最新刊期
卷 ， 期 1 ， 2014
- 摘要：Translocation of polymer chains through nanopores (ultrafiltration behavior) is not only a basic problem in polymer physics and biophysics, but also related to many physical and chemical processes, such as gene transfection, protein transportation, and separation of polymer chains by size exclusion chromatography. However, due to the lack of appropriate polymer model samples as well as ideal elongational flow fields, the ultrafiltration behavior of polymer chains has not been systematically explored experimentally for a long time. To deeply understand the ultrafiltration behavior of polymer chains and verify relevant theory, we have made much effort on this subject in the past decade. In this article, we'll first review the classic theory of polymer chains passing through nanopores, and then provide an overview of our recent theoretical and experimental research achievements in this field, more specifically, we have (1) successfully observed the coil-to-stretch first-order transition of polymer linear chain passing through nanopores, and found that the critical flow rate (qc) is indeed independent on the chain length, but dependent on the pore size, inconsistent with de Gennes' prediction; (2) developed a unified theoretical description of polymer chains with different topologies passing through a nanopore; (3) systematically studied the effects of polymer chain topology and pore structure on the ultrafiltration behavior of polymer chains; and (4) successfully applied the ultrafiltration method into the separation of polymer chain mixtures and the rapid transition between various polymeric aggregated structures.关键词：Ultrafiltration;Cylindrical pore;Topological structure;Critical flow rate;Separation;Structure transition
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发布时间：2021-03-19
Feature Articles
- 摘要：The application of polymer materials is significantly influenced by their crystallization behaviors.Up to now,it is hard to study the crystallization behavior of polymer on the molecular level,because of the large molecular weight,wide molecular weight distribution and many kinds of mesophases.Normal alkanes,with the same linear hydrocarbon chain structure as polymer,are ideal model systems for polymers and have attracted more attention on their confined crystallization behaviors.There are three kinds of confinement systems for n-alkanes crystallization,which are one-dimensional-confinement film,two-dimensional-confinement mesopores or nanochannels and soft three-dimensional-confinement microemulsions,respectively.The crystallization behaviors and phase transitions of n-alkanes confined in media behave differently from their bulk counterparts,which can be attributed to the confinement effect on nucleation and phase transitions.This article reviews the crystallization behaviors and phase transitions of n-alkanes in three kinds of confinement systems,and also makes a brief overview on polymer confined crystallization behaviors in the same systems,trying to illustrate that n-alkane is the excellent model for the study of complex confined crystallization behaviors of polymers,especially for polyethylene.关键词：n-Alkanes;Confinement;Crystallization
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发布时间：2021-03-19
Reviews
- 摘要：A series of radiopaque iodinated polyurethanes (I-PUs) used for embolic agents were synthesized via coupling reaction between poly(butylene succinate) PBS and iodinated bisphenol-A (IBPA) with varying compositions using isophorone diisocyanate (IPDI).The IBPA with four iodine atoms per molecule was applied as a chain extender and X-ray contrast agent.The chemical structure and composition of I-PUs were characterized by FTIR and 1H-NMR.The effects of IBPA on crystallization and thermal properties of I-PUs were systematically studied by means of differential scanning calorimetry (DSC),thermogravimetry analysis (TGA) and wide-angle X-ray diffraction (WAXD).The results showed that the crystallization behavior and thermal stability were restrained with the introduction of IBPA,which was also confirmed by WAXD.However,in the X-radiography analysis,all the synthesized I-PUs and their microspheres exhibited high radiopacity compared with an aluminum wedge of equivalent thickness.As expected,the X-ray visibility was increased with the iodine content increased.Basic cytotoxicity test was conducted by the method of thiazolyl blue tetrazolium bromide (MTT) colorimetric assay and fluorescent live/dead staining.Cells proliferating well on the polymer-coated coverslips demonstrated that all the synthesized I-PUs were noncytotoxic biomaterials.This study presents a facile synthetic route of radiopaque polyurethanes with high iodine contents,which are expected to possess significantly advantage over the traditional polymer counterparts used for embolic agents and other related biomedical applications.关键词：Polyurethane;Iodinated Bisphenol-A;X-ray radiopacity;Embolic agents
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发布时间：2021-03-19 - 摘要：Crystalline/amorphous triblock copolymers PMMA-b-PHBV-b-PMMA with bacterial polyester poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as crystalline component and polymethyl methacrylate (PMMA) as amorphous component were prepared via atom transfer radical polymerization (ATRP).Molecular weight and molecular weight distribution,molecular structure have been characterized by gel permeation chromatography (GPC),together with Fourier transform infrared spectroscopy (FTIR),and 1H nuclear magnetic resonance (1H-NMR).The morphology of the triblock copolymers was characterized by polarizing optical microscopy (POM).Thermal stabilities have been studied by thermal gravimetric method (TG),and the degradation activation energy was calculated by Horowitz-Metzger method.Results showed that the maximum yield of triblock copolymer was 92.39%.The crystalline morphology of neat PHBV shows obvious banded spherulites.With PMMA content increase,the crystalline morphology of triblock copolymers changes from banded pattern to radial pattern,with a decreasing radius of spherulites.When the molar ratios of PMMA and PHBV is 10:1,the edge of spherulites becomes unclear.The TG analysis revealed that T0,T5%,Tmax of triblock copolymer with the molar ratios of PMMA and PHBV between 2:1 and 8:1 were raised to 25,15 and 40℃,and the degradation activation energy of triblock copolymers may decrease from 428.25 kJ mol-1 to 169.83 kJ mol-1.关键词：Crystalline/amorphous;PHBV;PMMA;Triblock copolymer;Thermodegradation kinetics;ATRP
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发布时间：2021-03-19 - 摘要：Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA) is a known endocrine disruptor which possesses estrogenic activity and interferes with the endocrine system.Further,BPA has been shown to adversely affect development and/or reproduction in many animal species.In order to rapidly identify and effectively adsorb BPA,a molecularly imprinted polymer (MIP),template with BPA,has been synthesized in polar solvent.4-Vinylpyridine was selected as the functional monomer.UV analysis results revealed BPA and 4-vinylpyridine completed the self-assembly process by noncovalent interaction,which was presumed to - stacking.The complex ratio was 1:2 by calculation.The MIP was prepared in precipitation polymerization and characterized by infrared spectra.It demonstrated that MIP had the necessary characteristics of the structure and successfully accomplished imprinting and reversible separation to BPA.The ChemDraw pictures were used to display the imprinted mechanism of the polymers.The preservation of the mesoporous structure was confirmed visually by scanning electron microscopy (SEM) of MIP.Evidence of imprint sites buried within the pore walls was found through careful characterization of MIP and its comparison to similarly prepared non-imprinted ones.The thermal adsorption experiment examined the specificity recognition and the selective adsorption mechanism.The specificity adsorption was 37.39 mol/g and the imprinted index was 4.31.The separation factors of tetrabromobisphenol A,phenol,atrazine,naproxen and quercetin were 2.51,2.06,2.14,2.26 and 2.63 respectively,which showed that molecularly imprinted polymer had a good recognition characteristic to BPA.The recognition factor of the non-imprinted polymers was close to 1,which indicated that the adsorption substrate was non-selective.This demonstrated that it was the formation of precise and stable cavities retained the exact memory of the size,shape,and orientation of the functional groups during the templating polymerization steps.关键词：Imprinting mechanism;- stacking;Precipitation polymerization;Imprinted index;Bisphenol A
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发布时间：2021-03-19 - 摘要：A kind of low cost and toxicity ceramic precursor with zirconium (PZC) used for impregnation was successfully synthesized with phenol,paraformaldehyde (PA),ZrOCl28H2O,acetylacetone (Hacac) and H2O2 as raw materials.The precursor was air stable and can be diluted in ethanol to any expected viscosity.The composition,structure,viscosity and pyrolysis process of the precursor were analyzed by X-ray diffractometer (XRD),X-ray photoelectron spectroscopy (XPS),nuclear magnetic resonance (NMR),Fourier transform infrared spectra (FTIR),the cone and plate rheometer and thermogravimetric analyser-differential scanning calorimetry (TG-DSC).The results showed that incorporation of Zr on to the polymer backbone was successfully done,using Hacac as complexing agent and ethanol as solvent,and the obtained precursor might be ZrO and ZrOC chain polymer with acetylacetone and hydroxymethyl phenol as ligands.During reaction,the coordination compound [Zr] prepared by the coordination reaction between ZrOCl28H2O and acetylacetone (Hacac) was the main reactive group.And PZC was prepared by the coordination reaction of [Zr] and the hydroxymethyl phenol which was synthesized by reaction between phenol and formaldehyde.Results indicated that the precursor showed long temperature range of 40~80℃ and low viscosity of 50~800 mPas,which was suitable for impregnation.The ceramic yield ratio of the precursor was 48% at 1400℃,pyrolysis products were ZrO2 and ZrC,while initial formation temperature of ZrC was higher than 1200℃,and the precursor transformed into ZrC completely at 2000℃.Thus,it is a kind of ceramic precursor suitable for infiltration and pyrolysis to obtain ZrC modified carbon/carbon composites.关键词：Ceramic precursor;Precursor infiltration and pyrolysis;ZrC
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发布时间：2021-03-19 - 摘要：A novel comb-like polymer was synthesized by solution polymerization with methyl methacrylate and poly(ethylene glycol) methly ether methacrylate as monomers,and the conductive properties of solid polymer electrolytes incorporated with LiClO4 were investigated thoroughly.The characteristic comb-like structure of polymer was confirmed by FTIR and 1H-NMR.The solid polymer electrolytes based on the comb-like polymer were found to be almost amorphous at room temperature,which was verified by DSC and XRD measurements.SEM and FTIR results revealed that,at the salt content less than 16 wt%,the salt could dissolve in the polymer matrix well and anions mainly presented in the polymer matrix in terms of free ions.When the salt content was more than 16 wt%,the content of ion pairs increased significantly,indicating the bad solubility of salt in the polymer matrix.The ionic conductivity of the electrolytes was up to 4.8110-5 S/cm at 30℃ with the addition of 16 wt% LiClO4.Increasing the content of salt would lead to a dramatic decrease in the ionic conductivity of the polymer electrolytes,which could be attributed to the negative effect of large number of ionic pairs.关键词：Comb-like solid polymer electrolytes;Ionic conductivity;Methyl methacrylate;Conduction mechanism
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发布时间：2021-03-19 - 摘要：Polyurethane/silica nanocomposites were prepared by solution mixing procedure,and the effect of nano-silica on the crystalline behavior in these nanocomposites was investigated by a variety of techniques.TEM results indicate that nano-silica is well dispersed in the polyurethane matrix.It is found from the DSC experiments that the crystallization of soft segments are obviously enhanced after annealing at high temperature and subsequent isothermal crystallization at 10℃,the addition of nano-silica affects the final glass transition temperature and the crystallinity of soft segments,as well as the rate of increment.Solid-state NMR analyses reveal that the mobility of soft segments is is restricted after annealing,while the mobility of hard segments obviously enhanced.The above results reveal that the interchain hydrogen bonding among hard segments is broken at high temperatures,and the increased interaction of hard segments and nano-silica results in the high mobility of hard segments,thus promoting the crystalline ability of the soft segments connected with hard segments.On the basis of the above results,a suggested model concerning the evolution of structure and dynamics in polyurethane nanocomposites under high-temperature annealing and subsequent isothermal crystallization is proposed.关键词：Polyurethane;Nano-silica;Crystallization;Structure and dynamics;Nanocomposites
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发布时间：2021-03-19 - 摘要：All- proteins simplified by NHP model with its secondary structure information were studied by molecular dynamics simulation.The transitions of potential energy in 50 all- proteins under different temperatures were well discussed in this paper.It is concluded that the bond-stretching and bending energies increase linearly with the chain length.The bond-stretching and bending energies of each bond also increase linearly with the temperature due to more obvious bond vibration under high temperatures.The slope of the linear relationship between bond-stretching energy and temperature is larger than the one of bond-bending energy as the function of T*.The bond-torsional energy decreases linearly with the number of -helix in each protein chain,instead of the chain length.It increases with the temperature when the temperature is lower than 0.3.And then it decreases with the temperature increasing.Non-bond energy is mainly dependent on hydrophobic-hydrophobic interactions.It doesn't show obvious linear relationship due to the mutual interactions between hydrophilic,hydrophobic,or neutral residues.The transition temperatures are shown in bond-torsional and non-bond potential energies.The native structure is related to the mutual effect of bond and non-bond potential energies,which compete with each other for lower potential energy.These conclusions provide a natural realization of understanding the structure of proteins.关键词：All- proteins;Molecular dynamics simulation;Energy transition
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发布时间：2021-03-19 - 摘要：The morphology and dynamics of viscoelastic phase separation in polymer solutions are investigated by the use of a graphic process unit (GPU) accelerated three-dimensional numerical simulation of a viscoelastic model for the first time.The results show the bulk stress is a prerequisite to the phase inversion.In agreement with the phase inversion observed in previous experiments,the polymer rich domain first forms a continuous network structure and then shrinks and inverts to a dispersed droplet structure.Interestingly,the growth of the bulk relaxation modulus suppresses the concentration fluctuation in the early stage of phase separation,and the phase inversion is thus delayed by the increase of bulk relaxation modulus.On the other hand,the growth of the bulk relaxation modulus increases the domain growth rate in the late stage of phase separation and leads to larger-sized polymer rich domains.Additionally,the growth of the shear relaxation modulus can help polymer rich domains to maintain network-like structures,and in the case of a larger shear relaxation modulus,the shear stress can exist for a longer time due to the slow relaxation of irregular polymer-rich domains in the late stage of phase separation.关键词：Viscoelastic Model;Polymer solution;Viscoelastic phase separation;Three-dimensional numerical simulation
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发布时间：2021-03-19 - 摘要：A series of molecular dynamics simulations were conducted to investigate the interaction between protein (lysozyme) and two typical non-fouling membranes (PDMS and SBMA). Lysozymes were initially put on the surfaces of two non-fouling membranes with a minimal separation distance 0.5 nm,1.0 nm and 1.5 nm. Centroids of proteins were fixed during the first 15 ns simulation to determine the forces that membranes extended on proteins. Then the fix was cancelled in the following 20 ns simulations. At the end of simulations, both the proteins were adsorbed on membranes. By analyzing the types of residues near adsorption sites, contact areas, hydrogen bonds, VDW contacts between protein and membranes, we concluded that PDMS has a better combination with lysozyme than SBMA. This closely adsorption makes the protein not easy to leave from membranes. To fully understand the molecular mechanism of non-fouling materials, the simulation results were analyzed from two aspects: interaction between protein and membrane, interaction between surface hydration layer and membrane. Combined with our previous work which concentrated on properties of surface hydration layers it is concluded: (1) PDMS has a larger attractive force on protein than SBMA at the whole distance range. Both the interactions between protein and membranes were energetically favorable, but Lysozyme interacted much more strongly with PDMS than SBMA. (2) SBMA has plenty of hydrogen bonds, electrostatic interactions, and cage effects with surface waters that lead to a stable surface hydration layer. The hydration layers were believed to form a physical and energetic barrier to prevent protein adsorption on the surface. At last we proposed a possible mechanism of protein adsorption or anti-fouling: the first obligatory step of protein adsorption was the dehydration of both protein and the membrane. After that, protein induced a series of conformation changes to change its surface hydrophobic/hydrophilic properties, charge distributions etc. Then it came to the final stable adsorption state by forming hydrogen bonds, VDW contacts and electrostatic interactions between protein and substrates.关键词：Bio-fouling;Non-fouling material;Lysozyme;Molecular dynamics
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发布时间：2021-03-19 - 摘要：A new hyper-crosslinked resin TAMR was prepared by post-crosslinking of chloromethyl low crosslinking macroporous polystyrene and subsequent chemically modifying with tannic acid. The physicochemical structure of TAMR was elaborately characterized using Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), scanning electron microscopy (SEM) and was further morphologically characterized using BET and BJH methods.The specific surface area of TAMR was about 780.1 m2/g and the micropore specific surface area was about 482.3 m2/g. The content of phenolic hydroxyl group (OH) in TAMR was about 1.87 mmol/g. The adsorption performances and mechanism of TAMR towards phenolic compounds (phenol, p-nitrophenol and p-chlorophenol) were studied through the isotherm adsorption and batch kinetics experiments. The isotherm adsorption results showed that TAMR had good adsorption capabilities to phenol, p-nitrophenol and p-chlorophenol because of the high specific surface area and relatively abundant micropore distribution, as well as the phenolic hydroxyl groups on the surface of TAMR. The adsorption capacities of phenol, p-nitrophenol and p-chlorophenol were 1.43, 2.07 and 2.48 mmol/g at 288 K (c0 was 500 mg/L), respectively. The adsorption of phenolic compounds on TAMR was an exothermic typical physical adsorption process which was in accordance with both Langmuir and Freundlich isotherm equations. The phenolic compounds adsorbed onto TAMR kept constant under acidic pH conditions and descended dramatically when the solution pH turned to alkaline, especially when pH was over their pKa value. The molecular form of phenolic compounds was favorable for the adsorption. Quasi-first kinetic adsorption equation could describe the adsorption dynamics behavior perfectly, which meant inner diffusion of the particles was the major controlling step of adsorption process. The perfect regeneration adsorption performance meant that TAMR could be applied widely for treating of phenolic compounds wastewater.关键词：Hyper-crosslinked resin;Tannic acid;Chemical modification;Adsorption;Phenolic compounds
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发布时间：2021-03-19 - 摘要：A surfactant-encapsulated polyoxometalate complex SEP-PMo was prepared by phosphomolybdic acid (H3PMo12O40, abbreviated as HPMo), via electrostatical interaction between HPMo and N-[12-(4-carboxylphenoxy)dodecyl]-N,N-dimethylammonium bromide (CDDA). The resulting complex was characterized in detail by elemental analysis, thermogravimetric analysis (TGA), as well as FT-IR spectra. SEP-PMo was further complexed with poly(4-vinyl pyridine) (P4VP) via hydrogen bonding interaction to get P4VP(SEP-PMo)n(n=0.01, 0.05, 0.1, 0.3, 0.5 and 1). Mesomorphic phase behaviors of CDDA, SEP-PMo as well as P4VP(SEP-PMo)n were studied by a combination of differential scanning calorimetry (DSC), polarized light microscopy (PLM), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Surfactant CDDA has a bilayer smectic A structure with a layer thickness about 4.8 nm. When increasing the temperature to 140℃, the phase structure turns into a monolayer smectic A structure with a layer thickness around 2.4 nm. SEP-PMo exhibits thermotropic liquid crystal phase behavior induced by microphase separation from organic and inorganic composites. SAXS and TEM studies revealed that SEP-PMo could form lamellar structure with the layer thickness about 2.5 nm, and within the layer PMo has relatively ordered structure. Comparing with the phase structure of P4VP-PMo-n composites, the mesophase structure of SEP-PMo could be partially kept in the hydrogen bonded complex, P4VP(SEP-PMo)n.关键词：Polyoxometalate;Liquid crystals;Surfactant;P4VP
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发布时间：2021-03-19 - 摘要：A series of diblock copolymers MePEG-b-PBYP were firstly synthesized by the ring-opening polymerization of 2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane (BYP) using polyethylene glycol monomethyl ether (MePEG) as the macroinitiator and Sn(Oct)2 as catalyst.Subsequently,the alkyne groups on PBYP blocks were modified with three mercaptans by thiol-yne click reaction to yield polyphosphoester-based diblock copolymer with various pendant functional groups (NH2,COOH and SO3Na).The molecular structures,molecular weights,and molecular weight distributions of the block copolymers were characterized by NMR and GPC analyses.MTT assay indicated that these block copolymers show relatively low cytotoxicity against L929 fibroblast cells.The microgels were prepared through electrostatic interaction between these oppositely-charged polyelectrolytes.The particle size,zeta potential and morphologies of the particles were also analyzed by DLS and TEM techniques.In order to enhance the physical crosslinking,-cyclodextrin (-CD) was added into the system to interact with PEG chain via inclusion complexation,resulting in the formation of stronger crosslinked hydrogels.SEM was utilized to observe the surface morphologies of microgels and hydrogels,XRD was used to analyze the inclusion complexation and rheology test was employed to monitor the gelation kinetics of the hydrogels.These biodegradable hydrogels with good biocompatibility and favorable mechanical properties provide a promising injectable material and have potential applications in the fields of controlled drug delivery and tissue engineering.关键词：Polyphosphoester;Thiol-yne click reaction;Microgel;Hydrogel;-CD
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发布时间：2021-03-19 - 摘要：Using chitosan (CTS) as a model polymer,the feasibility of obtaining aligned ultrafine CTS fibers were demonstrated by employing a small amount of ultrahigh molecular weight poly(ethylene oxide) (PEO) to formulate the solution viscoelasticity,which enables to suppress the electrospinning bending instability to form a pretty long and stable jet (this approach was termed as stable jet electrospinning,SJES).This makes continuous fabrication of aligned ultrafine fibers,as achievable in those traditional fiber forming methods (e.g.,dry spinning or dry-wet spinning),to come into reality.Here,a systematical parameter study is reported on the SJES process including mass ratio of CTS/PEO,applied voltage,collecting distance,coagulation bath and rotating speed of drum.Characterization of the resultant electrospun CTS fibers by SEM,FTIR,WAXD and nano-tensile testing was also performed.The result showed that SJES enabled to produce individual CTS fibers with a diameter of 10 m.The diameters of CTS fibers could be attenuated to ca.3 m by varying applied voltage and stretching speed.The electrospun CTS fibers by SJES were of high mechanical performance,with the measured tensile strength and modulus of (76293)MPa and (116)GPa,respectively.SJES facilitated polymer chain and crystalline orientation,which may have contributed to the significant improvement in the mechanical properties of thus made ultrafine CTS fibers.关键词：Electrospinning;Aligned ultrafine fibers;Chitosan;Crystalline orientation
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发布时间：2021-03-19 - 摘要：Polyphenylene sulfide (PPS) with the melt temperature about 280℃ and low-melting temperature glasses (LMTG) with the soft-temperature (Ts) about 325℃ were used to prepare PPS/LMTG organic-inorganic hybrids by melt compounding above both characteristic temperatures. The surfaces of PPS/LMTG prepared at different processing conditions were observed by scanning electron microscope (SEM). Meanwhile, the mechanical properties for the composites marked as PPS/LMTG300 and PPS/LMTG400 prepared below and above Ts of LMTG respectively were investigated. The results indicate that liquid-liquid melt compounding is feasible in a wide temperature range from 325℃ to 450℃ for the selected composites. The SEM images show that dispersed phase in situ morphologies are influenced significantly by processing temperature, shear time and the mixer rotation speed. During liquid-liquid compounding, the dispersed phase, i.e. LMTG drops, goes through a series of process of deformation, break-up, coalescence and recovery in shearing field, similar to the evolution of dispersed polymer phase in immiscible blends with sea-island structure. Compared with PPS/LMTG300, the size of in situ morphology for LMTG phase in PPS/LMTG400 obtained by liquid-liquid melt compounding is much smaller, leading to weaker interfacial interaction between the filler and matrix. In addition, LMTG particles still have an excellent strengthening effect on PPS/LMTG400 containing 66 wt% inorganic filler since particle dispersion is improved by liquid-liquid compounding.关键词：Polyphenylene sulfide;Low melting-temperature glass;Liquid-liquid melt compounding;Dynamic mechanical analysis;Tension strength
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发布时间：2021-03-19 - 摘要：Intrinsic viscosity and strength of hydrophobic association of hydrophobically associated water-soluble polymers (HAWSP) were investigated in different solvents containing formamide and salt, through the capillary tube method and fluorescence probe technique. Weight-average molecular weight of HAWSP was measured by static light scattering method under suitable solvent conditions that could eliminate the hydrophobic association and polyelectrolyte effect. The experimental results showed that NaCl had the capability of eliminating the polyelectrolyte effect,but NaCl can not destroy hydrophobic association. And NaCl promoted hydrophobic interaction because of increasing the polarity of HAWSP solutions. Macromolecular aggregation would be greater at higher levels of hydrophobe,which explains the observed rise in molecular weight. As a result, the weight-average molecular weight of HAWSP measured in NaCl solvent was not the real molecular weight. However,hydrophobic association can be completely destroyed by formamide. Moleculars of HAWSP dispersed in the formamide solvent,and real molecular weight of HAWSP can be measured. The results showed that weight-average molecular weight of HAWSP can be measured accurately in 50% formamide solvent with 0.2 mol/L NaCl. When hydrophobic association was eliminated completely, the values of weight-average molecular weight were identical with increasing formamide concentration; when the polyelectrolyte effect was removed, altering the salt concentration would not change the results of weight-average molecular weight.关键词：Intrinsic viscosity;Hydrophobic association;Polyelectrolyte effect;Fluorescence probe;Weight-average molecular weight
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发布时间：2021-03-19 - 摘要：Polyaniline is an emerging ammonia sensor material,mainly due to its reversible protonic doping-base dedoping property.Though many factors influence the performance of ammonia sensor,this work focuses on the role of relative humidity (RH) on polyaniline ammonia sensor.For RH from 10% to 80%,the relative sensitivity of polyaniline film on ammonia was enhanced with increasing ammonia concentration when it changed from 10 L/L to 2500 L/L,however,when ammonia concentration was less than 400 L/L,no obvious change in relative sensitivity was observed with various RH.At fixed ammonia concentration,for RH above 40% and ammonia concentration over 500 L/L,fast response was observed while relative sensitivity decreased with the increasing RH,which was due to the increasing formation of NH4OH from the reaction of NH3 and H2O at higher humidity.The NH4OH formation reaction was accelerated and response time was shortened since polyaniline was more easier to be doped by NH4OH,while the protonation of water when RH was over 40% reduced the relative sensitivity.Therefore,RH must be considered as one of the important factors for polyaniline ammonia gas sensor.关键词：Polyaniline;Ammonia sensor;Relative humidity;Relative sensitivity
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发布时间：2021-03-19 - 摘要：5,8-Dibromoanthraquinone-2,3-dicarboxylic acid and the corresponding acid anhydride were designed and prepared through simple and efficient synthetic routes at the first time. Then,a novel electron-deficient molecule N-(1-hexylheptyl)-5,8-dibromoanthraquinone-2,3-dicarboxylic imide was obtained from the imidization. Stille-coupling of this electron-acceptor anthraquinone imide with various electron-rich units gives rise to a series of donor-acceptor conjugated polymers with the aid of computational study. Herein,polymers with a benzodithiophene derivative as the donor unit and 3,4-ethylenedioxythiophene as the bridge unit were obtained with high yields. P2 exhibits intense absorption in the UV-Vis range owing to the intramolecular charge transfer between the donor and acceptor units. The LUMO (lowest unoccupied molecular orbital) levels of polymers are around -3.85 eV. Bulk heterojunction photodetectors were prepared from spin coating owing to their good solubility. The photodetector devices were fabricated with a configuration of ITO/PEDOT:PSS (35 nm)/active layer/bphen (6 nm)/Al (100 nm),in which the active layer comprises a blend of polymer blends with (6,6)-phenyl-C61-butyric acid methyl ester (PC61BM) in a different weight ratio. The photodetector based on P2 exhibited a better photovoltaic response than P1 over the UV-Vis range,with an external quantum efficiency (EQE) of 26% and detectivity of 2.21011 Jones at 505 nm at -4 V biases,when the weight ratio of P2:PC61BM is 1:1.关键词：Anthraquinone imide;Donor-Acceptor polymer;Photodetector;Electron-acceptor
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发布时间：2021-03-19
Research Article
- 摘要：An electrochemical technique involved facile method of cyclic voltammetric oxidation of dopamine to fabricate thickness controllable PDA films (ePDA) was reported. This process was preceded under a neutral environment and in the absence of oxygen. Most importantly, with precisely controlled electrochemical parameters, this dopamine electropolymerization technique can be further combined with bioactive molecules modification via a one-pot strategy to construct functionalized surfaces. By electropolymerization of dopamine in a one-pot mixture with REDV peptide, an endothelial cells (ECs) specific ligand, ECs adhesion enhanced bioactive surface incorporated with REDV was obtained. Ellipsometry and scanning electron microscopy (SEM) confirmed the homogeneous ePDA film fabrication. X-ray photoelectron spectroscopy (XPS) and fluorescence analysis results demonstrated the successful incorporation of REDV peptide into ePDA films (ePDA@REDV). Cells adhesion experiments suggested an excellent activity of incorporated REDV peptide was retained. Furthermore, ECs exhibited improved attachment, spreading and vinculin formation on ePDA@REDV functionalized surface. This dopamine electropolymerization assisted one-pot strategy for rapid construction of bioactive surfaces provides an innovative approach for multifunctional modification of complicated conductive biomaterials and devices.关键词：Electropolymerization;Polydopamine;REDV peptide;One-pot;Endothelial cells
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发布时间：2021-03-19
Research Bulletin
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