最新刊期
卷 ， 期 4 ， 2007
- 摘要：Viscosities of casein in dilute 0.1 mol/L NaOH solutions at different temperatures were carefully measured.The upward phenomena of the apparent viscosity of casein in NaOH solutions was attributed to the adsorption of the solute on the inner wall of the glass capillary,and a corrected viscosity equation was used to deal with the obtained viscosity data.Five viscosity parameters have been obtained to describe the state of casein molecules in the solution and on the interface.It seemed that the size of casein molecules in solution changed little with temperature,and the adsorption layer thickness varied regularly with the adsorption amount.
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发布时间：2021-03-19
Rapid Communications
- 摘要：A series of soluble aromatic polyamide copolymers were prepared by the one-step polymerization or two-step polymerization of p-phenylene diamine (A2 monomer),trimesic acid (B3 monomer),and p-aminobenzoic acid (AB monomer).The structure of resulting polymers was confirmed by IR,1H-,and 13C-NMR measurements.The copolymerization behavior was investigated by IR and 1H-NMR.1H-NMR spectra of the polymers indicated that the AB monomer reacted by inches with the increasing of reaction time.The copolymers synthesized by two-step polymerization had different structures as compared with the one-step copolymer.The influence of three different monomers on the polymerization was investigated.
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发布时间：2021-03-19 - 摘要：Based on the modified Higashi’s direct polycondensation method,a series of poly(ester imide)s (PEIs) derived from N,N′-hexane-1,6-diylbis(trimellitimide),4,4′-dihydroxybenzophenone and 6-hydroxy_2-naphthoic acid (HNA) were synthesized by a “step-feeding” polycondensation process.The liquid crystalline behavior,structure and thermal properties of these PEIs were characterized by nuclear magnetic resonance (NMR),polarized-light microscopy (PLM),wide-angle X-ray diffraction (WAXD),differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).The results showed that all the copolymers possessed a typical nematic thermotropic liquid crystalline character,if the feeding HNA ratio is greater than 33 mol% to the total monomer content.However,this type of liquid crystalline polymers shows only the liquid crystalline phase transitions during heating.In the cooling process,the phase transitions of liquid crystalline phase were not observed.These polymers possessed high glass transition temperature (Tg) and relatively lower melt temperature (Tm),which would find their potential usages as a new category of liquid crystalline polymer materials having a lower processing temperature but a higher application temperature.
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发布时间：2021-03-19 - 摘要：With the action of catalyst and cosolvent,a series of hydroxyl-terminated polydimethylsiloxane (HPMS) based polyurethane (PU) micro emulsion were successfully prepared by self-emulsifying copolymerization.They were prepared by the reacton of isophorone isocyanate (IPDI),poly(tetramethylene oxide)glycol (PTMG) and HPMS with N-methyldiethanolamine (MDEA) as chain extender and trimethylolpropane (TMP) as crosslinker.Effects of HPMS content on the particle size and morphology of HPMS/PU micro emulsion were analyzed.The effects of HPMS content,N-methyldiethanolamine content,TMP content,and the molecular weight of the prepolymer on the emulsion's rheological properties were studied.The results revealed that the average diameter of the particles and the distribution width became greater and wider with HPMS addition.Emulsions exhibit a Non-newtonian behavior,and they are endowed with pseudoplasticity and thixotropy.It is noticed that the apparent viscosity decreases with increasing the shear rate,that is,the emulsions show a characteristic of shear thinning,and their flow-behavior index (n) ranges from 0.885 to 0.531.It is also noticed that their zero shear viscosity ranges from 13.59 mPa\5s to 25.08 mPa\5s,changing with the content of HPMS,N-methyldiethanolamine,TMP and the molecular weight of the prepolymer.
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发布时间：2021-03-19 - 摘要：MWNTs were modified by amphiphilic polymer poly(vinyl pyrrolidone) (PVP) with ultrasonic assistance methods.The modified MWNTs were characterized by Fourier transform infrared spectroscopy (FTIR),thermogravimetry (TG),high-resolution transmission electron microscopy (TEM) and Raman spectrum.The results show that the surface of modified MWNTs was covered by PVP at special conditions.Modified MWNTs exhibit remarkable dispersion in water,glycol and dimethyl formamide (DMF).FTIR spectrum analysis show that amphiphilic polymer existsd on the surface of MWNT.Raman spectrum analysis show that the G band of modified MWNTs shifts to high wavenumber and is divided into two bands,which indicates that the chemical graft reaction has occurred between MWNTs and the amphiphilic polymer.TEM shows that the amphiphilic polymer unevenly covered on the surface and ends of modified MWNTs.The content of the amphiphilic polymer had little effect on graft mass,but the ultrasonic time affected the graft mass greatly,and the graft mass of PVP reached a maximum,when the ultrasonic time was 4 h.The modifying effect of the amphiphilic polymer was different from that of surfactant.MWNTs modified with surfactant SDBS can't dissolve in water again after washing and filtration,but MWNTs modified with amphiphilic polymer can dissolve in water again.
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发布时间：2021-03-19 - 摘要：Several PVC/ultrafine vulcanized powdered nitrile rubber (NBR-UFPR) binary composites and PVC/NBR-UFPR/nano-CaCO3 ternary composites were prepared.TEM images showed that three kinds of NBR-UFPRs,P-248 (about 150 nm,33%AN),P-6387 (about 90 nm,33%AN) and P-26 (about 70 nm,26%AN),were dispersed well in PVC matrix.Those NBR-UFPRs can increase the toughness,heat resistance and thermal stability of PVC/NBR-UFPR binary composites simultaneously.At the same time,it was found that the addition of CaCO3 nanoparticles (40 nm) can further increase the toughness,heat resistance and thermal stability of PVC/NBR-UFPR/nano-CaCO3 ternary composites,and TEM images showed that the distance between two particles (PVC ligament thickness) become shorter.It was discussed why the toughness,heat resistance and thermal stability of PVC composites can be improved simultaneously.
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发布时间：2021-03-19 - 摘要：Sulfonated poly(ether ether ketone) (SPEEK) is a very promising alternative membrane material for direct methanol fuel cells.However,with fairly high degree of sulfonation (DS) SPEEK membranes can excessively swell or even dissolve at high temperatures.This restricts the membranes from working above a high tolerable temperature to get the high proton conductivity.To deal with this contradictory,insolvable zirconium tricarboxybutylphosphonate(Zr(PBTC)) powder was employed to make composite with SPEEK polymerwith the attempt to improve the temperature tolerance of membranes.SPEEK/Zr(PBTC) composite membranes were obtained by casting homogeneous mixtures of Zr(PBTC) and SPEEK in N,N-dimethylacetamide on glass plates and then evaporating solvent at 60℃.Many characteristics of composite membranes were investigated,including thermal stability,liquid uptake,methanol permeability and proton conductivity.Results show that not only the temperature tolerance but also the methanol resistance of the SPEEK/Zr(PBTC) composite membranes was improved.The composite membranes with 30 wt%～40 wt% of Zr(PBTC) have their methanol permeability around 10-7 cm2\5s-1,which is one order of magnitude lower than that of Nafion ?115.High proton conductivity of the composite membranes can be also achieved because of the increased high tolerable temperature.Under 100% relative humidity the conductivity of the composite membrane with 40 wt% of Zr(PBTC) exceeded that of the Nafion ?115 membrane at 90℃ and reached a high value of 0.36 S\5cm-1 at 160℃.Improved applicable temperature and high conductivity of the composite membrane indicate its promising application in DMFC operating at high temperature.
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发布时间：2021-03-19 - 摘要：Elastic behaviors of a single three-dimensional compact chain adsorbed on the attractive surface are investigated using the pruned-enriched-Rosenbluth method (PERM).The size and shape of the chain,such as mean-square end-to-end distance R2,mean-square radii of gyration S2xy and S2z,and shape factor δ* are studied with different adsorption interaction energy and different positions of the chain on which the force is exerted.During the elasticity process,the shape factor δ* first decreases with the shape of chains in a sphere,then increases and the chain extends to be a rod shape along the direction of the force.It decreases again,and at the end it remains a constant value.If the chain is far away from the adsorbing surface,all of the conformational properties remain constant,and there would appear the “jump point”.On the other hand,some thermodynamic properties such as the average Helmholtz free energy per bond A,average energy per bond U/N,average attraction energy per bond Ua/N,average contact energy per bond UC/N,elastic force f and energy contribution to elastic force fU are also calculated during the elasticity process.Different thermodynamic behaviors are obtained when the force acts on different monomers of the chain.Obviously,there exist several long plateaus for elastic force f with strong adsorption interaction,which agrees well with experimental results.We also discuss elastic behaviors of compact chains with weak adsorption interaction,which cannot be obtained from experimental methods.
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发布时间：2021-03-19 - 摘要：The homogeneous copolymerization of acrylamide (AM) and sodium 2-acrylamido-tetradecane sulfonate (NaAMC14S),which is a kind of acrylamide-type anionic surface-active monomer,was carried out in aqueous solutions.The concentrations of NaAMC14S were controlled above and below the critical micellar concentration (CMC),respectively,and the copolymers with two types of chain structures,random and microblocky were obtained.The structures of the copolymers were characterized by FTIR spectra,and their molecular weights were correspondingly expressed by the intrinsic viscosities obtained with an Ubbelohde viscometer.The hydrophobically associating properties of the copolymers and rheological characters of their aqueous solutions were studied mainly by using the fluorescence probe method and apparent viscosity measurements.The experimental results show that the copolymers with microblocky structure have strong hydrophobically associating properties,and the apparent viscosities of their aqueous solutions increase rapidly as their concentrations are over 0.2 wt%.The shear thinning behavior of their aqueous solutions is obviously reversible,and they exhibit strong shearing resistance.There is a special finding about a positive salinity sensitivity of the aqueous solution viscosity of the microblocky copolymers.For those copolymers with microblocky structure the apparent viscosity of their brine solution is much higher than that of their pure water solution.The apparent,viscosity of the salt solution is enhanced actually by three orders of magnitude as the concentration of the copolymer is 0.3 wt% and the concentration of CaCl2 is 2 wt%,and a unique positive salt sensitivity,i.e.salinity thickening,is displayed.
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发布时间：2021-03-19 - 摘要：The kinetics of the anionic ring-opening polymerization of hexamethylcyclosiloxanes (D3) initiated by hexaphenylcyclotrisilazane trilithium(P3NLi),in the presence of DMSO or THF as a promoter was studied.The conversion of D3 at different reaction time was determined from the ratio of the peak area of the NMR spectrum of D3 to that of the polymer.The reaction orders for THF,DMSO,D3 and P3NLi were calculated.The polymerization is a reaction of 1st order with respect to D3,THF and P3NLi,and 2nd order with respect to DMSO.The kinetic equations of the polymerization reactions were also proposed.The kinetics of THF and DMSO is vp=-d［D3］/dt=k［I］［D3］［THF］ and vp=-d［D3］/dt=k［I］［D3］［DMSO］2,respectively.The accelerating effect of DMSO was stronger than that of THF,and the rate constant of polymerization with DMSO as promoter was nearly 100 times as high as that of THF.
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发布时间：2021-03-19 - 摘要：The coordination crosslinking reaction of (NBR/PVC)/CuSO4 composites was investigated by differential scanning calorimetry(DSC) and Fourier transform infrared(FT-IR) spectrometry.The kinetic parameters of coordination crosslinking were evaluated by Kissinger method.The results showed that (1) the existence of PVC in the system accelerated the coordination crosslinking and reduced the activation energy of the coordination between nitrile groups (—CN) and copper ions(Cu2+);(2) the content of CuSO4 didn't affect the coordination crosslinking reaction.
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发布时间：2021-03-19 - 摘要：Polyethyleneimine (PEI)was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyltrimethoxysilane (CP),and the novel composite material PEI/SiO2 with chemical bond linkage was prepared.Then the molecular imprinted polyethyleneimine on the surface of silica gel was prepared using Cu2+ as template ions and epichlorohydrin (ECH)as crosslinking agent via coordination bond effects,and composite ionic imprinted material IIP-PEI/SiO2 was obtained.Both static and dynamic methods (i.e.batch and column methods)were adopted to study the binding properties of IIP-PEI/SiO2 for Cu2+,and the effects of main imprinting conditions,the concentration of Cu2+ and the used amount of epichlorohydrin,on the binding properties of IIP-PEI/SiO2 were examined.The experiment results show that the ionic imprinted material IIP-PEI/SiO2 possesses strong recognizing ability for Cu2+,and the ability is displayed in two aspects:(1)IIP-PEI/SiO2 has high selectivity for Cu2+,in relation to Cd2+ the selectivity coefficient of IIP-PEI/SiO2 for Cu2+ is 83.79,and in relation to Zn2+ the selectivity coefficient of IIP-PEI/SiO2 for Cu2+ is 80.21;(2)The binding amount of Cu2+ on IIP-PEI/SiO2 is much greater than that on PEI/SiO2,which was not ion-imprinted,and the former is two times greater than the latter.Besides,the ionic imprinted material IIP-PEI/SiO2 has excellent elution property,and it is easy to be regenerated and reused.
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发布时间：2021-03-19 - 摘要：The photoluminescence behaviors of poly(2-methyoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV)/organoclay (OMMT) nanocompsites in both solvent and solid were investigated in this paper.The results demonstrated that nano-layered silicates may enhance the luminescent performance of MEH-PPV primarily based on structural and conformational modulation.The appearance of OMMT could induce more J aggregates other than H aggregates of MEH-PPV,which result in a red-shift of the emission and higher electroluminescence efficiency.To understand the mechanism of the luminescent enhancement for the nanocomposites,the measurements of steady fluorescence emission,fluorescence lifetime (τ) and spin-lattice relaxation time (t1) of the individual carbon atoms in MEH-PPV for the nanocomposite films were carried out.It is obviously that with increasing OMMT content in the nanocomposites,the Stokes shift together with the fluorescence lifetime showed a prolonging tendency,and the t1 of the conjugated carbon atoms in MEH-PPV backbone shortened linearly.All of the results indicated that,with the increase of OMMT content,the interchain interaction and π-π* transition decreased,the proportion of J-aggregation and the mobility of the conjugated segments increased.Consequentially,both the self-aggregation of the polymer chains and the self-quenching of luminescent emission reduced.
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发布时间：2021-03-19 - 摘要：A novel norbornene derivative containing oxyethylene repeating unit and imidazolium ionic moiety was designed and synthesized.The monomer was polymerized via ring-opening metathesis polymerization initiated by Grubbs catalysts （PCy3）2 Ru（CHPh）Cl2（1） and （SIMes）（PCy3）Ru（CHPh）Cl2（2）.The polymerization reactions were conducted in organic solvents as well as in ionic liquid ［BMIm］PF6 under various conditions.The results demonstrated that complex 2 possessed higher catalytic activity than complex 1.The ROMP using 2 as catalyst in organic solvents was not controlled and the resulting molecular weights were much higher than the calculated values,while the polymerization in ionic liquid was homogeneous and the molecular weights of polymers could be preferably controled.The monomer and the polymers were characterized with NMR spectroscopy,DSC and cyclic voltammetry,respectively.The polymer has a glass transition temperature of -17.34℃ and an electrochemical stability window of 3.0 V.
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发布时间：2021-03-19
Research Article
- 摘要：Photo-induced Fenton reaction was utilized in this paper to control the sizes of polyethylenimine hydrogels (M-PEIs,M,Fe atom) as gene delivery vector.H2O2 and FeCl2 were mixed with PEI pre-polymer in water in a 3-neck quartz flask,and the mixture was stirred vigorously.M-PEIs nanogels dispersed very well in water could be prepared under illumination by use of low-pressure Hg lamps at room temperature.This system was protected from oxygen with N2.By changing reaction conditions,such as the pH value,reaction time and concentrations of solutes,sizes of M-PEIs nanogels could be controlled.It was found that the sizes of M-PEIs decreased with the pH value and the concentrations of FeCl2.The increasing of the initiator (H2O2) concentrations would make the particles more tighten,but might result in crosslinking or degradation of particles.A suitable irradiation time ensured formation of homogeneous nanogel products,but prolonged irradiation would cause degradation of nanogels.After photo crosslinking,the products were purified with membrane filters of 0.45 μm and treated further by dialysis bags with size exclusion below 10 kDa in order to make them more stable for storage.
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发布时间：2021-03-19 - 摘要：The phase morphology,thermal behavior and mechanical properties of syndiotactic polystyrene/isotactic polypropylene (sPS/iPP) blends compatibilized by copolymer of syndiotactic polystyrene-b-poly(1-butene)(B30) were investigated.It was found that the typical morphology of an incompatible blend where iPP domains had a clear spherical shape in sPS matrix.However,compatibilizer B30 had an improved effect on the phase morphology of the resultant blends.DSC results showed that in these blends the onset temperature of the iPP-Tg region shifted toward the sPS-Tg,and the sPS-Tg shifted inward slightly.The typical blend of sPS/iPP/B30 = 90/10/10 coupled the best mechanical properties with unnotched izod impact strength 42.3 kJ/m2 and tensile strength 33.7 MPa.
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发布时间：2021-03-19 - 摘要：A new hydrogelator,2,6-di［N-(carboxypropylcarbonyl)amino］ pyridine (defined as DPAP) was synthesized from 2,6-diaminopyridine and glutaric anhydride by a one-step procedure.Self-supporting supramolecular hyrogels were formed through cooling DPAP aqueous solution and DPAP mixed solution of 1,4-dioxane and water with 1,4-dioxane content no more than 15 wt%.However,only fiber-like crystals were obtained in pure 1,4-dioxane system.SEM observation of the xerogels indicated that the gelator molecules assembled into large sized sheet-like aggregates.The powder XRD diagrams indicated that the xerogel samples possess onset diffraction at 5.6°(2θ),corresponding to a d spacing of 1.580 nm.Such a length corresponded well with DPAP molecular length of 1.895 nm if considering the aggregating chain tilting with respect to the normal to the layer plane.So the hydrogen bonded molecular chain direction represents the main aggregating direction.Meanwhile,the xerogel samples have another preferred diffraction at 16.64°(2θ) due to the preferred arrangement of molecules under the help of hydrophobic association,therefore resulting in two-dimensional aggregating structure.
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发布时间：2021-03-19
Research Bulletin
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