最新刊期
卷 ， 期 9 ， 2009
- 摘要：A new 2,5-dithienylsilole (TST) with triphenylamine substituents at the 3,4-positions was synthesized.The TST was utilized to construct conjugated silole-containing poly(3,6-carbazole)s PCz-TST with TST contents of 1%～20%.The weight-average molecular weights of the PCz-TST were between 9000 and 10600,with polydispersity index between 1.3 and 1.5.Optoelectronic properties of the PCz-TST,such as UV absorption,cyclic voltammetry,photoluminescence (PL) and electroluminescence (EL) were investigated.The main absorption peaks of PCz-TST,which were ascribed to the contribution of the carbazole segments,were at 305 nm,while the absorption of the TST units was around 498 nm.The optical band gaps of the PCz-TST were between 2.06～2.18 eV.PL spectra of the copolymers showed excitation energy transfer from the carbazole segments to the silole units,displaying one orange peak for the film PL spectra.The peak positions of red EL spectra were between 604～645 nm,showing obvious red-shifts relative to the PL spectra.HOMO levels of PCz-TST were between -4.95 eV and -5.09 eV,with more than 1 eV energy barrier for holes to enter TPBI blocking layer.In EL devices with a configuration of ITO/PEDOT/PCz-TST/TPBI/Ba/Al,a maximum external quantum efficiency of 1.94% was achieved for the copolymer with 5% TST.The TPBI hole blocking layer largely improved the efficiency of the exciton formation,from which the highly efficient red EL from the silole units could be displayed.Red shifted EL spectra were found for the introduction of the TPBI layer,from which the color purity of red light was modified.
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发布时间：2021-03-19 - 摘要：A water-soluble hyperbranchend β-glucan,extracted from sclerotia of Pleurotus tuber-regium was fractionated to obtain the fractions with different molecular weight.The polysaccharide fractions were treated with chlorosulfonic acid to synthesize sulfated derivatives.The antitumor activities of the water-soluble hyperbranched polysaccharide fractions and their sulfated derivatives were evaluated by in vivo test using SARCOMA 180 xenografted BALB/C mice,and in vitro measurement against HepG2 cell,respectively.The effect of introduction of sulfate groups in the polysaccharide on antitumor activities was compared with that of the native polysaccharides by morphological,histological and ELISA methods.The results indicated that the native polysaccharides,in the radius of gyration(〈S2〉z1/2) range from 42.5 nm to 113 nm,exhibited significantly inhibition impact on the xenografted tumor cell growth and antiproliferative activities against HepG2 cell in vitro. The antitumor activities of the sulfated derivatives increased progressively with the 〈S2〉z1/2 change from 17.8 nm to 34.9 nm.Mechanism study indicated that the native and sulfated glucans inhibited the proliferation of HepG2 cell through inducing the tumor cells apoptosis in a time dependent way.Immunological test demonstrated that both the native polysasaccharide and its sulfated derivatives using low dose (20 mg/kg) increased production of tumor necrosis factor alpha (TNF-α) in mouse plasma while the native one decreased amount of TNF-α using high does (60 mg/kg) with or without liopolysaccharide (LPS) stimulation.
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发布时间：2021-03-19 - 摘要：Basing on the rotational-isomeric-state model and the statistic generator matrix method,the formulas of mean-square dipole moment were deduced in the improved investigation of the disubstituted inorganic polymers,which had considered the dipole moments of both the skeletal bonds and side groups.The revised expression was used to analyze the configurational_conformational dependent dipole moments for the stereoregular and stereoirregular polysiloxane chains,and to compare the mean-square dipole moments of poly(dimethylsiloxane) chain (PDMS) and poly(methlphenylsiloxane) chain(PMPS) with and without considering the side group orientations.The calculated characteristic ratio of mean-square dipole moment for PDMS is in agreement with the experimental data 0.36, which is larger about 46% than the ratio without considering dipole moment of side groups.The temperature coefficient of dipole moment is obtained 1.29×10-3 K-1.The characteristic ratio and its temperature coefficient of for the atactic PMPS (50% i-PMPS) are 0.61 and 1.73×10-3 K-1,respectively.The ratio without considering the side group orientations is 0.20,which is in agreement with the ratio of PDMS without considering the dipole moment of side groups.Following the investigation between PMPS dipole moment and tacticity of chains,it is found that the dipole moment ratio of the syndiotactic PMPS is larger than that of the atactic and isotactic chains,however,its temperature coefficient of the isotactic PMPS is the least.Dependence of the on the first order interaction energy is increasing in the order of the syndiotactic,atactic and isotactic chains.The second order interaction energy has larger effect on for the isotactic and syndiotactic PMPS than that of the atactic chains.
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发布时间：2021-03-19 - 摘要：Aliphatic polyether-based polyurethane(PU) elastomers with hyperbranched polyester segments were synthesized by prepolymer process from polytetramethylene ether glycol,hydroxyl-terminated hyperbranched polyester (HB-20),IPDI and 1,4-butanediol.The crosslinking density of the PU elastomer was calculated by using the Flory-Rehner equation.The degree of hydrogen bonding,the microstructure and the morphologies of these PU materials were characterized by means of FTIR,WAXD and DSC,respectively.The experimental results indicated that the PU elastomers containing small amount of HB-20 exhibited the enhanced hydrogen bonding and the micro-phase separated morphologies as well as the mechanical properties.As compared with the comparable PU specimen,the tensile strength of the polyether-based aliphatic PU containing 6 wt% HB-20 increased by 2.1 times,up to 37.9 MPa,and the elongation at break was still as high as 414%,resulting from the dual effects of the hydrogen bonding and the crosslinking density in the PU system.
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发布时间：2021-03-19 - 摘要：A series of 2-aminopyridine Ni(II) complexes bearing different substituent groups {(2-PyCH2NAr)NiBr, Ar=2,6-dimethylphenyl (a),Ar=2,6-diisopropylphenyl (b),Ar=2,6-difluorophenyl (c)} have been synthesized.In the presence of methylaluminoxane (MAO),these Ni complexes could be highly efficient to catalyze β-pinene polymerization and afforded poly(β-pinene)s with higher molecular weight than those prepared by traditional cation polymerizations.Among these complexes,complex c with ortho-electroattracting-substitution exhibited the highest catalytic activity up to 1.48×107g/(molNi#12539;h),while complex b with bulky ortho-isopropyl-substitution gave the highest molecular weight of the polymer.The effects of polymerization conditions on the catalytic activity and the molecular weight of poly(β-pinene)s were also studied.With an increase in temperature,the catalytic activity increased and reached a maximum value at 40～50℃,and the molecular weight of the obtained polymer decreased.Increasing in monomer concentration,molar ratio of MAO to the Ni complexes or decreasing in Ni complex concentration would increase the catalytic activity for β-pinene polymerization.The 1H-NMR and 13C-NMR analyses of the obtained polymers revealed that the polymers consisted of alternating sequences of isobutylene and cyclohexene units,indicating the propagation proceeded in a manner typical for conventional carbocationic polymerization process.
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发布时间：2021-03-19 - 摘要：The synergistic enhanced viscosity of self-assembly networks of wormlike micelles and cationic hydrophobically associative copolymer P(DTAB-co-AM) synthesized by copolymerization of cationic hydrophobic monomer,dimethyltetradecyl(3-acrylamidopropyl)ammoniumbromide (DTAB),with acrylamide (AM) was studied,and the effect of hydrophobic monomer content on the self-assembly systems was also probed.Two kinds of stable wormlike micelles with high viscosity,Octadecyltrimethyl ammonium chloride CTAC/sodium salicylate and potassium erucate/benzyltrihydroxyethylammonium chloride,were prepared.The copolymer P(DTAB-co-AM) and anionic wormlike micelles,potassium erucate/benzyltrihydroxyethylammonium chloride,could form self-assembly system with synergistic enhanced viscosity because both of hydrophobic association and electrostatic interactions play an important role.But the viscosity enhancement of the associative system composed of the copolymer P(DTAB-co-AM) and cationic wormlike micelles,CTAC/sodium salicylate,was weaker than that of the former because of the single hydrophobic association interaction.The results of the viscosity experiments show the viscosity of the self-assembly system made up of P(DTAB-co-AM) and anionic wormlike micelles first increased,then decreased with the increase of feed content of hydrophobic monomer in copolymer.When the feed content of DTAB in P(DTAB-co-AM) was 0.15 mol%,the viscosity of association system reached the maximum.When the feed content of DTAB was 0.3 mol%,the viscosity of this self-assembly system was lower than that of the system formed by this copolymer and cationic wormlike micelles because of more strong electrostatic interaction leading to phase separation.In contrast,the viscosity of the system self-assembled by this copolymer and cationic wormlike micelles appear a slight decrease with the increase of the DTAB content because hydrophobic association and electrostatic repulsion offset each other.Based on the above discussions,the aim to mediate the viscosity of self-assembly system by the feed content of hydrophobic monomer can be realized.
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发布时间：2021-03-19 - 摘要：In order to improve the dispersibility of carbon black (CB),natural rubber (NR) degraded under high temperature and powerful shear force was grafted onto the CB surface by in situ solid state grafting method.The morphology of original CB and grafted carbon black (GCB) particles was investigated by transmission electron microscope (TEM) and atom force microscope (AFM).The results showed that original CB particles fused together and presented as big dendritic agglomerates whose size was several microns,while the size of GCB particles diminished greatly and displayed as small aggregates of about 200 nm, which was because the aggregates of original CB were partly broken by powerful shear force and at the same time the degraded NR molecules was grafted onto the newly CB surface which prevented CB particles from aggregating again.The particle size of original CB and GCB was measured by using a laser light scattering particle sizer.The volume particle size of GCB was 164 nm which was largely less than that of original CB,797 nm.The dispersion and dispersion stability of original CB and GCB were determined with sedimentation,ultraviolet spectrophotometer and zeta potential measurement.Compared with original CB,the dispersion of GCB in the solvent of grafted molecules became better,moreover,the dispersion stability of GCB also was improved.
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发布时间：2021-03-19 - 摘要：An efficient,clean and simple preparation method of polymer hollow microspheres was provided.Ultrasonic irradiation was applied to prepare hollow polymer microspheres,which provided multi-functions of intensive dispersion,agitation,emulsification and initiation.As a result,poly(butyl acrylate) (PBA)hollow microspheres were prepared by ultrasonically initiated encapsulation emulsion polymerization.The structure and size distribution of the obtained products were investigated by transmission electron microscopy (TEM),dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR).The results showed that PBA hollow microspheres had quite uniform size and even shell thickness.PBA shell was adsorbed on the surface of SiO2 core by strong physical interaction.Furthermore,the formation mechanism of PBA hollow microspheres was studied.The results suggested that the adsorbed cationic surfactant cetyltrimethylammonium bromide (CTAB) formed a local bilayer structure with a lower layer of head groups adsorbed on the substrate surface and an upper layer of head groups in contact with solution-admicelles.And then,the hydrophobic SiO2 surface favored the adsorption of a hydrophobic monomer butyl acrylate (BA)-adsolubilization.As a result of the ultrasonically initiated polymerization,SiO2 particles were embedded by PBA,resulting in PBA-SiO2 core-shell particles-polymerization.The PBA hollow microspheres were obtained by etching the inorganic SiO2 cores in a hydrofluoric (HF) aqueous solution.And the conversion rate of BA monomer reached 88.8% in 30 min.
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发布时间：2021-03-19 - 摘要：Polyamide 6/acrylonitrile-butadiene-styrene (PA6/ABS) blends were prepared by melt processing with and without organ-montmorillonite (OMMT) or styrene-maleic anhydride copolymer (SMA) as compatibilizer.The effects of compatibilizer on morphology and mechanical properties of the PA6/ABS blends were investigated by X-ray diffraction (XRD),transmission electron microscopy (TEM),scanning electron microscopy (SEM) and mechanical property tests.Through morphology observation,the ABS particle sizes tended to decrease with the addition of compatibilizers.Structural analysis of the PA6/OMMT (100/5) composite revealed that the PA6/ABS/OMMT nanocomposites showed fully exfoliated OMMT structures,and OMMT were fistly dispered in PA6 matrix,whereas the PA6 based nanocomposites showed a mixed exfoliated and also partly non-intercalated morphology.XRD and TEM results revealed that the most crucial factor in controlling the morphology and achieving different levels of dispersion is the extent of interaction between clay and the polymer matrix.Moreover,increasing matrix viscosity helps to obtain better dispersion of OMMT.The addition of OMMT led to mechanical stiffening as indicated by the mechanical test results.
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发布时间：2021-03-19 - 摘要：The structures of partial hydrolysis polyacrylamide samples crosslinked before and after by trihydroxymethyl phenol were characterized by 13C solid nuclear magnetic resonance (NMR) spectroscopy. The structures forming during self-crosslinking between hydroxymethyls and crosslinking between hydroxymethyl and primary amine were generated after reaction means two kinds of reactions were occurred. In further tracing test of infrared spectrometry (IR) and X-ray electron spectroscopy (XPS), the results of quantificational calculation demonstrated that the increase of second amide group is correspond to decrease of the primary amide group and about 50%～60% primary amide groups participated crosslinking. Moreover, the crosslinking rate between hydroxymethyl and primary amine is greater than that between hydroxymethyls. On the basis of above results, a crosslinking mechanism between trihydroxymethyl phenol and partial hydrolysis polyacrylamide was put forwarded.
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发布时间：2021-03-19 - 摘要：A post-crosslinked polymeric adsorbent was prepared by Friedel-Crafts reaction of the pendant vinyl groups.It was obvious that both the specific surface area and the pore volume of starting copolymers increased significantly after post-crosslinking.Nitrogen adsorption/desorption isotherms and pore size distribution curves revealed that the new pores of the resulted copolymers formed by post-crosslinking reaction were mainly micropores.The results of static adsorption indicated that the adsorbents sorption capability of phenol had been greatly improved after post-crosslinked,while this phenomenon was not obvious to VB12. It could be attributed to the molecular size of VB12,which prevented VB12 diffusing from solution phase into the micropore region formed by post-crosslinking.PDT-55pc exhibited higher adsorption capacity of phenol than the commercial macroporous resin XAD-4 The adsorption capacity of VB12 onto adsorbent PDT-55(polydivinylbenzene,toluene as porogen)，PDT-55pc(post_crosslinking of PDT-55)，PDH-55(polydivinylbenzene,heptane and toluene as porogen)，PDH-55pc(post-crosslinking of PDH-55) was larger than that onto XAD-4.The equilibrium adsorption curves for resins adsorbed phenol and VB12 showed good agreement with the Langmuir and Freundlich isotherm equations.Correlation coefficients were larger than 0.99. Adsorption kinetic curves indicated that the time for adsorption equilibrium of phenol was shorter than that of VB12. The kinetic data were then fitted to the pseudo-first order and pseudo-second order models.The results showed that phenol uptake onto adsorbents could be followed by the pseudo-second order model,while VB12 onto adsorbents would be more suitably represented by the pseudo-first order model.
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发布时间：2021-03-19 - 摘要：A series of poly(acrylamide-acrylic acid) microgels with different mole percentages of monomers,based on acrylamide (AM),acrylic acid (AA) have been prepared by inverse microemulsion polymerization.Aqueous solutions of AM and AA were used as the dispersed phase for microemulsion with Span80/Tween80/isooctane solution as the dispersion medium.The polymerization was carried out at 30℃ in the presence of (NH4)2S2O8/NaHSO3 and N,N′-methylenebisacrylamide (MBA) as the oxidation-reduction initiator and crosslinker, respectively.The presence of characteristic functional groups,pH-sensitive behavior,morphology,particle sizes and distribution of microgels have been characterized through Fouriertransform infra red spectroscopy (FTIR),turbidimetric method,transmission electron microscopy (TEM) and dynamic light scattering (DLS).FTIR studies confirm the occurrence of AM and AA construction units within the macromolecular chains of microgels.TEM photographs of microgels show that particle number-average diameter of P(AM-co-AA) microgels with the mole percentage of AA 60% in the feed is about 90 nm,so they have large specific surface area.Comparing with PAM micogels,the spherical morphology of P(AM-co-AA) microgels are not very regular due to shrinking during drying operation.Moreover,DLS shows that particle sizes of microgels are increasing and the size distribution of microgels becomes slightly wider with increasing of mole percentage of AA in the feeds.Investigations of turbidimetric method suggest that P(AM-co-AA) microgels are provided with pH-sensitive behavior because of the presence of AA in the feed,and the sensitive pH value is related to the dissociation constant of AA.Due to their interesting properties,P(AM-co-AA) microgels will have a number of potential applications such as drug delivery,adsorption of heavy metal ions and so on.
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发布时间：2021-03-19 - 摘要：A new phosphorylated polyvinyl alcohol hydrogel was prepared by the crosslinking reaction of phosphorylated polyvinyl alcohol with glutaraldehyde,taking the urea as the catalyst in the phosphorylating reaction of polyvinyl alcohol.Swelling performance,mechanical properties and electro-stimulate response behavior of the phosphorylated polyvinyl alcohol hydrogel were studied.The experimental results show that its equilibrium swelling ratio decreased as the ionic strength of NaCl solutions increased,and the mechanical properties of phosphorylated polyvinyl alcohol hydrogel swollen in the NaCl aqueous solution of the ionic strength range of 0～02 were shown as follows: 0.300～0.356 MPa of Young’s modulus,91.5～137.8 kPa of tensile strength and 32.0%～37.5% of elongation at break ，and they all increased with the increasing of ionic strength.The phosphorylated polyvinyl alcohol hydrogel bended toward the cathode under non-contact D.C.electric field in deionized water and NaCl aqueous solution,the bending speed and strain increased with the increasing of the applied voltage, and there was an ionic strength of 0.005 at which its bending speed and strain reached their maximum values.That could be explained as follows. When the ionic strength of NaCl solution is lower than 0.005,the increase of ionic strength of NaCl solution induces the increase of free ions moving from the surrounding solution toward their counterelectrode or into the hydrogel,so the bending speed and strain increase.However,if the ionic strength of NaCl solution is higher than 0.005,a shielding effect of the polyions caused by the ions in the electrolytic solution occurs,leading to the decrease of the bending speed and strain.Under a cyclically varying electric field ,the hydrogel exhibited a good reversible bending behavior.The hydrogel may be applied to the fields including artificial muscle,robotic actuator and micromechanics,etc.
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发布时间：2021-03-19 - 摘要：A series of waterborne polyurethane(WBPU) adhesives for shoes were synthesized by a prepolymer process using dimethylol propionic acid(DMPA) and sucrose as a hydrophilic agent and a cross-linking agent,respectively.Their structures and thermal behaviors were studied by means of FTIR and DSC.Their water swelling,curing time,mechanical properties, e.g. tensile strength,elongation at break and T-peel strength were measured for all samples with different sucrose contents (0～6.82 wt%).The results showed that the sucrose dispersed well as an incorporated state in the polyurethane phase.The curing time of WBPU samples were decreased with increasing sucrose content at the same treating temperature.The water swelling decreased with increasing sucrose content having an optimum sucrose content at 4.13 wt%,and then it increased slightly with further increase of sucrose content.The tensile strength increased from 8.1 MPa to 22.8 MPa,while the elongation at break decreased from 933.5% to 618.7%.The initial peel strength and final peel strength were significantly increased up to an optimum content of sucrose and then decreased slightly with excess sucrose.In addition,it is noted that polyurethane prepolymers more easily remained at an aggregated state during the process of synthesis,and the adhesive strength of the result products decreased when the sucrose content was more than 5.52 wt%.
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发布时间：2021-03-19 - 摘要：The effect of hydrophobic blocks on the formation of micelle and gel for amphiphilic triblock copolymers of poly(methyl methacrylate)-b-poly(ethylene glycol)-b-poly(methyl methacrylate) (PMMA-b-PEG-b-PMMA) and polystyrene-b-poly(ethylene glycol)-b-polystyrene (PS-b-PEG-b-PS) was examined by fluorescence excitation spectra of pyrene probe,dynamic light scattering (DSL),atomic force microscopy (AFM),transmission electron microscopy (TEM) and rheology measurements.The core-shell micelle with hydrophobic PS or PMMA core and hydrophilic PEG loopchain corona formed in aqueous solution.The critical micelle concentration (CMC) was less than 0.01 mg/mL for all samples and decreased with increasing PS and PMMA block length,while the PEG block length had less effect on the CMC.The hydrodynamic radius Rh,app ranged from 15. to 24.3 nm and increased with increasing PEG block length.Increasing hydrophobic PS and PMMA block length effectively promoted the micelle formation in aqueous solution.The spherical shape of the micelle of the triblock copolymers was observed by AFM and TEM.The physical gel of PS-b-PEG-b-PS formed when the concentration was higher than 4.5 wt%.The gel formed by PMMA-b-PEG-b-PMMA when its concentration was higher than 7.5 wt%.The storage modulus G′ and loss modulus G″ increased with increasing of triblock copolymer concentration and the length of PS or PMMA blocks.The equilibrium modulus Ge was 103 Pa for PS-b-PEG-b-PS at 7.5 wt%,while less than 10 Pa for PMMA-b-PEG-b-PMMA at 15.0 wt%.The stronger hydrophobicity of PS blocks comparison with PMMA block resulted in the stronger hydrophobic interaction and formation of stronger gels.
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发布时间：2021-03-19 - 摘要：The novel exfoliated polymer nanocomposites (PMMA/MgFe(DS)-LDH) were synthesized by in situ polymerization based on poly(methyl methacrylate) (PMMA) and dodecyl sulfate-intercalated MgFe-layered double hydroxide (MgFe(DS)-LDH).The nanostructures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM),the PMMA/LDH nanocomposites were partially interacted and partially exfoliated.The thermal degradation mechanism was discussed by thermogravimetric analysis (TG) and Tg.The participation of Fe3+ ion is found to play an important role in the improvement of thermal stability of nanocomposites with small inorganic loading and well-dispersed inorganic components.The thermal degradation temperature of the nanocomposites was 37～69 K higher than that of pure PMMA at 50% weight loss， and the exfoliated nanocomposite containing 1.6 wt% inorganics had the best thermal stability.All nanocomposites have excellent transparency on the visible range due to molecular level dispersion of inorganic nanolayer,the transparence of nanocomposite containing 8.0 wt% inorganics in the visible range was almost over 90%.This sufficient dispersion was very helpful and important to the improvement in properties.The DSC showed that the Tg of the nanocomposite containing 8.0 wt% inorganics was about 34.7 K higher than that of the pristine PMMA.The increment in Tg is probably a result of the polymer-filler interactions that restrict the polymer-chain mobility.These findings demonstrated that using effective molecules and rational synthesis of nanocomposites were suitable for subsequent novel nanocomposites synthesis.
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发布时间：2021-03-19
Research Article
- 摘要：The secondary structure of adsorbed protein-like chain was investigated by using Monte Carlo simulation method based on the modified orientation-dependent monomer-monomer interaction model (ODI).The number of secondary structure such as α-helics,β-sheets and contacts are all calculated for different adsorbed energy and different chain length.When adsorbed energy εa2εh,the secondary structure of protein-like chains is nearly not changed.The chain is like a globe.While 2εhεa4εh, the number of α-helixs,β-sheets and contacts is reduced quickly.However,when εa4εh,secondary stucture is almost keeping again.The chain is flat because most residues are adsorbed on the surface.The reduced number of α-helixs is 90% of that without adsorption.However,the reduced number of β-sheets is 45%,and that of contacts is 35%.That is to say the effect of adsorbed energy on α-helix is the most,while effect on contact is the least.On the other hand,the fluctuations of the number of α-helix, β-sheets and contacts δNh,δNb are not changed at εa2εh.A peak is shown at εa=3εh,which is the transition point of secondary structure.Phase behavior of secondary structure is found with adsorbed energy changing.The fluctuation of the number of contact δNc and adsorbed residues δNa has the maximum at εa=3.75εh.
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发布时间：2021-03-19 - 摘要：The uniform dispersion of carbon nanotubes in the high viscous polyether polyol was obtained by a mechanochemical ball milling process with the aid of dispersing agent.Polyurethane (PU) /carbon nanotubes (CNTs) composite foams were prepared by a further in-situ polycondensation.The stability of MWNT/polyol suspension was studied by a centrifugal approach.The microstructure of the obtained PU/CNTs composite foams were characterized by FTIR and SEM.The compression strength and water retention rate were also measured.It indicated that the multi-walled carbon nanotubes (MWNT) can be dispersed individually and stably in polyol.The SEM images suggested that 0.4 wt% CNTs can make the pore size more homogeneous,but as the CNTs content increased to 0.8 wt%,the pore becomes much bigger due to the high viscosity of the reaction system.As the CNTs content increased,the compression strength of the composites become higher.With the aid of 0.8 wt% carbon nanotubes content,the compression strength of the PU/CNTs composite foams were dramatically enhanced to two times compare to blank PU.Water retention rate was also improved 60% with the aid of 0.8 wt% CNTs.
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发布时间：2021-03-19 - 摘要：9,9-Bis(4-hydroxyphenyl)xanthene (BHPX) was synthesized with good yield from xanthenone in one-pot,two-step synthetic procedure.A novel cardo poly(ether ether ketone ketone) (PEEKK-X) containing xanthene structure was successfully prepared via a typical nucleophilic aromatic substitution polycondensation of BHPX and 1,3-bis(4-fluorobenzoyl)benzene with the use of sulfolane as solvent.The polymer was characterized by FTIR,DSC,TGA and WAXD,etc.The results showed that the polymer had excellent heat-resistance,the glass transition temperature (Tg) was 215℃.The onset temperature taken at 5% weight loss of the polymer in nitrogen was 558℃.The polymer was noncrystalline and was soluble in common organic solvents such as DMF,DMAc,NMP and CHCl3 at room temperature.The polymer formed transparent,strong and flexible films with tensile strength of 81.5 MPa,Young’s moduli of 2.48 GPa and elongation at break of 16.8%.
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发布时间：2021-03-19 - 摘要：A double metal cyanide complex catalyst (DMC) was used to catalyze the ring-opening polymerization of γ-glycidoxypropyltrimethoxysilane,and homopolymers PKH560 with regular structure were obtained.The molecular structure of the polymer was analyzed and characterized by FTIR, 29Si-NMR and 1H-NMR.It was found that DMC can successfully catalyze the ring-opening polymerization of γ-glycidoxypropyltrimethoxysilane,and polymers of high molecular weight were obtained.The number average molecular weight was greater than 10000,and the molecular weight distribution index was between 1.10 and 1.35,both of which were measured by gel permeation chromatography/multi-angle laser light scattering (GPC/MALLS).By varying reaction time,the polymers with different number average molecular weight were obtained.The results of GPC/MALLS show that the number average molecular weight of polymers and the monomer conversion present a linear growth relationship,and the molecular weight distribution of polymers is also narrow (Mw/Mn is between 1.10 and 1.35),which indicate that the polymerization has a characteristic of living polymerization.
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发布时间：2021-03-19 - 摘要：Polylactide (PLA)/poly(ethylene oxide) (PEO) blends were prepared by melt-mixing, and the influence of molecular weight of PEO on the thermal-mechanical properties and rheological behaviors of the blends was investigated.Four kinds of PEO with molecular weight of 2 kDa (PEG2),10 kDa (PEG10),100 kDa (PEO100) and 600 kDa (PEO600) were used in this study.It was found that all PEOs were miscible with PLA to an extent of ca. 20 wt% and their quenched blends were completely amorphous.The decrease of Tgshowed the plasticization effect of PEO on PLA.When the molecular weight of PEO was over 10 kDa,the plasticization effect was not dependence on the molecular weight of PEO,which did not decrease with the increase of molecular weight of PEO.Increasing the molecular weight of PEO can increase the tensile modulus and melt intensity of PLA/PEO blends,while the ductility of the blends was not decreased.All blends with 20 wt% PEO had a similar elongation at break of about 330%,but tensile moldulus of the blends changed from 250 MPa for the PLA/PEG2 blend to 550 MPa for the PLA/PEO600 blend.The rheology experiments indicated the G′increased significantly with the increase of molecular weight of PEO for the blends with same composition.
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发布时间：2021-03-19
Research Bulletin
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