最新刊期
卷 ， 期 5 ， 2009
- 摘要：Two series of novel main chain liquid crystalline copolyesters with biphenyl-mesogenic units and azo type crown ether cycles were prepared via solution polycondensation from 4,4′-(α,ω-alkanedioyloxy)dibiphenylyloyl dichloride (M1), cis－4,4′-bis(4-hydroxy-phenylazo)dibenzo-18-crown-6(M2), trans 4,4′-bis (4-hydroxy-phenylazo) dibenzo-18-crown-6 (M3) and 1,10-decanediol (M4) as the monomers.The intrinsic viscosity ［η］ of the two series of copolyesters ranges from 0.25～0.35 dL/g and 0.27～0.38 dL/g,respectively.The structures of monomers were identified by elemental analysis,IR,UV-Vis,1HNMR and MS.The properties of copolyesters were investigated by using DSC,TGA,WAXD and POM.All the copolyesters are able to form nematic mesophase after melting.The threaded texture,or ball granul texture or Schlieren texture of nematic phase can be observed on POM.Their melting temperature (Tm) and isotropic temperature (Ti) decrease regularly with increasing the length of flexible spacer in the copolyesters,and the Tm and Ti of copolyesters containing trans crown ether cycles are higher than those of the copolyesters containing cis crown ether cycles.
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发布时间：2021-03-19 -
NUCLEATION PROCESS AND NUCLEATION MECHANISM OF MMA/BA SEEDED SEMI-CONTINUOUS EMULSION POLYMERIZATION
摘要：A water-insoluble dye (BL-S) was used as a probe to study the influence of some factors on the process of nucleation and nucleation mechanism in seeded semi-continuous emulsion polymerization.Some parameters were analysed for quantitative study on nucleation mechanisms,the parameters include the amount of dye incorporated into the resultant latex particles (Pdye),number of the resultant latex particles (Ncp) and the different numbers of particles which are formed by micellar nucleation (Nm) and homogeneous nucleation (Nh).The results of the study and analysis show that Pdye,Nh,Nm and Nh/Ncp all increase with increasing initiator concentration ［I］,but Nm/Ncp decreases as Nm/Ncp=-0.0262［I］+0.8833,which can illuminate the proportion of homogeneous nucleation increases while micellar nucleation decreases with increasing ［I］.The influence of the emulsifier concentration ［E］ on nucleation mechanisms is different at different concentration range,when ［E］ equals to 0.7216×10-2 mol·L-1,the proportion of homogeneous nucleation is equal to micellar nucleation,both of them are 50%.When ［E］ is greater than 0.7216×10-2 mol·L-1,the nucleation time t1,2 decreases and Nm/Ncp increases with increasing ［E］,Nh/Ncp decreases accordingly,and the proportion of micellar nucleation is larger than homogeneous nucleation,so that the micellar nucleation mechanism predominates gradually in the particle nucleation process; when ［E］ is less than 0.7216×10-2 mol·L-1,the proportion of micellar nucleation is less than homogeneous nucleation,the main nucleation mechanism becomes to homogeneous nucleation.In the system of MMA/BA copolymerization,when fMMA increases from zero to 06,the value of Nm/Ncp decreases from 80.93％to 50％,which means that the proportion of micellar nucleation is larger than that of homogeneous nucleation,so that micellar nucleation plays a key role in the particle formation period.When fMMA increases from 0.6 to 1,Nm/Ncp is reduced to 40% and Nh/Ncp is raised to 60％,but homogeneous nucleation is more important than micellar nucleation in this system.In addition,the t1,2 is 12 min and 6 min for the conventional and seeded semicontinuous emulsion polymerization,respectively,but Pdye change is less.All these show that the both semicontinuous emulsion polymerization techniques only have some effect on the formation process of particles and the neculeation time,but little effect on their specific nucleation.- 12
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发布时间：2021-03-19 - 摘要：Interpenetrating network (IPN) hydrogels composing of poly(N-isopropylacrylamide) (PNIPAAm) using inorganic clay (Laponite XLS) as physically crosslinking agent and polyacrylamide (PAAm) chemically crosslinked by N，N′-methylenebis(acrylamide) (MBAAm),were prepared by ultraviolet irradiation polymerization.The structure of resultant IPN hydrogels was successfully characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM); the water retention at 50℃ was measured gravimetrically; dependence of storage modulus on temperature and phase transition behavior were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC),respectively.The results show that this kind of IPN hydrogels are temperature-sensitive,and,compared with inorganically crosslinking PNIPAAm hydrogels,these IPN hydrogels exhibit enhanced storage modulus and ultrafast response rate,such as losing water of 90% within 10 min because of the porous structure which provides the waterreleasing channel; by incorporation of PAAm network,the phase transition of PNIPAAm hydrogels is weakened,but the lower critical solution temperature (LCST) is increased.
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发布时间：2021-03-19 - 摘要：Recently structure and morphology of polymers under nanoscale confinements have attracted much attention. For semicrystalline polymer materials,the degree of crystallinity and the orientation of the crystalline domains are important factors in controlling their physical properties,and many efforts have been devoted to the understanding of crystallization and orientation of polymers in nanocylindrical confinements. In this paper,polyethylene nanofibers of 200 nm diameter were prepared by infiltrating porous anodic aluminum oxide (AAO) templates with polymer melt,and the crystallinity and orientation of polyethylene crystals in the nanofibers were studied by FTIR spectroscopy,polarized light microscopy (PLM),and Xray diffraction (XRD). FTIR results showed that the degree of crystallinity in the nanofibers was lower than that in the bulk due to the confinement of the nanopores,and the crystals formed in the nanofibers oriented preferentially with the b axis aligning parallel to the axial direction of the nanofibers,while the a axis was perpendicular to the nanofiber direction. XRD data further confirmed that the b axis of the crystals was parallel to the fiber direction. It was found that the nuclei located mainly at the interface between the nanotemplate and the polymer bulk and radially grew with the fastest crystallographic growth direction (b axis) toward the bulk and the nanofibers. The crystals formed in the bulk were typical banded spherulites,while in the nanofibers,only the crystals with the growth directions compatible with the cylindrical confinement imposed by the pore geometry can grow bigger,and other growth directions were suppressed,leading to the preferred orientation of the crystals with the b axis aligning along the nanofiber direction.
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发布时间：2021-03-19 - 摘要：Graft copolymers (SPI-g-NH-PAMPS) were prepared by a graft reaction between the free carboxylic acid groups of soy protein isolate (SPI) and the amino groups of poly(2-acrylanmido-2-methyl propane sulfonic acid) (H2N-PAMPS) using 1-(3-(dimethylamino)propyl)-3-ethyl-carbodiimide hydrochloride/N-hydroxysuccinimide as the condensing agents in a buffer solution.H2N-PAMPS and SPI-g-NH PAMPS were fully characterized by 1H-NMR,FTIR and 13C-NMR spectroscopies.The aqueous solution properties of SPI and SPI-g-NH-PAMPS were studied by zeta potentiometer,UV-Visible spectroscopy,fluorescence spectrometer,dynamic laser light scattering (DLS).The charge of SPI-g-NHPAMPS measured by zeta potentiometer was negative within the whole pH range studied,which was due to the ionization of sulfonic groups of grafted chains.UV-Visible spectroscopy measurements demonstrated that the solubility of SPI was improved after the graft reaction,especially around the isoelectric point of SPI where it was increased by about 40%,because of the grafted hydrophilic H2N-PAMPS chains.Fluorescence probing studies with 1-anilinonaphthalene-8-sulfonic acid (ANS) in aqueous solution revealed that the surface hydrophobicity of SPI-g-NH-PAMPS was much weaker than that of SPI.The average hydrodynamic radius (h) of SPI aggregates measured by dynamic laser light scattering (DLS) was increased from about 140 nm to about 200 nm.TEM studies indicated that SPI-g-NH-PAMPS aggregates presented a unique core-shell structure because hydrophilic PAMPS long chains surrounded on the surface of SPI globulins,and formed more hydrophilic shell,and the average size of SPI-g-NH-PAMPS aggregates was also bigger than that of SPI aggregates.The graft reaction using EDC provides a new method to modify SPI and expands the application fields of SPI.
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发布时间：2021-03-19 - 摘要：The fabricating conditions for the in situ coacervated polyelectrolyte microcapsules were optimized,and their influences on the capsule structures and properties were elucidated.Poly(styrene sulfonate)(PSS) doped CaCO3 was first used as an additive to modify the growth of CaCO3 microparticles.During this process,the PSS molecules were integrated into the CaCO3 particles or adsorbed on their surfaces.By changing the feeding concentration of the PSS during the fabrication,the PSS doped CaCO3 particles with a PSS content of 4%～11% were obtained.After only one layer of poly(allylamine hydrochloride)(PAH) was adsorbed onto the PSS doped CaCO3 particles,the templates were dissolved by disodium ethylene diamine tetraacetate dihydrate (EDTA) to liberate the PSS molecules,which in situ coacervated with the coated PAH to form the capsule walls.After complete removal of the templates,intact complex microcapsules were successfully obtained.Results showed that all the CaCO3 particles with different PSS amount could be used as the templates to fabricate the coacervated microcapsules.The structures of the as-prepared microcapsules were characterized by confocal laser scanning microscopy (CLSM),transmission electron microscopy (TEM) and scanning force microscopy (SFM),finding no significant influence of the PSS doped amount in the CaCO3 particles.Compared with layer-by-layer (LbL) assembled polyelectrolyte microcapsules,the complex microcapsules shrank more seriously in 5 mol/L NaCl solution because their walls have net negative charge which is more sensitively screened by the salt.Due to the repulsion of the negative charge in the capsule walls,the complex microcapsules showed better ability against the thermal induced shrinkage.Because of the less ordered structures compared with the LbL microcapsules,the coacervated walls of the complex microcapsules possessed higher cut-off molecular weight.Therefore,one can conclude that the amount of the doped PSS in the CaCO3 particles has no significant influence on the structures and properties of the coacervated microcapsules,and thus the method is more attractive in terms of quality control.Moreover,the method can be extended to other polyelectrolyte systems as well,for example,natural biomacromolecules.
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发布时间：2021-03-19 - 摘要：Azo initiator 2,2′-azobis(isobutyramidine) dihydrochloride (AIBA) can be stably absorbed onto TiO2 particles by electrostatic action.The adsorbed AIBA can initiate the in situ anchoring of butyl acrylate from TiO2 particles surface,and thus poly(butyl acrylate)/TiO2 composite latex particles (PBA/TiO2) were prepared via in situ emulsion polymerization.It was found from centrifugation experiment and UV measurement that there was an upper limit of AIBA adsorbed on TiO2 particles surface,and its value was 0.084 mmol/g(relatived to the amount of TiO2) in pH=10 system.The adsorption of AIBA played a more important role both in polymerization behavior and in polymerization product.Only when the addition amount of AIBA was slightly less than the upper adsorption limit,the inhibition period was shorter,the polymerization rate and the monomer conversion were higher and the reaction stability were and the product stability were perfect.It was further proved by thermogravimetric analysis (TGA) and infrared spectrometry (FTIR) with soxhlet extraction experiment of PBA/TiO2 composite particles that 13.5% non-extraction poly(butyl acrylate) were anchored on TiO2 particles surface.It was also found from dynamic light scattering (DLS) that part of TiO2 softaggregation had been disaggregated stably,and both the dispersion and dispersion stability of TiO2 particles in latex can be significantly improved because of the anchoring modification of TiO2 by PBA.This action resulted from anchoring modification,in essence,was different from the reversible disaggregation action of ultrasonication treatment onto TiO2 softaggregation.Thus,this study is favourable for maintaining the good dispersion and dispersion stability of nanoscale inorganic particles in organic matrix during its application in the fields of coatings,painting,plastics,rubber,textile,and cosmetic.
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发布时间：2021-03-19 - 摘要：RAFT dispersion copolymerization was carried out using methyl methacrylate (MMA) and tripropylene glycol diacrylate (TPGDA) as comonomers and ethanol/water as a mixed solvent and S-1 dodecyl-S′-(α,α-dimethyl-α″-aceticacid)trithiocarbonate as a chain transfer agent to inhibit the occurrence of gelation.The long nucleation period and gelation were observed in onestep,batch dispersion polymerizations.These problems can be overcomed by a two-stage method — half of MMA,solvent and all RAFT agent and TPGDA were added to the system after the end of the nucleation stage.In this way,coagulum was avoided and the particle size was controlled.The morphology of PMMA particles was observed by optical microscope.Branched poly(methyl methacrylate)(MMA) particles with an average diameter within 1.9～2.7 μm and size distribution of 1.12～1.24 were prepared.Molecular weight,molecular weight distribution,compositions and structure of copolymers were investigated by GPC and 1H-NMR characterization.The GPC curves showed a bimodal distribution,indicating that MMA homopolymer was formed during the nucleation stage and MMA and TPGDA branched copolymer was formed after the nucleation stage as proved by 1H-NMR.TPGDA fraction in the copolymer was determined to be lower than that in the initial monomer system.In addition,the intrinsic viscosity of the copolymer decreased with conversion,and the Mark-Houwink exponent α of copolymer reduced from 0.643 to 0.548,which further confirmed the branched structure of the copolymer.
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发布时间：2021-03-19 - 摘要：Polycondensation of nylon salt of hexamethylerediamine and terephthalic acid was performed in imidazolium ionic liquids (ILs) as solvent and triphenyl phosphate (TPP) as activating agent.The influence of reaction parameters,including the reaction time,the reaction temperature,the concentration of 6T salts and the amount of TPP on molecular weights of the resultantpolymers was investigated.The intrinsic viscosities of PA6T are ranging from 0.49 dL/g to 1.68 dL/g.Otherwise,two other methods were used for the preparation of polyamide from the same monomers to compare the efficiency of polymerization in IL.The polymers obtained were characterized by means of Fourier transform infrared spectroscopy (FTIR),hydrogen nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC).The molecular weight of PA6T obtained in IL is improved and the distribution of molecular weight is narrow compared with prePA6T synthesized in highpressure autoclave with water as solvent and the products of subsequent solidstate polycondensation for 8 h,and the reaction time was obviously shortened.The thermal properties of PA6Ts were studied by means of TGA,and the thermal stabilities of PA6T polymerized in IL was better than those of prePA6T.
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发布时间：2021-03-19 -
SYNTHESIS AND APPLICATIONS OF SULFONATESUBSTITUTED,TRIPHENYLAMINE-BASED CONJUGATED POLYELECTROLYTES
摘要：Two kinds of sulfonate-substituted,triphenylamine-based conjugated polyelectrolytes,PTP11 and PTP31 were synthesized by waterphase Suzuki coupling reaction,and the control polymer PTPOBS was prepared using the same polymerization condition for comparison.The chemical structures of these polymers were verified by NMR and elemental analyses.The maximum absorptions of PTP11,PTP31 and PTPOBS in solid state appeared in the range of 361～376 nm,with the optical bandgaps of 2.87～2.93 eV.These polymers emitted blue light under the excitation at wavelength of their absorption maximum and showed the maximum emission at the region of 445～450 nm.Investigation of the electrochemical properties of these copolymers suggests that they have HOMO levels (-5.08～-5.16 eV) closing to the work function of ITO and possess relative high-lying LUMO levels (-2.23～-2.20 eV).The solubility of these polymers is distinct from that of `neutral-charged’ polymers due to the presence of anionic sulfonate groups in the side chain,thus the intermixing between hole-transport and emitting layers can be facilely avoided by choosing different solvents during the fabrication process of multilayer PLEDs.The devices’ performance was remarkably enhanced when using these polyelectrolytes as hole-transport layers in PFO-DBT15 based red-emitting PLEDs,and the device performance can be influenced by the different substitution manner of sulfonate groups.The external quantum efficiency of these devices at the current density of ca. 33.3 mA cm-2 slightly decreases with the increasing composition ratio of directly sulfonated triphenylamine moiety in the polymers’ backbone.The better device performance was obtained by using ITO/PTPOBS as anode,with the efficiency of 1.6% and brightness of 158 cd m-2.- 44
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发布时间：2021-03-19 - 摘要：Ambient temperature self-crosslinking acrylic latexes were prepared through semicontinuous emulsion polymerization using 3 different polymerizable alkoxysilanes, i.e. vinyltri(β-methoxy ethoxy)silane (A172),vinyl-triethoxysilane (VTES) and γ-methacryloxypropyltrimethoxysilane (A174).The hydrolysis of these siloxanes under different pH was characterized,and dependence of the latex and polymer properties on these siloxanes and their incorporated amounts in the polymers was studied.Results revealed that the lowest hydrolysis was observed around neutral pH between 7 and 9.A172 was more quickly hydrolyzed at all tested pH,and its hydrolysis was fully accomplished within 5 h at pH 8.4.Polymer crosslinking,mechanical performance and water resistance of the final polymers were significantly enhanced with incorporation of VTES and A174.The hydrolysis can be controlled through pH adjustments during emulsion polymerization and film formation so that to reduce the hydrolysis during emulsion polymerization and to enhance it when film being formed,which entrained higher crosslinking in the final polymer films.It was found that acidic pH was more preferable compared to alkali pH although in both cases films performances were improved when compared with films cast without pH adjustment under neutral pH.This pH adjustment effect was more pronounced in latexes prepared with VTES than in those done with A174.
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发布时间：2021-03-19
Research Article
- 摘要：By thiolene addition reaction,we successfully synthesized a silylated terpyridine monomer.This compound was characterized by NMR,IR and MS.Two lanthanides inorganicorganic molecular hybrid materials with lanthanide (Eu3+,Tb3+) nicotinate complexes covalently linked to silica were prepared by this monomer and a sol-gel approach.IR,NMR,UV and photoluminescence spectra were applied to characterize the obtained hybrid materials.The above spectroscopic data present that the triplet energy of silylated terpyridine efficiently matches with the emissive energy level of metal ions and initiates the antenna effect.As a result,the intramolecular energy transfer process completed within these molecular based hybrid materials and strong green or red emissions of lanthanide ions (Eu3+,Tb3+) have been obtained.The most prominent emission lines of red (Eu3+) and green (Tb3+) emission hybrid materials were observed at approximately 617 nm and 544 nm.The terbium (Ⅲ) hybrid materials exhibited higher luminescence.Its lifetime was 0.68 ms which suffered a small change.The europium (Ⅲ) hybrid materials’ lifetime was 0.66 ms.All these hybrid materials are homogeneous,and their decay curves can be wellfitted by a single exponential function confirming that all Ln3+ ions are in the same average environment.
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发布时间：2021-03-19 - 摘要：A new kind of polyimide foams was successfully prepared using 3，3′，4，4′-benzophenone tetracarboxylic dianhydride (BTDA) and 4，4′-methylene dianiline (MDA) as main materials.First,BTDA diester was synthesized by esterification with methyl alcohol as a solvent.Subsequently,the polyamic ester precursor was polycondensated in the solution.Finally,polyimide foams were prepared through heating the precursor powder.The chemical structure of precursor powder,morphorlogy and size of cell,thermal properties and acoustical behavior of foams were characterized by Fourier transform infrared spectroscopy (FTIR),1H nuclear magnetic resonance(1H-NMR),scanning electron microscopy (SEM),thermal conductivity measurer,thermogravimetic analysis(TGA),differential scanning calorimetry (DSC) and standing wave tube，respectively.The results show that the precursor powder exists mainly as ammonium salt.Cells of the foams are uniform,and the cell size gets smaller with increase of drying temperature for precursor.The thermal conductivity λ of foams is 7.62×10-3 W/(m#8226;K),temperature of 5 wt% weight loss is 540℃ and glass transition temperature Tg is 316℃,which reveals the favorable thermal properties.And it can be known that the sound absorption coefficient comes up to 0.79 while the soniferous loss reaches 19.4 dB at 0～2000 Hz,which indicates the foam has low frequency sound absorption and sound insulation properties.
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发布时间：2021-03-19 - 摘要：Compared to the traditional lithographic-based techniques for fabricating polyimide patterns,micropen direct-write deposition technique has many advantages such as simple,low-cost,maskless,flexible, etc. The poly(amic acid) (PAA) solution was synthesized based on the PMDA and ODA in DMAc solvent by the low temperature solution co-polymerization method,and viscosity of the PMDA-ODA PAA solutionwas adjusted to make it suitable for the micropen direct-write depositing process.Polyimide patterns are fabricated by two steps,the micropen direct-write deposits PAA solution,and then a cure heating cycle converts the PAA to the insoluble polyimide and drives out remaining solvent.An Au/PI micro-bridge array was fabricated by the micropen direct-write deposition technique,which indicated its potential applications in MEMS manufacture field.
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发布时间：2021-03-19 - 摘要：Phosphorus-containing thermotropic liquid crystalline copolyesters (BDQTE) with higher molecular weight and thermal stability,lower thermo-transition temperature and broader mesogenic temperature region,based on p-acetoxybenzoic acid (ABA),terephthalic acid (TPA),ethylene glycol (EG) and 2(6-oxido-6H-dibenz1,2oxaphosphorin-6-yl)-hydroquinone (DOPO-HQ),have been synthesized via melting pre-polymerization along with solidstate polymerization (SSP).Thermal properties of the solid-state-polymerized BDQTE (SSP-BDQTE) were investigated via thermomechanical analyzer (TMA),thermogravimetric analyzer (TGA),differential scanning calorimeter (DSC) and polarized optical microscopy (POM).Through the investigations on intrinsic viscosity (［η］),viscous flow temperature (Tf) and the carboxyl group-concentration (［COOH］) of the target copolyesters at different SSP stages,synthetic conditions and the control mechanism of SSP were also briefly discussed.Results suggested that increases of the SSP temperature and time had positive influences on the progression of polymerization,and an obvious diffusion-controlled mechanism existed in the SSP courses of BDQTE.When the SSP temperature reached 235℃,SSP-BDQTE with the optimal above-mentioned properties could be obtained.At the early stage of SSP carried out at 235℃,with the increase of reaction temperature and time,［η］,Tf and ［COOH］ of the SSPBDQTE changed sharply,but changed very slowly and even unchanged after about 6 h.
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发布时间：2021-03-19
Research Bulletin
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