical nano-hybrid architecture may find applications in microfabrication and other related fields.展开更多
Oriented “shish-kebab” structures could be obtained by shearing to enhance the mechanical properties of polymer samples markedly.However,the effect of shear mode on mechanical properties is still uncertain.The study...Oriented “shish-kebab” structures could be obtained by shearing to enhance the mechanical properties of polymer samples markedly.However,the effect of shear mode on mechanical properties is still uncertain.The study of stepped hoop shear field on the isotactic polypropylene(iPP)pipe was developed through applying a self-designed rotational shear system(RSS).The effect of stepped shear field on the microstructure and comprehensive properties of iPP pipe was investigated by the comparison with continuous shear.It could be found that the loosely-assembled shish-kebabs with the larger size were formed in the continuous shear pipes,but the smaller and tightly-stacked ones existed in the pipes with stepped shear.Surprisingly,due to differential morphologies under different shear modes,better comprehensive mechanical properties were obtained in the pipes with stepped shear.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 29674025) and the Natural Science Foundation of Henan Province.
文摘A new series of chiral shish-kebab type liquid crystal block copolymers that form the smecticC(Sc~*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC.DSC. TG, POM. X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whenthey were heated to their melting temperatures (T_m) and the copolymers 8 were in liquid crystal phase at roomtemperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM.All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiralsmectic C(Sc~*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal blockcopolymers that form a chiral smectic C(Sc~*) phase. The variation of melting and isotropization temperatureswith molecular structure was also discussed.
基金This work was supported by China Scholarship Council and Grant-in-Aids for Scientific Research from Ministry of Education, Culture and Science of Japan.
文摘The novel shish-kebab-type liquid crystalline poly(p-phenylene)s were synthesized through Suzuki coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]1,4-dibromobenzene (monomer 1) and 1,4-benzenediboronic acid bistrimethylene cyclic ester (monomer 2). Their structure and properties were characterized by GPC, DSC, X-ray diffraction and polarizing optical microscope (POM). It was found that the polymers turned to liquid crystalline phase above their melting point. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The mesophase was identified by X-ray diffraction method. The polymers could dissolve in common organic solvents and show strong blue fluorescence. The maximum absorption bands of polymers prepared from annealed films have large red-shift due to the spontaneous orientation of the liquid crystalline side chains. The same phenomena were also observed in the fluorescence spectra.
基金This work was supported by the China Scholarship Council and the Grant-in-Aids for Scientific Research from Ministry of Education, Culture, Sports, Science and Technology, Japan.
文摘Novel shish-kebab type liquid crystalline poly(p-phenylenevinylene) derivatives were synthesized by Stille coupling reaction from 2,5-bis[(4-n-alkoxyl)benzoyloxy]l,4-dibromobenzene (monomer 1) and 1,2-bis(tributylstannyl) ethylene (monomer 2). The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point (Tm) of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.
基金financially supported by the Academic leadership program Priority 2030 proposed by Federal State Autonomous Educational Institution of Higher Education I.M. Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation (Sechenov University)The preparation and modification of UHMWPE samples were financially supported by the Russian Science Foundation (No.18-13-00145)SEM investigation was supported by the State Assignment (No.0090-2019-0002, IPAC RAS)。
文摘For the first time, a highly crystalline porous shish-kebab structure with a high degree of crystallinity was obtained by using a combination of two methods for the formation of porous polymeric materials. A treatment procedure using supercritical carbon dioxide(sc CO_(2))was carried out for oriented ultrahigh molecular weight polyethylene(UHMWPE) films, which provided special conditions for the crystallization of dissolved UHMWPE macromolecules on the surface of oriented UHMWPE crystals. The prepared porous materials were investigated by scanning electron microscopy(SEM) and differential scanning calorimetry(DSC). The particularity of the obtained porous shish-kebab is the absence of the amorphous phase between lamellar crystals(kebabs). The obtained pores had an oval shape, and they were oriented in the orientation direction of the UHMWPE macromolecules. The pore size ranged from 0.05 μm to 4 μm. Controlling the conditions for the crystallization of the UHMWPE macromolecules using supercritical CO_(2) gives the possibility to control the size of both lamellar disks and pores formed.
基金Fundamental Research Funds for the Central Universities,China(Nos.2232018G-01 and 2232020G-01)Initial Research Funds for Young Teachers of Donghua University,China。
文摘Improving wound healing efficiency is a key issue for high performance dressings.The surface topology of fibers in wound dressings plays an important role in regulating cell behaviors during the regeneration.Herein,a polycaprolactone(PCL)scaffold with a shish-kebab structure was prepared by electrospinning and solution-induced crystallization.L929 cells were used to investigate the behavior of fibroblasts on the multi-level microfiber.The results showed that the shish-kebab fiber-based scaffold enhanced the cell proliferation when compared with the normal fiber and the fiber with a porous structure.Protein absorption,cell adhesive force,and cell modulus also increased by the shish-kebab fiber.The shish-kebab fiber-based scaffold with improved fibroblast-regulation ability can be applied in rapid wound healing.
文摘Ultra-high strength and modulus polyethylene fibers can be produced from UHMW-PE(ul-tra-high molecular weight polyethylene) by gel spinning and ultra-high drawing method.The spe-cial supermolecular structure of″shish-kebabs″ is the intrinsic course for the fiber having highperformance.In this paper,the formation mechanism of the characteristic structure of PE fibershas been investigated by means of SEM,DSC,WAXD,SAXS and TEM,The experimental resultsshow that the extended-chain structure of PE fibers is formed originally from the bridged mole-cules in amorphous region and increased gradually during further drawing porcess.The″shish-kebab″ structure is formed by the combination of extended-chalnS and originalfolded-chains.
基金financially supported by the Fundamental Research Funds for the Central Universities (No. 22A201514030)China Postdoctoral Science Foundation (No. 2015M571504)+2 种基金the National Natural Science Foundation of China (Nos. 51503065 and 51273065)the Wisconsin Institute for Discovery in University of Wisconsin-MadisonChina Scholarship Council
文摘The electrospinning process was applied to fabricate the nanofibers of biodegradable poly(ε-caprolactone)(PCL) in which different contents of multiwalled carbon nanotubes(MWCNTs) were embedded. Afterward,the electrospun nanofibers were successfully decorated with shish-kebab structure via a self-induced crystallization technique. The topographical features and the mechanical properties of the composite scaffolds were characterized,and the biocompatibility of the material was assessed by using human osteogenic sarcoma osteoblasts(MG-63 cells). The carbon nanotube(CNT) concentration is found to affect the fiber diameter and mechanical properties of electrospun nanofibers and the periodic distance of the shish-kebab architecture. Cellular attachment and proliferation assays reveal that 0.5 wt% CNT-embedded PCL scaffold shows enhanced biocompatibility with MG-63 cells than their counterparts made of neat PCL, and the collagen-like nanotopology provided by the shish-kebab structure further facilitates the cell adhesion and proliferation. The superior interactions between cells and scaffolds demonstrate that the shish-kebab-structured CNTs/PCL nanofibers may be promising candidate for tissue engineering scaffold application.
基金the National Natural Science Foundation of China(Nos.51773101 and 51973097).
文摘Formation of shish-kebab crystals using a bimodal polyethylene system containing high molecular weight(HMW)component with different ethyl branch contents was investigated.In situ small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)techniques were used to monitor the formation and evolution of shish-kebab structure sheared at low temperature in simple shear mode and low rate.Only the bimodal PE with no branch formed shish-kebab crystals at the shear temperature of 129℃,and the shish length increased with the crystallization time,while bimodal PE with branch has no observable shish under the same conditions.The degree of crystallization for bimodal PE with no branch increased with time up to above 7%,while those with ethyl branch increased continually up to above 23%.Furthermore,bimodal PE's Hermans orientation factor with no branch increased to 0.60,while those with ethyl branch only increased to a value below 0.15.This study indicated that the shish-kebab crystal formed at the low temperature of 129℃is due to the stretch of entangled chains under shear for the bimodal PE with no branch.Only partly oriented lamellar crystals were formed for the bimodal PE with ethyl branch.All the results at the shear temperatures higher,closed to,and lower than the melting point,the modulation of shish crystals formation owing to different mechanisms of the coil-stretch transition and the stretched network by changing shear temperature was achieved in the bimodal PE samples.
基金the financial support from the National Center for International Joint Research of Micro-Nano Molding Technology in Chinathe International Science&Technology Cooperation Program of China(No.2015DFA30550)。
文摘In recent years,the hybrid shish-kebab structure with excellent physical properties and functionalities has attracted much attention because it provides a way of blending nanofibers with different properties into polymer matrix in a regular arrangement.It is often not easy to induce the formation of the hierarchically ordered structure for the semi-crystalline polymer in heterogeneous shish-kebab structure.A poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL)heterogeneous shish-kebab structure,i.e.,the PCL crystals periodically crystallized onto PLA nanofibers,was successfully created and the interfacial crystal morphology of the PLA/PCL heterogeneous shish-kebab structure was observed using scanning electron microscopy and atomic force microscopy.NaOH aqueous solution was applied to modify the surface of the PLA nanofibers to produce adsorption sites and carboxyl groups.The total reflectance Fourier transform infrared spectroscopy(ATR-FTIR)and X-ray diffraction(XRD)results demonstrated that the formation of the heterogeneous shish-kebab structure was mainly due to the hydrogen bonding interaction between the kebab and shish interface,and the growth process of the kebab crystals also promoted the crystallization of the shish fibers.This heterogeneous nanostructure of biodegradable polymers will have great applications in tissue engineering and regenerative medicine.
基金the Science and Technology Program of Sichuan Province,China(No.2018G20332)the National Natural Science Foundation of China(No.21627804).
文摘The role of mold temperature on the morphology and properties of rotational shearing polyethylene(PE)pipes was studied via a self-.developed rotational shear system(RSS).The result indicated that when the mold temperature was 150℃,the hoop tensile strength and Vicat softening temperature were enhanced rapidly,which were 383.6%and 137.9%higher than those of the conventional PE pipes,respectively.Morphology and crystal structure studies by SEM and DSC revealed that once the rotational shear was applied,the shish-kebab structure began to appear.With the increase of the mold temperature,due to the relaxation of most of the oriented molecular chains,the preservation of shish-kebab structure became difficult.When the mold temperature was 190℃,only the inner layer of the pipes,where the cooling rate was the largest,could preserve the shish-kebab structure.According to WAXD,there was less shish structure,and the growth of kebab was distorted in the inner layer of the pipes at 210℃.The result of SAXS suggested that the length of shish changed most within the temperature range from 170℃to 190。C.The results of DSC and WAXD showed less change in crystallinity and degree of orientation between the two temperatures.It can be concluded that the reduction of shish length leads to a decrease in mechanical properties and heat-resistance.
基金the National Natural Science Foundation of China (20974102)the Program for New Century Excellent Talents in Universities (NCET)
文摘One-dimensional carbon nano-materials,in particular carbon nanotubes (CNTs) and carbon nanofibers (CNFs),are of scientific and technological interest due to their satisfactory properties and ability to serve as templates for directed assembly.In this work,linear high density polyethylene (PE) was periodically decorated on CNTs and CNFs using a supercritical carbon dioxide (scCO_(2))antisolvent-induced polymer epitaxy (SAIPE) method,leading to nano-hybrid shish-kebab (NHSK) structures.The formation mechanism of different morphologies of PE lamellae on CNTs and CNFs has been discussed.Palladium nanoparticles were synthesized and immobilized on the PE/CNF NHSK structure with the assistance of scCO_(2).The obtained hierarchical nano-hybrid architecture may find applications in microfabrication and other related fields.
基金supported by the National Natural Science Foundation of China(No.21627804).
文摘Oriented “shish-kebab” structures could be obtained by shearing to enhance the mechanical properties of polymer samples markedly.However,the effect of shear mode on mechanical properties is still uncertain.The study of stepped hoop shear field on the isotactic polypropylene(iPP)pipe was developed through applying a self-designed rotational shear system(RSS).The effect of stepped shear field on the microstructure and comprehensive properties of iPP pipe was investigated by the comparison with continuous shear.It could be found that the loosely-assembled shish-kebabs with the larger size were formed in the continuous shear pipes,but the smaller and tightly-stacked ones existed in the pipes with stepped shear.Surprisingly,due to differential morphologies under different shear modes,better comprehensive mechanical properties were obtained in the pipes with stepped shear.
