最新刊期
卷 ， 期 5 ， 2003
- 摘要：A new method to prepare functional polymeric materials was introduced．The materials were manufactured by using supramolecular blocks other than monomers．The supramolecular block,which is an assembly of many same kinds of molecules or different kinds of molecules and particles,can show unique properties different from its original molecule or particle．As an example,a supramolecular luminescent block was prepared by assembly of organic luminescent molecules of (4-methacryloyloxy) trans-stilbenyltrimethylammonium bromide (MSTAB) with semiconductor nanoparticles of CdSe．CdSe nanoparticle is as a core and MSTAB as shell．The block showed a very high increase in photoluminescence intensity of CdSe nanoparticles. A composite material with unique optical properties and good compatibility of two different kinds of phases was obtained by “polymerization” of the blocks．
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发布时间：2021-03-19
Rapid Communications
- 摘要：This review describes four methods for functionalizing vinyl polymers with photo-labile S2CNEt2 as ω-end groups．The normal atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) with a p-toluenesulfonyl chloride／Cu(S2CNEt2)／bpy initiation system was performed regardless of the original feed ratio of monomer／initiator,reaction temperature or solvent polarity. In conjunction with 2,2′-bipyridine (bpy),Cu(S2CNEt2)catalyzed the BPO-initiated radical polymerization of MMA in bulk．The reverse ATRP of MMA and styrene (St) with the AIBN or BPO initiator could be successfully carried out in the presence of Cu(S2CNEt2)Cl／bpy complex．S2CNEt2 groups were demonstrated to ω- end-cap the obtained polymeric chains via the pseudo-halogen transfer reaction between the active and dormant species．Photo-polymerization of vinyl monomers under UV irradiation initiated by the resulting PMMA progressed at ambient temperature yielding extended PMMA and PMMA-b-PSt copolymers．Well-defined extended PMMA could be produced with the obtained PMMA and CuCl／bpy complex via the normal ATRP procedure.
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发布时间：2021-03-19
Feature Articles
- 摘要：A novel polyelectrolyte (PBANT-AC) functionalized with branched electron donating-accepting azobenzene chromophores has been synthesized through post-polymerization azo coupling reaction and characterized by 1H-NMR,FTIR and UV-Vis spectrometry．The degree of functionalization (DF) of PBANT-AC was 17％ measured by elemental analysis．The degree of polymerization and its distribution were determined by GPC to be Xn=588 with a polydispersion index 1.3．A glass transition temperature of 139℃ was observed from DSC thermogram．H-Aggregation of azo chromophores of PBANT-AC in H2O-THF mixed solvent was detected from UV-Vis spectra and controlled by the ratio of VTHF／VH2O. The H-aggregates in water-tetrahydrofuran mixture were successfully fabricated into self-assembled multilayers with poly (diallydimethylammonium cloride) by an electrostatic layer-by-layer process．Birefringence and dichroism were optically induced in the self-assembled films under the irradiation of a polarized Ar+ laser beam at 488 μm．The resulting dichroism was easily detected from UV-Vis spectra and exhibited long-term stability．The orientational order parameter obtained was 0.05 for the film. Upon irradiation,the H-aggregates of azo chromophores were changed to ‘isolated’ form after the cis-trans isomerization．
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发布时间：2021-03-19 - 摘要：Submicron polystyrene／magnetite (PS／Fe3O4) composite microspheres were prepared by miniemulsion polymerization by using three kinds of low molecular weight polymer,Disperbyk-106,Disperbyk-108 and Disperbyk-111,as dispersant for magnetite particles and styrene．The effects of dispersants on the miniemulsion polymerization were discussed in detail,which showed that the addition of dispersant had a crucial effect on the preparation of the composite microspheres．Disperbyk-106,which contains both acid and basic groups,has a better effect on the improvement of the interface between magnetite particles and styrene．X-ray powder diffraction (XRD),thermogravimetric analysis (TGA) and transmission electron microscopy (TEM) were conducted to character the magnetite particles and PS/Fe3O4 composite microspheres．The average size of the composite microspheres is 340 nm and the magnetite content of the composite microspheres is around 8％．The XRD patterns showed that the magnetite particles preserve their crystal structure during the miniemulsion polymerization．The TEM observation revealed that magnetite particles distributed unevenly in the composite microspheres and there were some defects on the microspheres where magnetite particles agglomerated．
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发布时间：2021-03-19 - 摘要：A series of ethylene-acrylic acid copolymers either isothermally crystallized or melt-quenched were studied by 13C CP／MAS and variable-temperature 1H wide-line NMR spectroscopy,with the emphasis on the mobility of the noncrystalline region．It is found that with the increase of the comonomer (acrylic acid) content,the chain mobility of the noncrystalline region decreases,while the content of the noncrystalline ethylene segments increases．Such an extraordinary observation can be explained by the fact that the hydrogen bonds formed between the carboxyl groups in the noncrystalline region increases with increasing the acrylic acid content．An indirect measurement of 1H spin-spin relaxation time by employing a modified 13C CP／MAS pulse sequence suggests that the mobility of the noncrystalline ethylene segments is greatly restricted by the hydrogen bonding interactions．
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发布时间：2021-03-19 - 摘要：A new kind of water-soluble asymmetric hyperbranched poly(amide-ester)s was synthesized by direct polycondensation of benzene-1,2,4-tricarbonylic acid-1,2-anhydride (BTAA) and diethanolamine (DEA) via pseudo-divergent or one-step approach．The terminal groups of the hyperbranched polymer can be controlled by the feed molar ratio of BTAA to DEA. The resulting hyperbanched poly(amide-ester) was characterized by FTIR spectra,1H-NMR spectra,and TGA．No gelation was observed when the feed molar ratio of BTAA to DEA was higher than 2.04 in one step approach,while gelation did occur when the ratio was lower than 2．In pseudo-divergent approach,it was not necessary to separate the obtained oligomers or macromolecules in each step,and hyperbranched polymers with high molecular weight were prepared．Compared with the divergent approach utilized in the synthesis of dendrimers,the pseudo-divergent approach is much simpler and more convenient,which might be useful in the large-scale fabrication of highly branched polymers．
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发布时间：2021-03-19 - 摘要：Waterborne polyurethanes (WPUs) were synthesized by self-emulsification. The WPU was copolymerized with methyl methacrylate (MMA) by emulsion polymerization．The micelle diameters of WPUs and the copolymers were measured by dynamic light scattering method,and the particle morphology was determined by TEM．The results showed that the micelle diameter greatly depended on the component of diol in the WPU’s main-chain,and the micelle diameter composing hydrophilic diol was bigger than that composing hydrophobic diol．With the increase of the flexibility of the side-chain and the rigidity of the main-chain in WPUs,the WPU particles exhibited a shell-core structure.
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发布时间：2021-03-19 - 摘要：The self-interference flow (SIF) in the cavity can be formed by two streams of melt flow injected through a new type mold gate,which consists of two orifices sharing with the same runner,the two streams of melt are superposed in the direction parallel to injection,and collide with each other in the direction perpendicular to injection leading to a crosswise flowing. The interactions between the two streams of flow undoubtedly have an influence on the morphology of the solid stale. The effect of SIF on orientation degree of injection molded polypropylene (PP) samples was investigated．The macromolecular chain orientation in the amorphous state of SIF and CFP (conventional flow process) PP samples was tested by the use of a heat-shrinkage method. The results showed that the chain orientation degree in the SIF samples was lower than that in the CFP one. Transmission X-ray diffraction analysis showed that high crystal orientation occured in the shear layer for both samples,and the SIF sample exhibited a lower orientation degree of the crystal (040) planes as compared with the CFP sample.
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发布时间：2021-03-19 - 摘要：Koniac glucomannan (KGM) is a natural polymer from a plant．It possesses excellent biodegradability,biocompatibility and many unique physiological and pharmacological functions．In this work the effects of various factors (i．e,temperatures,pH,medium) on the activity of β-mannanase was firstly studied．The results show that β-mannanase possesses high activity in the aqueous medium (pH 9.4) containing enthanol less than 5％ (V／V) at about 50℃,and basically lose its activity in the medium with pH lower than 7.0 or containing enthanol more than 20％ (V／V),or at temperatures lower than 30℃．Based on these results,the degradation reaction of KGM catalyzed by β-mannanase and its affecting factors were investigated,and a series of KGM samples with different molecular weights was prepared by adjusting the reaction conditions．Moreover,the intrinsic viscosity ([η]) and the weight-average molecular weight (Mw) of the degraded KGM products were measured,obtaining the following equation：[η] =5.06×10-4 Mw0.754. This work makes it possible to realize controllable degradation of KGM by means of an enzyme-catalyzed reaction,thus laying a solid experimental and theoretical foundation for further studying the structure and properties of KGM and its derivatives,and developing new application fields of them．
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发布时间：2021-03-19 - 摘要：OREC (organic rectorite clay)/TPUR(thermoplastic polyurethane) nanocomposites were prepared via melt blending．There were four temperature ranges in the extruder．The temperature was 120℃ at the extruder head,and was 130℃,140℃ and 120℃ in the former,middle and back parts,respectively．OREC was prepared with natural rectorite and dodecanic quaternary ammonium salt through ion-exchange．The nanoscale dispersibility of the OREC layers in the TPUR matrix was revealed by using transmission electron microscopy (TEM). The thermodynamic mechanical analysis (DMA),thermogravimeric analysis (TG),oil-resistant and hot air aging of nanocomposites were also measured. The results showed that the largest storage modulus is 7 times more than that of pure TPUR’s,and the largest loss moduli is 4 times more than that of pure TPUR’s．The other thermal properties of the composites have been enhanced as compared with those of the TPUR matrix due to the well-dispersed OREC layered particles in the OREC／TPUR nanocomposites．When the content of OREC is 2％,the initial degradation temperature of the composite is 15℃ higher than that of the pure TPUR,and the ratio of the residual tensile strength to the original strength is over 86％ after oil treatment for 168 h,or air aging at 120℃ for 72 h．
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发布时间：2021-03-19 - 摘要：A novel biporous spherical matrix of poly (glycidyl methacrylate-co-ethylene dimethacrylate) was prepared by suspension polymerization with superfine granules of calcium carbonate as solid porogenic agent and cyclohexanol plus dodecanol as solvent porogenic agents．After being functionalzed with diethylamine,the matrix (denoted as matrix A) was used as an anion exchanger for protein adsorption．The types and concentration of dispersing agents,the amount of calcium carbonate and solvent porogenic agents,as well as cross-linking agents for the preparation of the matrix had been optimized．It was found that in matrix A the macropores(＞180 nm) took 37.9％ of all the pore volume,while in the beads(matrix B) prepared with only solvent porogenic agents 86.8％ of the pore volume was in the range 4 ～ 180 nm．Due to the presence of the macropores,convective flow occurred through matrix A in chromatography,leading to a high dynamic capacity up to 51.6 mg·g-1 (wet resin) at a flow rate as high as 25 cm·min-1,nearly 4 times higher than that of matrix B. Moreover,the column of mattrix A showed much lower backpressure than that of matrix B. These results indicated the potential application of the biporous matrix in high-speed chromatography for protein separation.
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发布时间：2021-03-19 - 摘要：Poly (ε-caprolactone)s (PCLs) with different molecular weight were cross-linked by γ-radiation．The radiation crosslinking feature was examined by Soxhlet extractor with toluene and analyzed by using the Charlesby-Pinner equation．The crosslinking degree is related to molecular weight and radiation dose,and the relation between the sol fraction and the radiation dose follows the Charlesby-Pinner equation．Radiation may cause a drop of tensile strength and elongation for all the samples d．The DSC diagrams demonstrated that radiation caused an increase of crystallinity and a decrease of melting temperature of PCL crystals．The DMA analysis indicated that radiation crosslinking raised heat deformation temperature of PCL and caused a rubbery state after the melting of PCL crystals．The shape memory results indicated that only those specimens that had a sufficiently high cross-linking degree (gelcontent is higher than about 15％) were able to show the typical shape memory effect,a large recoverable strain and a high final recovery rate．The response temperature of the recovery effect (about 55℃) was related to the melting point of the samples．The PCL shape memory polymer was characterized by its low recovery temperature and large recovery deformation．
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发布时间：2021-03-19 - 摘要：A polymerization system,which contains inter- and intramolecular reactions,was designed on the basis of the random coil type morphology of macromolecules in solutions．The polytetramethylene glycol,4,4′-diphenylmethane diisocyanate and hexanediamine were used to synthesize the soluble microgels in concentrated solutions successfully．Through varying the use level of the extender i．e．hexanediamine,a series of samples were obtained,namely 1200H-X,where 1200 stands for the molecular weight of soft segments,H stands for the extender and X is the ratio of the number of hydrogen of hexanediamine and that of end groups of the oligomer (from scheme 1). In our system two kinds of functional groups that can react with each other located in the same macromolecular chain,resulting in the existence of inter- and intramolecular reactions,which were a pair of competitive reactions．In the presence of the intramolecular reaction the intermolecular reaction was prevented from unlimited development,so the cross-linking process was controlled,producing the soluble and fusible microgels i．e．cross-linked macromolecules instead of cross-linked polymer macrogels．By using the technique of dynamic light scattering,the molecular dimensions of the samples in solution were measured at different concentrations,showing a sharp distinction of solution behavior between this kind of cross-linked macromolecules and other macromolecules such as the linear ones．It was found that this kind of macromolecules possessed cross-linked structure,which was affected by the use level of the extender：the less the extender was used,the more compact the cross-linked structure was. In solutions these macromolecules preferred to form molecular clusters. The formation and disassociation of molecular clusters was off balance,and the solution concentration had influence on the size of the molecular clusters.
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发布时间：2021-03-19 - 摘要：Poly(butyl cyanoacrylate) (PBCA) nanocapsules with an aqueous core containing bovine serum albumin (BSA) were prepared by interfacial polymerization in a W／O emulsion．The nanocapsule sizes and their distribution were measured by laser scattering technique and transmission electron micrography．The change of Zeta potential,encapsulation efficiency,drug loading and in vitro release of nanocapsules were investigated using BSA as a model drug. The experimental results showed that nanocapsules were approximately 200 nm in diameters,0.226 in polydispersity. Encapsulation efficiency and drug loading were depended on the initial BSA concentration in aqueous phase. When the concentration was 0.8 mg／mL,encapsulation efficiency and drug loading were 35％ and 0.485×10-9 ～mol／mg of polymer．With the increase in the wall thickness of nanocapsules,the release time of BSA in PBS solution increased．The release rate could be controlled through adjusting the wall thickness of nanocapsules.
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发布时间：2021-03-19 - 摘要：LLDPE／nano-SiO2 composites wele prepared by melt-blending,and the mechanical and optical properties of the composites were investigated．The results showed that the elastic modulus of the composites obviously increased with the increase of SiO2 content,and the breaking elongation remained unchanged at low content of SiO2．Both the impact strength and the tensile strength of composites were improved with an increase of nano-SiO2 content and reached maximum when 3 phr nano-SiO2 were introduced．The IR absorptivity (ranging from 7 μm to 11 μm) of the composite films increased dramatically with a small amount of nano-SiO2 introduced．Although the visible light transmittance of the film declined a little compared with the pure LLDPE,the haze value increased much. It was also found that the surface-treatment method of nano-SiO2 has great influence on the optical properties of the composite films．The infrared absorptivity and haze of the composites filled with nano-SiO2 treated by silane coupling agent in ethanol were superior to those of the composites filled with nano-SiO2 treated by silane coupling agent in a ball mill,because the former has smaller particle size and more uniform dispersion in matrix than the latter.
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发布时间：2021-03-19 - 摘要：Reverse atom transfer radical polymerization of styrene initiated by benzoyl peroxide(BPO) or potassium persulfate(KPS) in emulsion systems with phenanthroline as ligand and sodium lauryl sulfate as surfactant was studied．For the BPO initiator system,the good control over the polymerization of styrene was observed when both CuBr and CuBr2 were simultaneously introduced into the reaction system．In this case,the fast initiation could be expected as a result of the quick redox reaction of CuBr and BPO,and the addition of CuBr2 at the beginning of polymerization could further improve the controllability of the polymerization．For the polymerization initiated by KPS,the pH value of the reaction medium played a crucial role in affecting the polymerization rate of St which increased with the increase of the pH value of the medium．The particle size and particle size distribution of the synthesized polystyrene with BPO or KPS were measured,and found to be quite different．
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发布时间：2021-03-19 - 摘要：The rheological properties of aqueous suspension of curdlan (ASC) with different molecular weights were investigated with dynamic viscoelastic experiments．Solid-like behavior for ASC was observed at room temperature.The storage shear modulus G′ demonstrated a slight frequency dependence over the range measured,whereas the loss shear modulus G″ and loss tangent δ showed a shallow minimum．The viscoelasticity of ASC increased with increasing molecular weight and concentration of curdlan．The flow curves were approximated by the Herschel-Bulkley rheological model．The fact that ASC manifests an elastic behavior is attributed to the formation of percolating network established by the aggregation or flocculation of curdlan particles,which can be described by the scalar elasticity model of percolation theory．The shear modulus G′ showed a scaling relationship with the curdlan concentration in excess of a threshold concentration cs=0.3％,G′=Goεt,where the scaling exponent t=2.54．
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发布时间：2021-03-19 - 摘要：In accordance with the trend towards cheap and trouble-free curing techniques,electron beam (EB) curing of composites involves using electron radiation to initiate the polymerization and crosslinking reaction in suitable matrix resins．EB curing technology of composites offers many advantages compared to conventional thermal curing and is an important innovative technology at present．Most variety of epoxy resins has been confirmed to possess radiation reactivity and has already become the chief resin matrix used in EB curable composites．The physical characteristics of epoxy resin systems cured by electron beam radiation were studied．The results of observing the cured areas indicate that EB-cured resins extend layer upon layer around active centers．Whole cured area consists of many lamellar structures. Through the analyses on the changes of curing degree with the radiation depth in the cured samples,it can be found that the gel fraction of cured epoxy resin increases with the rising of radiation dose. A maximum curing degree occurs at a certain depth of resin systems,but not at the top surface. A model interpretation was made for the process of electron beam curing．The dimension of cured areas is dependent on the pervasion power and concentration of high-energy electrons in the resin systems,and the influence of diffusion of reaction active centers is weak.
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发布时间：2021-03-19 - 摘要：By using spectroscopic characteristics of azo chromophores in different states as a‘probe’,H-aggregation of the azo chromospheres of a polyelectrolyte poly {2-[4-(4′-ethoxyphenylazo) phenoxy] ethyl acrylate-co-acrylic acid} (PEAPE) aqueous solutions and its effect on photo-responsive behavior were studied．Compared with the azo polyelectrolytes in DMF,PEAPE in H2O showed an obvious blue-shift of the maximum absorbance due to H-aggregation of the ago chromophores formed in the solution．There also exists H-aggregation of the azo chromospheres in PEAPE solution in DMF／H2O,and the degree of H-aggregation depends on the ratio of DMF and H2O．The UV-Vis spectra of PEAPE aqueous solution change with different degrees of functionalization of the azo chromophores. With the degree of functionalization increase,the λmax of PEAPE gradually blue shifts,which suggests the degree of H-aggregation increase. H-Aggregation of the azo chromospheres results in a slower photo-isomerization rate and lower photo-isomerization efficiency of the azo polyelectrolyte PEAPE．The photo-isomerization kinetics of the PEAPE aqueous solution doesn’t obey the first order exponential decay function,which also indicates that the coexistence of H-aggregates and “isolated” azo chromospheres in the system.
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发布时间：2021-03-19 - 摘要：The pH effect on H-aggregation of two aZO polyelectrolytes PNAPE and PEAPE was studied by using UV-Vis spectroscopy．Experimental results showed that the existing states and UV-Vis spectroscopic character were closely related with the ionization degree of the carboxylic groups of the two polymers．The pH range of the azo polyelectrolyte solutions can be divided into three parts．In the pH area where the carboxylic groups initially ionized,the solution was unstable and not discussed here；in the pH area where the carboxylic groups fully ionized,the λmax had little change with pH decrease；in the pH area where the carboxylic groups partly ionized,the λmax showed an obvious red-shift with pH increase because of deaggregation of the H-aggregates of the azo chromospheres of the azo polyelectrolytes．The deaggregation of H-aggregates of azo chromospheres had significant influence on their photo-responsive behavior,which was characterized by increasing both the trans-to-cis isomerization rate and isomerization efficiency with pH increase．
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发布时间：2021-03-19 - 摘要：N-phthalolyl chitosan with the degree of substitution 1.0 was prepared from completely deacetylated chitosan．Its chemical structure was characterized by means of FTIR and 1H-NMR．This polymer was used to investigate the thermotropic phase transition of lytropic liquid crystalline solutions in dimethylsulfoxide (DMSO) by using differential scanning calorimetry (DSC)．The critical concentration of mesophase formation was 43 wt％determined both by DSC and polarizing light microscopy．An evident gel-sol transition in addition to a liquid crystal-isotropic liquid transition (the clearing transition) was observed by means of DSC in solutions whose concentration was higher than 43 wt％. It means that the isotropic liquid transferred into anisotropic sol and then into anisotropic gel with the decrease of temperature. The gel-sol transition temperatures and transition heats of N-phthalolyl chitosan／DMSO solutions were much higher than those of random substituted N-phthalolyl-O-acetyl chitosan solutions in some solvents reported previously．It may imply that the regularity of substitution is very important for the formation of anisotropic gel．A phase diagram of temperature and polymer weight fraction was presented according to the DSC results for the N-phthalolyl chitosan／DMSO system．
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发布时间：2021-03-19 - 摘要：The dispersion polymerization of VAc initiated by gamma ray irradiation was carried out in polar media using poly (N-vinylpyrrolidone) as a steric stabilizer at room temperature．This method takes advantages of the specialities of radiation induction,and highly uniform polymer microspheres were obtained．The molecular weight of the polymer increased with the increase of stabilizer content and polymerization temperature,and the decrease of absorbed dose rate,monomer concentration,and ratio of alcohol／water. Based on the experimental results (XPS and element analysis),only the physical adsorption of stabilizer was found in the polymer particles．Compared with other monomers,vinyl acetate may not be inclined to graft-copolymerize with poly(N-vinylpyrrolidone) in radiation polymerization systems．This is maybe due to the low activity of VAc grafting with the stabilizer according to the theory of radiation grafting．
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发布时间：2021-03-19 - 摘要：A molecularly imprinted polymer (MIP) was synthesized from the photoinduced polymerization of acrylamide and butylene diacrylate in the presence of L-2-chloromandelic acid (L-2-MDA) as template and was used as a highly selective separation materials for L-2-MDA．UV analysis showed the template L-2-MDA and functional monomer acrylamide formed complexes before polymerization．The structures of complexes were simulated by using Hyperchem and the binding energies were calculated as -1.6437×104 J·mol-1 and -4.2799×104 J·mol-1．The binding capacity of MIP to L-2-MDA was higher than that of other analogs and the chiral separation factor α was 1.76．Scatchard analysis suggested that the MIP recognized α-2-MDA with two classes of binding sites,which is accordant with the two kinds of complex simulation models．
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发布时间：2021-03-19 - 摘要：The phase transition behavior of polystyrene／trans-decalin polymer solutions was observed under pressure with a hand-made high-pressure light scattering apparatus．The relationship between the phase transition temperature and the pressure was found,i．e．,the results show that the transition temperature increases with pressure．We also obtained phase diagrams in the T-φ plane and P-φ plane,but we could not get the critical pressure of the phase diagram in P-φ plane at low temperature under normal pressure．In these cases critical pressures can be obtained by extrapolation to the negative pressure range．
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发布时间：2021-03-19
Research Article
- 摘要：A soluble blue-light emitting polymer,Poly(9,9-dihexylfluorene),was prepared by using the oxidative polymerization method．The monomer,9,9-dihexylfluorene,was prepared in a DMSO／benzene mixture with solid KOH as catalyst and the product was purified by chromatography with ethyl ether／n-hexane (5／95) as the eluant．Poly(9,9-dihexylfluorene) was synthesized by chemical polymerization utilizing FeCl3 as an oxidizing agent under argon atmosphere at room temperature for three days．Its structure and properties were characterized by FTIR,1H-NMR,TGA,GPC,UV-Vis and photoluminescence spectra. The experimental results showed that the molecular weight of the polymer measured with GPC was Mw／Mn=27692／24476. The thermal degradation temperature (weight loss 5％) of the polymer was over 400℃ either in air,or in Ar．The polymer was found to be fusible at high temperature and soluble in most common organic solvents,such as chloroform,tetrahydrofuran and dichlomethane. Both in solution and film state,the polymer shows strong fluorescent excitation characteristics．The peak wavelength of its photoluminescence in chloroform solution was around 420 nm excited at 320 nm．The polymer can be processed as film by a solution-casting method and shows unique blue light emitting properties,and may be widely used in electronuminescent devices as blue-light emitting diodes and polymer lasers.
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发布时间：2021-03-19 - 摘要：Fluorine-containing block copolymer ionomers were prepared by atom transfer radical polymerization (ATRP) of 2-[(perfluorononenyl)oxy]ethyl methacrylate (FNEMA) using bromine-endcapped poly (styrene) (PSt-Br) as macroinitiators,followed by partial sulfonation of the styrene blocks．The formation of the block copolymers before sulfonation was confirmed with gel permeation chromatography (GPC) and 1H-NMR．The sulfonation products were characterized by FT-IR and elemental analysis．Furthermore,their solution behavior and wettability were examined and comparied with those of the parent copolymers．The results show that the ionomers,especially the metal salt ionomers exhibit higher viscosity than that of the parent block copolymers．Although the polar groups-sulfonated groups were introduced to the copolymer,the film of the ionomer kept high hydrophobic ability．
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发布时间：2021-03-19 - 摘要：A preparation process of PMMA／graphite nanocomposites was developed via in situ polymerization of monomers in the presence of sonicated expanded graphite with the aid of sonication．Expanded graphite was sonicated in a 70％ aqueous alcohol solution to get graphite platelets (NanoG) with thickness of 30～80 nm and diameter of 0.5～20 μm．The NanoG were dispersed in MMA monomers with BPO initiator．In situ polymerization was taken place when the mixture was heated under sonication．The TEM studies showed that the graphite nano-platelets were well dispersed in the PMMA matrix．Solution cast films of the nanocomposite were used for electrical conductivity measurements．The percolation threshold of polymer/NanoG nanocomposite films at room temperature was lower than 1.0 wt％,which was much lower than that of the composites with conventional graphite filler which was 5.5 wt％．The electrical conductivity reached 10-3 S／cm at a graphite content of about 4.0 wt％．The special structure of graphite nano- platelets with high aspect ratio of as high as 100～500 (width-to-thickness) played an important role in forming a conducting network within the PMMA matrix．
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发布时间：2021-03-19 - 摘要：Dendrimer-containing hydrophobically associating polymers (PDAM) have been synthesized by micellar copolymerization of acrylamide (AM) with a small amount of polyether dendrimer monomer(DA)．The association behaviors and rheological properties of this polymer in aqueous solution were studied by viscometry and fluorescence probe．It was found that such polymers exhibit a large hydrophobic effect and easily self-association in dilute aqueous solutions．Their solution viscosities show a pronounced nonlinear dependence on dendritic hydrophobe content in the polymer and a maximum value appeared at an appropriate content．This behavior can be attributed to the balance between inter- and intraaction associations,which can be controlled with the hydrophobe content of the polymer．
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发布时间：2021-03-19 - 摘要：Porous membranes of polyacry lonitrile were prepared directly on carbon paper with the phase inversion method,and then cross-linked under γ-ray radiation．Carbon foam materials were obtained from these cross-linked composite porous membranes after oxidation at 220℃ in air,carbonization at 850℃ in nitrogen and activation at 850℃ in CO2．Morphologies of the carbon foam materials were observed with scanning electron microscopy,and the specific surface area was measured with the Brunauer-Emmett-Teller(BET) technique．It was found that the network structure of the carbon foam materials was affected by γ-ray radiation,and that the BET value could reach a high value of 500 m2／g after treatment with CO2 at 850℃．These carbon foam materials can be used directly as electrodes of electrochemical capacitors in suitable shapes and size．Cyclic voltammetry,AC impedance spectrum and galvanic cycles of the carbon foam electrode were tested both in aqueous and organic media for evaluating its electrochemical performance．The results show that the specific capacitance of such a carbon foam electrode in 1 mol／L aqueous solution of sulfuric acid is 174 F／g,which is at the high level of carbon electrodes．
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发布时间：2021-03-19 - 摘要：A pseudo AB2 monomer,N-(2-acetoxyl ethyl)-N-(2′,4′-dicarboxylic benzoyl) amine (F2),was synthesized by two steps．Firstly the ring-opening reaction of 1,2,4-benzenetricarboxylic anhydride was carried out with ethanolamine resulting in N-(2-hydroxyl ethyl)-N-(2′,4′-dicarboxylic benzoyl) amine (F1),and then F1 was acetylized by acetic anhydride to afford F2. The yields for F1 and F2 are 90％ and 84.5％,respectively. By bulk polycondensation of F2 catalyzed by Zn(OAc)2,a novel hyperbranched poly(ester-amide) was effectively prepared in a yield of 92％. The structure of the product was characterized by mean of IR,1H-NMR,DSC and TGA. The obtained polymer has good thermal properties as expected．The effect of the polymer on the rheological behavior of polycarbonate (PC) was studied by using Haake Rheomix 600．It was shown that the torque of melt PC was reduced by 70％ with the addition of 5wt％ of the obtained hyperbranched poly(ester-amide).
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发布时间：2021-03-19 - 摘要：The preparation and micwave-absorbing behavior of nanosize PSZFe magnetic particles were studied．Nanosize PSZFe magnetic particles were prepared as following：nanosize Fe particles generated by themal decomposition of Fe(CO)5 in organic solvents were encapsulated with synthesized polysilazane (PSZ) precursor and then irradiated under ultraviolet light．PSZFe particles were characterized by using transmission election microscope (TEM),X-Ray powder diffraction(XRD) and vibrating sample magntometer(VSM),and their microwave-adsorbing properies were measured by means of a vector network analyzer．The influence of the polysilazation layer on corrosion and magnetization of PSZFe particles and the relationship between polysilazation layer and micwave-absorbing behavior of PSZFe particles were investigated. Results showed that the average diameter of PSZFe particles was 30 nm,the structure of iron in PSZFe magnetic particles was α-Fe．The formation of a PSZ layer on nanosize Fe particles enchanced the corrosion resistance of PSZFe．In addition,PSZFe particles coated with 3 wt％ PSZ demonstrated high corrosion resistance and fine microwave-absorbing ability as well．The reflection loss was less than - 10 dB in the range of 9.8 ～ 16 GHz,and a reflection loss value of -20 dB was detected at 13 GHz．
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发布时间：2021-03-19 - 摘要：Poly(bisphenol A-co-decane) could form spherulites in a wide-range of temperatures．The growth of lamellae at the interface of spherulites was studied in real time using atomic force microscopy (AFM) with a high temperature heater accessory．The results indicated that the lamellae from different spherulites could penetrate each other and form “lamella bridges” when the growth directions of lamellae were nearly parallel．The lamellae in different directions could join and stop growing by each other at the interface of spherulites,which lead to the formation of defects.
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发布时间：2021-03-19
Research Bulletin
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