最新刊期
卷 ， 期 2 ， 2005
- 摘要：The dual-wavelength spectrephotometry and para-dimethylaminobenzaldehyde chmmogenic reaction were used to investigate the tryptophan content in silk fibroin of the inner,middle and outer cocoon layers and the distribution of tryptophan along the radial direction of silk fibers．The tryptophan content changes after light exposure and dry heating treatments were also examined．The results show that there ale obvious differences in tryptophan content of fibroin in different cocoon layers The order of tryptophan content is as follows：outer cocoon layer> middle cocoon layer > inner cocoon layer．The distribution of tryptophan in silk fiber is not even．with the highest tryptophan content in the outermost surface layer,and the lowest tryptophan content in the inner layer；the content in the middle layer is higher than that in the hypo-outer surface．Lilght exposure and dry heating treatment destroy tryptophan and reduce tryptophan content in fibroin．
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发布时间：2021-03-19 - 摘要：New alternative π-conjugated copolymers were obtained by nickel(Ⅱ) complex catalyzed polycodensation of N, N'-diehlorediphenoquinonediimine or 3,3'-dimethyl-N,N'-dichloredipheno-quinone diimine with 2,5-thiophenylene dimagnesium dibromide．The monomers were prepared from the corresponding benzidines oxidized by NaOCl．The monomers were characterized by FT-IR and 1H-NMR．The eopolymers wele characterized by FT-IR,UV-Vis,cyclic vohammogram and XRD．The obtained eopolymers were partially soluble in DMF,DMSO and CF3COOH．The soluble part (in DMSO) of copolymer Ⅱ showed two absorption peaks at about 310 nm and 450 nm,respectively,while copolymer I showed two absorption peaks at about 290 nm and 430 nm,respectively．The results from cyclic vohammogram and XRD showed that the eopolymers had electrochemical activity,and the copolymers were amorphous．
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发布时间：2021-03-19 - 摘要：The polyurethane/polystyrene(PU/PSt) composite emulsions with core-shell structure were prepared by seeded soap-free emulsion polymerization．the polyurethane aqueous dispersion was used as seed particles．The thermodvnamie equilibrium morphologies of synthesized PU/PSt composite emulsion particles were predicted using a simplified interfacial tension calculation method based on the minimum interracial energy change principle and validated using transmission electron microscopy and contact angle method．The results showed that the minimum interfacial energy change principie can be extended to PU/PSt system and the simplified inteffacial tension calculation is viable．
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发布时间：2021-03-19 - 摘要：A series of high molecular weight,readily soluble eopolymers of 9,9-dioctylfluorene with pyndine are synthesized by Suzuki polycondensation．The results indicate that the light-emitting color of the polymers could be midified by the introduction of pyridine units into the polynuorene backbone．The energy levels of the polymers are widened,and PL,EL spectra are blue-shifted by the introduction of the meta-pyfidine groups．However,the PL,EL spectra are red-shifted by the introduction of para-pyridine groups．The introduction of pyfidine units at 3,5- or 2, 6-position into polyfluorene backbone significantly depresses the excimer formation．The intensity of excimer emission decreases with increasing 3,5-pyridine content．Narrow and pure blue EL emission is obtained for the copolymer with 3,5-pyridine content of 40 mol％．Therefore,meta-pyridine-co-fluorene copolymers ate promising blue-emitting electroluminescent materials.
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发布时间：2021-03-19 - 摘要：The premixing self-assembly solution of horseradish peroxide with poly(sodium 4-styrenesulfonate)(RRP +PSS) is made by blending HRP and polyelectrolyte PSS,and the active[(HRP+PSS)/PDDA]。enzyme muhilayer biofilm is fabricated by altemate deposition of (HRP+PSS) and PDDA on the surface of negative ionized PET．The topography of films,the stepwise growth of layers and the activity of HRP in the film are measured with UV-Vis and AFM．HRP and PSS are assembled on the PDDA layer together from the premixing solution of (HRP+PSS),and the ratio of HRP to PSS in every layer of(HRP+PSS) is the same．The banded stmcture of HRP under the PSS is observed on the PDDA layer．The Michaelis Constant of the reaction of H2O2 and 4-amino-antipyrine(4-AAP) catalyzed by HRP in biofilm is 9.7×10-5mol·L-1 and is lowet than that of the reaction catalyzed by HRP in solution (1.52×10-4 mol·L-1)．The affinity between H2O2,and HRP in biofflms is rather strong．
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发布时间：2021-03-19 - 摘要：Suspension-emulsion combined polymerization(SECP) process,in which methyl methacrylate (MMA) emulsion polymerization constituents(EPC) were drop-wisely added to styrene(St) suspension polymerization(SP) system at different stages of St suspension polymerization,was applied to prepare polystyrene/poly (methyl methaerylate) (PS/PMMA) composite particles．The particle features of the resuhing polymer particles and the particle formation mechanism of SECP were studied．It was found that PMMA latex particles gradually coagulated with PS particles after the addition of EPC at the mid stage of St suspension polymerization,and core-sheU structure PS/PMMA composite particles with greater size were finally formed．St/MMA copolymer particles composed of primary particles and imperfect core-shell structure PS/PMMA composite particles were obtained by adding EPC at the initial and late stages of St SP,respectively．According to the particle formation mechanism of St suspension polymerization and the vafiations of particle features of PS/PMMA composite particles,a particle formation mechanism of St-MMA SECP was proposed．
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发布时间：2021-03-19 - 摘要：A novel 2,6-bis (imino) pyridyl iron complex hearing flouoro and methyl substituents has been synthesized and used for ethylene oligomerization．The activity of this complex could reach 1.8×107g／mol Fe·h when used for ethylene oligomerization,and most of the resulting products(>90％) are low-molar-mass oligomers,such as 1-butene,1-hexene and 1-octene．The catalytic activities are influenced greatly by reaction temperature．With increase of reaction temperatures,the activities decrease rapidly and more low-molecular-weight products are Droduced．The distribution of obtained oligomers is almost invariant with the Al/Fe molar ratio,but the catalytic activities increase rapidly at first and then decrease because of the deficient protection provided by small steric bulk nf bluoro at ortho position of aryl rings．As a result the chain transfer to MAO occurs more easily．Another three complexes have also been synthesized for comparison．Adapted ortho-and para-substituents on aryl rings are the inain effects on oligomerization activities and distributions of oligomers for 2,6-bis(imino) pyridyl iron complexes．
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发布时间：2021-03-19 - 摘要：Triethyleneglycol monomethacrylate(TREGMA) was synthesized by two steps and characterized using IR and 1H-NMR．It then was copolymerized with N-isopropylaeryl-amide (NIPAM) using N,N-methylene bisacrytamide (BA) as crosslinker through surfaetant-free emulsion polymerization to prepare temperature-sensitive microgels containing functional hydroxy groups．Investigation on the deswelling behavior of the microgels indicated that the microgels prepared had good temperature sensitivity,and the incorporation of TREGMA made the volume-phase transition temperature of the microgels shifted to higher temperature This type of mierogels might be good candidate for biomedical materials．
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发布时间：2021-03-19 - 摘要：Confined crystallization behavior of pofy(ε-caprolactone) was studied by DSC,WAXD and SAXS in the mixtures of poly(ε-caprolactone)(PCL) and poly(styrene-co-aceonitfile)(SAN) Because the crystallization and melting temperatures of PCL ale lower than the slass transition temperature of SAN,the experimental results indicated that multi-scale crystallization behavior of PCL is confifled in the mixtures．DSC measurements showed that the erystallinity of PCL is reduced with increasing the SAN concentration in mixtures．WAXD and SAXS results indicated that both PCL crystallite size and lamellae structure are disturbed by SAN with high glass transition temperature in the mixtures.
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发布时间：2021-03-19 - 摘要：To encapsulate extractants by method of microencapsulation can solve the problems of phase dispersion,phase mixing,phase separation,the leakage of extractant,as well as complicated structure of equipment in the extraction process．In the present work polysuffone and polystyrene as polymer materials were used to encapsulate the extractants such as TBP,D2EHPA,TOA,Aliquat 336 etc by means of solvent evaporation．The influence of shell materials,dispersants,stirring speed and composition of the organic phase has been investigated．The experimental results showed that TBP and D2EHPA were successfully encapsulated with polysulfone as the shell material while for the preparation of TOA and Aliquat 336 the shell material of polystyrene should be applied．The spherical shape and monodispersity of the microcapsules were related to the dispersion agent used in the O/W system．The mean diameter of the microcapsules decreased greatly with an increase of the stirring speed．Besides the stirring speed,the viscosity of polymer solution and the interfacial tension of working systems are the major factors that influence the size of the microcapsules．An optimal encapsulation efiqciency of the mierocapsules was reached when the content ratio of the shell rnaterial to the extractant in the polymet solution was optimized．
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发布时间：2021-03-19 - 摘要：Free-radical melt grafting of the multi-monomre system of maleic anhydride(MAH)/styrene(St) onto ABS resin was studied using a Hakke rheometer The maximum MAH graft degree was obtained when the molar ratio of MAH to St was approximately 1：1．The addition of St,an assisting monomer,improved the grafting reactivity of MAH．and St also reacted with MAH to form the St-MAH copolymer(SMA) before the two monomers grafted onto BAS．The site of grafting is mainly at the double bonds of ABS．ABS-g-(MAH-co-St) was used as a precursor on in-situ compatibilizer for incompatible blend of PA6 and ABS．The changes in morphologies of PA6/ABS／ABS-g-(MAH-co-St) blends with different contents of ABS-g-(MAH-co-St) were investigated using SEM．The addition of ABS-g-(MAH-co-St) markedly improved the morphologies of the blends,and an uniform and fine dispersed phase was obseved whh size being about 0.1μm for a PA6/ABS-g-(MAH-co-St)(70/30) blend．The addition of ABS-g-(MAH-co-St) also greatly improved the mechanical properties of PA6/ABS blends．The Izod impact strength of the blends greatly increased with increasing the content of ABS-g-(MAH-co-St) in the blends,and the tensile strength of the blends also incresed The PA6/ABS blends with balanced mechanical properties could be obtmned by addition of ABS-g-(MAH-co-St).
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发布时间：2021-03-19 - 摘要：UV-Vis absorption spectrum and cyclic vohammetry were adopted to study the influence of o,m,p-phenylenediamine monomers on the polymerization rate of aniline and the degradation process of PAn films,respectively．The results showed pPDA accelerated the polymerization of aniline and the degradation of PAn films,while oPDA and mPDA both restrained the polymerization and the degradation．A possible Feason for this phenomenon was that the different structures of phenylenediamine affected the polymerization mechanism and changed the chemical physics pmperties of PAn films to a certain extent SEM images displayed that the films becattle more compact and smoother compared with pure PAn films,which indicated the addition of phenylenediamine fiqononmers also had an apparent influence on the morphology of PAn films．
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发布时间：2021-03-19 - 摘要：The mono-dispersed colloids of poly(styrene-methyl methacrylate-3-sulfopropyl methacrylate,potassium salt) P(St-MMA-SPMAP) were prepared with soap-free emulsion copolynmrization usinge a one-step or two-step method．The particle size decreases with increasing the SPMAP amount mainly due to the formation of more nucleus at higher concentration of SPMAP．Although homogeneous latex with narrow particle size dispersion can be obtained with the one-step method,the colloids prepared with this method are difficult to use in preparation of colloidal crystals because of heavy aggregation of the colloids．The two-step method can resolve this problem,the colloids prepared do not show any aggregation and are suitable to the preparation of colloidal crystals．A homogeneous nucleation is realized when the concentration of water．soluble monomer．SPMAP．is 1ess than 17mmol·dm-1 If 3-sulfooetyl-methacrylate,sodium salt (SOMAS) is used instead of SPMAP the mechanism of the emulsion polymerization becomes rather complex,because the SOMAS will play a role of emulsion agent and in this case the mono-dispersed colloids are difficult to be prepared．In this article the preparation of poly (styrene-methyl-methaerylate-3-sulfooctyl-methacrylate,sodium salt)P(St-MMA-SOMAS) colloids using a one-step method is also reported preliminary．
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发布时间：2021-03-19 - 摘要：Nonisothermal crystallization behavior of nylon 6,nylon 1212 and their blends using maleared SEBS as eompatibilizers were studied by differential scanning ealofimetry (DSC)．The results showed that the processing history had a great influence on the crystallization and melt behavior of nylons．The extruded nylons showed improved crystallization temperature(Tc) and multiple melting phenomena due to the stress induced molecular orientation．In blends,the heterogeneous crystallization of nylon 1212 on the interface of nylon 1212 and nylon 6 occurred．Therefore,the Tc of nylon 1212 was increased．With the addition of maleated SEBS,the forrnation of grafted copolymers between nylon 1212 and maleated SEBS restrained the movement of molecules and decreased the Tc of nylon 1212．The melt temperature (Tm) of nylon 1212 was declined and the upper melting peak disappeared with increase of maleated SEBS in blends．However,the melt behavior of nylon 6 in blends was nearly unchanged．
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发布时间：2021-03-19 - 摘要：The liquid crystalline epoxy resin/organoclay nanocomposites were prepared based on 4,4'-diglycidyloxy bipbenyl (BP) with the rigid-rod mesogen unit,sulfanilamide (SAA) and the organoclay (93A) modified with methyl,dihydrogenatedtallow ammonium ion．It was found that the organoclay could be intercalated by BP and the layer spacing increased from 2.3 nm to 3.7 nm．The XRD results showed that the exfoliated nanoeomposite could be formed when the content of the organoclay was 2 percent．The hybrid with 10 percent of 93A formed the intercalated nanocomposite and a blend of two types of nanocomposites were formed with 5 percent of 93A．POM observation showed that the organoclay retarted the formation of a fan-shape smectic liquid crystalline phase as in pure resin system．The curing reaction of BP was studied by differential scanning calorimetry (DSC) at various heating rates, and the active energy at ditierent conversion was caleulated with Kissinger-Akahira-Sunose method．The results showed that the addition of organoclay decreased the active energy at the early curing reaction and promoted the curing reaction of the liquid crystalline epoxy resin.
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发布时间：2021-03-19 - 摘要：A primary study on the synthesis of polylactone-grafted polyphosphazene copolymers has been carried out for the purpose of using them as cell scaffold material in tissue engineering．It was found that the copolymer could be obtmned via transesterification of hydroxyl-ended polylactone,such as polycaprolactone (PCL) and polylactide (PLA),with poly[bis(glyeine ethyl ester)phosphazene] (PGP)．However,it was needed to note that this process seemed more suitable for the preparation of PCL-grafted polyphosphazene copolymer than for other polylactone-grafted polyphosphazene copolymers,because the melting point of PCL(ca．60℃) was far below the reaction temperature (160℃),whichfacilitated the mixing of the two polymers．Moreover,the transesterifieation of PCL with PGP could proceed satisfactorily only if the molecular weight of PCL was less than 8000,which was considered due to the weakened reactivity of hydroxyl end groups with molecular weight increase．Further detailed study is underway to optimize the reaction and it will be focused on the thermostability of poly[(amino acid alkyl ester)phosphazenes] influencing the transesterifieation．
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发布时间：2021-03-19 - 摘要：A nickel catalyst,his(α-naphthyl)-2,3-butanediimine nickel(Ⅱ)dichloride {[C10H7一N=C(CH3)C (CH3)=NC10H7]NiCl2} was synthesized andthen activated by methylaluminoxane(MAO)．By usingthis catalytic system branched polyethylenes(PE) of bimodal (wide) molecular weight distribution (MWD) wele prepared．The effects of various conditions,including the polymerization temperature(Tp),ethylene pressure and nAl／nNi on the catalytic activity,molecular weight,degree of branching and branching types of PE were investigated The catalytic activity and the resulting polymer micmstructure were sensitive to the polymerization temperature．The microstructure of the resulting PE was determined by FTIR and 13C-NMR．According to Gel Permeation Chromatography(GPC)．the resulting PE exhibited a bimodal molecular weight distribution．The influence of the existence of three possible stereo isomers of the Ni single-site catalyst with unsymmetrical imino-substituted bulky ligands on the molecular weight distribUtinn was discussed.
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发布时间：2021-03-19 - 摘要：Bisphenol A epoxy rosin was modified by dimethyldichlorosilane(DMS),or the mixture of DMS and α, ω-dichloro-polydimethylsiloxane(DPS)．The connections between the properties of the modified systems and the composition and content of the organic silicons were investigated by measuring the impact strength,tensile strength,elongation, and glass transition termperoture(Tg) of the cured materials．The results showedthat,aftermodification with DMS of 5.7 phr．the materials exhibited improved impact strength (20.2 kJ/m2),tensile strength (67.0 MPa),elongation(11.3％) and Tg(168.0℃),which all were higher than those of the pure epoxy resin,they wero 10.8 kJ/m2, 45.9 MPa,5.9％ and 135.4℃,respectively．For materials modified by the mixture of 0.7 phr DMS and 10 phr DPS．the properties wero further improved especially,the impact strength reached 31.6 kJ/m2 and the elongation reached 81.6％．The fracture surfaces of the modified resins were investigated by scanning electronic microscopy(SEM)．They showed typical characteristics of tough plastics,and for the one modified by 0.7 phr DMS +10 phr DPS many microparticles were observed which were supposed to be related with the significant increase in impact strength．
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发布时间：2021-03-19 - 摘要：In the presence of template molecules of N-Boc-L-Tryptophan (Trp) and N-Boc-L-Tyramine (Tyr),two kinds of molecularly imprinted polymers (MlPs) were synthesized by photo induced and thermal induced polymerization,respectively．High pressure liquid chromatography analyses using MIPs as the stationary phase showed that both MIPs could specifically recognize the corresponding imprinted molecules from the racemic mixtures of amino acid derivatives．The separation factors of N-Boc-L-Trp and N-Boc-L-Tyr on the corresponding MIPs were 2.318 and 1.373,respectively．The surface structure observation of MIPs by Scanning Electronic Microscopy showed that both MIPs and blank polymers polymerized by photo and thermal inducement were porous granules with different kinds of pores．From pore structure analyses,some differences between MIPs and blank polymers in pore-structures were found,and the difference in pore-diameter between MIPs and blank polymers by photo-induced polymerization was more obvious than that of the thermal induced polymers．When the imprinted molecules were removed from MIPs by elution,the structures of pores of various sizes in the MIPs were all markedly changed,showing that the imprinted molecules could be adsorbed by MIPs in any kinds of pores．All these results indicated that the pore-structure of MIPs played very important roles in the process of molecular recognition of the imprinted molecules．
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发布时间：2021-03-19 - 摘要：Using vhase contrast microscope,the evolution of the phase separation was investigated for poly(methyl methacrylate)(PMMA)/hyperbranched poly(ester-amide)(HBP)blend thin films on glass substrates．The films with different component ratios show different phase morphologies and phase separation processes．At a film thickness of about 500 nm．a cylinder-like dispersed phase Was observed in the films with low HBP content．The conditions for the special morphology occurring were also studied．The interaction between the substrate and HBP and the thickness of blendfilms are essentialfactors for the formation of the phase morphology．It was also found that the appearance of the special cylinder-like morphology depends on the component ratio and the fdm thickness．Only the film thickness was between the upper critical film thickness and the lower critical film thickness can the special structure be observed．There was a transition in the critical thickness as the HBP weight percent varied．
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发布时间：2021-03-19 - 摘要：A series of well-defined fluofinmed block copolymers with suffonic groups P(SSt-b-FNEMA)(PSSF) were synthesized by atom transfer radical polymerization (ATRP),followed by sulfonation reaction of polystyrene blocks in these block copolymers．The unique solution properties of these block eopolymers were studied by viscosity and surface tension measurements．The experimental results showed that the fluorinated block copolymers exhibited higher surface activity in N-methyl pyrrolidone solutions than in aqueous solutions．Interestingly,the surface tensions of aqueous solutions for sodium salt systems are nearly the same,resulting from the aggregation behavior of sodium salts of PSSF in water．The morphologies of these block copolymers in organic solvents and water were further observed by TEM and 1H-NMR．It was foand that PssF had a core-shell structure in aqueous solutions．but had a mieelle structure in N-methyl pyrrolidone solutions．Furthermore,poly (urethaneurea-acrylate) (PUA) aqueous dispersions wele modified by adding a small amount of PSSF It was found that the water absorption ratio of the modified PUA films dropped appreciably from 10 wi％to 4 wt％ because of the addition of PSSF．
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发布时间：2021-03-19 - 摘要：Novel conductive graft copolymers with oligoaniline side chains were synthesized by the reaction of oligoaniline with polymethacrylie chloride．Conjugated oligoanilines,tetraaniline (TA) and octaaniline (OA) were introduced into PMAA and P(MAA-co-MMA) main chains to combine the specific properties of oligoanilines and the desirable mechanical strength and film-forming properties of polymers．Four graft eopolymers were synthesized in this work：PMAA-g-TA,PMAA-g-OA,P(MAA-co-MMA)-g-TA and P(MAA-co-MMA)-g-OA,which were characterized by 1H-NMR．FTIR．elementary analysis and thermogravimetric analysis．Compared with their original polymers,the thermal stability of the sraft copolymers was improved to a certain extent．Some of these eopolymers showed electrical properties similar to polyaniline,exhibiting different states of oxidation,i．e．,fully reduced,partially oxidized and fully oxidized states．Doped copolymers grafted with tetraaniline．PMAA-g-TA and P(MAA-co-MMA)-g-TA,did not show conductivity because their effective doped aniline lengths were less than four aniline units．On the other hand,copolymers grafted with octaaniline side chains,PMAA-g-OA and P(MAA-co-MMA)-g-OA,can be doped,and the pmtonic-doped copelymers may exhibit a conductivity value up to 10-5S／cm．It suggests a new way to prepare conductive polymer materials．which are superior to conventional conductive polymer blends with unstable properties due to phase separation and have much better processibility than polyaniline．
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发布时间：2021-03-19 - 摘要：Pnly-N-metbylaniline/montmorillonite nanocomposite(PNMA-MMT) particles with high dielectric constant and suitable conductivity were prepared hy an intercalating polymerization method and characterized by IR,XRD and TEM,respectively．The structure analysis showedthatthelayer spacing ofMMT was swelledfrom 0.96 nm to 1.34 nm and the diameter of PNMA-MMT particles was about 30～100nm．The electrorheological(ER) properties of the suspensions of PNMA-MMT particles in silicone oil (20 wt％) were investigated under DC electric fields．It was found that the mechanic performance of PNMA-MMT ER fluids displays a notable ER effect under DC current field．The shear stress of PNMA-MMT ER fluid was 6.0 kPa(E=3 kV／mm,74.5 s-1),which was 3.6 times as hish as that of the ER fluid at zero field．Furthermore,the sedimentation ratio of PNMA-MMT ER fluid was about 97％ after 60 days．The dielectric constant and the dielectric loss tangent of PNMA-MMT nanocomposites were higher than those of the two components．PNMA and MMT．It is apparent that the notable ER effect of PNMA-MMT ER fluid was attributed to the prominent dielectric property of the poly-N-methylaniline-montmorillonite nanocomposite particles．
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发布时间：2021-03-19 - 摘要：The radiation cmsslinking and shape-memory behavior of the blends of poly(ε-caprolactone)(PCL) and polyfunctional polyester acrylme (PEA) were studied．The influences of the usage of PEA,the number of functional group and radiation dose on radiation crosslinking,dynamic mechanical properties and shape memory behaviors of PCL were investigated．It was concluded that radiation crosslinking of PCL／PEA blends didn’t follow the classic Charlesby-Pinner equation,but was in agreement with Chen-Liu-Tang relation．The efficiency of radiation crosslinking of PCL could be distinctively improved by using polyfunctional PEA．The more the usage and the functional group number．the more the gel content and the more distinctive the radiation erosslinking effects．This also indicated that the polyfunetional PEA directly participated in the erosslinking reaction．The DMA analysis indicated that enhanced radiation cross-linking raised the heat deformation temperature of PCL and presented a hisher and wider rubbery state plateau．whereas rendered more enotlsh strength at temperatures above the melting point of PCL and provided enough force to reeover mote strain than in the case of pure PCL．The shape memory results revealed that the well crosslinked PCL presented 100％ strain recovery with quick recovery rate．
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发布时间：2021-03-19
Research Article
- 摘要：Photovohaic properties of blend composites,composed of N,N’-didodecyl-3,4,9,10-perylene- biscarboximide(PDI) and a soluble conductive polymer poly(3-hexylthiophene) (PHT),are reported．PDI can form the interpenetrating network structure with PHT chmns,as evidenced in the UV-Vis spectrum．The investigation of the photoluminescence (PL) spectra revealed that PL of PHT was quenched when it was blended with PDI．The Dhotovohaic devices using PHT as both the sensitizer and hole conductor,and PDI films as the electron conductor were prepared to estimate the photovoltaie performance of the blend films．An improvement of conversion efficiency in the blending ceHs compared with that of the pure PHT cells was observed．Spectral properties and current-voltage(I-V) characteristics of the PHT/PDI composite films showed that the perylene diimide dopant can improve the photovoltaic performance of PHT films significantly through the increase of visible light absorption,exeiton dissociation,diffusion and transportation．
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发布时间：2021-03-19 - 摘要：“One-pot”reaction of 1,3,5-tfibromobenzene with nonylmagnesium bromide,prepared by 1-bromononane with magnesium in THF,catalyzed by Ni (PPh3)2Cl2,was used to obtain hyperbranched polyphenylene 1．The maeromolecule was characterized by GPC with molecular weight Mn=4247 and polydispersity PD=1.36．Under the conditin of Heek reaction catalyzed by palladium-complexes,the terminal bromine groups on this macmmolecule coupled with styrene and phenylacetylene,respectively,to provide correspondign hyperbranched polyphenylene 2 and 3 with stilbenyl and diphenylacetyl fluorophores on their surface．These two polymers both exhibited two bands E1 and E2 at near 260 nm and 300 nm in their UV spectra．In their powder photoluminescence spectra,the maximum emitting peaks at 401 am and 386 nm in the range of blue luminescence were observed,respectively．
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发布时间：2021-03-19 - 摘要：Monodisperse silicon dioxide particles have been prepared by the seed growth method,and different coupling agents were used for modifying these silica particles．The results show that the size deviation of silica particles modified with[3-(methacryloyloxy)pmpyl] trimethoxysilane(KH-570) is much lower than that of silica particles modified with vinyl triethyloxy silane as the coupling agent．In the presence of ethanol and water,styrene may react with silica modified by KH-570 in dispersion polymerization．It was discovered through transmission electron microscopy and energy spectrum that the modified silica particles were successfully encapsulated with polystyrene．The number of silica particles encapsulated with polystyrene was continually decreased with the increase of the size of silica particles．Moreover,the number of silica particles was nearly unity in each SiO2/PS composite particle when the silica particle size was greater than 410 nm．
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发布时间：2021-03-19 - 摘要：The emulsifier-free emulsion polymerization of styrene and N-isopropylacrylamide(NIPAM) was successfully carried out with microwave irradiation,and the thermosensitive particles with diameters in the range 130～150 nm were prepared．The effect of temperature on the hydrodynamie diameter of particles was characterized by PCS the diameter of particles was decreased as the temperature increased from 25℃ to 40℃．and the particles showed thermo-reversible phase transition phenomenon at 32℃．The morphology,size and size distribution of the particles were characterized by SEM and PCS．The ordered two-dimensional films were prepared by using the capillary force method on the clean glassware wafers,and the molpbology of two-dimensional films was studied by AFM.
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发布时间：2021-03-19 - 摘要：PLA/MWNT/HA hybrid nanofibers were prepared via electrospinning technology．Multi-wailed carbon nanotabe (MWNT) wem first treated by anodie oxidation,which resu／ted in various functional groups such as C一O,C一O and O—C=O on the surface of oxidized MWNT．Then the MWNT/hydroxyapatite (HA) nano-composites (MWNT content 3 wt％) were in situ synthesized by wet method with the help of ultrasonic treatment．Because of the strong interaction between the functional groups on the surface of MWNT and C2+ in HA．the obtained HA nano-particles were deposited onto the surface of oxidized MWNT．The as-received MWNT/HA nano-composites with excellent biocompatibility and osteoinduction were introduced into a bioabsorbable polymer,polylactide (PLA),and the PLA/MWNT/HA hybrid nanofibers were electrospun through a double solvent method under the voltage of 18 kV and the capillary to target distance was 4 cm．The structure and morphology of hybrid nanofibers were characterized by SEM．Because of the nanoscaled diameters,miemscaled interconnected pores and suitable surface chemistry,the hybrid nanofibers would match the requirements of ideal bone tissue engineering scaffold and may be a potential material for preparing bone tissue engineering scaffold.
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发布时间：2021-03-19 - 摘要：Aliphatic hyperbranched pely(ester-amine)s with terminal acrylate groups were synthesized by Michael addition reaction between pizine and trimethylol- propanetriacrylate (TMPTA) under various molar ratios,and their structures were characterized by 1H-NMR．GPC and DSC analysis．The multi-peaks within δ 4.04～4.18 (RCH2OCOR’)in the 1H-NMR spectra were analyzed andthe peaks at δ4.15,δ4.06～4.07 and δ 4.04 can be assigned to terminal(T),linear(L) and dendritic units(D),respectively．Based on 1H-NMR spectra,the degree of branching (DB) for these polymers were calculated by using both the Frechet method and the Frey method．With the molar ratio between pizine and TMPTA increased to 1/1,the terminate units decreased,both of the dendritic and linear units increased,while Mn and Mw/Mn became large and the Tg value became hish,accordingly．Moreover,cured films were obtained throuIsh UV radiation of the polymers．The gel contents for the films decreased with increasing the molar ratio between pizine and TMPTA,which may account for the changes of their mechanical properties．
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发布时间：2021-03-19 - 摘要：An optically active rod-coil-rod tfibloek eopolymer containing poly(ethylene oxide)(PEO) as the flexible segment and poly {(+)-2,5-bis[4’-((s)-2-methyl butoxy) phenyl] styrene} (PMBPS) as the rigid segment,PMBPS-b-PEO-b-PMBPS．was synthesized via atom-transfer radical polymerization．The PMBPS block had a stable helical conformation with an excess of screw sense in solution．The self-assembly behavior of the tnblock copolymer in dioxane/water mixed solvents was examined by means of TEM and turbidity measurements．The tfiblock copolymer molecules aggregated when water content in the system was about 2wt％ The higher the initial polymer concentrations,the lower the critical water content．They formed vesicles with highly dispersed outside diameters,but they had a relatively uniform wall thickness of (27±3) nm．
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发布时间：2021-03-19 - 摘要：Depolymerization of polybutylene terephthalate (PBT) in supercritical methanol was studied using a stainless stirred batch-type autoclave under high temperature (453～533 K) and high pressure (7～12 MPa) conditions．The main depolymerization products were dimethyl terephthalate (DMT) monomer and ethylene glycol．The effects of different reaction temperature and pressure on depelymerization of PBT were investigated by analysis of the solid phase and liquid phase products．Considering the critical point of methanol (512.6 K,8.09 MPa),the reaction pressure was varied with in the mge of 7～12 MPa．The resuks silowed that the reaction pressure had littie influence on the depolymerization and the depolymerization rate was affected greatly by the reaction temperature．The depolymerization of PBT was only 30％ in 40 min at lower temperatures (453～463 K) but reached 100％ in 20 min when the temperature was above 513 K．Depolymerization kinetics of polybutylene terephthalate in supercritical methanol was studied．The results showed that the depolymedzation reaction rate constant (k1) in the temperature range of 513～533 K was much larger than the rate constant (k2) in the range of 453～483 K．The dissolution characteristics of PBT in supercritical methanol were the critical factors for depolymerization of PBT in a short time．These findings suggest that the supercfitical methanol treatment for depelymerization of polymers such as PBT will be potential for obtaining useful chemicals.
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发布时间：2021-03-19
Research Bulletin
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