最新刊期
卷 ， 期 2 ， 2012
- 摘要：A novel polymer PTST bearing substituted squaric acid units in the main chain is synthesized via Yamamoto coupling reaction in the presence of Ni(PPh3)2Cl2 as catalyst,and the chemical structure of PTST is confirmed by1H-NMR,13C-NMR and FTIR.The polymer PTST is readily soluble in common organic solvents such as chloroform,tetrahydrofuran,methylene dichloride,chlorobenzene and 1,2-dichlorobenzene,thus uniform thin films can be prepared from these solutions.The result from TGA shows that the polymer has excellent thermostability.The UV-Vis absorption spectrum of the polymer in tetrahydrofuran shows broad and strong absorption bands in the range of 270~700 nm and low band gap,suggesting that the polymer has good coverage with the solar spectrum.The result of cyclic voltammetry indicates that the lowest unoccupied molecular orbital (LUMO,-3.77 eV) and band gap (Eg) of the polymer are decreased by incorporation of the 3-cyclobutene-1,2-dione segment,implying that the polymer is nearly similar to that of perylene diimide-based polymers (-3.9 eV),indicating that the polymer PTST is a potential n-type polymer material for fabrication of polymer solar cells.When blend poly(3-hexylthiophene) (P3HT) with the polymer PTST,even under a low doping ratio of 20 wt%,P3HT would lead to the PL quenching of P3HT obviously,while higher doping ratio of 1∶1 (W∶W) would lead to completely quenching of emission from P3HT,suggesting that there exists efficient photoinduced electron transfer from P3HT to the target macromolecule.All these photophysical and electrochemical properties indicate that the objective copolymer PTST is a potential polymer acceptor material.关键词：Yamamoto coupling reaction;Polysquaraine;Novel conjugated polymer;Polymer solar cells materials;Acceptor materials
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发布时间：2021-03-19 - 摘要：The characterization of relative molecular mass and distribution of phenolic resins by modern analytical techniques is detailed.Common VPO,GC,HPLC and GPC methods are referenced.But these methods are restrictive in analysing the phenolic resins with more isomers.Field desorption (FD) is a term used to describe the formation of ions in the gas phase from a material deposited on a solid surface (known as an 'emitter') in the presence of a high electrical field.The field desorption mass spectrometry (FD-MS) of the phenolic resins can give the molecular ion peak and the content of the every phenol unit without fragment ion peaks.A series of phenolic resins was made with various raw materials.The phenol-formaldehyde resole resin,the phenol-formaldehyde novolac resin,the cresol-formaldehyde novolac resin and the phenol-cresol-formaldehyde novolac resin were determined by FD-MS.The sample concentration is 10 mg/mL,the heating current is 10~30 mA/min,the ionization voltage is 5~8 kV.The FD-MS shows us the molecular ion peak and the content of the every phenol unit without any fragment ion peaks.By FD-MS analysing we can also get the informations about the degree of polymerization,raw materials,characteristics and so on.So the FD-MS method is convenient and impactful for differentiating of the various phenolic resins,suitable for the characterization of relative molecular mass and distribution of the phenolic resin.关键词：Field desorption mass spectrometry (FD-MS);Phenolic resin;Cresol novolac resin;Relative molecular mass and distribution
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发布时间：2021-03-19 - 摘要：A negatively charged monodisperse PSt seed emulsion was first synthesized via batch emulsifier-free emulsion polymerization,and then polyethyleneimine (PEI) was added to modify the particle surface at 25℃ to prepare the positively charged PSt seed particles.Finally,the core-shell PSt/TiO2 composite microspheres were obtained by adding the diluted modified PSt seed emulsion into the medium of ethanol with certain amount of tetrabutyl titanate (TBT) under neutral condition.Influence of PEI amount on zeta potential of PSt seed emulsion,and influences of reaction time,addition models and EtOH/H2O mass ratio on the morphology of PSt/TiO2 composite microspheres were investigated.Results showed that zeta potential of PSt seed emulsion increased with the increase of PEI amount,and reached its optimum value of 38.3 mV from -40.3 mV when the amount of PEI was increased to 15 wt% of PSt seed weight.In the preparation of core-shell PSt/TiO2 composite microspheres,the encapsulation ratio of TiO2 onto the modified PSt particles increased with the increasing reaction time,and a maximum value of 90.2% achieved when the reaction time prolonged to 7 h.With the decrease of EtOH/H2O,the number of TiO2 nanoparticles absorbed onto the composite microspheres decreased,and the uniform core-shell PSt/TiO2 composite microspheres with the shell thickness of about 29 nm were obtained in the medium with EtOH/H2O mass ratio of 100/6.0.关键词：Composite microspheres;Surface modification;PSt/TiO2;Zeta potential;Morphology
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发布时间：2021-03-19 - 摘要：Monodisperse core-shell microspheres of polystyrene (PSt) contained photo-iniferter moieties were prepared first by a two-stage dispersion polymerization in which -methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate (MAEDCA) was charged into a reaction system after nucleation.Subsequently,raspberry-like PSt/poly acrylamide (PAM) particles were achieved by an ultraviolet light-induced surface grafting polymerization of acrylamide (AM) using the as-prepared photosensitive PSt particle as an initiator,and in a medium of methanol which is not a good solvent for the grafted chain of PAM.The morphology and core-shell structure of as-produced particles were revealed by scanning electron microscope (SEM) and transmission electron microscope (TEM) observation.Fourier transform infrared spectroscopy(FTIR),ultraviolet and visible absorption spectroscopy(UV-Vis),nuclear magnetic resonance (1H-NMR) and X-ray photoelectron spectroscopy (XPS) analyses demonstrated that the degree of incorporated photo-iniferter moieties on particle surface improved with the increase of MAEDCA added in system.In addition,it is advantageous to achieve narrowly distributed microspheres when a mixture of MAEDCA,styrene (St),2,2'-azodiisobutyronitrile (AIBN),methanol (MeOH) and H2O were introduced into the system in the second stage of dispersion polymerization.The surface of PSt particles grafted with PAM became hydrophilic,and on which Ag nano-particles were attached readily.关键词：Dispersion polymerization;Monodispersity;Core-shell structure;Photosensitive;Rraspberry-like microspheres
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发布时间：2021-03-19 - 摘要：Wattle tannin (TN),a kind of polyphenols compound originated from black wattle,was introduced into poly(vinyl alcohol) (PVA) to prepare PVA/TN blend films by solution blending method.Glutaraldehyde was used to slightly crosslink PVA/TN blend films.The PVA/TN blend films were characterized by scanning electron microscopy(SEM),wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry(DSC).The SEM observations revealed that PVA and TN was miscible in the blend films,which may due to the strong intermolecular hydrogen bonding between the hydroxyl groups from PVA and TN.The melting temperature of the blend film decreased from 231.7℃ to 221.3℃ when the TN content in the blend film increased from 0 to 20%,but the crystallinity of PVA was slightly decreased.It was found that less than 1.8% of the total amount of TN in blend films could be leached out when the blend films were soaked in water even for 24 h.This implies the good stability of PVA/TN blend films in water,which is beneficial to the long duration of antibacterial activity.The antibacterial activities of PVA/TN blend films were challenged by Escherichia coli (CMCC 44103),Staphylococcus epidermidis (ATCC 12228) and Staphylococcus aureus (ATCC 6538) with contact mode.The results showed that with the addition of TN,these PVA-based polymer films exhibited strong antibacterial activities against both gram-negative and gram-positive bacteria.For instance,only 0.5% of E.coli was survived on the blend film with 20% TN after 1 h contacting.Therefore,the PVA/TN blended films may have great potential in packaging material and coating fields.关键词：Tannin;PVA;Blend films;Antibacterial activity
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发布时间：2021-03-19 - 摘要：A new type of shape-memory poly(methyl methacrylate-co-2-hydroxyethyl acrylate)/hydroxyl terminated polydimethylsiloxane (P(MMA-co-HEA)/PDMS-OH) hydrogen-bonded complexes were obtained by the copolymerization of MMA and HEA on the presence of PDMS-OH. The chemical structures, morphologies and dynamical mechanical properties of these hydrogen-bonded complexes were determined by FTIR, SEM and DMA analysis. The results show that the content of PDMS-OH significant impacts on the morphology of P(MMA-co-HEA)/PDMS-OH hydrogen-bonded complexes. The morphology of hydrogen-bonded complexes transform from sea-islands structure to inversed phase structure when the weight content of PDMS-OH increases from 20% to 30%. Shape-memory effects of hydrogen-bonded complexes were studied by bending tests. The results show that P(MMA-co-HEA)/PDMS-OH complexes achieved excellent shape memory properties with strain fixity ratio of above 98% and strain recovery ratio of above 99%. Compared to poly(methyl methacrylate-co-ethyl acrylate)/PDMS-OH (P(MMA-co-EA)/PDMS-OH) complexes, P(MMA-co-HEA)/PDMS-OH hydrogen-bonded complexes exhibit higher modulus ratio owing to the hydrogen-bonding. Furthermore, the recovery speed of hydrogen-bonded complex is faster than that of the P(MMA-co-EA)/PDMS-OH at the same temperature conditions.关键词：PDMS;Complex;Hydrogen bonding;Thermo-mechanical behavior;Shape-memory
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发布时间：2021-03-19 - 摘要：An organic/inorganic support of immobilizing catalysts for ethylene polymerization was devised.The composition of the hybrid catalyst is as following: styrene and acrylic copolymer (PSA) is the organic part for binding iron (Ⅲ) acetylacetonate and bis(imino)pyridyl ligand catalyst,and SiO2 (Davison 955 silical gel) is the inorganic part.The inorganic part is coated by the organic part (PSA) by sol-gel method.The catalyst could produce not only high crystallinity (72%) polyethylene,but also -olefin.We considered the impact of different membrane materials and polymerization conditions (different cocatalyst,pressure,temperature,Al/Fe molar ratio) to the polymerization activity and properties of polymers and found that temperature had the greatest impact to the weight ratio of oligomer to PE.Because of the poor thermal stability of catalyst, the catalytic activity significantly attenuated with increasing temperature. When pressure increased,catalytic activity would increase too.The relationship of pressure and catalytic activity met the cossee catalytic reaction mechanism,which was widely accepted in Ziegler-Natta catalyst's ethylene polymerization mechanism.Different membrane materials would affect the final polyethylene product performance,the pure PSA as organic part would increase the molecular weight significantly.Cocatalysts affect not only the catalytic performance,but also the property of the final product.The alkylaluminium as cocatalyst tended to decrease the molecular weight.The iron catalyst system binding on the PSA after the treatment of magnesium chloride could produce the polyethylene of lower molecular weight (Mw=11.9104) and higher crystallinity (72%).And the polyethylene's melt index MI (2.35 g/10min) was higher than the iron catalyst binding on other membrane materials.The polyethylene can be used as the low molecular weight part of bimodal polyethylene.
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发布时间：2021-03-19 - 摘要：A phosphorus-containing organic silicone was synthesized from -glycidoxypropyltrimethoxysilane and phosphoric acid reacting.Phosphorus-containing organic silicone/epoxy hybrid resins were prepared by sol-gel method,and the cured resins were prepared from the in situ curing of the bisphenol-A type epoxy resin/4,4'-diaminodiphenylmethane,and phosphorus-containing organic silicone.The properties of the hybrid resin and neat epoxy resin were studied by using thermogravimetric analysis,differential scanning calorimetry,limited oxygen index,tensile strength and impact strength measurements.The flame retardancy was indicated by the limited oxygen index in the range of 25.8~29.3, higher than that of the neat epoxy resin.The glass transition temperature is in the range of 161~179℃,higher than that of the neat epoxy by resin.The thermal stability of the hybrid resin is not superior to that of the neat epoxy resin at low temperature,however,the char yield of it can reach 26.5%,higher than that of the neat epoxy by 36% at 800℃.The tensile strengths of the hybrid resin are 60~80 MPa,higher than that of the neat epoxy resin and the impact strengths can reach 14.36 kJ/m2,higher than that of the neat epoxy resin by 14%.Compared to the neat epoxy resin,the hybrid resin possesses better flame retardancy and thermal stability,and the tensile strength and impact strength are improved.关键词：Hybrid;Phosphorous;Organic silicon;Thermal stability;Flame retardant;Tensile strength;Impact strength;Sol-gel procedure
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发布时间：2021-03-19 - 摘要：Based on the principle of microchannel emulsification,a simple device with a detachable T-shaped microchannel junction was fabricated to prepare poly(lactic-co-glycolic acid) (PLGA) microparticles where aqueous solution of polyvinyl alcohol (PVA) was used as the continuous phase and PLGA dissolved in dichloromethane solution as the disperse phase.The effects of some important parameters such as the amount of emulsifier used in the continuous phase,the PLGA concentration,the disperse phase flow rate and the continuous phase flow rate on the average diameter of PLGA microparticles and the coefficient of variation (CV value) were examined in detail.The experimental results indicated that a decrease of the disperse phase flow rate,an increase of the continuous phase flow rate and increasing the amount of emulsifier used in the continuous phase led to the decrease of the average diameter of PLGA microparticles.When the PLGA concentration was between 5 g/L and 20 g/L,the average diameter of PLGA microparticles kept nearly constant.The uniform spherical PLGA microparticles with smooth surface were successfully prepared and no pores in the interior.By adjusting operating conditions,the average diameters of particles obtained ranged from 30 m to 200 m,and CV value of all the microparticles prepared under different operating conditions was below 15% while the lowest CV value was about 3%.This improved method can use organic solvents as disperse phase and avoid the easily blocking in the traditional method,which can be applied in the preparation of micrometer drug/polymer complex spheres with monodispersity and has great potential to be used in control-released drug delivery systems.关键词：Microchannel;Monodisperse;Poly(lactic-co-glycolic acid);Microparticles
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发布时间：2021-03-19 - 摘要：The dynamics of fluid-driven translocation of polymers chains through a microchannel is investigated by dissipative particle dynamics (DPD) approach. Unlike implicit solvent models, this approach naturally preserves many-body energetic and hydrodynamic interactions by incorporating explicit solvent particles in this approach. An externally applied body force is exerted on each solvent particle to generate a Poiseuille flow in the microchannel, which drives the polymer chain across the narrow channel. The DPD simulations show that the polymer chain undergoes affine-deformation, and three stages can be identified during the translocations: (1) the polymer chain initially drifts along the flow direction; (2) the polymer chain approaches the entrance of the narrow channel by undergoing a continuous conformational deformation to make its size match the pore size of the narrow channel, and part of polymer chain enter into the pore mouth of the narrow channel; (3) the polymer chain rapidly travels through the narrow channel to fulfill complete translocation. The results also show that the average translocation time steadily decreases with the increase of fluid flux. In addition, the results also demonstrate that chain rigidity exerts a considerable influence on the dynamics of polymer chain translocations, and the average translocation time steadily increases when the polymer becomes more rigid. These findings in this study may be helpful in understanding the dynamic behaviors of fluid-driven polymer and/or DNA molecules during the translocation processes.关键词：Polymer chain translocation;Fluid-driven;Hydrodynamic interactions;Dissipative particle dynamics
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发布时间：2021-03-19 - 摘要：The blend porous membranes of biomedical polyurethane (BPU) and poly(L-lactic acid) (PLLA) were prepared by the immersion precipitation phase inversion method.The influences of different BPU/PLLA mass proportions on the coagulation of polymer/dioxane (DO)/water ternary systems was investigated,and the structure and performance of blend porous membranes were characterized and discussed.It was found that the thermodynamics stability of polymer/solvent/nonsolvent ternary systems was enhanced with varying BPU/PLLA mass proportions from 75/25,50/50,25/75 to 10/90,while the viscosity of blend solutions increased.And the porosities,thickness,average pore diameter,water vapor transmittance rate (WVTR) and water uptake of blend membranes increased first and then reduced.But the time reaching the equilibrium water uptake prolonged gradually.The reason was that WVTR and water uptake were controlled by the membrane porosity,while the time reaching the equilibrium water uptake was governed by the hydrophilicity of membrane materials.The changes of membrane structures and performances resulted from the transformation of the membrane-formation mechanism.With BPU/PLLA mass proportion changing from 75/25,50/50,25/75 to 10/90,the main factor controlling the membrane formation was transformed from diffusion kinetics to thermodynamics of membrane-formation systems.The phase separation type was changed from the delayed demixing to the instantaneous demixing first,and then changed to the delayed demixing.关键词：Biomedical polyurethane;Polylactic acid;Immersion precipitation phase inversion;Coagulation;Blend porous membrane
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发布时间：2021-03-19 - 摘要：Polyoxymehtylene (POM)/multiwalled carbon nanotubes (MWCNTs)/glass fiber (GF) and POM/carbon black (CB)/GF composites were prepared by melt mixing in a rotational rheometer.The effects of GF on the electrical conductivity,crystallization behavior and dynamic mechanical properties of the composite materials were investigated.The morphology of the composites was observed by field emission scanning electron microscopy (FESEM),showing that GF does not significantly affect the dispersion state of MWCNTs and CB.Although GF is electrically inert,its presence can increase the effective concentration of the conductive filler by holding up some space,therefore the conductivity of the material increases.The electrical resistivity/effective concentration data points are all around the electrical resistivity/conductive filler concentration curve of POM/MWCNTs and POM/CB composites,proving that the concept of effective volume concentration can be used to explain the decrease in the electrical resistivity with the incorporation of GF.The crystalline behavior of POM in the composites was investigated by differential scanning calorimetry (DSC).The crystallization temperature,melting temperature and degree of crystallinity have no significant change by incorporation of GF,revealing that GF does not have obvious influence on the crystalline behavior of POM.The storage modulus,as measured by dynamic mechanical analysis (DMA),increases significantly by the presence of GF,showing a strong reinforcing effect.Therefore,GF-filled POM/MWCNTs and GF-filled POM/CB are promising materials having both good electrical conductivity and good mechanical properties.关键词：Glass fiber;Carbon nanotubes;Carbon black;Polyoxymethylene;Conductivity
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发布时间：2021-03-19 - 摘要：Amphiphilic chitosan derivatives(N-octyl-N-mPEG-chitosan,OPEGC)were successfully synthesized via sequential Schiff base reduction reaction of chitosan with mPEG- aldehyde and n-octanal,with chitosan acting as the backbone of the grafted copolymers,and mPEG- aldehyde providing hydrophilic chain and n- octanal providing hydrophobic alkyl chain,respectively,thereby hydrophobic moiety inclining to segregate into the core of the polymeric micelles,while hydrophilic moiety forming a stabilizing interface between the hydrophobic core and the external medium.The structure of grafted copolymers with both hydrophilic and hydrophobic composition simultaneously was confirmed by characterization employing FTIR and 1H-NMR.In the subsequent procedure,water-soluble quantum dots (QDs),widely used as nanoprobe for medical application,were achieved by incorporation of QDs inside the polymeric micelle core through the hydrophobic interaction between the acyl chain ligand capped on the QDs and the hydrophobic inner core of the polymeric micelles.The size and distribution of the polymeric micelle was determined by dynamic light scattering (DLS),as well the effect of the amount of alkyl chains on the size of the hollow polymeric micelles.The result showed that with grafting level increasing,the size of these nanoparticles diminished accordingly.Moreover,critical micelle concentration (CMC) was determined based on I3/I1 derived from emission spectrum afforded by fluorescence spectroscopy with pyrene as fluorescent probe,with the value of CMC 2.03210-2mg/mL.At last,the optical properties of OPEGC/QDs were characterized by UV-Vis spectroscopy,fluorescence spectroscopy and the morphology of their assembly formed in water was observed by TEM.The results indicated that the OPEGC/QDs nanoparticles with narrow size distribution were prepared here,which represented good water solubility and high quantum yield.关键词：Amphiphilic;PEG;Chitosan;Grafting level;Quantum dots
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发布时间：2021-03-19 - 摘要：An unsaturated monomer bearing luminescence group,acryloyloxyfluorescein (Ac-Flu) was synthesized from fluorescein and acryloyl chloride in the presence of triethylamine in dry dichloromethane (CH2Cl2) at room temperature.The synthesized Ac-Flu was identified by IR,MS and 1H-NMR spectra.Copolymer of Ac-Flu and acrylamide was synthesized with thermal initiator, and poly(Ac-Flu-co-AM) was characterized by the method of IR,UV-Vis and DSC.The photophysical behaviors of the copolymer were explored by recording the fluorescence spectra in solution and film.In addition,the pH and temperature dependence of fluorescence of the water-soluble poly(Ac-Flu-co-AM) was investigated in detail.The results showed that the relative fluorescence intensity of poly(Ac-Flu-co-AM) at near 520 nm had an excellent linear response to temperature in the range of 0~60℃,the linear regression equation of the calibration graph was FI=740.06-3.0683T,(FI was relative fluorescence intensity,T was temperature),with a correlation coefficient of linear regression of 0.9974.Moreover,the fluorescence intensity increased continuously from low pH to high pH from 4.0 to 10.0 after the addition of HCl or NaOH,which resulted from the fact that the predominance of tautomeric forms of Ac-Flu changed at different medium.This investigation may provide a convenient way to prepare multifunctional macromolecule biomaterial bearing fluorescein to probe pH and temperature in biological system.
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发布时间：2021-03-19 - 摘要：By using a shearing-drawing two-dimensional compound stress field die developed by the authors,two-dimensional self-reinforcement polypropylene random copolymer(PP-R C180) pipes were extruded.The tensile strength, molecule orientation and crystal melting were studied.The results indicate that the molecule degree of order is improved by shear-inducement of shearing-drawing two-dimensional compound stress field.The orientation of molecule is easier along the circular and axial directions of PP-R C180 pipes respectively.The heat resistance and crystallization velocity are kept,and even improved.The degree of crystallinity is reduced.The self-reinforced PP-R C180 pipes show different crystallization structure and morphology.-phase is induced in the self-reinforced pipes.The tensile strength is improved too.The crystallinity decreases from 44.96% of conventional pipes to 40.03% of self-reinforced pipes.The best axial tensile strength of self-reinforced pipes is 25.49 MPa,but that of the conventional pipes' is 23.35 MPa. And that the circular tensile strength increases from 22.71 MPa of conventional pipes to 26.54 MPa of self-reinforced pipes at the most and the improvement is 16.9%.At the same time,the melting point of self-reinforced pipes is kept,even higher than that of the conventional pipes'.Moreover,the circular tensile strength of self-reinforced pipes is higher than the axial tensile strength and it rather satisfies the requirement of pipes.关键词：Shearing-drawing two-dimensional compound stress field;Shear-inducement;Two-dimensional self-reinforcement;PP-R
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发布时间：2021-03-19 - 摘要：Polysaccharide derivatives were immobilized on the surface of polyurethane (PU) through layer-by-layer self-assembly technique and photochemical modification method.At first,azido-chitosan(AzCS) was synthesized and immobilized on the polyurethane substrates by UV irradiation.Then,lentinan sulfate (LS) and azido-chitosan were alternatively deposited on the polyurethane substrates through layer-by-layer self-assembly technique.Finally,the self-assembled multilayers were cross-linked by UV irradiation.From above steps,the polysaccharide derivatives modified polyurethanes were prepared.The surface properties of the modified polyurethanes were evaluated by infrared spectroscopy,UV-Vis spectroscopy,X-ray photoelectron spectroscopy and water contact angle measurement.The antibacterial activity against Escherichia coli and blood compatibility of unmodified and modified PU were tested in vitro,respectively.The results showed that the water contact angle of the modified surfaces decreased gradually during the successive buildup of the multilayers.The hemolysis test and platelet adhesion test both indicated that the blood compatibility of PU surfaces was improved after surface modification.Moreover,the modified surfaces showed antibacterial activity against Escherichia coli. The number of viable Escherichia coli on the modified surface decreased by 49%.Thus,the surface modification of polysaccharide derivatives through layer-by-layer self-assembly and photochemical modification not only improves the hydrophilicity and hemocompatibility of the modified PU,but also introduces special antibacterial bioactivity onto the modified surfaces.关键词：Layer-by-layer self-assembly;Photochemical reaction;Polyurethane;Polysaccharide;Surface modification
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发布时间：2021-03-19 - 摘要：Two epoxy-based azo polymers (PEP-AZ-CF3 and PEP-35AZ-CF3) containing trifluoromethyl-substituted azo chromophores with high density were synthesized by using post-polymerization azo-coupling reactions between two epoxy-based precursor polymers (PEP-AN and PEP-35AN) and diazonium salt of 4-(trifluoromethyl)aniline.The structures and properties of these two azo polymers were characterized by using 1H-NMR,FTIR,UV-Vis and thermal analyses.The self-structured surface pattern formation of these two azo polymers was studied by irradiating the polymer films with laser light at three different wavelengths (488,532,and 589 nm) under a normal incident condition.The incident laser light was linearly or circularly polarized.The intensity of the incident laser light was 200 mW/cm2 and the irradiation time was 30 min.The results indicate that the photoinduced self-structured surface patterns could be formed on films of both azo polymers only when the azo polymer films were irradiated with the laser light at 488 nm.The photoinduced self-structured surface pattern formation showed close correlation with the wavelength of incident laser light.Compared with the linearly polarized laser light,the circularly polarized laser light could induce the patterns with higher saturated amplitudes.The methyl substituents in anilino moieties of the azo groups in 3,5 positions showed steric hindrance to the self-structured surface pattern formation.关键词：High chromophore density;Epoxy-based;Azo polymer;Photoinduced self-structured surface patterns;Trifluoromethyl-substituted
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发布时间：2021-03-19 - 摘要：Epoxy resin/PEI/MWCNTs composites were prepared by solution blending,and the effects of MWCNTs with hydroxyl group on the phase separation of the systems were investigated by scanning electron microscope (SEM),infra-red spectrum (IR),rheological measurements and differential scanning calorimetry (DSC).The SEM results showed that the MWCNTs were uniformly dispersed in both phases of the composite after curing.The phase separation morphology of epoxy resin/PEI blends without MWCNTs or containing 0.75 pbw MWCNTs showed an island-sea structure,and the blend containing more MWCNTs presented a bicontinuous structure when the blends were cured at 150℃.And when the blends were cured at 120℃,the phase separation morphology of the blends without MWCNTs or containing 0.75 pbw MWCNTs showed a bicontinuous structure and the blend containing more MWCNTs presented a phase inversion structure.The IR and DSC data showed that the rate of curing reaction was accelerated and the activity energy of the curing reaction was decreased by introducing MWCNTs into the system due to the existence of the hydroxyl group on their surface.In addition,the results of rheological measurements revealed the fact that,for one hand,the MWCNTs which crossed both phases increased the viscosity of the system,causing an inhibiting effcet on phase separation; for another hand,the gelation time of the composites decreased as the MWCNTs content increased,which indicated that the addition of MWCNTs to the blend restricted the phase separation and morphology evolution in the earlier stage of phase separation,implying that the introduction of MWCNTs with hydroxyl groups into the system was a feasible method to achieve the goal of phase morphology control.关键词：MWCNTs;PEI;Epoxy resin;Phase separation
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发布时间：2021-03-19 - 摘要：Poly(3-hexylthiophene) (P3HT) was for covalently grafted on the graphene (GN) surface to form polymer brushes (P3HT-GN) via combining diazonium addition with Kumada catalysis-transfer polycondensation (KCTP).GNs was prepared according to the well-established oxidization-reduction method where the surfactant was used to prevent the reduced GNs from aggregation.The bromobenzene molecules were then grafted onto the GN surface through the diazonium addition at the presence of surfactant,which allowed immobilization of the initiator Ni(PPh3)4 on GNs and subsequent growth of P3HT following the KCTP mechanism.Atomic force microscopy and thermogravimetric analysis results indicate that the thickness and weight percentage of P3HT brushes grafted on GNs are 5 nm and 20.1 wt%,respectively.When assuming these P3HT chains were grafted on GNs in fully extended configurations,the grafting density was estimated to be one P3HT chain/6.53 nm2 with an average inter-chain distance of 2.556 nm.There is no visible characteristic X-ray diffraction peak in the scanning range of 3~60,indicating that these P3HT-grafted GNs are well exfoliated.UV-Vis spectra revealed that P3HT-GN had a weaker absorption peak than the pristine P3HT in the wavelength range of 300~500 nm,suggesting a significant interaction between P3HT and GN.This is consistent with the increased content of oxidized thiophene units observed in the X-ray photoelectron spectroscopy of P3HT-GN relative to that of the pristine P3HT.The strong interaction between P3HT and GN made the photo-induced fluorescence nearly quenched completely.The obtained quantum yield for P3HT-GN is 0.042% (only an eightieth of the pristine P3HT quantum yield),exhibiting an extraordinary charge transfer efficiency between P3HT and GN.This opens up a new pathway for developing novel,high-efficient graphene-based functional materials.关键词：Graphene;Polythiophene;Diazonium salt addition;Kumada catalyst-transfer polycondensation (KCTP);Charge transfer
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发布时间：2021-03-19
Research Article
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