SBS和反应性单体本体接枝共聚合机理

以过氧化苯甲酰（ＢＰＯ）为引发剂，ＳＢＳ分别与甲基丙烯酸甲酯（ＭＭＡ）、甲基丙烯酸丁酯（ＢＭＡ）及乙酸乙烯酯（ＶＡＣ）进行本体接枝共聚合。根据均聚物的生成量和聚合物的相态结构，认为ＳＢＳ防与ＭＭＡ（或ＢＭＡ）的反应机理与系山、伊田等的研究结果一致；ＳＢＳ与ＶＡｃ的反应机理是，ＢＰＯ·与ＶＡｃ生成ＰＶＡｃ链自由基，继而向ＳＢＳ主链转移。

Influence of Preparation Conditions on Structural Stability of Ordered Mesoporous Carbons Synthesized by Evaporation-induced Triconstituent Co-assembly Method

Various ordered mesoporous carbons （OMCs） have been prepared by evaporation-induced trieonstituent co-assembly method. Their mesostructural stability under different carbon content, aging time and acidity were conveniently monitored by X-ray diffraction, transmission electron microscopy, and N2 sorption isotherms techniques. The results show mesostruetural stability of OMCs is enhanced as the carbon content increases from 36% to 46%, further increasing carbon content deteriorates the mesostructural stability. Increasing aging time from 0.5 h to 5.0 h make the mesostructural stability go through an optimum （2.0 h） and gradually reduce framework shrinkage of the OMCs. Highly OMCs can only be obtained in the acidity range of 0.2-1.2 mol/L HC1, when the acidity is near the isoelectrie point of silica, the resulting OMCs have the best mesostructure stability. Under the optimum condition, the carbon content of 46%, aging time of 2.0 h, and 0.2 mol/L HCl, the resulting OMCs have the best mesostrueture stability and the highest BET surface areas of 2281 m2/g.

Pyrolysis-Gas Chromatography/Mass Spectrometry for Microstructure and Pyrolysis Pathway of Polyester-Polyether Multiblock Copolymer

The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.

Self-assembly of Asymmetric Dimer Particles in Supported Copolymer Bilayer

Using self-consistent field and density functional theories, we investigate the self-assembly behavior of asymmetric dimer particles in a supported AB block copolymer bilayer. Asymmetric dimer particles are amphiphilic molecules composed by two different spheres. One prefers to A block of copolymers and the other likes B block when they are introduced into the copolymer bilayer. The two layer structure of the dimer particles is formed within the bilayer. Due to the presence of the substrate surface, the symmetry of the two leaflets of the bilayer is broken, which may lead to two different layer structures of dimer particles within each leaflet of the bilayer. With the increasing concentration of the asymmetric dimer particles, in-plane structure of the dimer particles undergoes sparse square, hexagonal, dense square, and cylindrical structures. In a further condensed packing, a bending cylindrical structure comes into being. Here we verify that the entropic effect of copolymers, the enthalpy of the system and the steric repulsion of the dimer particles are three important factors determing the self-assembly of dimer particles within the supported copolymer bilayer.

Enhanced permeation performance of polyether-polyamide block copolymer membranes through incorporating ZIF-8 nanocrystals

Membrane-based CO_2 separation is a promising alternative in terms of energy and environmental issues to other conventional techniques. Polyether-polyamide block copolymer(Pebax) membranes are promising for CO_2 separation because of their excellent selectivity, but limited by their moderate gas permeability. In this study,fresh-prepared zeolitic imidazolate framework-8(ZIF-8) nanocrystals were integrated into the Pebax?1657matrices to form mixed matrix membranes. The resulting membrane exhibits significantly improved CO_2permeability(as high as 300% increase), without the sacrifice of the selectivity, to the pristine polymer membrane. Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices. The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored. Mixed-gas permeation for both CO_2/N_2 and CO_2/CH_4 was also evaluated. The separation performance for CO_2/CH_4 mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound, and thus is technologically attractive for purification of natural gas.

Non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 copolymers:Effect of sebacic acid as a third comonomer

Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.

Adsorption of Diblock Copolymers from Non-selective Solvent: Comparison Between Scheutjens-Fleer Theory and Monte Carlo Simulation

Systematic comparison between computer simulation results and those predicted by Scheutjens-Fleer (SF) self-consistent-field theory is presented for the adsorption of diblock copolymers from a non-selective solvent on attractive surface. It is shown that although SF is a mean-field theory, it can qualitatively describe the adsorption phenomena of diblock copolymers. However, systematic discrepancy between the theory and simulation still exists. The approximations inherited in the mean-field theory such as random mixing inside a layer and the allowance of direct back folding may be responsible to those deviations.

Morphologies of Core-Shell-Cylinder-Forming ABC Star Triblock Copolymers in Nanopores

The self-assembly behavior of ABC star triblock copolymers can lead to a large number of nanostructures. Indeed, many new and interesting structures have already been discovered and proven to be hotspot in soft matter physics research. In this work, we introduce different phase diagrams of core-shell-cylinder-forming ABC star triblock copolymers under different conditions, including in-bulk and pore geometries with different sizes. The relation between the pore size geometries and their corresponding structures are also revealed. The different properties of the surface potential field that significantly affect the self-assembly process of ABC star triblock copolymers are investigated as well.

Morphology of Films of SEBS Triblock Copolymers

Surface morphologies of the films of poly [styrene-b-（ethylene-co-butene）-b-styrene] （SEBS） have been studied by using tapping-mode atomic force microscopy （TM-AFM）. The films of block copolymer were prepared both by spin-coating on mica and by solvent-casting on different solution surfaces. For spin-coating samples, the effect of solution concentration, solvent, and annealing temperature are investigated. It is shown that changing the concentration of the solution makes no difference on the morphology of the film of the block copolymer. The microstructures are quite stable during thermal annealing; only the size of the domains changes toward the equilibrium configuration. However, solvent annealing can notably change the microstructures. When different selective solvents are used for film spin-coating, different morphologies can be obtained and explained by the different solubility parameters of the solvents. As expected, significant different morphologies in the top and the bottom surfaces of the casting films were observed. The images of the top surfaces reveal cylinder microdomains, while those of the bottom surfaces were spherical morphologies.

Synthesis of Mesoporous Chromium Silicates Molecular Sieves in Strong Acidic Media by Assembly of Preformed CrS1 Precursors with Triblock Copolymer

Chromium-incorporated mesoporous silica materials （MCrS） have been successfully prepared in strong acidic media by assembly of preformed CrSI precursors with triblock copolymer of the Pluronic type （P123） by a two steps procedure. Various techniques including XRD, N2 adsorption, FT-IR spectroscopy, diffuse reflectance UV-vis （DRUV-vis） and EPR were employed for the materials characterization. MCrS materials have a hexagonal structure with uniform mesopores and contain Cr（V） and Cr（VI） under low and high Cr content and that the mesoporous walls contain the MFI structure building units.

Effect of polyoxypropylene chain length on the critical micelle concentration of propylene oxide-ethylene oxide block copolymers

In this work, the surface activity of block copolymer nonionic surfactants (RPE) has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A), surface tension at CMC (γCMC). A linear decrease of ln[CMC] vs number of oxypropylene units in copolymer molecule was observed. The change in the work of cohesion per oxypropylene group when passing from molecular into micellar state, calculated from the Shinoda equation, was 0.43kT for the studied compounds.

Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method

Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with polyethersulfone(PES) via a nonsolvent-induced phase separation(NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid)(PMAA) segments, abbreviated as PMAA n–F127–PMAA n,were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectrum, water contact angle, Zeta potential and X-ray photoelectron spectroscopy(XPS). The enrichment of hydrophilic PMAA segments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had signi ficant p H-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low p H values of feed solutions than that at high pH values. The pH-responsive ability of the membranes was enhanced with the increase of the degree of PMAA near-surface coverage.

Large-area nanopatterned graphene for ultrasensitive gas sensing

Chemical vapor deposited （CVD） graphene is nanopatterned using a spherical block copolymer etch mask. The use of spherical rather than cylindrical block copolymers allows homogeneous patterning of cm-scale areas without any substrate surface treatment. Raman spectroscopy was used to study the con- trolled generation of point defects in the graphene lattice with increasing etching time, confirming that alongside the nanomesh patterning, the nanopatterned CVD graphene presents a high defect density between the mesh holes. The nanopatterned samples showed sensitivities for NO2 of more than one order of magnitude higher than for non-patterned graphene. NO2 concentrations as low as 300 ppt were detected with an ultimate detection limit of tens of ppt. This is the smallest value reported so far for non-UV illuminated graphene chemiresistive NO2 gas sensors. The dramatic improvement in the gas sensitivity is believed to be due to the high adsorption site density, thanks to the combination of edge sites and point defect sites. This work opens the possibility of large area fabrication of nanopatterned graphene with extremely high densities of adsorption sites for sensing applications.

Co-delivery of doxorubicin and paclitaxel with linear-dendritic block copolymer for enhanced anti-cancer efficacy

A series of well-defined amphiphilic linear-dendritic block copolymers （telodendrimers, MPEG-b-PAMAM-cholesterol） with 1,2,4 or 8 cholesteryl groups （named as P1, P2, P4, P8, respectively） were synthesized. Their chemical structures were char- acterized with IH NMR and mass spectrum （MALDI-TOF MS）. The telodendrimers could self-assemble into micelles in aqueous solution, and encapsulate chemotherapeutic drug doxorubicin （DOX） and paclitaxel （PTX） for combination therapy. All the telodendrimers could encapsulate DOX with similar capability. However, their drug-loading capability of PTX is in- creased with the increasing number of cholesteryl groups. P8 exhibited much higher PTX loading efficiency than its counter- parts. Thus, P8 was selected for further application of drug delivery in the paper. The drug-loading micellar nanoparticles （NPs） of P8 were spherical in shape and their diameters were less than 150 nm which were determined by dynamic light scattering measurements （DLS） and transmission electron microscope （TEM）. In vitro drug release experiment demonstrated that P8 ex- hibited a controlled release manner for both DOX and PTX, and the two drugs were released simultaneously. In vitro cytotoxi- city experiment further demonstrated that the co-delivery of DOX and PTX in P8 exhibited better anti-cancer efficiency than the delivery systems encapsulated with single drug （DOX or PTX）. This indicates a synergistic effect. The co-delivery system showed potential in future anti-cancer treatment.

Block Copolymer-Templated BiFeO3 Nanoarchitectures Composed of Phase-Pure Crystallites Intermingled with a Continuous Mesoporosity： Effective Visible-Light Photocatalysts？

Herein is reported the soft-templating synthesis of visible-light photoactive bismuth ferrite （BiFeO3） nanoarchitectures in the form of thin fihns using a poly（ethylene-co-butylene）-block-poly（ethylene oxide） diblock copolymer as the structure-directing agent. We establish that （1） the self-assembled materials employed in this work are highly crystalline after annealing at 550 ℃ in air and that （2） neither the bismuth-poor Bi2Fe4O9 phase nor other impurity phases are formed. We further show that there is a distinct restructuring of the high quality cubic pore network of amorphous BiFeO3 during crystallization. This restructuring leads to films with a unique architecture that is composed of anisotropic crystallites intermingled with a continuous mesoporosity. While this article focuses on the characterization of these novel materials by electron microscopy, krypton physisorption, grazing incidence small-angle X-ray scattering, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, UV-vis and Raman spectroscopy, we also examine the photocatalytic properties and show the benefits of the combination of mesoporosity and nanocrystallinity. Templated BiFeO3 thin films （25% porosity） with a direct optical band gap at 2.9 eV exhibit a catalytic activity for the degradation of rhodamine B much better than that of nontemplated samples. We attribute this improvement to the nanoscale porosity, which provides for more available active sites on the photocatalyst.

Polypeptide dendrimers: Self-assembly and drug delivery

Amphiphilic dendritic poly（glutarnic acid）-b-polyphenylalanine copolymers were synthesized using generation 3 dendritic poly（glutamic acid） as the macroinitiator in the ring-opening polymerization of NCA-Phe. The block copolymers self-assembled micelles with polyphenylalanine segments as core and dendritic poly（glutamic acid） segments as shell. The biocompatibility of the micelles was studied. The release of the anticancer drug doxorubicin from the micelles was investigated in vitro. The results showed that the sustaining release of the drug could last for 60 h. The micellar drug release system was efficient in inhibiting the proliferation of HepG2 liver cancer cells, 75% cancer cells were killed under appropriate in vitro incubation.

Efficient perovskite solar cells based on novel three-dimensional TiO2 network architectures

Mesoscopic lead halide perovskite solar cells typically use TiO2 nanoparticle films as the scaffolds for electron-transport pathway and perovskite deposition. Here, we demonstrate that swelling-induced mesoporous block copolymers can be templates for producing three- dimensional TiO2 networks by combining the atomic layer deposition technique. Thickness adjustable TiO2 network is an excellent alternative scaffold material for efficient per- ovskite solar cells. Our best performing cells using such a 270 nm thick template have achieved a high efficiency of 12.5 % with pristine poly-3-hexylthiophene as a hole transport material. The high performance is attributed to the direct transport pathway and high absorption of scaf- folds, small leakage current and largely reduced recombi- nation rate at interfaces. The results show that TiO2 network architecture is a promising scaffold for meso- scopic perovskite solar cells.

Mesoporous CeO_2 nanowires as recycled photocatalysts

Mesoporous CeO2 nanowires(NWs) were synthesized through a facile hydrothermal process by using triblock copolymer F127 as the template.XRD analysis confirmed the cubic phase of the synthesized CeO2 NWs.High-yield one-dimensional NWs with accessible mesopores could be observed from SEM and TEM images,and the surface area of the material was confirmed to be 273 m2 g-1 with pore width distribution of 6.9-13.8 nm.The mesoporous CeO2 NWs could be used as efficient photocatalysts for organic dye degradation under UV light irradiation,which was superior compared with commercial photocatalyst P-25 and commercial CeO2 powders.The NW structure facilitates the recovery of catalyst by sedimentation,leading to the impressive reusability of these mesoporous CeO2 NWs.

Polymers with tertiary amine groups for drug delivery and bioimaging

Over the past decade, biopolymers have gained great interests especially in biomedicine due to their physical properties and/or chemical structures changes in response to external stimuli in a certain time fiarne or at a specific location. Among them, poly（β-amino ester）s, methacrylate-based block copolymers and polypeptide with tertiary amine groups have been extensively studied and exhibit pH sensitive properties due to the protonation of tertiary amine groups. The pH values in normal organs, tissues, and subcellular compartments are always different from those in pathological tissues. These interesting properties allow their applications in a variety of fields ranging from diagnosis and therapeutics of diseases. Here, we review the recent progress of poly（β-amino ester）s, methacrylate-based block copolymers and polypeptide with tertiary amine groups and their applications in drug delivery and bioimaging.

Alkali metal salts doped pluronic block polymers as electron injection/transport layers for high performance polymer light-emitting diodes

A series of alkali metal salts doped pluronic block copolymer F127 were used as electron injection/transport layers (ETLs) for polymer light-emitting diodes with poly[2-(4-(3′,7′-dimethyloctyloxy)-phenyl)-p-phenylenevinylene] (P-PPV) as the emission layer. It was found that the electron transport capability of F127 can be effectively enhanced by doping with alkali metal salts. By using Li2CO3 (15%) doped F127 as ETL, the resulting device exhibited improved performance with a maximum luminous efficiency (LE) of 13.59 cd/A and a maximum brightness of 5529 cd/m2, while the device with undoped F127 as ETL only showed a maximum LE of 8.78 cd/A and a maximum brightness of 2952 cd/m2. The effects of the doping concentration, cations and anions of the alkali metal salts on the performance of the resulting devices were investigated. It was found that most of the alkali metal salt dopants can dramatically enhance the electron transport capability of F127 ETL and the performance of the resulting devices was greatly improved.