最新刊期
卷 ， 期 8 ， 2007
- 摘要：The present paper provides a quantitative size exclusion chromatography (SEC) method based on the principle of absolute quantification of SEC to solve the problem.The conventional data treatment procedure for the D.R.I. signal of SEC H(V) is improved first by dividing it with the injected sample weight and leads to a novel defined weight normalized distribution Hw(V) and its integral Iw(V).These two distributions reflect the response constant of the sample in addition to the conventional relative total area normalized distribution F(V).The difference of the response constants of the mixtures provides a method to compute their composition from the Hw(V) or Iw(V) of its single component by method of summation.The calculations are carried out in a Mathcad worksheet with the principle of least sum square deviation.The method was applied to mixtures of a kind of industrial asphalt and paraffinic diluents as an example and successful results are obtained.
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发布时间：2021-03-19
Rapid Communications
- 摘要：A new polycondensation based on Friedel-Crafts electrophilic substitution reaction was studied.Triphenylamine is a very reactive aromatic compound for the electron-donating substituent of amion group,while fluorenol is an alkylating agent of high reactivity,which makes polycondensation by the Friedel-Crafts procedure feasible.Two synthetic routes for polycondensation are explored,one is “A-A,B-B” polymerization,and the other is “A-B” polymerization.As a result,the steric 4,4′-bis(phenyl-p-tolylamino)biphenyl (TPD)-linked oligofluorene is synthesized with the Mn of 1.5×10sup>4～2.0×10sup>4 by “A-A,B-B” polymerization,and “A-B” polymerization gives the monodisperse steric macrocylic oligofluorene.The studies on optoelectronic properties of these sertic copolymers are under going.
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发布时间：2021-03-19 - 摘要：Polystyrene (PSt),polymethylmethacrylate (PMMA) and copolymers (poly(MMA-co-St)) were grafted from silicon wafer via RAFT agent that was anchored to the surface.X-ray photoelectron spectroscopy showed that while the polymers were successfully grafted,the control of polymer molecular weight (MW) behaved very differently.The Si-PMMA system yielded MW much higher than the theoretically targeted,broad molecular weight distribution and low grafting density (ca. 0.03 chains/nm2).In contrast,the Si-PSt system gave MW close to the theoretical value with polydispersities around 1.3.The grafting density increased to 0.21 chains/nm2.In Si-poly(MMA-co-St) system,the polymer layer thickness increased linearly with monomer conversion and molecular weight of free polymer in solution,suggesting that the RAFT copolymerization grafting of MMA and St from silicon wafer was well controlled.The MW was close to the theoretical value.The grafting density reached 0.31 chains/nm2,which was higher than those obtained in their homo-polymerizations.
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发布时间：2021-03-19 - 摘要：The viscoelastic responses for the melts of low density polyethylene (LDPE)/ethylene-vinyl acetate copolymer (EVA)/nanoclay composites containing different contents of nanoclay were studied.It is found that the viscoelasticity dependence of the melts on shear rate,shear strain and shear history is related with the dispersion and amount of nanoclay added.A negative primary normal force difference (N1) appears when the composites are sheared at lower shear rate during steady flow,while N1 is independent of the nanoclay amount at higher shear rates.Moreover,compared with the polymer matrix,the composites exhibit different dependence of transient stress or N1 on the strain.The viscoelastic responses of polymer matrix are independent of the pre-shear that the samples are exposed to.However,for the composites containing 3 wt% or more nanoclay,the level of transient stress,stress overshoot and the steady stress observed in flow reversal experiments with pre-shear are found to be lower than those of the samples without pre-shear.With the increasing of nanoclay content,the differences of transient stress at steady state increase for the composites with and without pre-shear,and a positive N1 instead of a negative one appears for the composites subjected to pre-shear.It is believed that the layers of nanoclay are exfoliated or intercalated by polymer chains,resulting in the formation of directors in the polymer matrix.The reason for the composites melts showing abnormal nonlinear viscoelastic response is ascribed to alignment or orientation of the directors under shear stress.
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发布时间：2021-03-19 - 摘要：The fatigue crack growth behavior of polycarbonate (PC) and the alloy of PC and acrylonitrile-butadiene-styrene (PC/ABS) is experimentally investigated in this paper.An improved compliance method is employed to measure the fatigue crack length of these polymers.The fatigue crack growth law from low (10-6 mm/cycle) to high(10-3 mm/cycle) growth rate is obtained for polymer PC/ABS,which could be fairly represented in terms of stress intensity factor through the well-known Paris law,i.e.da/dN=9.5587×10-5(ΔK)2.88381.The fatigue crack growth rate of PC is about two times higher than that of PC/ABS.Variation of the crack growth rate in the lower crack growth rate region is larger than that in the higher crack growth rate region.For PC/ABS,dimple features are observed on the fatigue fracture surfaces of PC/ABS alloy for the crack growth rate region tested in the experiment,which are coarser for larger crack growth rate,smoother for smaller crack growth rate.The fatigue crack surfaces for PC are smoother than that for PC/ABS,and discontinuous crack growth bands are observed.
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发布时间：2021-03-19 - 摘要：Poly(p-xylylene)(PPX) membranes were prepared by chemical vapor deposition polymerization.Chemical surface modification of PPX membranes by succinic anhydride and maleic anhydride was carried out.Thus the active substituting groups of carboxyl have been successfully introduced into the surface of PPX membranes.The surface roughness of PPX after modification increases a little but still within 10 nm.The water contact angle after the modification decreases obviously.The antioxidation time of PPX-SM-COCH2CH2COOH is the same as PPX of 35 h,while the time of PPX-SM-COCH==CHCOOH decreases 3 h due to the existence of double bond in the membranes.The heparin content of surface modified PPX after heparinization is near 7 μg/cm2. The platelet adsorption test shows that the herinized PPX membranes have good blood compatibility.The improvement of blood compatibility is mainly concerned with the surface heparin content and whether the heparin molecules could maintain the anticruor configuration freely.
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发布时间：2021-03-19 - 摘要：The phase separation processes of various thermoplastics modified thermosetting systems including the UCST,LCST systems and the system with complex crosslinking reaction were experimentally studied with emphasis on the temperature dependency of the phase separation time.It was found that the Arrhenius type function can well describe the phase separation time/temperature relation,no matter how the viscoelastic and hydrodynamic factors were changed.Also,the activation energy keeps constant with the variations of TP content,TP molecular weight,curing rate and phase separation detecting means,while it varies with the chemical environment compatibility and the time/temperature dependence of the cure reaction.
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发布时间：2021-03-19 - 摘要：Monodisperse carboxylated superparamagnetic polymer composite microspheres with high magnetite content were prepared by miniemulsion copolymerzation,in which acrylic acid and styrene were used as polymeric monomers,and Fe3O4 microparticles were costabilized by undecylenic acid /oleic acid.Extensive characterizations by transmission electron microscopy (TEM),Zeta-sizer,thermogravimetric analysis (TGA),fourier transform infrared spectrometer (FTIR) and physical property meaturement system (PPMS) showed that the surface modification of Fe3O4 microparticles played an important role in controlling the magnetite content and the morphology of the composite microspheres.Under optimized experimental conditions,the superparamagnetic polymer composite microspheres with diameter of 137.9 nm,high magnetite content (77 wt%) and 0.0894 mmol carboxyl groups/g microspheres were successfully produced.
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发布时间：2021-03-19 - 摘要：A series of electric field sensitive gels were prepared by free-radical polymerization with acrylic acid(AA) and methyl acrylate (MA) as monomers,N,N′-methylene bisacrylamide as crosslinking agent,ammounium persulfate and tetramethylethylenediamine as initiator and accelerator,respectively.The structures and properties of the gels were changed with monomer ratio of AA and MA.The influences of the concentration of aqueous NaCl solutions and pH buffer solutions on the equilibrium swelling ratios of the gels were studied in detail.It is shown that the concentration of NaCl and the pH of the buffer solution affect the swelling properties of the P(AA-co-MA) gels greatly.Moreover,the contraction of the gels induced by a direct current electric field was investigated.The gels exhibited excellent electric sensitivity.Among the gels obtained in this investigation,the gel with a monomer ratio,VAA/(VAA+VMA) of 0.667 showed the best electrical contraction properties.According to the results of the experiment,the mechanism of the electric field induced contraction was discussed.
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发布时间：2021-03-19 - 摘要：A new kind of sulfonated copolyimides (SPIs) with higher hydrolysis stability containing both of naphthalene and phthalazinone moieties in polymer's main chain were successfully synthesized from 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid (BAPBDS),1,2-dihydro-2-(4-aminophenyl)-4-［4-(4-aminophenoxy)phenyl］-phthalazin-1-one (DHPZDA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) via direct polymerization,which are potentially utilized as proton exchange membrane in PEMFC.The obtained sulfonated polymers (SPIs) had high molecular weight with the inherent viscosity ranged from 0.41 to 1.00 dL/g in concentrated (95%) sulfuric acid when samples varied from 20% to 140% of sulfonation degree.The chemical structure of the SPIs was carefully characterized by FT-IR and 1H-NMR,and the thermo-behavior of copolymers by thermalgravimeteic analysis (TGA) was also investigated.The yellow,transparent and tough membranes cast from m-cresel solutions of the SPIs were obtained,which were utilized to investigate the physicochemical properties of these new copolymers. The data demonstrated that the membranes had better solubility and hydrolysis stabilities than the other analogeous SPIs.
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发布时间：2021-03-19 - 摘要：The interaction of cytochrome c with two copolymers:poly(isobutylene-alt-maleic acid) (PIMA) and poly(1-tetradecene-alt-maleic acid) (PTMA) was studied in this report to investigate the electrostatic and hydrophobic influence of the copolymers on the structure of cytochrome c at acidic conditions.UV-Vis,circular dichroism and intrinsic tryptophan fluorescence were measured to study the secondary structure,Soret structure and tryptophan environment of cytochrome c.Cytochrome c maintains its native-like structure at pH=2.9.After interacting with the alternating copolymers of maleic acid and alkene at pH=2.9,the α-helical structure of cytochrome c is basically unchangeable,whereas its tertiary structure is destroyed.On the other hand,at pH=2.1,cytochrome c unfolds to random coil,and the alternating copolymers can induce a structural transition to α-helical structure for the acid-denatured cytochrome c but cannot induce the tertiary structure.In acidic solutions with lower copolymer concentration,the influence of PIMA on cytochrome c structure is stronger than that of PTMA,but at higher PTMA concentrations PTMA can reach similar effect as PIMA.The reason may be that at the same copolymer weight concentration,PIMA carries more negative charges therefore has stronger electrostatic interaction with cytochrome c,and that PTMA forms stable particles with hydrophobic cores which may decrease its effective concentration and decrease the interaction with cytochrome c.Compared to small molecules,the polymeric structure provides a favorable microenvironment for the structural transition of protein at very low copolymer concentrations.
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发布时间：2021-03-19
Research Article
- 摘要：A new tetra polymerization model was proposed to handling the atom transfer copolymerization as well as the microstructure of its products.According to this model,computer simulation has been carried on to produce this ATRcP propagation including activation-deactivation process.After filtering two “monomers" which represent the dormant state of activate units,the chains' microstructure was found to be the same as that of the stationary FRcP,and all the values of structure parameters had nothing to do with the dormancy and reactivation probabilities.This conclusion can be supported by the existing experimental results.It is concluded that under stationary conditions,the copolymer's microstructure of the ATRcP is the same as that of the FRcP product,this structure includes the average segment length,composition,triad sequence concentration and segment length distribution.
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发布时间：2021-03-19 - 摘要：The nano-sized polyaniline powders are synthesized in the ionic liquid/water micro-emulsion system.The ionic liquid/water (O/W) micro-emulsions which are composed of water and ionic liquid ［bmim］PF6 with aniline dissolved are prepared by use of emulsifier OP-10. It is the first time for ionic liquid to be used in micro-emulsion synthesis of polyaniline.The results of IR spectrometry and EDX show that ionic liquid doped polyaniline is synthesized successfully.The polyaniline exhibits good thermal and electrochemical stability and charge/discharge performance.
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发布时间：2021-03-19 - 摘要：In this contribution novel acid-base sulfonated poly(phthalazinone ether nitrile ketone)s (SPPENKs) membranes are introduced.The membranes are composed of SPPENKs as the acidic compounds,and polyetherimide(PEI) as the basic compounds,furthermore,redissolving SPPENKs and PEI in N-methylpyrrolidone (NMP) then cast directly onto clean glass substrates in dust free environment at 60℃ aiming at enhancing membrane toughness and other relative properties.The chemical structures of acid-base polymers were characterized by FT-IR.The properties of acid-base membranes were detected by swelling ratio (SR),water uptake(WU),hydrolysis resistance(HR),oxidative resistance (OR),thermal stability and ion-exchange capacity (IEC) et al.The results indicate that membranes of acid-base SPPENKs have good physicochemical properties.The broken time of acid-base proton conducting polymer membranes at 80℃ in water is over 2000 h except for SPPENK-40/PEI membrane.The IEC value of acid-base membranes with SPPENK-60/PEI and SPPENK-80/PEI was 1.08 mmol/g and 1.32 mmol/g,respectively.The swelling ratios of SPPENK-60/PEI and SPPENK-80/PEI is lower than those of Nafion117.These data showed that the properties of SPPENK-60/PEI and SPPENK-80/PEI membranes were more promising compared to Nafion117.Accordingly,the acid-base SPPENKs membranes for fuel cell proton exchange membrane materials hold great potential in the long perspective.
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发布时间：2021-03-19 - 摘要：Thermosensitive core-shell particles were synthesized through grafting copolymerization of N-isopropylacrylamide (NIPAM) with ［3-(methacryloyloxy) propyl］ trimethoxysilane (MPT) coupled on the surface of ultra fine silica dioxide beads.The grafting copolymerization was carried out at the present of polyvinyl alcohol as a surfactant,H2O/cyclohexanol as mixed solvents,and 2,2′-azobis(isobutyronitrile) as an initiator.The effect of surfactant concentration and the composition of mixed solvents on the grafting rate was investigated.The infrared spectrum has confirmed the structure of the modified silica.Differential scanning calorimetry (DSC) has indicated the thermosensitivity of the particles.The thermosensitive particles were used as packing materials of high-performance liquid chromatography (HPLC) for separating naphthalin derivatives.The results revealed that satisfactory separation was attained by controlling temperature of the column.As a comparison the packing material of silica-MPT has no such separating efficiency due to absence of thermosensitivety.The mechanism for the temperature-controlled separation is attributed to the polarity change of the PNIPAM on silica surface when PNIPAM undergoes volume phase transition.
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发布时间：2021-03-19 - 摘要：The crystalline structure of isotactic polypropylene/ ethylene-propylene rubber (iPP/EPR,85∶15,W/W) blends prepared by melt-blending and solution-blending methods,respectively was studied by using modulated differential scanning calorimetry (MDSC) and wide angle X-ray diffraction (WAXD).The experimental results reveal that α-iPP and β-iPP coexist in the PP85m sample prepared by melt-blending method,but only α-iPP appeared in the PP85s sample prepared by solution-blending method,and its crystalline structure is independent on isothermal crystallization temperature.The β-iPP content in PP85m is dependent on the crystallization temperature and approaches to a maximum at about 125℃.In addition,it is found that the iPP/EPR samples experienced annealing at 200℃ for different times(5～30 min)demonstrate the same melting behavior,indicating that the annealing treatment for different times at 200℃ has little effect on the formation of β-iPP in PP85m samples.It is suggested that the formation of β-iPP in PP/EPR blends is dependent on its thermomechanical history.
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发布时间：2021-03-19 - 摘要：This paper presents a solvent evaporation method with silicone oil (PDMS) as the continuous phase for preparation of microcapsules.No surfactant was used in the microcapsule preparation process.Polyacrylonitrile(PAN),cellulose acetate (CA) and chitosan (CTS) microcapsules containing Aliquat 336 (ALQ),tetraethylene glycol (TEG) and bovine serum albumin (BSA) have been prepared respectively.The prepared microcapsules are orbicular with very compact surfaces,and the mean diameters are around 10～100 μm.With increasing the viscosity of PDMS or decreasing the concentration of polymer solution,the mean diameters of microcapsules decrease.The loading ratio of microcapsules can be easily controlled by adding separation agents into PDMS.The loading ratio of ALQ/PAN,TEG/CA and BSA/CTS microcapsules can reach up to 0.43,0.38 and 0.08 g/g respectively.
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发布时间：2021-03-19 - 摘要：Two novel degradable hyperbranched polycarbosilazanes were synthesized via hydrosilylation reaction and well characterized by FT-IR,1H-NMR,13C-NMR,29Si-NMR and size exclusion chromatogram-multi-angle laser light scattering (SEC-MALLS) technology.First,two monomers,bis(N,N-bis(dimethylvinylsilyl)amino)-methylsilane (AB4M) as well as (N,N-bis (dimethylvinylsilyl)amino)-dimethylsilane (AB2M),were prepared by nucleophilic substitution of MeHSiCl2 and Me2HSiCl with lithium teramethyldivinyldisilazane,respectively.Then the two monomers were polymerized for obtaining hyperbranched polycarbosilazanes via hydrosilylation reaction using a Karstedt catalyst.The structure analyses indicate that α-addition mainly occurs during the polymerization,and the polymers synthesized consist of N(==Si—C==)3 linkages with hyperbranched architecture and a large amount of functional vinyl bonds as end groups.The molecular weight (Mw) and its polydispersity index (Mw/Mn) were determined to be 7800 and 2.54 for PAB4M,and 5860 and 2.31 for PAB2M,respectively.Preliminary studies on the chemical stability of polymers shows that the hyperbranched polymer synthesized is stable to chlorosilane as well as water.However,it can be hydrolyzed with hydrochloric acid solution,and the degradation rate can be controlled by changing the concentration of HCl.The results suggest that controlled degradation of these hyperbranched polymers is attainable.
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发布时间：2021-03-19
Research Bulletin
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