最新刊期
卷 ， 期 11 ， 2014
- 摘要：(S)-6-(3-Chloropropionyl)-2-methoxy-2'-pivaloyloxy-1,1'-binaphthyl 2a was synthesized via acylation of (S)-2-methoxy-2'-pivaloyloxy-1,1'-binaphthyl using AlCl3 as a catalyst.In the presence of triethylamine,HCl was eliminated from 2a to create monomer (S)-6-acrylyl-2-methoxy-2'-pivaloyloxy-1,1'-binaphthyl 3.The monomer 3 was anionically polymerized using n-BuLi as an initiator in toluene.The absolute value of specific optical rotation []58925 of poly-3 is +96 and is about 8 times of that of starting monomer 3.The large increase in magnitude indicates that the optical activity of poly-2 is not solely attributed to the configurational chirality in the side pendant of binaphthyl and suggests that a higher chiral structure,most likely a secondary helical structure,has been formed.Poly-3 was confirmed to exist in the form of one-handed helical structure in solution by means of comparing the specific optical rotation and the CD spectra with that of 3 and the model compounds such as (S)-6-propionyl-2-methoxy-2'-pivaloyloxy-1,1'-binaphthyl 2b and (S)-6-heptanoyl-2-methoxy-2'-pivaloyloxy-1,1'-binaphthyl 2c.This conclusion was also confirmed by the fact that the g value of poly-3 is about 18 times of that of monomer 3.关键词：Chirality;Synthesis;,-Unsaturated ketone;Anionic polymerization;Helical polymers
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发布时间：2021-03-19 - 摘要：Effect of structure and polarity of side groups on the physical properties of poly(vinyl alcohol) (PVA),poly(vinyl acetate) (PVAc) and poly(vinyl methyl ether) (PVME) chains is investigated by the unified expressions of mean-square dipole moment and mean-square radius of gyration,which are deduced by an improved method of configurational-conformational statistics.The characteristic ratios of mean-square dipole moments for their isotactic chains are obtained to be 2.51,2.15 and 1.39,respectively.The differences of temperature coefficient of the syndiotactic chains reached to 5.6810-3 K-1.Moreover,the dependence of mean-square dipole moments on the polar orientation of side groups and chain configuration,and the dependence of the mean-square radius of gyration on dimension and flexibility of side groups are obvious.From comparing the differential values of conformational energies,it is found that effect of interaction energies of side groups on the ratios of PVA,PVAc and PVME is greater than that of poly(vinyl pyrrolidone),the differential values of PVME reached to -81.210-2 mol/J for instance.From contrasting intrinsic viscosity,it is observed that the values of poly(methyl acrylate) are more changeable than those of PVAc.Therefore,it suggests that the improved methods and obtained results may be used in investigation of the polymers in coating materials,adhesives and modifier of textile fibers and paper products.关键词：Poly(vinyl alcohol);Poly(vinyl methyl ether);Poly(vinyl acetate);Characteristic ratios;Temperature coefficient;Intrinsic viscosity
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发布时间：2021-03-19 - 摘要：Densely grafted cylindrical polymer brushes with more than one side chains on each repeating unit of backbone were synthesized by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction via grafting-onto method.The ketal-protected monomer,2,2-bis-(hydroxymethyl) propyl methacrylate (bis-MPMA) was prepared and polymerized by reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerization to yield linear polymer backbone with narrow distribution of molecular weight.The polymer backbone with two hydroxyl groups at each repeating unit was obtained after deprotection under acid condition.Then the hydroxyl groups were converted to alkyne groups by reacting with 4-pentynoic anhydride.Azido-terminated poly(ethylene oxide) (PEO) or polystyrene (PS),which were obtained by post-polymerization modification,were coupled with the alkyne groups on the backbone by CuAAC reaction.The grafting ratio and structure of the obtained polymer brushes were characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR).The reaction efficiency of PEO113-N3 and PS18-N3 in CuAAC was 85.1% and 78.0%,and the grafting ratios were 64.7% and 54.6%,respectively.The denseness of the alkyne groups on the polymer backbone or the steric hindrance of the polymer side chains may be holdback of the grafting.关键词：Cylindrical polymer brush;Grafting-onto;Reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerization;Copper-catalyzed azide-alkyne cycloaddition (CuAAC)
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发布时间：2021-03-19 - 摘要：Acetylized modification with acetyl chloride was carried out on alkali lignin (AL) which comes from pulping and papermaking industry,to obtain the acetylated alkali lignin (ACAL).The structural changes between AL and ACAL were characterized by infrared spectroscopy (IR) and nuclear magnetic resonance (NMR),and the results showed that the hydroxy groups in AL were displaced by the acetyl groups in ACAL.ACAL can form spherical micelles which are in the nonoscale by self-assembly in the mixed solvent of tetrahydrofuran (THF) and water.Static light scattering was used to monitor the forming process of the micelles and to measure the critical water content.The diameter and the polydispersity of the micelles were affected by the initial concentration of ACAL in THF and the dropping speed of water was studied,and were measured by the dynamic light scattering.The scanning electron microscope (SEM) and the atomic force microscope (AFM) were also used to characterize the feature of the micelles.Results show that the acetylized modification is a good method for perparing lignin-based spherical micelles with regular structure,and the structure also has a good rigidity and stability in the drying condition.The diameter and the polydispersity of the micelles can be controlled by the solution initial concentration and the water added speed.According to the analaysis,the - interaction between the aromatic nucleus in ACAL is stronger than in AL,and the stronger - interaction is considered to play an important role in the formation of the micelles.关键词：Alkali lignin;Acetylation;Self-assembly;Spherical Micelles
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发布时间：2021-03-19 - 摘要：2,2-Dimethyl-N-hydroxyethyl-1,3-oxazolidine (OX) and two kinds of poly-oxazolidines based on OX:malonic acid diethyl-2,2-dimethyl-N-hydroxyethyl-1,3-oxazolidine ester (OX1) and 1,1,5,5-pentane end tetracarboxylic acid tetra-2,2-dimethyl-N-hydroxyethyl-1,3-oxazolidine ester (OX2) have been designed and successfully synthesized.Their structures have been confirmed by 13C-NMR,ESI-MS,elemental analysis and FTIR.Their applications as latent curing agents in single component polyurethane (SPU) systems have been investigated.The results show that the SPU system cured in air without oxazolidine forms lots of foaming and can be swelled,its tensile strength is 3.2 MPa and the elongation at break is 364%.However,the tensile strength and elongation at break of the SPU system cured with the synthesized OX2 can reach 27.2 MPa and 457%,about 9 times and 1.26 times as compared with those the cured SPU system without OX,respectively.The addition of the synthesized OX1 or OX2 can greatly improve the apparent performance,mechanical properties and thermal stability properties of the cured SPU system.关键词：Oxazolidine;Synthesis;Latent curing agent;Single component moisture curable polyurethane
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发布时间：2021-03-19 - 摘要：Graphene oxide (GO) sheets were first synthesized through oxidation of natural graphite by a modified Hummers method,and then their homogeneous and stable dispersion in N,N'-dimethylformamide (DMF) was obtained.Stable and homogeneous solution mixtures of GO and PAA (polyamic acid) in DMF at different mass ratios of GO/PAA were readily prepared.Uniform composite films of GO-PAA were subsequently prepared by solution casting.PAA was turned to polyimides (PI) and GO reduced in situ to graphene (GS) at the same time by a subsequent thermal imidization of GO-PAA films,leading to composite films of GS-PI.Electrical resistivity,thermal stability and mechanical property of GS-PI films were studied.The results indicate that the surface resistivity of GS-PI films was significantly decreased with the increase in GS content,lowered to about 106 ,the standard of the anti-static electricity film,in the film prepared with 1.0 wt% of GO in GO-PAA.The tensile strength and the elongation at break of GS-PI composite films were both increased with increase in GS content,reached their maxima in the film prepared with 0.6 wt% of GO in GO-PAA,followed by regular decreases with further increase in GS.Different from the tensile strength and the elongation at break,the tensile modulus of GS-PI was in constant increase with GS content in the film.An increase of 37% was detected in GS-PI film prepared with 3.0 wt% of GO.Moreover,the ductility and the thermal stability of GS-PI were well kept in all the composite films regardless of its GS content.关键词：Graphene sheet-polyimide films;In situ reduction;Anti-static film;Surface resistivity;Mechanical properties
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发布时间：2021-03-19 - 摘要：The objective of this study is to evaluate the effect of poly(ether sulfone) (PES) concentration on microstructure of the electrospun hanofifers and the effect of nanofiber layer density on filtration efficiency and pressure drop of filters with nanofibers coated on a substrate.In order to reduce the pressure drop,the influence of composite methods on the filter performance by adding a certain amount of microspheres into the fibers was studied.The substrate is a non-woven polypropylene (PP) medium with negligible filtration efficiency and pressure drop as compared to the nanofiber layer.Experimental results show that when PES concentration(W/V) is 280 g/L well-distributed nanofibers with mean diameter of 510 nm are formed,and when PES concentration is 200 g/L a structure of microspheres with mean diameter of 2.74 m is obtained.The pressure drop increases from 706.58 Pa to 1444.52 Pa when packing density increases from 7.5 g/m2 to 10.5 g/m2,while the filtration efficiency can generally reach to 99.99%.This suggests nanofiber packing density has less prominent effect on filtration efficiency than pressure drop.By adding microspheres between two layers of fibers,the pressure drop across the filter decreases but the filtration efficiency also decreases.For the microspheres/fiber composite membranes,an appropriate amount of microspheres in the fibers will reduce the pressure drop but the filtration efficiency is reduced little.However too much microspheres will increase the filter pressure drop.Hence,the method of adding microspheres into nanofiber is proposed to fabricate nanofiber filter with greatly reduced pressure drop.This is advantageous for high efficiency applications with nanofibers of low pressure drop.关键词：Electrospinning;Microspheres;Low pressure drop;Air filteration
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发布时间：2021-03-19 - 摘要：A non-isocyanate route to synthesize high molecular weight aliphatic thermoplastic polyurethanes through transurethane polymerization from a diurethanediol was provided.A homopolymer of 1,6-bis(hydroxyethyloxy carbonyl amino)hexane (BHCH),i.e.PBHCH,was synthesized via melt polycondensation of BHCH.The PBHCH had Mn of 29200,Mw of 39700,tensile strength of 28.41 MPa and elongation at break of 3.91%.Meanwhile,a nylon-6 oligomer having H2N and HO terminal groups (H2N-PA-OH) was prepared via ring-opening polymerization from caprolactam with ethanolamine,and was transformed into HO terminated nylon-6 oligomer (HO-PA-OH) through reaction with excessive caprolactone.Co-polycondensation of BHCH with HO-PA-OH was carried out at 170 ℃ under normal pressure for 4 h and at 180 ℃ under reduced pressure of 399 Pa for 6.5 h.Several aliphatic thermoplastic poly(amide-urethane)s having short nylon-6 segments (s-PAUs) were prepared.They were characterized by viscometry,gel permeation chromatography,FTIR, 1H-NMR,differential scanning calorimetry,thermogravimetric analysis,wide angle X-ray scattering and tensile test.The s-PAUs had Mn above 26000,Mw above 33900,Tm between 123.85 and 170.89 ℃,and initial decomposition temperature over 267.86 ℃.Their tensile strength reached 28.53 MPa with elongation at break up to 299.0%.These s-PAUs were constituted with short nylon-6 segments and PBHCH sequences or merely dicarbamate units.The s-PAUs were crystallizable thermoplastic polyurethanes.Introducing about 10 mol% short nylon-6 segments having polymerization degree of 2.55 increased the crystallinity of the PBHCH sequences,and improved the toughness of the s-PAUs obviously.关键词：Non-isocyanate route;Thermoplastic poly(amide-urethane)s;Diurethanediol;Polycondensation;Transurethanization
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发布时间：2021-03-19 - 摘要：An enzyme-modified gelatin/silver nanoparticle composite biomaterial was prepared in this work.The silver nanoparticles were prepared in aqueous solution at first.Then,the blend of gelatin and silver nanoparticles was used as the composite matrix,and microbial transglutaminase (mTG) was employed as the biological modifier.Atomic force microscopy tests show that silver nanoparticles are distributed uniformly on the surface of the composite material,and no obvious aggregation of silver nanoparticles was observed.Vial inversion tests and rheological measurements both confirm that the gel formation and the covalent junctions of the composite can be triggered by microbial transglutaminase.Microbial transglutaminase can crosslink gelatin molecules by catalyzing the transamidation of glutamine and lysine residues to form covalent junctions.The mTG-modified gelatin/silver nanoparticle composite material has better stability in aqueous medium at a moderately high temperature due to the formation of covalent junctions and crosslinks.The results of tensile tests show that the tensile strength of mTG-modified gelatin/silver nanoparticle composite films increases after enzymatic modification.In addition,compared with the mTG-modified gelatin material lacking silver nanoparticles,the mTG-modified gelatin/silver nanoparticle composite material shows better in vitro antibacterial activity against Staphylococcus aureus. The viable cell number of Staphylococcus aureus of mTG-modified gelatin/silver nanoparticle composite material decreases by 60.15%.With its improved antibacterial activity,stability in aqueous medium,and mechanical strength,this mTG-modified gelatin/silver nanoparticle composite material could be a promising candidate in future applications of skin biomaterial.关键词：Gelatin;Silver nanoparticles;Microbial transglutaminase;Biomaterial
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发布时间：2021-03-19 - 摘要：1,2,3,4-tetrachlorotriptycene was synthesized by Diels-Alder reaction using tetrachlorophthalic acid and anthracene.Then by nitration and reduction of 1,2,3,4-tetrachlorotriptycene,2,6-diamino-13,14,15,16-tetrachloro triptycene diamine monomer was prepared.Novel triptycene polyimides were synthesized via a two step polycondensation by 2,6-diamino-13,14,15,16-tetrachloro triptycene diamine and bisphenol A dianhydride and hexafluoro dianhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride.The structure of 2,6-diamino-13,14,15,16-tetrachloro triptycene diamine monomer was characterized by 1H-NMR,13C-NMR and FTIR.The structure of polyimides were characterized by 1H-NMR,FTIR,the properties of the polymers were investigated by solubility,thermal properties,inherent viscosity and BET.The results showed that polyimides containing the tetrachlorotriptycene structure had good solubility,polymers could be dissolved in common organic solvents,such as DMAc,DMF,NMP,THF,pyridine and m-cresol.In particular,polyimides based on bisphenol A dianhydride and hexafluoro dianhydride were easily dissolved in chloroform at room temperature.These polyimides had excellent thermal properties,the glass transition temperature of the polymers was not found between 0~300 ℃ and the 10% weight loss temperatures of these three polyimides were all above 500 ℃.The three polymimides also had good film forming properties giving light transparent films,wherein the polyimide films based on bisphenol A dianhydride were colorless transparent.The polyimide based on hexafluoro dianhydride with BET specific surface area of 370 m2/g was a novel porous polymer.关键词：Polyimides;Triptycene;Solubility;Thermal stability;BET specific surface area
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发布时间：2021-03-19 - 摘要：Heterogeneous reinforced (HR) polywinylidene fluoride(PVDF) hollow fiber membranes consisting of polyvinyl chloride (PVC) matrix membrane and PVDF coating layer were fabricated via concentric circles coating process.The polyvinyl chloride (PVC) matrix membrane with macroporous structure was prepared by melt-spinning method.While the coating layer was obtained by non-solvent induced phase separation method with PVDF as the polymer matrix,dimethylacetamide (DMAc) as the solvent,and polyvinylpyrrolidone (PVP) as the pore-forming agent.During the coating process,high concentration DMAc of polymer solutions could infiltrate into the surface pore of PVC hollow fiber membranes due to the effect of capillary force.Interface layer was formed between the coating layer and the matrix membrane of the HR PVDF hollow fiber membranes with compact structure.Therefore,pre-wetting solutions were used for the pretreatment of PVC matrix membranes before the coating process.The influences of pre-wetting solutions on structure and performance of HR membranes were investigated.The results showed that the interface layer of HR membranes without pre-wetting solutions was thick and dense.Because of the protection of pre-wetting solutions to surface pores of matrix membrane,the interface layer of HR membranes was thin and porous.The performance of HR membranes with pre-wetting solutions of ethanol and ethanol aqueous solutions were better than that of the DMAc aqueous solutions.The optimal permeability of HR membranes was obtained as the ethanol concentration of pre-wetting solutions reached to 60 wt%.The tensile strength of HR PVDF hollow fiber membrane was nearly 9 MPa.The results also showed that the interface adhesion between reinforcement and separation surface had a good combination in the range of 40% elongation.关键词：Polywinylidene fluoride;Heterogeneous Reinforce;Hollow fiber membrane;Pre-wetting;Interface
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发布时间：2021-03-19 - 摘要：The present work reports on a method of ultrasound emulsification-Pickering emulsion polymerization,which was developed to fabricate polystyrene (PSt) microspheres through the assistant technique of ultrasonic emulsification in a reaction system consisting of the immobilizer aminolyzed poly-(divinylbenzene-alt-maleic anhydride) nanoparticles (PDVB-alt-MAH nanoparticles,PDMNPs),the initiator 2,2-azobisisobutyronitrile (AIBN),the medium deionized water and monomer styrene (St).The morphology and diameter were characterized through scanning electronic microscope (SEM) and laser particle sizer.The influences of emulsion stability,mechanical agitation speed and stabilizer usage on polymerization were investigated,respectively.It can be found that ultrasonic emulsification and mechanical agitation were necessary for the formation and stabilization of emulsion; meanwhile,the diameter of PSt microspheres could be controlled in the range of 200 nm to 90 nm with increasing amount of aminolyzed PDMNPs.Moreover,studies on the polymerization kinetics and the chemical structure of PSt microspheres were then conducted through gel permeation chromatography (GPC),Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectra (XPS).Based on the results,the highlights of this polymerization method are as follows:(1) high efficiency of stabilization of aminolyzed PDMNPs; (2) simple device of ultrasonic emulsification; (3) the surfactant-free polymer microspheres with narrow-distributed diameter.Furthermore,this polymerization method was then successfully used in polymerizations of other oil-soluble monomers,such as methyl methacrylate (MMA),glycidyl methacrylate (GMA) and -methyl styrene (AMS).It therefore indicated that the present work not only developed a novel strategy for Pickering emulsion polymerization,but also broadened the field of industrial preparation of polymer microspheres.关键词：Poly(divinylbenzene-alt-maleic anhydride);Polymeric nanoparticles;Pickering emulsion polymerization;Ultrasonic emulsification;Polymer microsphere
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发布时间：2021-03-19 - 摘要：To achieve (meth)acrylate UV-curing and thiol-ene photopolymerization combined in binary systems,vinyl monomers with high reactivity (meth)acryl carbon carbon double bonds and low radical reactivity (meth)allyl carbon carbon double bonds,specifically,methallyl acrylate,allyl acrylate and methallyl methacrylate,have been synthesized by an optimized carboxylate method.The photopolymerizations between trimethylolpropane tris(3-mercaptopropionate) (TMMP) and vinyl monomers,using 1173 as photoinitiator,are investigated by real-time FTIR to understand the effects of chemical structure of alkene,light intensity and amount of initiator on the photopolymerization behavior of thiol-vinyl binary systems,in which vinyl monomers contain two kinds of carbon carbon double bonds.It is discovered that,in all of these binary systems,(meth)-acryl carbon carbon double bond reactivity is the highest,followed by (meth)allyl carbon carbon double bond reactivity,while thiol group reactivity is the lowest.Methyl substituents on different carbon carbon double bonds of vinyl monomers have different effects on the thiol-vinyl photopolymerization.Methyl substituents on allyl carbon carbon double bonds have much greater influence on behavior of thiol-vinyl photopolymerization than the methyl substituents on acryl carbon carbon double bonds.The conversion of thiol decreases with increasing methyl substituent.In methallyl acrylate photopolymerization system,two types of carbon carbon double bonds (acryl and methallyl) present almost equal reactivity and achieve high conversion.关键词：Thiol-vinyl;UV-curing;(Meth)allyl (meth)acrylate;Structure;Synthesis
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发布时间：2021-03-19 - 摘要：Using iron sulphate as oxidant,poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared by chemical oxidation method under the condition of pH=2.The dispersion of PEDOT in nine different organic solvents was studied.N-methyl pyrrolidone displayed the best dispersibility for the polymer; after standing for 3 weeks,the dispersion system still retained a high concentration of 1.35 mg/mL.The density of the polymer was calculated by means of pycnometer method.According to group contribution method,the solubility parameters of the polymer were obtained.The dipole moment of polymer was also calculated with the assistance of the simulation of Chem 3D.Importantly,the solubility parameter and dipole moment were concluded to be two major factors affecting the dispersibility of the polymer in organic solvent.In other words,when both the solubility parameter and the dipole moment of PEDOT are simultaneously close to those of the solvent,the polymer will display good dispersibility in this solvent.Although the dipole moments of solvent NMP (13.6410-3 Cm) and DMSO (13.3410-3 Cm) are all very close to that of PEDOT (14.5810-3 Cm),the solubility parameter of solvent NMP (22.94 J0.5 cm-1.5) is more close to that of polymer PEDOT (21.28 J0.5 cm-1.5).From the viewpoint of the solubility parameter component,compared to DMSO (19.03 J0.5 cm-1.5),the solvent of NMP (18.03 J0.5 cm-1.5) has closer dispersion solubility parameter component to the polymer (16.39 J0.5 cm-1.5).Additionally,the observed Tyndall phenomenon suggests the colloidal state of PEDOT in the organic solvents.The structure stability of polymer was further confirmed via infrared spectroscopy and scanning electron microscopy.关键词：Poly(3,4-ethylenedioxythiophene);Dispersability;Solubility parameter;Dipole moment
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发布时间：2021-03-19 - 摘要：A series of novel aromatic poly(arylene ether)s containing diphenylfluorene and phenyl-s-triazine groups in the main chain were prepared by a solution nucleophilic polycondensation of 2,4-bis(4-fluorophenyl)-6-phenyl-1,3,5-s-triazine (BFPT) with Biphenol (BP) and 9,9'-bis(4-hydroxyphenyl)fluorine (BHF) to investigate the effects of bulky diphenylfluorene units on solubility as well as thermal and mechanical properties.The synthetic procedure was efficiently optimized,resulting in high Mn up to 6.3104 (GPC).The structure of the resulting polymers were characterized by elemental analysis,FTIR,NMR,and their thermal properties were evaluated by DSC,DMA,TGA measurements in succession.The solubility of polymers obtained was modified by the presence of diphenylfluorene groups in the polymer main chain resulting in being readily dissolved in common organic solvents,such as N-methylpyrrolidone (NMP),chloroform,1,1,1,2,-tetrachlorethane and pyridine,when the contents of diphenylfluorene structural units surpassed 20%.Moreover,PEPs had excellent thermal properties with glass transition temperarures (Tgs) in the range of 269~307 ℃ measured by DSC,and 269~291 ℃ detected by DMA,5% mass-loss temperatures lying between 544 ℃ and 580 ℃,char yields at 800 ℃ higher than 48% under N2atmosphere.The solubility and Tgs increase with the increase of diphenylfluorene contents in the polymer backbone.This kind of phenyl-s-triazine-based poly(arylene ether)s may be considered as a good candidate of high-performance structural materials.关键词：Phenyl-s-triazine;Diphenylfluorene;Solubility;High-performance resin;Poly(aryl ether)
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发布时间：2021-03-19 - 摘要：After utilizing coprecipitation method and subsequent modification with oleic acid,oil-based Fe3O4 magnetic nanoparticles with a narrow size distribution were obtained.And a kind of amphiphilic polymer containing rare earth was synthesized by using poly(ethylene glycol) methacrylate,methacryloxy propyl trimethoxyl silane and a complex Eu(AA)3 Phen as monomers.The oil-based magnetic Fe3O4 nanoparticles were then used as cores,and modified with the amphiphilic polymer via ligand exchange reaction to prepare water-based magnetic fluorescent particles (PMNPs).The morphology,molecular structure,superparamagnetic and fluorescent properties of the particles were characterized by nuclear magnetic resonance spectrometer (NMR),FTIR spectrometer (FEIR),transmission electron microscope (TEM),photon correlation spectroscopy (PCS),X-ray diffractometer (XRD),vibrating sample magnetometer (VSM),fluorescence spectrometer and thermo gravimetric analyzer (TGA).Results showed that the amphiphilic polymer was coated onto the surface of magnetic Fe3O4 nanoparticles effectively and evenly.The magnetic fluorescent particles had a good dispersibility in water phase and can keep a uniform particle size.The average diameter of the particles was just around 45 nm.The particles also had a saturation magnetization of 2.3 Am2/kg at room temperature,and the rare earth Eu3+ in these PMNPs had obvious characteristic emission spectra at 594 nm and 619 nm with a excitation spectra at 327 nm.关键词：Ligand exchange reaction;Rare earth;Magnetic fluorescent particles
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发布时间：2021-03-19 - 摘要：A new type of poly(ethylene oxide) (PEO) chain transfer reagent was synthesized and used to mediate the reversible addition fragmentation chain transfer (RAFT) polymerization of 3-(acrylamino)phenylboronic acid (AAPBA) to get three types of PAAPBA-b-PEO-b-PAABPA triblock copolymers with different PAAPBA lengths.The gelation of these copolymers at physiological pH was examined.It was found that hydrogel formation was dependent on the PAABPA block chain length,when the block was too long,no stable gel can be obtained due to the high hydrophobicity of the PAABPA segment.The effects of temperature, polymer concentration and glucose on the rheological properties of the gel were investigated in detail.The results indicated that the formed hydrogels possess solid-like behavior,at high polymer concentrations,gels with high strength and high phase transfer temperature could be obtained.In the presence of high concentration of glucose,interaction of glucose with the PAAPBA block can lead to the increase of the hydrophilicity of the PAAPBA block,thus leading to the break of the hydrogel network with time and finally the gel dissolved in about 1.5 h.Finally,the hydrogels could load FITC-BSA in the hydrophilic regions,and the release profile of FITC-BSA was accelerated in the presence of glucose.关键词：Phenylboronic acid;Poly(ethylene oxide);Block copolymer;Glucose-responsive;Hydrogel
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发布时间：2021-03-19
Research Article
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