最新刊期
卷 ， 期 12 ， 2009
- 摘要：Aminolysis was used to improve the hydrophilicity of poly(γ-benzyl-L-glutamate),PBLG.Hydrophobic benzyl side chain groups in PBLG were changed to hydrophilic hydroxyalkyl groups by aminolysis reaction.Poly(L-alanine-co-5,N-hydroxypropyl-L-glutamine),(P(A-co-HPG)) and poly(L-alanine)-b-poly(5, N-hydroxypropyl-L-glutamine),(PA-b-PHPG) were synthesized in this paper,both initiated by n-propylamine.The structure and basic properties were characterized by IR and 1H-NMR.Both PA-b-PHPG and P(A-co-HPG) have the amphiphilic properties,where PA is the hydrophobic part and PHPG is the hydrophilic part.Compared with the block copolymer,the synthesis of random copolymer P(A-co-HPG) was more simple and of high efficiency.At the same time, the micellization processes of PA10-b-PHPG40 and P(A10-co-HPG40) were monitored by 1H-NMR.TEM results showed that both PA10-b-PHPG40 and P(A10-co-HPG40) could selfassembled into evenly micelles in water.However,the size of the micelles made of random copolymers was smaller than that of block copolymers,and the shape of random copolymer micelles were not regular spheres as micelles made of block copolymer.At the same time,it was found that the ratio between hydrophiphilic and hydrophobic monomers played a very important role in micelle formation.The most uniform micelle size distribution was observed in P(A10-co-HPG40) micellar solutions.
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发布时间：2021-03-19 - 摘要：in order to investigate electrochemical properties of a novel composite made from poly［3′,4′-ethylenedioxy2,2′:5′,2″-terthiophene］ (PTET) and carbon nanotubes (CNT), a derivative of ethylenedioxysubstituted terthiophene was synthesized as the precursors via Stille reaction,and chemical polymerization method was used to prepare PTET-CNT nanocomposites by coating PTET on the surface of the CNT by FeCl3 as catalysts in dry CHCl3 at 0～5℃.The composite was characterized by Fourier transform infrared spectroscopy (FTIR),transmission electron microscope (TEM) and scanning electron microscopy (SEM).FTIR spectra indicate that PTET of the composite more easily exists at the α,α′-positions than pure PTET，TEM and SEM images reveal that this composite has a core-shell structure with nanometer scale PTET layers.Electrochemical behavior of the composite electrode was evaluated by cyclic voltammetry (CV),electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests with a threeelectrode system in 0.1 mol/L Et4NPF4/acetonitrile (AN) solution.CV curves of the composite electrodes indicate that the composites not only present a large background current,but also a couple of redox peak with potentials of Epa=1.2 V and Epc=-0.2 V(versus Ag/AgCl),respectively.Galvanostatic chargedischarge curves show that the composite possesses higher specific capacitance and performs much better than carbon nanotubes under high current densities.A comparative analysis of original carbon nanotubes electrode was also conducted under similar conditions.At a current density of 3 mA/cm2,the PTET-CNT nanocomposite electrode exhibits high specific capacitance of 86 F/g,in comparison with a value of 20 F/g for the carbon nanotubes electrode,increased by 3.3 times than carbon nanotubes electrode.And supercapacitors based on the PTET-CNT nanocomposite and carbon nanotubes have an energy density of 2.02 and 0.47 Wh/kg,respectively.
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发布时间：2021-03-19 - 摘要：Abstract The phosphomolybdic acid/polyvinylpyrrolidone (PMA/PVP) nanocomposite films doped with sodiumbentonite (Na-MMT) were been prepared.The structure,thermal stability and photochromic behavior of these composite films were studied with TEM,AFM,FTIR,TG-DTA UV-Vis and XPS analysis.FTIR results showed the Keggin geometry of PMA and the structure of PVP were still preserved in the PMA/PVP composite films, and the salts were formed by combination of the ions based on the N atoms in the polymeric molecules and H+ of the polyanions.The doping of Na-MMT had no influence on the effect of PVP and PMA,but enhanced the thermal stability.Irradiated with UV light,the composite film changed from colorless to blue,heteropolyacid had been deoxidized to heteropolybules.The doping of Na-MMT debased the photochromic response of PMA/PVP hybrid films owing to the exchange of ions between PMA and Na-MMT.
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发布时间：2021-03-19 - 摘要：A series of poly(vinyl alcohol)/water-soluble chitosan/glycerol hydrogels were prepared by irradiation followed by freeze-thawing.Yunnan Baiyao was loaded into the hydrogels by solvent sorption technique.The influences of pH,ionic strength,freeze-thawing cycles and PVA concentration on the swelling capacity and Yunnan Baiyao release behavior were investigated.The swelling capacity decreased with increasing ionic strength,and it was larger in acidic media than in neutral media.Much more amount of Yunnan Baiyao could be loaded into PVA/ws-chitosan/glycerol hydrogels than into PVA hydrogels.Yunnan Baiyao release behavior of the former hydrogel showed pH and ionic strength sensitivity due to the existence of ws-chitosan.Larger amount of Yunnan Baiyao was released in pseudo-extracellular fluid solution than in neutral media and only small amount of the drug was released in acidic media and in distilled water,which was opposite to the swelling behavior.However,it was found that the swelling capacity and Yunnan Baiyao release amount both decreased with increasing freeze-thawing cycles and PVA concentration.These results indicated that Yunnan Baiyao release amount in various release media was mainly determined by the ionic exchange capacity between the drug and the ions in the solution.However,the release amount was mainly determined by swelling capacity when the hydrogels were in the same release media for different hydrogels.The swelling rate was much larger than the drug release rate indicating that the drug release rate was mainly diffusioncontrolled.The pH sensitive drug release behavior indicated that the hydrogel had potential to be used for the oral delivery of Yunnan Baiyao.
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发布时间：2021-03-19 - 摘要：Three metal oxides,Bi2O3,Sb2O3 and SnO2,in different amounts were added into the polypropylene (PP)/ammonium polyphosphate (APP)/and dipentaerythritol (DPER) to study their enhancing effects on the intumescent flame retardance (IFR).The flame retardance of the PP/IFR composites was tested by the oxygen index (OI).TG,TG-FTIR and SEM were used to study the decomposition processes of PP/APP/DPER,APP/DPER and single APP or DPER with Bi2O3.The results showed that Bi2O3,Sb2O3 and SnO2 could increase the OI of PP/APP/DPER,and maximum OI values were found with increasing the amounts of the metal oxides.TG showed that Bi2O3 inhibited degradation of the APP/DPER at high temperatures and increased the charring;TG-FTIR indicated that the existence of Bi2O3 changed the release of NH3 and phosphorous oxides in the degradation process.SEM showed that the 0.1 wt% Bi2O3 made the char of the PP/APP/DPER homogeneous.Adding 0.1 wt% Bi2O3 and 1 wt% nanoclay into the IFR PP,the value of OI could reach 28.3% with 20 wt% retardant; the UL-94 could reach V-0 with 25 wt% retardant.The mechanical properties of the IFR PP system also increased by adding retardant with 0.1 wt% Bi2O3 and 1 wt% nanoclay.
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发布时间：2021-03-19 - 摘要：Hyperbranched polyurethane (HPU) was synthesized from toluene-2,4-diisocyanate(TDI) and diethanolamine (DEOA) by onestep method,which was further modified to prepare UV-curable hyperbranched polyurethane acrylate (UV-HPUA) and a series of dual curable hyperbranched polyurethane acrylate (DHPUA) with different ratios of acrylate and trimethoxysilane end groups.All resins were characterized by Fouriortransformed infrared spectroscopy (FTIR),1H and13C nuclear magnetic resonance (1H- 13C-NMR) and gel permeation chromatography (GPC).Then the resins were used as oligomers to prepare UV/moisture dual curable coatings.The surface topographies of the UV cured coatings were investigated by atomic force microscopy (AFM) before and after moisture cure.The results showed that the superficial degree of roughness of the coatings,with acrylate and trimethoxysilane end groups ratio 3～1 or 1～1,decreased after moisture cure.However,UVHPUA and acrylate and trimethoxysilane end groups ratio 1～3 coatings increased after moisture cure.Thermal gravimetric analysis (TGA) results indicated that the coating thermal stability increased with increasing trimethoxysilane end groups.Moreover the physical properties of the UV cured coating were also measured before and after moisture cure,which indicated that physical properties of the UV-HPUA coating were slight improved through moisture curing process.However,the physical properties were greatly improved for DHPUA coatings,the pencil hardness increased from 6B to 3H and 4H.
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发布时间：2021-03-19 - 摘要：The effects of hydrophobic SiO2 nanoparticles on the realtime morphology evolution of the immiscible blend of polydimethylsiloxane(PDMS)/polyisobutylene(PIB)(90 wt%:10 wt%) were investigated under simple shear flow with an online optical-shear system.The theoretical predication indicated that SiO2 particles were mainly trapped in the interface between two phases.It was found that the droplet size of PIB dispersed phases was determined by the content of SiO2 nanoparticles and shear rate.The coverage of SiO2 particles on the PIB dispersion droplets suppressed the coalescence of the dispersed phases and decreased their size at low shear rate.A bimodal distribution of the droplet size which originated from the uncompleted coverage of SiO2 on PIB dispersed phase was observed.With the increase in the content of particles,the peak on the droplet size curve which corresponded to those large dispersed phases,shifted gradually towards another peak corresponding to those small dispersed phases,and finally merged into a single one.It was also found that the incorporation of SiO2 nanoparticles in PDMS/PIB blends decreased the dependence of droplet size on the shear rate.The synergetic effects of particle coverage,droplet breakup and coalescence resulted in similar droplet size in PDMS/PIB blends under two different shear rates when the contents of SiO2 particles exceeded 2.5 wt%.
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发布时间：2021-03-19 - 摘要：A novel barrier material consisting of alternating layers of pure polypropylene (PP) and polypropylene conventionally blended with ethylene-vinyl alcohol copolymer (EVOH) was prepared by microlayer coextrusion.The morphology structure of(PP+EVOH)/PP microlayered composites and its effect on gasbarrier properties,mechanical properties and crystallization behavior were characterized by SEM,DSC,gas-permeability and tensile tests.The results suggested that,through microlayer coextrusion,PP layers and (PP+EVOH) layers were combined as an alternatingly multilayered structure along the extrusion direction.The morphology of EVOH phase in PP matrix was changed from zero-dimensional sphere to one-dimensional fiber,then to twodimensional sheet with the increase of layer number,which caused significant improving of gas-barrier properties and enlongation at break of (PP+EVOH)/PP microlayered composites compared with (PP+EVOH) conventional blends.The crystallization behavior of microlayered composites was also influenced obviously by their structure and morphology.In addition to the PP phase in (PP+EVOH) layer,PP layer was also affected by the heterogeneous nucleation of EVOH due to the thin PP layer and the increase of interface when the layer number exceeded 64 layers.
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发布时间：2021-03-19 - 摘要：Poly(ethylene glycol) methyl ether-block-poly(L-alanine)(MPEG-b-PA) was synthesized with the initiation of MPEGNH2.While MPEG is the hydrophilic block and PA is the hydrophobic block.It is known that poly(L-amino acid)s like polypeptides have their special secondary structures such asα-helix and β-sheet.1H-NMR and COSY-NMR were used to monitor the micellization process of a po ly(ethylene glycol) methyl etherblock-poly(L-alanine) copolymer (MPEG45-b-PA32).MPEG45-b-PA32 was dissolved in CF3COOD first,while poly(L-alanine) blocks were in random coil structure.When D2O was added in this CF3COOD solution,MPEG45-b-PA32 could selfassemble into micelles.In the micellization process,mobility of PA blocks decreased while MPEG blocks kept very high mobility.Based on the chemical shifts and COSY data analysis,it was concluded that poly(amino acid) tended trend to form α-helix structure from random coil while the copolymer assembled in water.At the same time,transmission electron microscopy (TEM) results revealed that the diblock copolymer formed spherical micelles with the size of 150～220 nm in an aqueous medium.
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发布时间：2021-03-19 - 摘要：Based on the bond-fluctuation lattice model and dynamic Monte Carlo simulation,with explicitly including the hydrophobic interaction between water molecular and polymer,the kinetic process for the coil-globule transition of a homopolymer chain was studied.The distribution of collapse time observed the Gaussian profile,and the variation of averaged collapse time on the quench depth was similar with that for protein folding,but exhibited no local minima.What’s more,the averaged collapse time was exponentially dependent on the chainlength.In the kinetic process,the polymer chain’s conformation was found to evolve from an ellipsoid-like random coil to necklace-like conformation,then to sausage-like conformation,and eventually to a spherical globule.The four-stage kinetic process previously proposed by other peoples has been distinctly defined in this paper via some characteristic parameters,i.e.,the number of cluster,cluster size and aspherity,thus providing a convenient criterion for stage partition and comparison for specific collapse process.
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发布时间：2021-03-19 - 摘要：Abstract To explore the possibility of treating polluted water containing both organics and heavy metals,the synthesis of polystyrene-divinylbenzene AJS02 modified by L-tyrosine acid and a comparison of adsorption-desorption performance toward phenol on NDA-150 and AJS-02 had been investigated.Tt was shown that the equilibrium adsorption data fitted to Langmuir isotherms,and the adsorption capacity decreased with increase of temperature suggesting the exothermic process.The equllibrium adsorption capacity of AJS-02 and NDA-150 toward phenol was 76.98 mg/g and 91.97 mg/g,respectively when the initial concentration was 100 mg/L and the adsorption temperature was 288 K.These results might be attributed to both the specific surface areas and the polar groups on the network of resins.Thermodynamic studies suggested that the adsorption of phenol on AJS-02 was a procedure of coexistence of physisorption and chemisorption.The kinetic data fitted to both the intraparticle diffusion equation and the film diffusion equation for NDA-150 and AJS-02.It was shown that the adsorption rate was mainly governed by film diffusion.It was showed in dynamic adsorption and desorption experiments for phenol on AJS02 the breakthrough adsorption capacity and the total adsorption capacity were 5.26×10-2 mmol and 6.60×10-2 mmol per milliliter resin,respectively.91.5% regeneration efficiency for AJS-02 was achieved by 95% ethanol in our study.
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发布时间：2021-03-19 - 摘要：A series of new conjugated rigid-rod polymer poly(9,9-alkyl fluorenolbenzo bisoxazole)s (PBOPFx) containing an fluorene and benzobisoxazole structures were synthesized by 4,6-diamino-1,3-benzenediol-dihydrochloride (DAR) and 9,9-dialkyl-2,7-dicarboxyl fluorine,The polymer was characterized by the elemental analysis,1H-NMR,FTIR,thermogravimetric analysis (TGA) and photoluminescence (PL) spectra.The absorption and photoluminescence spectra of the polymers were also studied.The protonated PBOPFx in methanesulfonic acid solutions exhibits a blue emission with a peak at 466 nm or so.In contrast with that of PBO,the maximal emissions spectra and absorption spectra of PBOF red-shifted due to the introduction of the fluorene group which enhanced effective conjugation of polymer structure unit.In addition,emission spectrum of PBOPFx at 320 nm and 430 nm were compared,the Oxidationreduction curve is observed,and at last that PBOPFx solution has two conjugated units was verified,but two conjugated units did not show a clear separation,electronic transmission occurred in hybrid,so PBOPFx mostly showed the absorption and emission of the main conjugated unit.Also as a result of existence of alkyl side chains in fluorene unit,the thermal stability of polymers (PBOPFx) is lower than polyphenylene Benzodiazepine oxazoline (PBO)polymer,the initial decomposition temperature is about 350℃,but in the respect of dissolved character,PBOPFx has a great improvement,can well dissolved in most organic solvents.
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发布时间：2021-03-19 - 摘要：Abstract The influences of cations,anions,anionic surfactant and non-ionic surfactant on the molecular coil dimension of hydrolyzed polyacrylamide (HPAM) were studied by using dynamic light scattering (DLS),and ther mechanism was analyzed by applying the Stern-Graham double electrode layer model theory,paternoster model theory and dynamic model.The results show that the influence of anions on the HPAM molecular dimension (Dh) is little,but comparing against anions,the influence from cations is much greater,and the decreasing degree of Dh with the cation concentration increasing decreases gradually.The order of action capacity of Ca2+,Mg2+,K+ and Na+ for Dh is Mg2+＞Ca2+＞Na+＞K+.When the anionic surfactant is introduced into polymer solutions,Dh decreases with the concentration of anionic surfactant increasing first,then increases and decreases again.Moreover,because of the powerful electrostatic repulsion,the capacity of anionic surfactant molecules to adsorb on the surface of polymer molecules is weak,and it is difficult to form the “anionic surfactant_polymer” complex.However,the nonionic surfactant can adsorb on the polymer molecular chains in the form of micellar aggregate,forming “nonionic surfactant-polymer” complex,and result in the Dh increasing with the nonionic surfactant concentration increasing.
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发布时间：2021-03-19 - 摘要：The thermal sensitive cotton-g-PNIPAAm was prepared through free radical grafting reaction initiated by different initiators including ammonium ceric nitrate (CAN), potassium persulfate (KPS) and hydrogen peroxide/ascorbic acid (H2O2/H2A system).The degrees of grafting (G) achieved by different initiators could be sorted into descent order as following: G(H2O2/H2A)G(KPS)G(CAN).The other factors affecting the degree of grafting, such as the concentration of initiator, reaction time, temperature and the concentration of monomer, were studied.The results showed that the optimal conditions for grafting reaction using H2O2/H2A initiating system were: initiator dosage 7.5 mmol/L (mole ration of H2O2to H2A=1∶0.6), reaction time 1.5 h, monomer concentration 5%～15% and the reaction temperature 25℃.FTIR spectrogram of grafted cotton fiber showed characteristic absorptions of —CH3,CO,—N—H,—C—N and —CH(CH3)2 groups at 2967.5, 2857.4, 1623.9, 1540.3, 1457.4 cm-1, 1385.6 and 1365.4 cm-1 giving the evidence for the successful grafting of PNIPAAm onto cotton fiber surface.The extraneous polymer attached to fiber surface can be observed in SEM images of grafted cotton samples.DSC analysis revealed that all grafted cotton fibers had the LCST around 32～33℃ which was very close to the LCST of pure PNIPAAm gel (32.48℃).The raising of grafting degree has little impact on LCST but increases the reversible enthalpy change (ΔH) of the cotton-g-PNIPAAm.In the fallingdrop test (AATCC 79) and capillary rise test (FZ/T 01071), the fabric samples of cotton-g-PNIPAAm demonstrated different water absorbing abilities at different temperatures which meant that the cotton fiber had been endowed with thermo sensibility by PNIPAAm grafting.A grafting degree between 25%～45% is suitable for creating high thermo sensitivity.Other grafting degrees out of above range were not suggested.The analysis and discussion about the relationship between ΔHand swelling/shrinking time of cotton-g-PNIPAAm indicated that cotton-g-PNIPAAm reacted to temperature much quickly than pure PNIPAAm gel.
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发布时间：2021-03-19 - 摘要：A series of galactose glycosylated thermoresponsive hydrogel (P(NIPAAm-co-GAC)) and chitosan glycosylated thermoresponsive hydrogel (P(NIPAAm-co-CSA)) were synthesized by free radical polymerization with different ratios. The temperature responsibility of the copolymerized hydrogels was investigated. The lower critical solution temperature (LCST) of P(NIPAAm-co-GAC) hydrogels was 30～35℃ in distilled water and cell culture media. However, the LCST of P(NIPAAm-co-CSA) hydrogels was 30～35℃ in distilled water and lower than 30℃ in cell culture media, respectively. Furthermore, behaviors of HepG2 cell cultured on the P(NIPAAm-co-GAC), P(NIPAAm-co-CSA)and poly(N-isopropylacrylamide) (PNIPAAm) hydrogels were investigated. Cell mo~rph~olo~gies on different hydrogels scaffolds were photographed under a phase contrast microscope equipped with a digital camera. Investigation of the growth behaviors and viability of HepG2 cells on different hydrogels indicated that HepG2 cell grew very well on the surface of P(NIPAAm-co-GAC) and PNIPAAm hydrogels. However, the growth of HepG2 cell was inhibited on the surface of P(NIPAAm-co-CSA) hydrogels. The 3-(4,5-dimethy thioazol-2-yl)-2,5-di-phenytetrazoliumromide (MTT) assay was used to quantify the cell viability of HepG2 on different hydrogels. Cell viability on P(NIPAAm-co-GAC) hydrogels was 10 times higher than that on P(NIPAAm-co-CSA) hydrogels after 6 day’s incubation. Moreover, the viability of HepG2 cell increased with increasing the amount of introduced galactose. On the contrary, the viability of HepG2 cell decreased with increasing the amount of introduced chitosan. Investigation of the temperature induced detachment indicated that the cell could be spontaneously detached from the surface of poly(NIPAAm-co-GAC) hydrogels by lowing temperature, which could avoid the damage to the cells caused by enzymatic digestion. The detachment rate of cell sheets was much faster than that of single cells, which was indicated by the detachment rate of 64% for cell sheets and 32% for single cells after 10 min at low temperature. Investigation of cells transshipment indicated that the viability of cells obtained by temperature induced detachment was much higher than that obtained by enzymatic digestion. In conclusion, the introduction of chitosan into PNIPAAm was not favorable for the growth of HepG2, but the incorporation of galactose greatly facilitated its growth. Further more, intact cell sheets could be obtained by controlling the environmental temperature. All these results provided a novel method and experimental basis for developing materials used in tissue engineering.
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发布时间：2021-03-19
Research Article
- 摘要：The thermal release products and thermal decomposition products of four food grade polycarbonate (PC) samples were studied by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The degradation products of PC samples were detected at difference desorption temperatures and different pyrolysis temperatures. The results showed that there was different between chemical components out-gassing from PC pellets polymerized with different methods; the initial out-gas was produced at 200℃ for all PC samples. Mainly phenol-end groups out-gas was produced. More chemical components produced at higher temperatures. The thermal decomposition mechanism was also explained by analyzing the pyrolysis products. During the pyrolysis process, PC molecular chains can be cleavaged and the fragments were rearranged. The pyrolysis products were mainly phenolic compounds. Whereas some phenolic compounds (for example bisphenue A) were harmful to human beings, The potential phenolic compounds in PC food package materials should be examined, and their special migration should be strictly limited.
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发布时间：2021-03-19 - 摘要：The ladder polyvinylsilsesquioxane (Vi-LPSQ) with high regularity was successfully synthesized via supramolecular architecture-directed stepwise coupling and polymerization:“synchronous growth polymerization,synchronous bridge-cleaving followed by in situ condensation”.Formation with branches or cross-linking is unavoidable if the effective template is absent.Here,it is necessaryly emphasized that ladder superstructure (Vi-LS) and hydrogen-bonding adduct (HBA) are two imperative supramolecular architectures determining the ladder regularity of Vi-LPSQ.The ladder-rung,diaminophenylenes,can self-assemble into real ladder superstructures (Vi-LS) as template by π-interaction-aided N—H’s hydrogenbonding.And when converting the real Vi-DLPS to the desired Vi-LPSQ,oxalyl chloride can initially form a stable hydrogen-bonded adduct (HBA) with the diaminophenylenes-bridge of Vi-DLPS by a synergy of hydrogen bonding between carbonyl and amino groups and dπ-pπ interaction of p-electrons of Cl-atom and d-orbital of Si-atom.As a result,the reactive Vi-LPSQ is obtained based-on this supramolecular architecturesdirected approach.The ladder regularities for either the Vi-DLPS or Vi-LPSQ are confirmed by the strong-diffraction peaks at small angle range of XRD patterns.Especially,29Si-NMR measurement gives the sharp peak with extremely narrow baselinewidth,Δca. 1,of the repeat moieties:Vi—Si(O2/2)—NH—Ph—NH—Si(O2/2)—Vi and Vi—Si(O2/2)—O—Si(O2/2)—Vi.Moreover,The target polymer Vi-LPSQ is a premising precursor for preparation of number of advanced functional materials due to a possibility of functionalization for the reactive vinyl group.
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发布时间：2021-03-19 - 摘要：A series of novel high-performance polymers——poly(imino sulfone)s (PISs) have been obtained by the aryl amination reaction of 4,4′-dichlorodiphenyl sulfone and a series of aromatic diamines,using the catalytic system-generated from tris(dibenzylideneacetone)dipalladium(0)(Pd2(dba)3) and 2,2′-bis(diphenyl phosphino)-1,1′-binaphthyl (BINAP).The structures and general properties of PISs are characterized by means of FTIR,1H-NMR spectroscopy,DSC,TG,XRD,etc. The results confirm the proposed molecular structure and show that PISs possess high molecular weight (Mw2.5×104),high glass transition temperature (Tg＞200℃) and good thermal stability with high decomposition temperatures (Td＞400℃).PISs possess amorphous structures and also exhibit the excellent solubility.PIS-3 and PIS-4 can be dissolved not only in high polar solvents,but also in common organic solvent THF at room temperature (25℃).
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发布时间：2021-03-19 - 摘要：Polyimide(PI)/polyaniline (PANI) nanocomposites were prepared as a electromagnetic wave absorption material. Nano-PANI was synthesized with DBSA as the emulsifier and doping agent and APS as oxidant by a microemulsion method. On this basis, PAA/PANI composites were synthesized in NMP saturated solutions of PANI at room temperature, then PI/PANI composites were prepared through imidization. The crystallization of polymers was characterized by XRD, the intermediate and polymer were also characterized by FTIR spectroscopy. It was found that the PAn component spread as nano-sized islands in the PI matrix, and the two polymers retained their individual crystal structure in the composites. The loss performance of the composites was characterized by using a digital bridge and selfmade electrodes. When the content of PANI was up to 3.4 wt%, the dissipation factor of composites was obviously high than that of PI and increased proportional to frequency.
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发布时间：2021-03-19 - 摘要：To enhance the stability of the layer-by-layer (LBL) self-assembled films fabricated from terpyridines and ruthenium ions, a new method of introducing mono-terpyridinyl groups onto the surface of substrates was designed in this paper. First, diazoresin (DR) and sodium salt of 4-formylbenzoic acid (FBA) were successively deposited on the surface of substrate by self-assembly (SA) technique. Following decomposition of the diazonium group in DR under UV irradiation, the ionic bonds between substrate, DR and FBA were synchronously converted to the covalent bonds. Furthermore, the terpyridinyl groups were introduced onto the outmost surface through the Schiff base reaction between 4′-(4-amino-phenyl)-2,2′:6′,2″-terpyridine (Atpy) and formyl groups in DR-FBA. So that, the DR-FBA-Atpy monolayer film anchored on substrate was formed and very stable, which achieved the modification to substrates and provided active sites to coordinatively react with ruthenium ions. Consequently, diffluent 1,4-bis(2,2′:6′,2″-terpyridine-4-yl)benzene (Bi-tpy) and RuCl3 multilayer films were formed on the DR-FBA-Atpy monolayer through coordination bonds based on LBL self-assembled technique. The UV-Vis analysis results indicated that the LBL Bi-tpy/RuCl3 self-assembled multilayer films were successfully fabricated and the progressive assembly ran regularly with almost equal amounts of deposition in each cycle. The AFM images of the 4-bilayer Bi-tpy/RuCl3 film on silicon wafer showed roundshaped small domains with size of 25 nm. Under illumination, the self-assembled film on ITO showed effective photoinduced charge transfer. A linear relationship between conversion efficiency and the number of bilayers was discussed.
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发布时间：2021-03-19
Research Bulletin
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