最新刊期
卷 ， 期 11 ， 2011
- 摘要：In order to study the structure and the catalytic activity of aliphatic tertiary amines,the ring-opening polymerizations of trimethylene carbonate (TMC) and L-lactide (L-LA) were catalyzed by aliphatic tertiary amines,including triethylamine (TEA),N,N,N',N'-tetramethylethylenediamine (TMEDA),1,1,4,7,7-pentamethyldiethylenetriamine (PMDTA) and 4-(dimethylamino)pyridine (DMAP),using benzyl alcohol as initiator in THF at 55℃.Studies revealed the catalytic activity of these tertiary amines was increased according to the order:TEA TMEDAPMDTA DMAP.The relationships of polymer molecular weight with the conversion of monomer were linear,which were consistent with a living polymerization character.Finally,the plausible polymerization pathway was through an alcohol-activating mechanism.Aliphatic tertiary amines which were abundant in source and cheap in price were suitable for catalyzing the ring-opening bulk polymerization of lactone in low temperature because of their low boiling point,being liquid under ordinary conditions and being easy to get rid of.关键词：Aliphatic tertiary amines;Trimethylene carbonate;L-lactide;Ring-opening polymerization
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发布时间：2021-03-19 - 摘要：Amphiphilic poly(N-isopropylacrylamide) with cholesterol as hydrophobic end group (Chol-PNIPAM) was synthesized through atom transfer radical polymerization (ATRP).The resulted Chol-PNIPAM was characterized with FTIR,1H-NMR and GPC.Simply mixing Chol-PNIPAM with methoxy poly(ethylene glycol) monostearate (mPEG-SA),a mixed micellar system was prepared.The lower critical micellization concentration (CMC) of the mixed micelles was 6.2310-3 g/L for the Chol/SA molar ratio of 0.2,and 1.0010-2 g/L for the Chol/SA molar ratio of 0.5,respectively,which were significantly lower than that of the virgin mPEG-SA or Chol-PNIPAM micelles.Dynamic light scattering (DLS) study showed the composited micelle core was formed by cholesterol of Chol-PNIPAM and the fatty chain of mPEG-SA.The result is similar to the phenomenon that the cell membrane was stabilized by embedding cholesterol into the bilayer phospholipid membrane.DLS study also showed that the thermo-sensitive phase transition temperature expressed in the size change of the mixed micelles was between 33℃ and 35℃.The particle size of Chol-PNIPAM/mPEG-SA micelles with the Chol/SA molar ratio of 0.2 was 13 nm.When temperature was above 35℃,the size increased to 65 nm.For Chol-PNIPAM/mPEG-SA with the Chol/SA molar ratio of 0.5,the particle size changed from 14 nm to 200 nm,and the change was revisable.In contrast,the mPEG-SA micelles did not exhibit any temperature responsiveness,and the Chol-PNIPAM micelle,though thermal responsive,was not stable and large aggregation formed because of the hydrophilic-hydrophobic transition of PNIPAM segment.The results show that the Chol-PNIPAM/mPEG-SA mixed micelles with the properties of higher stability and satisfactory thermo-responsiveness is worth to study further for the use as a drug delivery system.In vitro release study shows that the release behavior of IMC from the drug-loaded micelle was thermo-sensitive and the release rate increases with both the PNIPAM content and temperature.关键词：Mixed micelle;PNIPAAm;Cholesterol;PEG;In vitro release
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发布时间：2021-03-19 -
HYDROXYAPATITE/CHITOSAN COMPOSITE COATINGS ON TITANIUM SURFACES BY PULSED ELECTROCHEMICAL DEPOSITION
摘要：A pulsed electrochemical deposition(ED) method was employed to produce hydroxyapatite(HA)/chitosan(CS) composite coatings on Ti substrates.HA dispersed uniformly in the CS network.There was nano-scale hybridization between HA and CS due to in situ co-precipitation.ED was conducted in the cell that had three electrodes:a Ti plate as the working electrode,a platinum plate as the counter electrode and a saturated calomel electrode(SCE) as the reference electrode.Electrolytes were aqueous solution of 5 mmol/L Ca(NO3)2,3 mmol/L (NH4)2HPO4 and CS aqueous solutions with different concentrations (0.17 g/L,0.33 g/L,0.67 g/L).The coatings were prepared under constant voltage and pulsed voltage modes.The experiment results indicated that the pulsed voltage mode can improve the CS content in the coatings and obtain uniform coatings,compared with the constant voltage mode.The pulsed voltage mode also promoted the interaction between Ca and CS according to XPS analysis.Pulsed voltage affected the morphology of the coatings and improved the efficiency of the deposition.The suitable pulsed voltage was -1.3 V.The concentration of CS in the electrolyte affected the CS content in the coatings and the efficiency of the deposition.The suitable concentration was 33.1 g/L.The antibacterial test indicated that HA/CS coatings had good bactericidal ability.Osteoblasts were cultured on the coatings to evaluate the biocompatibility of coatings and the results indicated that the composite coatings favored the attachment and proliferation of the osteoblasts.The results of present study provided valuable references for the further research in developing composite coatings for biomedical applications.关键词：Pulsed electrochemical deposition;Hydroxyapatite;Chitosan;Composite coatings;Biocompatibility- 50
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发布时间：2021-03-19 - 摘要：The branching atom transfer radical polymerization(ATRP) of styrene has been studied using different divinyl monomers as the branching agent.The divinyl monomers used are triethylene glycol dimethacrylate (tri-EGDMA) with electron-poor double bonds and divinyl benzene (DVB) with electron-rich double bonds.The polymerization kinetics was studied using gas chromatography (GC).The consumption of the pendent double bond was analyzed using proton nuclear magnetic resonance (1H-NMR).The changes in molecular weight and polydispersity of the resulting copolymers,the development of branching and the formation mechanism of branched copolymers throughout the copolymerization and the characteristics of the resulting copolymers were analyzed using triple detection size exclusion chromatography(TD-SEC).As expected,the conversion of styrene(St) is almost the same in the two reaction systems.However,the conversion of tri-EGDMA is increased much faster than that of DVB at the same conversion of styrene,which is due to the interaction of the donor and the acceptor between St and tri-EGDMA.Since St and tri-EGDMA are typical monomers with electron-rich and electron-poor double bonds,respectively,while St and DVB are both monomers of electron-rich double bonds.The interactions of the donor and the acceptor between St and tri-EGDMA lead to high tri-EGDMA consumption rate,high reactivity of the tri-EGDMA pendent double bond,hence high development rate of the branched chain in the St and tri-EGDMA reaction system,high weight content of the branched chain and high molecular weight of the branched chain at the same styrene conversion.The Zimm branching factors of the branched chains at the same molecular weight from two reaction systems are almost the same,suggesting the branching agents do not affect the branch architecture of the obtained copolymers seriously.关键词：Branched polymer;Atom transfer radical polymerization;Triethylene glycol dimethacrylate;Divinyl benzene
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发布时间：2021-03-19 - 摘要：A series of 3-(trimethoxysilyl)propyl methacrylate(MPS) modified silica/poly(methyl methacrylate) composites(SiO2/PMMA) with different silica content and PMMA grafting percentage were prepared via in situ bulk polymerization.The grafting and crosslinking status of the composites were analyzed by Soxhlet extraction,and three parts were found:PMMA solution with free silica in extract solvent,PMMA film with connected silica on the inner wall of filter bag,PMMA gel with crosslinked silica in the inner of filter bag.The distribution of PMMA and silica in the above three parts were obviously affected by the silica content and PMMA grafting percentage.Based on the etching of silica by HF,the PMMA grafting percentage,the molecular weight of grafted PMMA and the grafting density of PMMA chain on different silica particles were measured by gravimetric method and gel permeation chromatography (GPC).The grafting percentage,molecular weight and grafting density of PMMA in gel were more than those in film,and the grafting density of PMMA chain both in gel and in film were close with the one of MPS in silica/MMA dispersion.The above phenomena can be attributed to the grafting of PMMA from the anchored MPS on silica surface and the chemical bonding between the PMMA chains grafted on different silica.Especially,in the case of higher silica content and higher MPS coupling amount,a three-dimensional crosslinked structure with silica as crosslinking point can be easily formed in the part and even in the whole of the SiO2/PMMA composite.The regulation to the grafting and crosslinking structure was of benefit to improving the composites properties,especially to the dispersibility of the accumulated silica on the melting shear field.关键词：Nanosilica particle;Poly(methyl methacrylate);Grafting;Crosslinking;Soxhlet extraction
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发布时间：2021-03-19 - 摘要：Electrospinning technique was employed to prepare molecularly imprinted polyethersulfone (PES) nanofiber membranes for the recognition and binding of bisphenol A (BPA).The PES was used as functional polymer to provide functional groups that interact with the template during the electrospinning process.The template was removed to afford binding sites in the nanofiber membranes that are capable of selectively rebinding the target molecule.Effects of the electrospinning conditions such as template amounts in PES solution,electrospinning voltage and solvent on the imprinting efficiency of nanofiber membranes were investigated.The recognition experiments with the molecularly imprinted nanofibers (MINFs) showed that 10 wt% BPA MINFs had higher binding ability to the BPA than the nonimprinted nanofibers (NINFs).Competitive binding experiment showed that 10 wt% BPA MINFs had high selectivity to BPA in the presence of hydroquinone (HQ),resorcinol (RSO) or phenol,but NINFs had low selectivity to BPA in the presence of bis-(4-hydroxyphenyl) methane (BPF) or 4-tert-butylphenol (TBP).Scatchard analysis and two-site binding model indicated that MINFs had two types of binding sites,namely specific and non-specific binding sites,and had high equilibrium binding constants of the specific binding sites and apparent maximum numbers of binding sites for BPA.The binding kinetics of MINFs was also studied.关键词：Molecularly imprinted nanofiber membranes;Electrospinning;Polyethersulfone;Bisphenol A;Molecular recognition
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发布时间：2021-03-19 - 摘要：A semicrystalline polyimide was synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride(s-BPDA)/1,3-bis-(4-aminophenoxy)benzene(TPER)/phthalic anhydride(PA).According to the crystallization exothermic peaks obtained from differential scanning calorimetry (DSC)when cooling from melt at 2,5,10,20 K/min, respectively, the method of Jeziorny,Ozawa and an approach proposed by MO Zhishen were applied to study the non-isothermal crystallization behaviour of this polyimide.The results suggested that s-BPDA/TPER/PA was a very special system, the onset crystallization temperatures were almost the same at different cooling rates.The apparent Avrami exponent n obtained by the Jeziorny method was 2.4 and then changed to 3.5 when cooling rate reached 20 K/min, indicating the mechanism of nucleation or the way of growth have changed.Besides, the kinetic parameter Zc increased with the increase of the cooling rate.Whereas deviations and fluctuations occurred in the later stage due to the secondary crystallization.The Ozawa method was also limited in obtaining the reliable kinetic parameters because of the substantial curvatures in the Ozawa plots.However, the approach proposed by Mo Zhishen appeared applicable due to the better linear relation, according to the new parameter a , the relationship between Ozawa exponent m and apparent Avrami exponent n was confirmed (n/m =1.3)and exact values of m were obtained.Finally, Kissinger method was used to get the value of the crystallization activation energy E, about -936 kJ/mol, which meant a fast nucleation rate of this system.关键词：Crystalline;Polyimide;Non-isothermal crystallization kinetics
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发布时间：2021-03-19 - 摘要：The HDPE microporous membranes were obtained by a melt-extrusion,annealing,cold stretching,hot stretching and heat setting method.The effect of roller rates and roller temperatures on the structure of the lamellae and the HDPE stretched microporous membranes was characterized by dynamic rheology,FTIR,DSC,SEM and other characterization methods.The results show that the molecular weight,molecular weight distribution and the relaxation time of the HDPE resin used in this experiment can meet the requirements of the present processing conditions for obtaining precursor films with arranged lamellar structure of larger lamellar orientation.Under the same roller temperature,the lamellar orientation of the unannealed and annealed precursor films increases,the lamellar thickness decreases,the micropores distribution regions of the microporous membranes increase and the micropores are more uniform with the roller rates increasing.The lamellar structures arrange more regularly when the roller temperature is 90℃ under the same roller rate,it is a perfect roller temperature to prepare large lamellar orientation precursor films for the resin used in this experiment.Under roller temperature of 90℃,the precursor film with the maximal lamellar orientation,the thinnest lamellar thickness and the narrower lamellar thickness distribution can be obtained,and the structures of the micropore and the micropore distribution are more uniform.关键词：High-density polyethylene(HDPE);Microporous membranes;Lamellar orientation;Lamellar thickness
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发布时间：2021-03-19 - 摘要：Polyaniline(PANI) was synthesized by chemical polymerization,and coated on the flexible stainless wire,and then a flexible reflective electrochromic device(ECD) based on PANI was successfully assembled.The electrochromic devices were measured in different fixed voltages,and scanned by the ultraviolet spectrometer,obtaining a UV-Visible light total reflectance spectrum.It was found the comparatively appropriate voltages for devices were +0.7 V and -0.6 V.The effects of the PANI content on the working electrode,the amount of the electrolyte layer and the amount of ion storage layer on the reverse electrode on the performance of electrochromic devices were studied.The results show that the inherent green of the emeraldine salt could affect the color characteristic of the device with the increase of the amount of PANI on the working electrode,making the light reflection of the device reduced. The reflectivity of the device generally increased first and then decreased with the increase of the amount of the electrolyte layer.The reflectivity of the device increased with the increase of the amount of ion storage layer on the reverse electrode and also the doped or dedoped level of the PANI on the working electrode would increase,and also the reflectible features would be more obvious.关键词：Polyaniline;Flexible reflective electrochromic device;UV-Visible spectrum
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发布时间：2021-03-19 - 摘要：In order to overcome the shortcomings of the conventional extrusion technologies and to prepare polyethylene(PE) pipes with higher performances,our research group designed and manufactured a novel rotation extrusion processing system.The effect of mandrel and die opposite rotation extrusion on PE pipe's microstructure and resistance to slow crack growth was studied.The experimental results showed that when the mandrel and die rotated in the opposite directions during the extrusion process of PE pipes,apart from the axial stress,the pipes were also subjected to the hoop stress,both of which could set up a tangential stress relative to the axial direction,so as to induce the shish-kebab crystal direction deviate from the axial direction.When a double cooling mode of both inner and outer walls was introduced into rotation extrusion,the relaxation of the oriented molecule could be slowed down and the shish-kebab structure in the PE pipe could be fixed.As a result,the PE pipe with better resistance to slow crack growth was prepared.Compared to the PE pipe produced by the conventional extrusion,the crack initiation time of the PE pipe manufactured by the novel method increased by 204% from 27 h to 82 h.关键词：Polyethylene pipe;Rotation extrusion;Slow crack growth;Stress;Temperature
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发布时间：2021-03-19 - 摘要：The statistical properties of systems composed of polymer brushes and magnetic nanoparticles placed in a magnetic field are studied by means of Monte Carlo simulation.The direction of the magnetic field is perpendicular to the substrate plane.Polymer brushes and magnetic nanoparticles are attractive to each other.The average heights of polymer brushes depend not only on the strength of applied magnetic field,but also on the brush grafting density,chain length and magnetic nanoparticle concentration.The applied magnetic field influences the arrangement of magnetic nanoparticles,and in turn the permutation of magnetic nanoparticles affects the spatial distribution of brush monomers.When the strength of the magnetic field increases,the average height of polymer brushes increases accordingly,because orientations of the magnetic moments of nanoparticles must be along the magnetic field direction.At the same time,the chain length,the grafting density of polymer brushes and the nanoparticle concentration also have an effect on the properties of the magnetic nanoparticles,such as the magnetic nanoparticles distribution,magnetic susceptibility and pair correlation functions.Our results are in agreement with the experimental ones,and this investigation can provide some insights into statistical properties of magnetic nanoparticle-loaded brushes induced by external magnetic field.关键词：Monte Carlo simulation;Polymer brush;Magnetic nanoparticle;External magnetic field
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发布时间：2021-03-19 - 摘要：Electrical percolation and dynamic rheological behavior of vapor grown carbon fiber (VGCF) filled polystyrene (PS) prepared at different processing conditions have been studied.Low-shear mixing condition facilitated formation of filler network,and as a result,resulted in composites with low percolation threshold and low volume resistivity above threshold.On the other hand,the description of the rheological behaviors of VGCF filled PS was achieved by fitting using the two phase model proposed by the authors.The results revealed that,at low rotation rate and short time mixing conditions (30 r/min,5 min),the composites can be characterized by high values of Af as well as characteristic moduli (Gf1 and Gf0) of the filler phase.Moreover,the processing-microstructure-properties relationship of VGCF filled PS was established.Increasing rotation speed from 30 r/min to 120 r/min and mixing time from 5 min to 10 min led to better VGCF dispersion,poorer electrical conductivities and lower characteristic moduli for composites with filler content above percolation threshold.It is suggested that the two phase model proposed by authors is a good probe of the state of the filler microstructure.关键词：Vapor grown carbon fiber;Polystyrene;Dynamic rheological behavior;Mixing conditions;Electrical percolation
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发布时间：2021-03-19 - 摘要：A series of mesogen-jacketed liquid crystalline polymers, poly[2,5-(4'-alkoxybi-phenyloxycarbonyl) styrene] (PnCbiPCS,n = 4, 6, 8, 10, 14) with long mesogenic side chains, were prepared by atom transfer radical polymerization (ATRP). Molecular weights and molecular weight distributions of the polymers were measured by gel permeation chromatography (GPC). The liquid crystalline (LC) behavior was studied by a combination of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy (PLM), one-dimensional (1D) and two-dimensional (2D) wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). All the polymers had good thermal stablility and exhibited stable LC properties, and no isotropization temperatures were observed before the onset temperatures of thermal decomposition. 1D SAXS and WAXD studies revealed that PnCbiPCS could form smectic structures with the long mesogenic side chains aligned parallel to each other. The d -spacings increased with increasing aliphatic tails. 2D WAXD results showed that the sheared samples exhibited Smectic A structures with the layer normal perpendicular to the shear direction. Comparing with the results of poly{2,5-bis[(para-substituted phenyl)oxycarbonyl]styrene}s, one may indicate that the length of the mesogenic group is crucial in determining the LC structure.关键词：Mesogen-jacketed liquid crystalline polymer;Long side chain;Smectic A phase
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发布时间：2021-03-19 - 摘要：Self-assembly of supramolecular AB diblock copolymer/C homopolymer mixtures in selective solvents was examined by real-space self-consistent field theory.The non-covalent bond is formed between the free end of hydrophobic B block of amphiphilic AB diblock copolymer and one end of hydrophobic C homopolymer,and thereby the mixtures consist of unbonded AB diblock copolymers,unbonded C homopolymers and supramolecular ABC triblock copolymers.The constitutions of the mixtures are dependent on the non-covalent bonding strength and the initial AB/C mixing ratio,which are essential to the morphologies of the self-assembled micelles.The AB diblock copolymer/C homopolymer mixtures are self-assembled into a variety of micelles such as core-shell-corona micelles and wormlike micelles in selective solvents.With increasing the bonding strength,the volume fraction of supramolecular ABC triblock copolymers increases,and that of unbonded AB diblock copolymers and C homopolymers decreases.In this process,transitions from core-shell-corona micelles to wormlike micelles were observed.In the core-shell-corona micelles,the bonded C homopolymers are distributed at the hydrophobic/hydrophilic interface,while the unbonded C homopolymers are dispersed in solvents due to their weak hydrophobic property.In the wormlike micelles,most bonded C homopolymers localize between two cores in one micelle,while the unbonded C homopolymers transit to the center of C domains.With increasing the volume fraction of homopolymers,the volume fraction of supramolecular ABC triblock copolymers increases to a maximum and then decreases.The morphological transitions of these micelles were also observed as a function of the volume fraction of homopolymers.The work provided an insight into the effect of non-covalent bonds on the morphology of supramolecular micelles.关键词：Non-covalent bond;Self-consistent field theory;Supramolecule;Micelle
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发布时间：2021-03-19 - 摘要：In order to fabricate a high performance silk fiber/fiboin composite,both effects of LiBr pretreatment and methanol post treatment on the interface compatibility between the silk fiber and the silk fibroin matrix were studied in this article.The mechanical properties,structure and morphology of the silk fiber/fibroin composite were investigated via tensile test,X-ray diffraction (XRD) and scanning electron microscopy (SEM),etc.The results of tensile test demonstrated that the optimized pretreatment method was achieved by employing 6 mol L-1 LiBr aqueous solution on aligned silk fibers for 10 min.Under such pretreatment,the longitudinal tensile stress,elongation at break and breaking energy of the silk fiber/fibroin composite with a silk amount of 20 wt% were 142 MPa,23.5% and 18.6 kJ kg-1,respectively.After methanol post treatment,the interface adhesions of the silk fiber/fibroin composite were further enhanced as compared to the untreated ones.The transverse tensile stress and elongation at break were 46 MPa (versus 20 MPa) and 2.4% (versus 1.3%),respectively.Besides,SEM images of the fracture section of silk fiber/fibroin composites in the directions parallel and perpendicular to the fiber array also showed that the compatibility between the silk fiber and the silk fibroin matrix was improved after both treatments.关键词：Animal silk;Secondary structure;Fiber modification
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发布时间：2021-03-19 - 摘要：Diels-Alder (DA) reaction between N-phenyl maleimide and the pendant furan ring of the CO2 and furfuryl glycidyl ether copolymer (PFGEC) was employed for stabilization of PFGEC by reducing the amount of furan ring and introducing bulky groups into PFGEC.The stability of the product was enhanced by increasing the cyclization degree,the PFGEC with cyclization degree above 70% was air stable.Optimal reaction conditions were obtained,taking the N-phenyl maleimide as an example,cyclization degree as high as 84.1% was realized when the DA reaction was carried out in dimethyl carbonate at 60℃ for 24 h with molar ratio of N-phenyl maleimide to furan ring of 3∶1. The DA reaction was endothermal reaction,raising reaction temperature generally can raise cyclization degree,however,DA reaction was also a reversible process,when the temperature was high enough,reverse reaction (r-DA) existed,e.g.,when the DA product of PFGEC with cyclization degree of 72.1% was heated in dimethyl sulfoixde solution at 100℃ for 10 min,the cyclization degree decreased to 40.4%,indicating that the r-DA reaction proceeded quite fast at temperatures above 100℃.关键词：Carbon dioxide;Furfuryl glycidyl ether;Aliphatic polycarbonate;Diels-Alder reaction
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发布时间：2021-03-19 - 摘要：A photoaffinity labeling molecule,4-azidobenzoic acid,was synthesized and introduced into P(LA-co-DHP) to form a photoactive copolymer P(LA-co-DAP).Tests showed that proteins could be immobilized on the polymer fibers of P(LA-co-DAP) within 5 min through a photoaffinity reaction.This suggested potential applications of photoaffinity coupling in protein immobilization and protein detection.Furthermore,PEG and 4-azidobenzoic acid were reacted in solution under UV irradiation to achieve the modification on PEG chains.The PEG molecules assembled on gold surface were reacted also with 4-azidobenzoic acid under UV irradiation.BSA adsorption test by FT-SPR showed that the 4-azidobenzoic acid moieties were successfully attached to the PEG segments so that the protein adsorption ability of the PEG surface was changed.In this way,functional groups likePhCOOH were introduced onto PEG chains in a convenient and quick manner.This would offer a new method to achieve the modification of the polymers lacking of functional groups.关键词：Photoaffinity labeling;Photoactive polymer;Protein immobilization;PEG modification
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发布时间：2021-03-19 - 摘要：1,6-Bis(hydroxyisopropyl urethane)hexane(BPU) was prepared by non-ioscyanide route from propylene carbonate and 1,6-hexanediamine,whose molecular weight was 320. Blends of biodegradable poly(propylene carbonate)(PPC) and BPU were prepared by melt blending.BPU as modifier to PPC was found to be miscible with PPC,and the thermal properties of the PPC/BPU blends were evaluated by differential scanning calorimetry(DSC) and thermogravimetry analysis(TGA).The thermal stability of the blends was significantly improved compared with pure PPC,a 24~33℃ increase in Td, 5%was observed.Toughening PPC was also realized,when the BPU loading was 15 wt%,the maximum of elongation at break of the blends could reach 53.4%,increased to four times of that of pure PPC,accompanied by the relatively high mechanical strength and modulus.When the content of the plasticizer was less than 10 wt%,reinforcing and toughening of PPC were achieved simultaneously.Shear deformation as well as crazing observed in the scanning electron microscopy(SEM) images of the blends provided good evidence for the toughening mechanism of PPC.关键词：Poly(propylene carbonate);Toughening;Reinforcing;Urethane compound
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发布时间：2021-03-19 - 摘要：Self-assembly of symmetric diblock copolymer AB/homopolymer A or C blends confined in spherical nanopores is studied by using a simulated annealing method.Three kinds of blends with different homopolymer chain lengths are investigated.Simulation results show that the self-assembly behavior of the blends depends on the content of the homopolymer,the chain length of the homopolymer,the degree of confinement (characterized by D/L0,where D is the diameter of the spherical nanopore and L0 is the period of the bulk lamellar phase of symmetric diblock copolymer),and the interaction strength between A-C monomers.With the variation of the content of homopolymer and the degree of confinement,the blends exhibit a variety of morphologies and morphological transitions.The observed morphologies include onion-like structures (with both concentric lamellae and nonconcentric lamellae),cage-like structures,deformed dome-like structures,helices or stacked toroids,a disk-like layer and spherical structures.Furthermore,the obtained simulation results also show that both the chain length of the homopolymer and the A-C interaction strength have a large effect on the compatibility of the blends.When the A-C interaction strength is relatively weak,the shorter the chain length of homopolymer,the better the compatibility of the blend,and the corresponding structures occur at a slightly smaller value for the homopolymer content.When the interaction strength between the A-C monomers is strong enough,the effects caused by homopolymer chain length become less pronounced and eventually disappear.In this case,the blend has a good compatibility.The simulation results are consistent with recent experimental results of similar systems.关键词：Confinement;Simulated annealing;Diblock copolymers;Blends;Self-assembly
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发布时间：2021-03-19
Research Article
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