最新刊期
卷 ， 期 5 ， 2013
- 摘要：From a structure-dominated performance point of view,the ultimate physical properties of polymer articles are directly related to their internal multiscale (hierarchical) structures,ranging from molecular,nanometer,submicrometer,to micrometer and mesoscope level.Since the features of hierarchical structure are strongly dependent on the external fields imposed during processing,many structural items can be well or precisely controlled,resulting in significant variables in hierarchical structure.Thanks to the fast developments of mechanical technique,various external fields,such as thermal,shear,extension,ultrasonic,electronic,magnetic,super-critical fluid fields,etc.,can be nicely introduced into polymer processing,leading to the significantly improved ability of tailoring the microstructure/morphology via processing.It is characteristic as externally applied field determined hierarchical structure,i.e.structuring processing,which represents the advance trend in the modern polymer processing area,and is of the topic of this contribution.关键词：Processing of polymer materials;Structuring;Hierarchical structure;Control of morphology/structure
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发布时间：2021-03-19
Feature Articles
- 摘要：In the past decades,researchers fabricated high refractive index (n) polymer optical materials by introducing aromatic rings,sulfur-containing groups,halogens except uorine and organometallic moieties.However,the refractive index of these pure polymer materials is usually below 1.80.Incorporation of high-n nanoparticles into polymer matrices seems to be a more promising strategy to achieve a refractive index higher than 1.80.And these high refractive index polymer-inorganic optical hybird materials have many promising applications in optical design and advanced optoelectronic fabrication due to its excellent performance combining the properties of polymer and inorganic materials.This article summarizes the general design principles,different fabrication approaches of high RI nanocomposites and reviews recent research advances and some important optical applications of these nanocomposites.关键词：High refractive index;Polymer materials;Inorganic materials;Optical hybird materials
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发布时间：2021-03-19 - 摘要：Transformation of CO2 into biodegradable polycarbonates by the alternating copolymerization with epoxides has attracted much attention not only in academic research but also in industry.The review first summarized the industry progress of CO2 based plastics,and the advantages and disadvantages of this CO2 based plastics have been discussed based on poly(propylene carbonate) (PPC),a typical CO2 based plastics from alternating copolymerization of CO2 and propylene oxide.One disadvantage lies in that the CO2 based copolymer is seldom functionalized,leading to its poor hydrophilicity.This review tries to emphasize that introducing functional groups to CO2 based copolymer,such as pendant ally groups,carbonate groups,mesogenic groups,can produce functionalized CO2 based copolymers,moreover,introducing urethane-amine group,ether group in the mainchain or side chain may be a practical way to adjust the balance of hydrophobicity and hydrophilicity of the copolymers,leading to novel thermal/pH dual responsive CO2 based copolymers.Of course,due to the strong polarity or hydrophylicity of the functional monomer,the functional CO2 based copolymers generally show relatively lower molecular weight,and unlike the common copolymerization between CO2 and propylene oxide,the catalytic activity for producing functional copolymers needs further improvement.关键词：Carbon dioxide;Copolymer;Functional;Hydrophilicity
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发布时间：2021-03-19
Reviews
- 摘要：In order to modulate the optoelectronic properties of thiophene-based conjugated polymers,two novel conjugated polymers ( P1 and P2 ) comprising dithieno[3,2-b:2',3'-d]phosphole oxides (DTPhos) and 2,2'-bithiophene have been designed and synthesized by Stille polycondensation,and their thermal,electrochemical and photophysical properties were studied.Both polymers are thermally stable with decomposition temperature above 400℃,and exhibit the absorption maxima of ca. 590 nm and the optical band gap of 1.76 eV.The incorporation of DTPhos units into polythiophene backbone results in a 0.15 eV reduction of optical bandgap.HOMO and LUMO energy levels of the polymers as measured by cyclic voltammetry are -5.1 and -2.9 eV,respectively.Thin-film transistors (TFT) and bulk heterojunction solar cells (BHJ-SC) were fabricated based on P1 and P2 .The performance of the devices increased with an increase of the alkyl chain length in the DTPhos units.With a bottom gate and top contact TFT device structure, P2 exhibited the hole mobility up to 0.0077 cm2V-1s-1.Under AM 1.5 G illumination (100 mW/cm2),BHJ-SC based on P2 displayed an open-circuit voltage of 0.68 V,a short-circuit current of 7.9 mA/cm2,a fill factor of 52% and a power conversion efficiency of 2.8%.These results imply that DTPhos unit is a potential building block for high-performance polymer semiconductors.关键词：Dithieno[3,2-b：2,3-d]phospholes oxide;Conjugated polymers;Thin-film transistors;Bulk heterojunction solar cells
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发布时间：2021-03-19 - 摘要：The development of outer-sphere electron mediators featuring low Femi-level brings forth a key advance of performance for dye-sensitized solar cells (DSCs).The judicious modulation of dye layer microstructure coated on the surface of titania to inhibit the interfacial charge recombination is one of the important research topics in the field based upon this rapid recombination device.In this paper,a high-absorptivity polypyridyl ruthenium sensitizer and a three-dimensional push-pull organic dye were employed to cosensitize the titania film.With respect to the cell involving pure ruthenium photosensitizer,the transient absorption spectrum measurements have disclosed that the employment of the three-dimensional organic dye can endow the cell with an improved efficiency of electron injection.Moreover,transient absorption and photovoltage decay measurements have revealed that this push-pull dye also confer the device with slower charge recombination of titania electrons with both photooxidized dye molecules and electron-donating species in electrolytes based upon the tris(1,10-phenanthroline)cobalt (Ⅱ/Ⅲ) redox couple,resulting in an evidently improved open-circuit voltage from 808 to 883 mV.Furthermore,the electron injection efficiency improvement and charge recombination diminishments through modulating the microstructure of interfacial photoactive layer can also overcompensate the adverse impact of reduced light-harvesting,bringing forth an enhanced photocurrent output observed in current-voltage measurements,and an overall power conversion efficiency improvement from 8.5% to 10.3% at the 100 mW cm-2,simulated AM1.5 conditions.关键词：Solar cell;Dye;Charge transfer;Interfacial microstructure
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发布时间：2021-03-19 - 摘要：A series of blue-emitting poly(2,7-carbazole)s substituted with N-phenylcarbazole (BCzPCz01-BCzPCz10) have been synthesized via Suzuki polymerization.By reducing the loading of Pd catalyst from 10 to 1,their number-average molecular weights are correspondingly increased from 27000 to 69000 while their polydispersity indexes (PDI) remain in the range of 2.5 to 3.0.And the effect of the molecular weight on their photophysical,electrochemical and device properties is then thoroughly investigated for these obtained polymers.Most importantly,the introduction of rigid N-phenylcarbazole can effectively tune the interchain interactions,and improve the color purity of blue emission.As a result,all the polymers show film photoluminescent quantum yields as high as 0.40 and excellent spectral stability,for no green emission often appeared in polyfluorenes is observed here under annealing or electric field conditions.Single layer polymer light-emitting diodes are fabricated with a configuration of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS)/polymer/Ca/Al.Among these polymers,BCzPCz01 exhibits a peak luminous efficiency of 0.33 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.18,0.12).The device performance is improved by about 65% in comparison to that of poly(2,7-carbazole)s substituted with triphenylamine.These interesting results will provide a novel platform for the design of highly efficient stable blue-emitting polymers in the future.关键词：Polymer light-emitting diodes;Poly(2,7-cabazole);N-phenylcarbazole;Blue-emitting polymer;Spectral stability
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发布时间：2021-03-19 - 摘要：Segment confinement is constructed by the coordination effect between copper(Ⅱ) and poly-(ethylene oxide).The crystallization and melting behaviors of PEO under segment confinement are studied.Broadband dielectric spectroscopy(BDS) is used to characterize the relaxation behaviors of PEO under confinement.The characteristic relaxation time of and process of PEO is found to be increased with copper(Ⅱ) contents,which indicates the cooperative motion of PEO segments and twisting motion of main chain are frustrated.The relaxation time obtained from BDS provides a quantitative evaluation of confinement degree.DSC results show a significant increase of glass transition temperature of PEO with increasing copper(Ⅱ) contents and cold crystallization is observed,which indicates the coordination effect of copper(Ⅱ) has actually restricted the segment motion of PEO.Meanwhile,the crystallinity and melting temperature of PEO decrease with the increase of copper(Ⅱ) contents.WAXD shows that copper(Ⅱ) bromide does not crystallize in the blends.No crystal modification of PEO is observed.AFM shows that in all thin films of PEO/CuBr2 blends,PEO forms extended chain crystals(IF(0)) and the lamella thickness of PEO does not change with copper(Ⅱ) contents.However,much more screw dislocations are observed as the copper(Ⅱ) content increases,which indicates a large number of defects are formed in the PEO crystals.Similar with the situation of metal material,the defects should be responsible for the melting point depression.关键词：Poly(ethylene oxide);Coordination;Confined crystallization;Defects;Screw dislocation
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发布时间：2021-03-19 - 摘要：Mesoporous xerogel has been prepared by a non-surfactant sol-gel process to encapsulate living yeasts.Trehalose and glycerol are chosen as both the protective agents and pore-forming agents.Hydroxyethylcellulose (HEC),an additive,is utilized to reduce the shrinkage of gel during drying process.The encapsulated yeasts survived in the xerogel and maintained the capability to assimilate glucose.The relationship between the yeast metabolic kinetics and the xerogel pore parameters was investigated.With tetraethoxysilane(TEOS) and methyl triethoxysilane (MTES) as precursors for reinforcing the material and transforming the hydrogel(60% moisture content) to xerogel(10%moisture content),the leakage of the yeasts is partially prevented.Through the uniaxial compressive strength test,the strength of xerogel can reach 7.13 MPa at least,which is twelve times more than that of the hydrogels.According to plate count method,the concentration of yeasts was about 1.5?108 mL-1 in sol and 6.4?108 g-1 in xerogel.Through the characterization of the specific surface area,pore structure and the yeast metabolic kinetics,we found that the metabolic dynamics of entrapped yeast was related to the pore parameters of silica matrix.The xerogel obtained by non-surfactant process could have the specific surface area of 800 m2g-1,the pore volume of 0.44 cm3g-1 and the pore diameter of 2.7 nm.Under such conditions,calculated from independent samples without free yeasts,statistically,the encapsulated yeasts can metabolize 89% glucose of the culture medium in 60 h.关键词：Non-surfactant sol-gel process;Mesoporous silica;Living yeasts;Metabolic dynamics;Xerogel
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发布时间：2021-03-19 - 摘要：The scandium dialkyl complex LSc(CH2SiMe3)2 (L=(2,6-iPr2C6H3)NC(Me)CHPPh2N-(2,6-Me2C6H3)) activated with [Ph3C]B(C6F5)4］ could initiate ethylene and propylene copolymerization with high activity (7.5105g(PE)mol-1 h-1 (105Pa)-1) under the conditions of room temperature (30℃) and atomphere pressure (1.0 105 Pa).The influence of comonomer feed content and polymerization temperature on activity and the composition of the copolymers using LSc(CH2SiMe3)2/[Ph3C]B(C6F5)4］ catalytic system were investigated.An increase in the initial propylene feed content leads to the increase in the incorporated propylene content of the resulting copolymer.At 30℃,the highest activity and incorporation of propylene were achieved.Determination of the reactivity ratios shows a much high reactivity for ethylene (rE=29.75 and rP=0.015).The resultant copolymers are elastomers having random sequence distibution of the two monomeric units evidenced by 13C-NMR spectroscopy and DSC analyses.关键词：Rare earth metal complex;Ethylene;Propylene;Copolymerization
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发布时间：2021-03-19 - 摘要：The influence of temperature on the morphology of polybutylene succinate (PBS) lamellae,obtained by self-seeding crystallization in dilute dichloride benzene solution,was systematically studied.The morphologies of the PBS single crystals obtained by this method all have a similar size and shape.The atomic force microscopy measurements,such as the average surface roughness,were summarized over tens of the PBS crystals.It was found that the nucleation and the surface roughness of the folding surface of PBS lamellae were significantly influenced by the isothermal crystallization temperatures and the seeding temperatures.The higher the crystallization temperature,the larger the surface roughness can be found and it preferred to grow the single layer PBS crystals.It is suggested that the defects are mainly distributed on the folding surface.However,during crystallization at a relatively lower temperature,the smooth folding surface and multi-layers PBS crystals can be observed.We postulated that the defects may be trapped in the PBS crystal and to induce the screw dislocation growth to form the multi-layer morphology.Based on our experimental results,a simple model is proposed to qualitatively describe the relationship between the probability of defects in the lamellae and the supercooling degrees during the isothermal crystallization.Moreover,an inducing nucleation mechanism on folding surface of a crystal is also proposed,it can be used to explain our experimental observations.关键词：Polymer single crystal;Lamellae;Folding surface;Induced nucleation;Self-seeding
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发布时间：2021-03-19 - 摘要：The fluorescence enhancement of green fluorescence protein (GFP) chromophore was realized through the self-assembly of amphiphilic block polymer and GFP chromophore.GFP chromophore and a series of amphiphilic poly(ethylene glycol)-b-poly(methyl methacrylate) (PEG-b-PMMA) with different PMMA lengths were synthesized.1H and 13C nuclear magnetic resonance (1H and 13C-NMR),high-resolution mass spectroscopy (HRMS),Fourier transform infrared spectroscopy (FTIR),gel permeation chromatography (GPC),ultraviolet-visible absorption (UV-Vis) and fluorescent spectroscopy were applied to study the structure and properties of chromophore and polymers.The maximum UV-Vis absorption peak and fluorescent emission peak were at about 371 nm and 428 nm,respectively.After the self-assembly of PEG-b-PMMA with chromophore,the UV-Vis absorption of chromophore disappeared while the fluorescent emission intensity increased markedly with a red-shift of 70 nm,which could be attributed to the chromophore's rotation restriction in polymeric nanoparticles.The size and shape of nanoparticles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM).Benefiting from the appropriate size and good fluorescent property,these PEG-b-PMMA/chromophore nanoparticles were used in cell imaging successfully.关键词：Green fluorescent protein;Chromophore;Amphiphilic polymer;Self-assembly;Imaging
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发布时间：2021-03-19 - 摘要：Isothermal crystallization behavior of carbon black (CB) filled high density polyethylene (HDPE) at a narrow temperature range from 124.3℃ to 125.3℃ was investigated using a rheology-electrical conduction simultaneous measurement method to detect the formation of percolation network and its influence on viscoelastic evolution involving in crystallization of polymer matrix.The results show that strain,frequency and pre-cooling rate have significant influences on both rheological behavior and electrical resistance evolutions as a function of time.The dynamic storage modulus (G') and resistance (R) exhibit abrupt changes upon crystallization of HDPE.R increases during the crystallization induction period,which is assigned to CB particle diffusion in the polymer melts resulting in a partial breakdown of the original percolation network.On the other hand,G' remains constant until induction time of crystallization and the dyanmic rheological method can detect the structural variation only when relative crystallinity reaching 1%~2%.With proceeding of crystallization,G' increases while R decreases markedly and the later is assigned to CB exclusion from the crystalline phase and aggregation in the amorphous phase.Both the rheological and electric donduction behaviors undergo interconnected changes during isothermal crystallization of filled HDPE while the R variation is much more sensitive than that of dynamic rheological behavior to detect the structural evolution because it can reflect the CB diffusion in the melts before crystallization and the CB aggregation in the amorphous phase upon crystallization.关键词：Rheology-electrical conduction simultaneous measurement;High density polyethylene (HDPE);Carbon black (CB);Composite system;Isothermal crystallization
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发布时间：2021-03-19 - 摘要：The effect of high density polyethylene (HDPE) on the crystallization and tensile behavior of the olefin block copolymer (OBC)-rich blends was enamined.Morphological studies revealed that the two components were phase separated in the melt state.Partial miscibility between the two components came from the phase mixing,which was attributed to the randomness of the block distribution produced by chain shuttling polymerization.Cocrystallization of HDPE and OBC was observed in slow cooling samples.Crystalline lamellae originating from the HDPE-rich phase passed through the OBC-rich phase and organized into spherulites in a space-filling manner.With increasing HDPE fraction,the modulus and tensile strength of the blends increased gradually.Meanwhile,high fracture strain and excellent strain recovery were retained.The stress-strain curves of the elastomeric blends could be nicely described by the Slip-link model.The crystalline part in blends provided the physical basis for sliplinks,while the tightened topological entanglements served as crosslinks.The density of sliplinks and crosslinks increased with increasing HDPE content.The increased crystallinity was shown to be the reason for the increased silplink number.By analyzing changes of microstructure imparted by HDPE,the structure property correlation was nicely established.It was clearly demonstrated that HDPE could effectively tailor the tensile properties of OBC by simple blending approach.关键词：Olefin Block Copolymer;High density polyethylene;Blends;Crystallization;Tensile behavior
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发布时间：2021-03-19 - 摘要：A new type of toothbrush like polypeptide with poly-L-lysine (PLL) as backbone was synthesized via a combination of ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP).A N-bromoisobutyryl functionalized N-CBZ-L-lysine was prepared and subsequently converted into -amino acid N-carboxyanhydride (Br-Lys-NCA).Then,a series of well-defined PZLL-PBrLL diblock copolypeptides were prepared via Ni(COD)depe mediated living ROP and sequential monomer addition strategy.These diblock copolypeptides containing a block of bromo-functionalized poly-L-lysine were then used as macroinitiator for subsequent ATRP of EGMA monomers to make toothbrush copolypeptides.The structure and composition of block and toothbrush copolypeptides were characterized using GPC/LLS,1H-NMR and FTIR.The successful reaction and chain extensions were firstly supported from FTIR characterization for NCA characteristic absorbance.The GPC results demonstrated the apparent increase of samples' molecular weight as the linear copolypeptide was converted into copolypeptide brushes.1H-NMR spectra verified the formation of homopolypeptide and copolypeptides.The secondary structures of both block and toothbrush copolypeptides were investigated using circular dichroism (CD).It was found that the -helical content of PZLL-b-PBrLL diblock copolypeptide decreased with the reduction of mass fraction and chain length of PZLL.For toothbrush copolypeptides,the helicity was substantially lower than corresponding diblock precursors,and decreased with growing side chain length of PEGMA.Herein,we demonstrated a facile method to synthesize the biodegradable copolypeptide toothbrush with tunable spatial configurations and secondary structures by combining NCA ring opening polymerization and controlled ATRP technology.Moreover,such strategy can be easily expanded to make temperature and pH responsive copolypeptide toothbrushes.关键词：Polypeptide;Ring opening polymerization;Toothbrush;-Helical;ATRP
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发布时间：2021-03-19 - 摘要：A series of water-soluble biodegradable oligo(lactide-co-acryloyl carbonate)-b-poly(ethylene glycol)-b-oligo(lactide-co-acryloyl carbonate) (OLAC-PEG-OLAC) triblock copolymers were synthesized by ring-opening copolymerization of lactide (LA) and acryloyl cyclic carbonate (AC) and applied for in situ formation of novel bioactive biodegradable hydrogels via photo-crosslinking.The rheology measurements showed that gelation times (0.8~8 min) and storage moduli (170~10000 Pa) of hydrogels could be controlled by AC content,polymer concentration and photo-initiator concentration.The results of degradation tests displayed that degradation rates of these hydrogels could be tailored by AC and LA contents.Notably,the multiple acryloyl functional groups in OLAC-PEG-OLAC copolymers allowed direct conjugation of thiol-containing biomolecules like RGD peptides via Michael addition reaction prior to gelation,which provides a facile access to injectable bioactive biodegradable hydrogels.The preliminary cell experiments demonstrated that RGD peptide modified hydrogels could well support adhesion and growth of MG63 osteoblast cells.These rapidly photo-crosslinkable biodegradable hydrogels with controlled mechanical properties,tailored biodegradation rates,and versatile bio-functionalization form an excellent basis for the development of advanced bioactive tissue engineering scaffolds.关键词：Hydrogel;Photo-crosslinking;Biodegradable;Bioactive;RGD peptide;Tissue engineering
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发布时间：2021-03-19
Research Article
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