最新刊期
卷 ， 期 3 ， 2000
- 摘要：By reaction of urushiol and MoOCl4, the urushiol-molybdenum chelate polymer was prepared which possessed properties of lacquer and chelate. This reaction forms non-dissolving,non-melting and black precipitates of urushiol-molybdenum chelate polymer.The Mo percentage by weight of polymer prepared by different reaction condition was measured. The reaction mechanism,structural characteristics and properties of the polymer were also investigated. The polymer has been characterized by ESR,XPS,GPC,IR,MS,TG and elementary analysis. The results have confirmed that the redox reaction ,coordination reaction and then polymerization occur in the process of formation of the polymer.The moiety of (C21H30O2)2MoOCl exists in the polymer.ESR analysis showed the atom Mo in the polymer exists in 5-valence.TG analysis shows that the polymer exhibits good resistance to heat.
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发布时间：2021-03-19 - 摘要：The dissolving properties of polyelectrolyte complex (PEC) in a new solvent system,an aqueous solution of ionic surfactant,were studied.The effect of the structure and content of the surfactant,temperature and the inorganic electrolyte added in the solution was investigated.The morphology of PEC dissolved in the aqueous solution was studied by using SEM technique.It was found that the increase of temperature and the carbon chain length of the ionic surfactant may promote the dissolving of PEC,and the addition of a small amount of inorganic electrolyte such as sodium chloride is also beneficial to the dissolving of PEC. It is supposed that the dissolving mechanism of PEC is the cooperating results of the dissociation function and the hydrophobic action of the ionic surfactant.
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发布时间：2021-03-19 - 摘要：A kind of ion-type hydrophilic comonomer was synthesized and utilized in the IBMA/MMA/BA emulsifier-free emulsion polymerization system.The particle size and flow behavior of the latexes,dynamic mechanical properties,tensile behavior,and water resistance of the copolymers,as well as the nucleation mechanism of latex particles were investigated.The experimental results showed that with the addition of hydrophilic ion-type reactive comonomer,latexes with particle size of about 0.6μm can be obtained and the solid content of stable latexes can reach as high as 60%,showing Bimgham flow characteristics.Only a single glass transition temperature appeared in the dynamic mechanical spectra indicating atactic copolymers were obtained.The tensile strength and water resistance are higher than those of samples parpared by conventional emulsion polymerization method.
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发布时间：2021-03-19 - 摘要：New copolyetherketones were synthesized from 4,4′-difluorobenzophenone,2,2′,3,3′,6,6′-hexaphenyl-4,4′-diphenyl-1,1′-diol and hydroquinone via polycondensation.The technique of 13C-NMR was employed to determine the content of the two bisphenols in the copolyetherketones.The chain structure was characterized by illustrating the average block length (LA,LD) in terms of the portion of different triads (AKA,DKD,AKD).The synthesized copolyetherketones have the properties of excellent solubility,high heat-resistance,goodtensile strength and good selectivity for gas permeability.
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发布时间：2021-03-19 - 摘要：A maleited impact modifier (TPEg) with polyethylene-octene rubber shell and semi-crystalline polymer core was used to toughen non-crystalline copolyester (PETG) resin.TPEg has a significant toughening effect on PETG.A sharp transition from brittle to super-tough states for PETG/TPEg blends occurred when the TPEg content was up to 10%.Although the maleited polyethylene-octene rubber (POEg) also results in a brittletough transition, this transition takes place at a higher POEg content indicating that the loss of thensile strength and modulus of PETG blends in more serious.The effects of TPEg on impact toughness of PETG blends are well reflected rfom their evolution processes of topography and morphology formed during the impact fracture testing.The impact fractured surface of PETG blend with 5 wt% TPEg exhibits a very small area of its slow crack growth region and feather-like markings in itsfast crack growth region under low magnification,indicating a brittle appearance.Whereas the impact fractured surface of PETG blend with 10wt% TPEg exhibits a very large area of its slow crack growth region and some parabola-like markings in its fast crack growth region under low magnification.Moreover,an extensive shear yielding of matrix can be seen both in the slow and the fast crack growth regions of the PETG/TPEg(90/10)blend under high magnification.It may dissipate a significant amount of impact energy,therby responsible for the super toughness.
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发布时间：2021-03-19 - 摘要：The Lagrangian-eulerian method has been used to simulate two dimensional creeping flows of Newtonian fluids in various flow fields.For Poiseuille and Couette flow and flow between rotating cylinders,the numerical results have been directly examined by the analytical solutions. For the flow around a cylinder between parallel plates, the present results are compared with the previous reports given by Mitsoulis and Liu et al.. The dimensionless drag of 130.94 is consistent fair well with the values given by Mitsoulis (132.31) and by Lu et al.(132.34),respectively.For the flow through abrupt contraction geometry,the numerical results have been compared with the experimental observations of Nguyen and the numerical prediions of Viriyayuthakorn and Caswell. The size of the upstream vortex,measured in terms of a dimensionless re-attachment length is 0.18,excellently agrees with the previous reports.For the flow through reounded re-entrant corner,excellent agreement between the present results and the experimental observations of Walters and Webster is obtained. In conclusion,the Lagrangian-Eulerian method has predicted accurate results for all cases of the flows presented in this paper.
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发布时间：2021-03-19 - 摘要：Free-radical solution copolymerization of itaconic acid (IA) and acrylonitrile (AN) was carried out in DMSO at 60℃ using azodiisobutyronitrile (AIBN) as initiator.The resulting polymerization solution was spun to form PAN precursors of carbon fibers,which were then characterized by elemental analysis,IR, 13C-NMR, DSC and so on.The effect of the itaconic acid content in copolymers on the structure and properties of PAN precursors was investigated.The comonmer content in the copolymer was analyzed quantitatively by IR.The adequate feed ratio of AN/IA was found to be 98/2(W/W).Copolymers having about 2 mol% of comonomer appeared to have higher isotacticity as calculated from methine group signals in the 13C-NMR spectra.Furthermore,in the case of P(AN-co-IA)copolymers,the cyclization may start at a lower temperature and propagate at a slower rate.
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发布时间：2021-03-19 - 摘要：N-phenylmaleimide(PMI)is used to copolymerize with vinyl chloride (VC) for improving the heat resistance of PVC,but the instantaneous and integral copolymer compostition varies greatly with conversion for vinyl chloride/N-phenylmaleimide copolymerization systems.The recurrence method deduced from Mayo-Lewis equation was applied to investigate quantitatively the variations of copolymer compositions wtih conversion for VC/PMI suspension copolymerization.The copolymer compositions can be controlled andzed by means of selecting a third monomer and its content.For VC/PMI suspension copolymerization,acrylonitrile(AN)was preferably selected to improve copolymer conposition homogeneity in order to improve heat resistance and other properties.The ranges of monomer feed fraction with the copolymer composition error of PMI lower than 0.05 ot 0.1 was gained,which could direct the study on VC/PMI/AN suspension terpolymerization.On the basis of the prediction,controland optimization of the copolymer composition variation with conversion and the features of the polymerization technology,the optimum region of monomer feed fraction for VC/PMI/AN suspension terpolymerization was obtained.
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发布时间：2021-03-19 - 摘要：The complex formation between Cu(Ⅱ) and chitosan was studied in aqueous solution at different pH values.The composition and structure of chitosan-Cu(Ⅱ) complexes were characterized by elemental analysis,infrared spectra,thermograms and X-ray diffraction.The ratios of glucosamine residue of chitosan molecule to Cu(Ⅱ) are 8∶3,4∶3 and 1∶1 at pH=5,6 and 7, respectively.The results of IR spectra indicated that the —NH2 and —OH of the secondary alcohol of chitosan molecules are coordinated to Cu(Ⅱ). New peaks at 555,532 and 551,551cm-1 appear in the chitosan-Cu(Ⅱ) complexes at pH=6 and 7,respectively.The absorption at 550cm-1 si suggested to be the asymmetric Cu-O vibration and absorption at 511cm-1 could be related to hydroxy-bridged compounds.The marked difference of X-ray diffraction patterns between the chitosan and its complexes indicated thaat the coordination of chitosan to Cu(Ⅱ) could be correlated with the conformation change of chitosan molecules at pH=6 and 7.Chitosan has three steps in the thermal weight loss process,but the complexes have four steps.Considering chitosan being a linear truck poolysaccharide of anti-appeal arrangement,together with its other physical properties,such as solubility and crystallinity,it can be concluded that the complexes of chitosan with Cu(Ⅱ) in the dilute formic acid solution of pH=7have the hydroxy-bridged structure.
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发布时间：2021-03-19 - 摘要：The extensional flow behavior of a modified PET/PHB type thermotropic liquid crystal copolyester (LCP80) was studied by using the contraction flow method with a capillary rheometer.The investigation focused on the effects of the extensional strain rate and temperature on the extensional viscosity and Trouton ratio through experimental measurements.The nematic texture variation and molecular orientation during extensional flow at various temperatures were also observed.Experimental results have shown that the entrance pressure losses,which decreased with temperature and increased with the flow rate,were particularly large.The entrance pressure loss reached about 30% of the total pressure drop even at L/D=50,which was significantly larger than that of conventional polymers.It meant that the end correction in the capillary rheometer could not be omitted even when a long capillary is used.In the entrance pressure loss the extensional component was dominant and the shear component was less than 4% in all cases.This was attributed to the orientation development due to extensional flow as the polymer flew through the comverging entry section,which was confirmed by the macroscopic ordered texture development after extension.At extensional strain rates from 1 to 100 s-1,LCP80 exhibited extension thinning,this phenomenon was more obvious at temperatures above 300℃ due to the increased orientation ability of the rigid molecule chains.The extensional viscosity and the shear viscocity both could be empirically described by the power law model at various temperatures,but the model parameters were quite different.Besides,the Trouton ratios,decreasing with the temperature and extensional rate,were always much greater than the Newtonian values,indicating a high elasticity of the LCP80 melt. The above rheological properties were explained according to the texture observation.
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发布时间：2021-03-19 - 摘要：The improvement of mechanical properties of high-density polyethylene(HDPE) and polypropylene (PP) blends was studied by controlling the phase compatibility versus phase separation．In the original injection molding processes,super mechanical properties of blend specimens have not been goteasily．Researches have been carried out in injection molding with high shear injection conditions．It has beenpointed out that the compatibility of blends will increase under the strong shear in injection processes due to the raise of LCST culwe．After the melt is injected into the cold mold．its temperature and compatibilitydecrease simultaneously,phase separation takes place and becomes frozen in the specimen．High mechanicalproperties will be got when the phase separation develope to some extent,but it is difficult to control thephase compatibility and separation The special method of oscillating packing injection molding under lowpressure provides a condition to control the phase separation degree．Because the phase morphology and crystal morphology of HDPE／PP blends compete with each other,it is difficult to control the micro-phaseseparation．In this paper,the fine struture combined with the micro-phase separation and orientation were controlled by using that special injection method and high strength and high toughness blends were obtained．DSC and WAXD results indicate that the improvement of tensile strength is dependent on the number of shish-kebab crystals and the degree of macromolecule orientation caused by the oscillating packing injection molding．SEM results indicate that the impact strength is dependent on the degree of macro-and micro-phase separation．The high tensile strength 97．1MPa and high toughness 45．5kJ／m2 of HDPE／PP blends were achieyed When the PP content in the blends was 8％and 20％．respectively．Which are 4.3 times and 9.5 times as high as the corresponding values of their static specimens respectively．The future work Will be carried out to investigate the phase morphology and crystal morphology as well as thepossibility of cocrystallization of PP and HDPE under oscillating packing injection conditions．
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发布时间：2021-03-19 - 摘要：The effects of oxygen on butadiene-styrene copolymerization initiated with n-BuLi were studied in this paper.The number of reactive species were investigated by the methods of polymerization kinetics and molecular weight.It was found that lithium reactive species could be killed by oxygen molecules.One oxygen molecule could kill two lithium reactive species.With the increase of the conversion and the oxygen contents,the number of reactive species decreased.The effects of the second-generation impurities on anionic reactive species and microstructure of copolymers were also introduced.At the same time,the coupling effect of oxygen was found to be obvious.With the increase of the oxygen contents and the reaction temperature,the coupling efficiency increased and the properties of styrene-butadiene copolymers were affected by the coupling efficiency of oxygen.With the increase of the coupling effect of oxygen,the vulcanized rubber could may exhibit an increased rolling resistance and a reduced wear resistance.
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发布时间：2021-03-19 - 摘要：A series of water soluble terpolymer (P3A) acrylamide/2-acrylamido-2-methyl propanesulfonate/acrylic acid (AM/AMPS/AA) with high molecular weight was obtained by partial hydrolysis from the corresponding (AM/AMPS) copolymers (P2A).The structure and composition of polymers prepared were characterized by potentiometric titration and 13C-NMR spectroscopy.The results obtained show that in the given experimental conditions the AMPS units of polymers (P2A) are stable enough in the hydrolysis process,while the acrylamide groups transform into acrylic acid smoothly.In all cases of various copolymers (P2A)the amide hydrolysis obeys an auto-retarded kinetic model due to the electrostatic repulsion between anionic groups and OH- ions.Finally the hydrolysis reaction rtends to a conversion limit,and the residual AM units is around 30mol%.The relationships between the intrinsic viscosity and compositions of various terpolymers(P3A)were also studied in detail.
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发布时间：2021-03-19 - 摘要：Silylate-terminated polyurethanes with built-in hydrophilic sites were synthesized.When the polymer is dispersed in water,the silane alkoxy end-groups of the polymer undergo hydrolysis,followed by condensation to form a stable cross-linked aqueous dispersion.TEM studies indicated that with more incorporation of hydrophilic sites,the particle size of the dispersion decreased.It was also found that the film property depended on the particle size when the crosslinking density in particels was much higher. The average molecular weight of the elastically effective network chain Mc measured by swelling experiments shows fairly good agreement with the theoretical value of Mc.It was also found that the cross-linking density of the casting film may increase during the film formation and drying process.
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发布时间：2021-03-19 - 摘要：Amphiphilic graft copolymers of acrylic acid with uniform polystyrene grafts were prepared by copolymerization of acrylic acid with polystyrene macromer using AIBN as initiator and dimethylformide as solvent.Effects of various factors,including copolymerization temperature,time,total monomer concentration,molecular weight of the macromer and charging ratio of the macromer to monomer on grafting efficiency and molecular weight of the copolymers were studied and optimum conditions were obtained.The crude products were purfied by extractions with water and toluene successively.The purified graft copolymers exhibited good emulsifying properties and high water absorbency.Their dilute solution behaved as polyelectrolyte,Their intermolecular complex membrane with poly(ethyl acrylate)containing uniform polyoxyethylene grafts behaved like a chemical valve, since its permeability can be controlled reversibly via change of pH value.
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发布时间：2021-03-19 - 摘要：Ketopinyl peroxide (KPO) was synthesized by the reaction of ketopinyl chloride with Na2O2 in the presence of 15-crown-5.The reaction of KPO with Cr(II) formed radicals,anions and Cr(III)s. The radicals existed as “free” radicals and in the form complexes which consisted of radicals,anions and Cr(III)s. After aging of the redox system,the “free” radicals were terminated by the coupling reaction,but radicals in the complexes were relatively stable due to the β-keto group and steric effect,and initiated methyl (meth).acrylae to polymerize with "living"characteristics,when polymerization was carried out bellow 30℃.Other monomers,vinyl acetate,hydroxyethylene methacrylate and acrylic acid (AA) could be polymerized using this initiator system and crosslinked PAA was obtained in several minutes.The initiator efficiency (f) of the aged KPO and Cr2+ was intensively affected by the aging temperature,and varied from 30% at 0℃ to 5℃ at 20℃.
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发布时间：2021-03-19 - 摘要：Poly(L-lactide) (PLLA) rods with high strength were prepared by fibrillated compression molding in a special mold designed for this purpose.It was showed that this compression molding method had a great effect on enhancement of the mechanical strength of the molded materials. PLLA rods (∮3.2mm) with bending strength and shear strength of 250～280 MPa and 170～185 MPa respectively were obtained by using PLLA materials of molecular weight (Mv) ranged from 53×104 to 76×104 and compression molding at 140℃.The molecular weight of PLLA reduced by 65% to 70% in the process of preparing billets due to its thermal instability,but the influence of compression molding on the molecular weight was not significant.SEM observation showed thatthe PLLA billet underwent oriented deformation and formed fibrous structure during compression molding,and this is the reason why the mechanical strength of the PLLA rods can be enhanced.Analytical results of differential scanning calorimetry (DSC)and X-ray diffraction (XRD) indicated that after compression molding,the melt temperature of PLLA crystals decreased while the degree of crystallinity increased.
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发布时间：2021-03-19 - 摘要：Magnetic nanoparticles,containing a magnetic core and a polymer shell, were synthesized by coating magnetic fluid with chitosan. Novel affinity magnetic microspheres were obtained after immobilizing dye\|ligand (Cibacron Blue 3GA)onto the nanoparticles by covalent coupling. Under the preparation conditions, the microspheres had a spherical appearance, narrow distribution of diameter, and 14.5μmol/mL immobilization capacity for reactive dye. The microspheres can be separated by magnetic field. Bovine serum albumin (BSA) and lysozyme (Lys) were used as target proteins to examine the adsorption properties of the adsorbent. Under appropriate conditions,the adsorbent had a capacity of 4 and 28mg/g for BSA and Lys, respectively,Adsorption could be expressed by the Langmuir adsorption model.Unlike adsorption time,the liquid phase ionic strength affects the adsorption prperties dramatically.
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发布时间：2021-03-19 - 摘要：The micellar conformation of polymeric surfactants CMC-AR12EO9 in aqueous solutions was studied by dynamic laser scattering and environmental scanning electron microscopy. The results show that the conformation of copolymer molecules is totally different from that of carboxy methyl cellulose because of the introduction of the surface active macromonomers. CMC-AR12 EO9 molecules aggregate to from rod-like micelles with hydrophobic cores. It is confirmed that the micelle size distribution function F(R) is dependent on scattering vector.So the micelles of CMC-AR12EO9 are not like sphere.In the range of concentration tested,the normalized first-order autocorrelation function g(1)(τ) of CMC-AR12EO9 can not be represented by single-exponential decays,which indicates polydisperse distributions of micelle sizes.At different concentrations,the sizes of micelles all distribute in two regions (low and high size). With the increasig of copolymer concentration,the lower size region remains in 30～100nm and is considered to be the region of mono-molecular micelles. While the particle size in higher size region increases gradually,which means that multi-molecular micelles are growing larger.
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发布时间：2021-03-19
Research Article
- 摘要：Nitrato-terminated polyalkylene glycols were synthesized from nitrating glycols with nitric acid and sulfuric acid in methylene chloride. Then azido-terminated polyalkylene glycols were prepared by a nucleophilic reaction of the nitrato-terminated polyalkylene glycols with sodium azide in different phase transfer catalytic conditions. All synthesized polymers were characterized by 1H-MNR, FT-IR, GPC and elemental analysis.
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发布时间：2021-03-19 - 摘要：Low temperature plasma has been used to modify the surface properties of polymers to a large extent. The effects of ECR microwave plasma with carbon dioxide (CO2) on the wettability of the poly(phthalazinone ether sulfone ketone) (PPESK) surface were discussed. Results showed that a shorter treatment time and a higher discharge power could give the best wettability of PPESK films. The toughness of the treated film surface increased with the discharge power. The wettability of PPESK films treated by CO2plasma declined with the aging time after treatment,and the changing rate of different power isresemble. The increase in water contact angle for plasma treated PPESK surfaces upon ageing is mainly ascribed to the surface rearrangement of macromolecular segments,the loss of oxygen-containing moieties introduced by the plasma treatment. ESCA analysis of CO2 plasma treated polymer surfaces showed that carbonyl groups could be increased by carbon oxide plasma treatment in short time.
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发布时间：2021-03-19 - 摘要：A diphenoxybis(βdiketonato)titanium complex, (dbm)2Ti(OPh)2, was synthesized and the corresponding MgCl2-supported catalyst was prepared by impregnation method. The polymerization activity was drastically improved by using MgCl2-supported (dbm)2Ti(OPh)2 activated by aluminoxane (MAO) for ethylene polymerization (1.5×105g/molTi with the heterogeneous catalyst and 1.3×103 g/molTi with the homogeneous one). When the molar ratio of Al to Ti increased from 50 to 1000, the crystallinity and molecular weight of polyethylene were decreased rapidly.Also,The molecular weight of polyethylene was decreased from 5.1×105to 2.8×105by increasing the molar content of titanium of the supported catalyst from 0.5×10-5 to 3.42×10-5.After 60 min of the reaction,the molecular weight was at 5.0×105or so. It is revealed that the MgCl2-supported β-diketonato titanium complex is influenced by the polymerization conditions markedly.
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发布时间：2021-03-19 - 摘要：Initiation and termination of crazes in high impact polystyrene (HIPS) were studied by transmission electron microscope. Instead of the first initiation of crazes in the vicinity of the equator or rubber particles, ribbon-shaped crazes beyond the region were observed on the TEM photos. The starting point and the end point of each ribbon were noticed not to be randomly located on the surface of the cellar particles in HIPS. The spots connecting to the ligaments between the PS rigid inclusions in the cellar particle are found to be the locations where crazes were initiated and terminated preferentially. In addition,the crazes generated at those spots were much thicker and longer.The thoughness of high impact polystyrene was enhanced by the multiple crazes formed in the matrices,through the reduction of the craze dispersed phase.These results conucted that not only the cell structure of the domains in HIPS was not homogeneous but alsoo the polybutadiene ligaments between PS rigid inclusions in the domains were inhomogeneous.Therefore,the responsibility of those polybutadiene ligaments with different thickness to the stresses was different and it forced the crazing initiation and growing preferentially.The crazes were created in some rehions in the matrices; On the contrary,rare crazes were formed in the other regions in spite of these regions surrounded around the same dispersed particles.The relation between the spots on the surface and the inner structure of the cellar particle was discussed in this paper.
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发布时间：2021-03-19 - 摘要：A method for preparing 3D ordered macroporous silicate materials was developed by using the ordered stacking structure of monodispersed polystyrene latex as a template. By using a modified sol-gel procedure, the ordered template was permeated and filled with silicate, and the title porous materials was formed after removing the template by calcination at high temperature. Moreover, the pores were highly ordered throughout all the sample. After observing the morphological profile of the sample before calcination,it was found that silicate existed in two typical morphologies: monodispersed particles in the cavities and interconnected network within the interstice of the template.The transition morphology was rod-like formed by the condensation of the silicate monodispersed particles. Two aspects concerning with the template effects of the ordered latexx film were emphasized: the polymeric spheres may result in orderly packed holes after calcination,and the dielectric interfacial layer surrounding the polymeric spheres may induce the formation of monodispersed silicatheres with ordered stacking.Both aspects played important roles in the formation of the highly orderd inorganic poous materials by calcination the gel at high temperature.
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发布时间：2021-03-19 - 摘要：The polymerization of γ-stearyl-L-glutamate-N-carboxyanhydride (SLGNCA) initiated by tetra(4-aminophenyl) porphyrin(TAPP) and bi(4-aminophenyl) porphyrin(BAPP) was investigated. The experimental results indicated that TAPP and BAPP can initiate the ring-opening polymerization of SLGNCA. The initiators have high activity and the products have high molecular weight while SLGNCA/TAPP is 50 and SLGNCA/BAPP is 25. The polymers were characterized by IR,UV,FR,1H-NMR and GPC/fluorescence technigues.It was proved that porphyrin linked covalently to the polymer chains and the products with porphyrin displayed and a-helical conformation.It is supposed that the polymer with BAPP (PSLG/BAPP)may present as monomolecular and bimolecular aggregation in THF and as monomolecular in CHCl3.
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发布时间：2021-03-19 - 摘要：The polymerization of tetrahydrofuran(THF) initiated by heteropolyacid—H3PW12 O40(PW12) in low concentrations could be effectively promoted by epichlorohydrin(ECH).However, the promotion activity of ECH is lower than that of EO or PO, especially when water was introduced. The polymerization started upon addition of epichlorohydrin.When the polymerization has stopped, it could be re-initiated with the addition of a new portion of ECH. The products were found to be copolyether glycols with hydroxyl groups at both ends.The percentage of the hydroxyl group attached to ECH moieties at the polymer chain-ends was higher than 50% of the total hydroxyl end-groups.Most of the ECH moieties in chains attached to hydroxyl end groups,and no primary hydroxyl groups derived from ECH could be detected.
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发布时间：2021-03-19 - 摘要：A new monomer-iniferter,allyl 2-N,N-diethyldithiocarbamylacetate (ADCA),was synthesized from allyl alcohol with chloroacetyl chloride then the chlorine groups were subsequently reacted with sodium diethyldithiocarbamate. The ADCA was used for preparation of well-defined functionalized polystyrene via radical polymerization of styrene (St) in bulk under UV light irradiation at ambient temperature. The bulk polymerization of St with ADCA proceeded a “living" process, i.e., both the yield and molecular weight of the resultant PSt increased with the increasing of reaction time,and the average number of end group Et2NCSS is about 1. The well-defined polymer was characterized by 1H-NMR and FT-IR spectroscopies to be an a-allyloxycarbonylmethylene-ω-diethyldithiocarbamyl-polystyrene.Under UV light irradiation,the C-S bond of ω-end groups of PSt can cleavage reversibly to initiate MMA polymerization forming a well-defined PSt-b-PMMA copolymer.
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发布时间：2021-03-19 - 摘要：Modified rhodamine 6G molecules (Rh-Al)with polymerizable double bonds were copolymerized with methyl methacrylate(MMA) and 1,8-naphthalimide derivative(N-AE).The structures of the two monomers(Rh-Al and N-AE)were confirmed and characterized by 1H-NMR and MS. The UV-Vis absorption spectra of the copolymer indicate that there is little or no interaction between the two chromophores in their ground state. However, the fluorescence emission of N-AE was partly quenched and the fluorescence emission of Rh-Al was enhanced in the copolymer.While the fluorescence emissions of N-AE and Rh-Al both were partly quenched in the corresponding mixture.The results show that in the excited state exists very effective intramolecular singlet-singlet energy transfer(Intra-SSET)channel from N-AE to Rh-Al in the copolymer.The experiments seem to indicate that the covalent binding of the chromophore to a polymer chain restricts its mobility and,therefore,hinders the internal micromotions of the excited groups,avoiding non-fluorescent deactivation and thus increasing its emission efficiency and photostability.
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发布时间：2021-03-19 - 摘要：Considering the inhomogeneity of the concentration distribution in the corona of a star-shaped micelle, an equation system of free energy components was suggested in order to predict the micro-phase separation of the diblock copolymer in selective solvents. All energetic and entropic contributions to the free energy of micellization were included in equations for the micellar solution, which was composed of the di-block copolymers with certain molecular weights and the solvent with special characters at a giving temperature.The minimization of free energy produced the equilibrium size and aggregation number of the micelle.The corona and core size of the micelle,the concentration profile of the soluble block in corona and the value of the aggregation number wereobtained based on the present theory.Moreover,the theoretical predictions of the aggregation number were in good agreement with the experimental data for systems of polystyrene-poly(2-cinnamoylethyl methacrylate)/cyclopentane and poly(4-vinylpyridine)-polystyrene/toluene.
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发布时间：2021-03-19 - 摘要：The interaction of cetyl trimethylammonium bromide (CTAB)and an anionic copolymer derived from 3-sulfopropylmethacrylate, potassium salt (SPMS) and styrene (St) in aqueous solutions has been studied. It was found that the viscosity of the anionic copolymer-CTAB solution rises suddenly in a specific molar ratio of CTAB/anion. For instance, the viscosity of polymer (No.1) solutions increases to about 20 times at CTAB/-SO3K=1.0～1.05, and increases to about 100 times at CTAB/-SO3K=1.4～1.5. In the caseof polymer samples No.2 and No.3,the changes of solution viscosity are similar to that of sample No.1,but the gelation takes place at CTAB/-SO3K=1.4～1.5 region because of the lower negative charge density on No.2 and No.3 polymer chains.It is proposed that the dramatical change of the P(SPMS-co-St) aggregates. This consideration was verified by fluorescence determination and laser light scattering experiments.Using DMAF as fluoresscent probe,the hydrophobic microdomain existed in P(SPMS-co-St)/CTAB aqueous solutions in the viscosity rising region has been confirmed and it is in agreement well with the results obtained by laser light scattering determination.
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发布时间：2021-03-19
Research Bulletin
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