最新刊期
卷 ， 期 8 ， 2014
- 摘要：The research field of conducting polymers has been developed since 1970 s,and attracted considerable attention due to their promising applications in organic electronics.However,most of the polymer optoelectronic devices are fabricated based on the films of conjugated polymers,which are inferior for us to investigate the intrinsic charge transport properties of conjugated polymers and the fabrication of high performance devices because of the large amount of defects and disordered molecules.Organic crystals are the best candidates for solving the above mentioned problems due to their long-range molecular order,low defects and no grain boundaries.However,it has been a big challenge for the production of high quality conjugated polymer micro/nano crystals,In this paper,we summarize the progress of preparation,characterization and field-effect transistor application of conjugated polymer micro/nano crystals,and finally we also give a concise discussion for the development prospect and existing problems of conjugated polymer micro/nano crystals and devices.关键词：Conjugated polymer;Micro/nano-crystals;Field-effect transistors;Mobility
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发布时间：2021-03-19 - 摘要：Polymer crystallization,together with glass transition and rheology,is one of the problems which have not been eventually solved in polymer science.Because the properties of polymeric materials are strongly dependent on the crystallization behavior and morphology,polymer crystallization is the most fundamental problem of polymer physics.Comparing with the crystallization of small molecules,the conformational entropy plays a critical role in polymer crystallization due to its linear structure.This leads to complex behaviors of polymer crystallization and the controversies on both the understanding of phenomena and the establishment of the polymer theory.Recently,as the accumulation of the new phenomena from the experiments and computational simulation and the advances in theoretical methods,it is the right time to reveal the nature of polymer crystallization in theory.In present review,from point view of the difference of crystallization in polymer and small molecule systems,the classic theory,new phenomena from both experiments and computational simulation of polymer crystallization and the development and difficulties of theories focusing on these new phenomena were reviewed.关键词：Polymer;Crystallization;Theory
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发布时间：2021-03-19
Reviews
- 摘要：Poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) as-spun fibers were prepared by melt spinning and drawn fibers were obtained by stretching the as-spun fibers at 60℃.The crystallization behavior of PLLA/PDLA fibers with different initial structure was investigated systematically with the combination of X-ray scattering,differential scanning calorimetry (DSC),scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).The key point was to clarify the effect of orientation on the crystallization transition of PLA fibers.The results indicated that orientation can induce the formation of the sc-crystals and increase the crystallinity of the PLLA/PDLA fibers.Furthermore,there was only the formation of sc-crystals during cooling process in the drawn fibers,while the -crystals appeared at 150℃ in the as-spun fibers.2D WAXS and FTIR results showed that the oriented sc-crystals hindered the formation of -crystals.Based on the above results,the highly-oriented PLLA/PDLA fibers containing pure sc-crystals with high crystallinity can be obtained by drawing the as-spun fibers at low temperatures and then annealing at a temperature above the melting point of -crystals.关键词：PLLA/PDLA fibers;Orientation;Crystallization
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发布时间：2021-03-19 - 摘要：In this work,a star-shaped light-harvesting concept is supported by the -cyclodextrin grafting polymer with 21 arms of poly(9,9-diethylfluoren-2-yl methyl methacrylate)-b-poly(N,N-dimethyl aminoethyl methacrylate) [-CD-g-(PFMMA-b-PDMAEMA)21] as a host molecule and anthracene as guest.The inner layer of FMMA units acts as antennae to absorb light energy and transfers inward to anthracene molecules included in hollow -CD cage.The intensity of energy transfer depends on the inclusion of anthracene in -CD core,which is sensitive to tetrahydrofuran fraction in aqueous solution.With the decreasing tetrahydrofuran concentration,the energy transfer from FMMA to anthracene increases linearly,i.e. a decrease of FMMA luminescence and an increase of anthracene emission in aqueous solution.The polymer is characterized by1H-NMR,MALDI-ToF-MS and GPC,and the energy absorption and transfer are investigated by UV-Vis and fluorescent analyses.1H-NMR and GPC measurements prove that each arm of the star polymer contains a block copolymer of 4.4 FMMA units and a long PDMAEMA segment.Such a light-harvesting system shows a promising potential in light-responsive equipment,solar cell or organic light-emitting diodes.关键词：FMMA;-cyclodextrin;Light-harvesting molecule;Energy transfer
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发布时间：2021-03-19 - 摘要：Coarse-grained molecular dynamics simulations within the framework of MARTINI force field were employed to study the G4 poly(amidoamine) (PAMAM) dendrimer interacting with the lysine-flanked (KALP) peptide.The influence of KALP peptide on the structure of the dendrimer under the neutral and acidic pH conditions was considered.The radius of gyration,shape factor and radial distribution function of the dendrimer were analysed.Meanwhile,the free energy between molecules was calculated.It was found that the peptide provided a slight effect on the size and density profile of the dendrimer under the two pH conditions,which implied that there existed enough space in the interior of the dendrimer for the KALP peptide penetration.The dendrimer keeps its sphere-like shape as the peptide approaches from the center-of-mass distance of 5.0 nm to 1.0 nm.The results of potential of mean force between two molecules imply that the dendrimer repels the peptide at low pH possibly due to the steric interaction and electrostatic repulsion.At neutral pH,a stable complex of two molecules is also hard to form under the influence of thermal fluctuation.The finding suggests PAMAM dendrimer is unfavourable to adsorb the KALP-like trans-membrane proteins.关键词：Dendrimer;Peptide;Molecular dynamics;Potential of mean force
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发布时间：2021-03-19 - 摘要：A novel wood-based adsorbent material was developed for removal of harmful anions from drinking water.First,wood pulp was partially oxidized by sodium periodate to form dialdehyde-modified cellulose; secondly,the aldehyde groups were coupled with polyethylene polyamine via Schiff base reaction to give amino-modified cellulose-based cationic adsorbent material.All reactions could be performed by mild and facile procedures.The adsorption performance of amino-modified cellulose-based cationic adsorbent against F-,Cr2O72- and AsO43- was studied in terms of adsorption capacity (isotherm) and rate of adsorption.The results showed that the amino-modified cellulose-based cationic adsorbent is effective for the harmful F-,Cr2O72- and AsO43- ions.High adsorption capacity for these species was displayed and rapid adsorption equilibrium could be achieved.The study of the adsorption isotherm has showed that,Langmuir monolayer adsorption isotherm is more favorable for description of the adsorption process within the studied concentration.The capacity was affected by the pH level:high pH gave increased adsorptivity for Cr2O72- and AsO43-,while neutral to low pH decreased the adsorption capacity of F-.This amino-modified cellulose-based cationic adsorbent showed selectivity for Cr2O72- and AsO43-,which were adsorbed under presence of other monovalent anions.This phenomenon is likely due to the chelating action of the cationic groups of polyamine in amino-modified cellulose-based cationic adsorbent.But for F-,the electrostatic force is probably dominant in the adsorption mechanism,which did not show this high selectivity in the presence of competing anions.
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发布时间：2021-03-19 - 摘要：Photopolymerization kinetics and gelation time of acrylate/liquid crystal syrups were characterized by photo-differential scanning calorimetry (P-DSC) and photo-rheology technology (P-Rheology),respectively.The effects of chemical structure and composition of acrylate monomers,and photopolymerization temperature on the kinetics of these syrups were discussed on the basis of the correlation between gelation time and temperature,as well as the polymerization rate constant and activation energy which were calculated from the autocatalysis model.Furthermore,the effects of photopolymerization kinetics on the electro-optical properties and phase-separated structure of the polymer dispersed liquid crystals (PDLCs) were studied.The results indicated that the polymerization rate constant increased and the gelation time decreased with increasing the photopolymerization temperature,the monomer reactivity,and the average functionality of monomers.In addition,the photopolymerization activation energy decreases with increasing the reactivity and average functionality of monomers.Meanwhile,the activation energy before gelation is lower than the global one.When the LC content is 50 wt%,the PDLCs show a bicontinuous phase structure at a submicron scale.Also,the gelation time is significantly shortened with increasing the photopolyemerization rate and temperature,leading to smaller LC domains and denser polymer networks in PDLCs.Consequently,the turn-off time is prolonged and the saturation voltage of the PDLCs lowers,whilst their turn-on time and threshold voltage show little variation.关键词：Polymer dispersed liquid crystals;Photopolymerizaion kinetics;Gelation;Phase separation
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发布时间：2021-03-19 - 摘要：The phase transition behavior of crystalline region in at-PAN fiber during heat treatment was investigated based on the temperature-dependence measurements of in situ synchrotron wide-angle X-ray diffraction (WAXD),DSC and FTIR.According to the results of WAXD,the position of diffraction arc for (110) planes was shifted to low q value with the increasing of temperature.However,there was an obviously mutation at 110℃ during this shifting.At this temperature,the linear expansion rate of crystalline region increased from 4.1510-4 nm/K (1) to 1.1310-3nm/K (2),and the DSC curve also emerged an exothermal peak around 110℃,which results from the phase transition of crystalline region.From the FTIR measurements,the relative intensity of 1230 cm-1and 1250 cm-1 bands,which stands for the 3/1 helix and planar zigzag conformation respectively,was also changed during heat treatment.Through the relationship between C=I1250/I1230 and heat treatment temperature,there was also a dramatical change at 110℃,where C was decreased obviously.It implies that the molecular chains in at-PAN fiber were more likely to take the planar zigzag conformation below 110℃ and transferred to 3/1 helix conformation above 110℃.So it can be concluded that the phase transition of the at-PAN fiber at 110℃ was originated from the transformation of planar zigzag to 3/1 helix in chain conformation.关键词：at-Poly(acrylonitrile) fiber;Phase transition behavior;In situ synchrotron WAXD;FTIR
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发布时间：2021-03-19 - 摘要：By using ionic liquid 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl) as reaction solvent and catalyst,and 1,1-carbonyldiimidazole as a coupling reagent,chitosan grafted with low molecular weight polyethylenimine (CS-g-PEI) was synthesized in a non-aqueous homogeneous solution.1H-NMR and FTIR experiments characterized the composition of copolymer CS-g-PEI and confirmed that the chitosan chains were successfully grated with polyethylenimine at a ratio of 42%.By using a coagulation method,CS-g-PEI/DNA complex nanoparticles were obtained,and their physicochemical properties were characterized with transmission electron microscopy (TEM),dynamic light scattering (DLS) and Agarose gel electrophoresis assay.The transfection efficiency of CS-g-PEI was evaluated in Hep-2 cell lines with pGL3 as reporting genes.The gene expressing mediated by CS-g-PEI was 160 times higher than that by CS.MTT assays results showed that CS-g-PEI had low cytotoxicity in the range of the experimental dose.The results indicate that CS-g-PEI synthesized in ion liquid [BMIM]Cl has a very good potential as efficient and safe non-viral gene vectors.关键词：Non-viral gene vector;Chitosan;Ionic liquid;PEI;Graftcopolymer
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发布时间：2021-03-19 - 摘要：A novel diamine monomer,2,5-bis(N,N-dimethylamino)methyl)-1,4-bis(4-aminophenoxyl)benzene (DMAPB),was synthesized.A series of sulfonated polyimide (SPI) were prepared from DMAPB,1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and sulfonated diamine (ODADS).By varying the molar ratio of the sulfonated diamine to the unsulfonated diamine,copolymers with 40%~ 80% sulfonation degree were obtained.The SPI membranes were obtained via solution casting with m-cresol as the solvent.The nitrogen atoms introduced in the side chains of the SPI could effectively resist membrane swelling due to the strong interchain interactions through basic nitrogen atoms and sulfonic acid groups.The copolymer SPI-40 showed higher water stability,it could maintain mechanical strength after being soaked in 100℃ liquid water for more than 1000 h.The copolymers were thermally stable up to 330℃ and displayed good oxidative stability.The membranes exhibit methanol permeability from 2.05 10-7 to 5.11 10-7cm2/s at 20℃,which was much lower than that of Nafion (2 10-6cm2/s).The SPI also showed reasonable mechanical strength under high moisture conditions.However,the cross-linked membranes showed lowered proton conductivities than the uncross-linked ones because that the crosslinking resulted in the more compact structure of membranes,which decreased the water uptake and hindered the mobility of water and H+.In addition,a part of the sulfonic acid groups was consumed during the cross-linking process.关键词：Sulfonated polyimide;Acid-base crosslink;Proton exchange membrane;Feul cell
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发布时间：2021-03-19 - 摘要：In order to develop novel chiral stationary phases (CSPs),chitosan was modified by benzoyl chlorides with various substituents,successively using methylsulfonic acid and N,N-dimethylacetamide as the solvents.In this way,new derivatives of chitosan bis(benzoate)-(benzamide),chitosan bis(4-methylbenzoate)-(4-methylbenzamide),chitosan bis(3,5-dimethylbenzoate)-(3,5-dimethylbenzamide) and chitosan bis(4-chlorobenzoate)-(4-chlorobenzamide) were synthesized.The corresponding CSPs were prepared by coating the chitosan derivatives on porous 3-aminopropyl silica gel employing N,N-dimethylforamide as the solvent.The chiral recognition capability of the CSPs was evaluated towards structurally various chiral compounds in normal phase conditions,and the results showed that these CSPs possessed satisfactory enantioselectivity.The CSP prepared from chitosan bis(4-methylbenzoate)-(4-methylbenzamide) with a coating ratio of 16% exhibited better chiral recognition capability than that prepared from the same derivative with a coating ratio of 20%.The CSP based on chitosan bis(3,5-dimethylbenzoate)-(3,5-dimethylbenzamide) showed stronger chiral recognition capability than the CSPs based on the other derivatives.Meanwhile,the CSP derived from chitosan bis(4-methylbenzoate)-(4-methylbenzamide) separated the chiral compounds with highest resolutions.This feature is similar to that of the CSP derived from cellulose tris(4-methylbenzoate),and different from that of the CSP prepared from amylose tris(4-methylbenozate) that bear poor chiral recognition capability.The reason may be related to the similarity of chitosan and cellulose in which the repeating units are all connected by -1,4-glycosidic bond,other than -1,4-glycosidic bond in amylose.In addition,the CSPs generally demonstrated better resolutions in the mobile phases simultaneously containing ethanol and methanol.关键词：Chitosan;Benzoylation;Coating;Chiral stationary phase;Chiral recognition
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发布时间：2021-03-19 - 摘要：The Langmuir-Blodgett (LB) technique was used to prepare thin films with cell outer membrane mimetic structure on the surface of cover glass.A crosslinkable amphiphilic random copolymer PMST,which was synthesized with acrylate monomers 2-methacryloyloxyethyl phosphorylcholine (MPC),stearyl methacrylate (SMA) and 3-trimethoxysilylpropyl methacrylate (TSMA) by free radical polymerization in solution,was applied to prepare the mononlayer,bilayer,and trilayer LB films according to the Y-type deposition mode.The surface hydrophilicity and surface morphology were measured by dynamic contact angles (DCA) and atomic force microscope (AFM) methods.The PMST polymer formed a dense and regular film on the surface of the cover glass,and the density of film increased with the number of layers.The surface hydrophilicity of monolayer and trilayer film was similar,and the bilayer was better than them in hydrophilicity.The difference can be attributed to the different surface structure:the bilayer film has the cell outer membrane mimetic structure and the other two have a reversed structure of the cell outer membrane.Once it contacts with water,the film surface structure will change as a result of the migration and reorientation of surface groups at the gas/water interface.关键词：Phosphorylcholine;LB film;Contact angle;Surface modification;Biomaterials
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发布时间：2021-03-19 - 摘要：The compatibility between olefin block copolymers (OBC1 and OBC2) and isotactic polypropylene (iPP) was studied in this work.The two OBCs have similar hard block content and octene content,but are different in molecular weight.The linear viscoelasticity of OBCs were systematically studied.It was found from linear viscoelasticity that OBC1 with high molecular weight tends to exhibit strong mesophase separation,while OBC2 with low molecular weight is homogeneous in the studied temperature range.The interfacial tensions between OBCs and iPP were measured by drop retraction and dynamic rheological method.Both methods have achieved consistent results for the interfacial tension of the blends.The interfacial tension between iPP/OBC1 is around 1.17 mN/m,which is larger than that between iPP/OBC2 (about 0.3 mN/m).The variation of glass transition temperature in iPP/OBC blends were also studied by dynamic mechanical analysis,and depressions in the glass transition temperature of iPP were observed in both blends,from which the solubility of OBCs in iPP was estimated by self-concentration model.It was found that although the interfacial tension between OBC1 and iPP is larger,their miscibility is better.This is ascribed to the strong mesophase separation of OBC1.Further study on the crystallization of iPP in blends also justified the miscibility difference between iPP and the two OBCs.关键词：Rheology;Olefin block copolymer;iPP;Mesophase separation;Compatibility
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发布时间：2021-03-19 - 摘要：A series of composite nucleating agents based on inorganic nano-particles (attapulgite and/or silica) and organic phosphate nucleating agent (NA11) were prepared via spray drying technique.The effects of nucleating agents on the mechanical properties and nucleation behavior of PP were studied.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),polarizing optical microscopy(POM) and wide angle X-ray diffraction(WAXD) were employed to characterize the dispersion of composite nucleating agents and their effects on the crystallization behavior of polypropylene.The mechanism of influences of composite nucleating agents on the properties of PP was also discussed.The research results suggested that the mechanical properties of PP were improved substantially with addition of composite nucleating agents into the system.The stiffness of PP was increased significantly with increasing the loading of composite nucleating agents.The ternary composite nucleating agents showed significant effect on improving the stiffness of PP at a loading of 0.2 wt%,which was similar as using pure NA11 at such loading.The observation on microscopic morphology showed that the three components in the ternary composite nucleating agent were inter-partitioned with each other,resulting in the improved dispersion of NA11and the inorganic nano-particles in PP matrix.关键词：Polypropylene;Composite nucleating agent;NA11;Silica;Attapulgite;Mechanical property;Crystallization
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发布时间：2021-03-19 - 摘要：In presence of different acrylate comonomers,polymer micro-tubes were fabricated directly by taking N,N'-methylenediacrylamide (MBA) organogel fibres as both the templates and monomer source via reversible addition-fragmentation chain transfer (RAFT) polymerization.The influences of RAFT polymerization and the functionality of comonomers on the yields and morphologies of the products were mainly investigated.The morphology,composition and thermal property of the products were analyzed by scanning electron microscopy (SEM),transmission electron microscopy (TEM),Fourier-transform infrared spectroscopy (FTIR),element analysis and thermogravimetric analysis (TGA).The results indicated that polymer micro-tubes with well-shaped morphology could be obtained by taking suitable amount of RAFT agent.The yield of polymer micro-tubes could be improved significantly by increasing the dosage of the comonomers.As increasing the functionality of the comonomer,the polymerization was enhanced and the yield became higher.As bifunctional comonomers with different chain lengths were used,the wall thickness of the obtained polymer micro-tubes was compared.The wall thickness became thicker with increasing the chain length of the comonomers.Besides,the yield of polymer micro-tubes could be improved significantly by including a small amount of tetrafunctional monomer in the reaction system with monofunctional comonomer.关键词：Polymer micro-tubes;RAFT polymerization;Comonomer;Functionality
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发布时间：2021-03-19 - 摘要：A Ziegler-Natta/metallocene composite catalyst(MgCl2/TiCl4/rac-Et(Ind)2ZrCl2)of reactor granule technology characteristics is combined with a co-catalyst pair of triethylaluminum (AlEt3,TEA) and methyaluminoxane (MAO) to activate its Ti and Zr catalytic species respectively.TEA exhibits a deactivating effect on the Zr species amid propylene homopolymerization,whereas ethylene restores the deactivated species during ethylene-propylene copolymeriation.By this way,a reversible deactivation of the metallocene Zr species has been realized in the preparation of catalyzed polypropylene alloys(propylene homopolymerization + ethylene-propylene copolymerization) with Ziegler-Natta/metallocene composite catalyst.New catalyzed polypropylene alloys have been prepared with MgCl2/TiCl4/rac-Et(Ind)2ZrCl2composite catalyst and TEA/MAO bi-component co-catalyst,with the catalyst and co-catalyst added in one-pot.The polypropylene (PP) matrix is selectively produced by the Ziegler-Natta Ti species,while the ethylene-propylene copolymer (EPR) is accounted for in large portion by the metallocene Zr species.Compared to conventional Ziegler-Natta catalysts,the Ziegler-Natta/metallocene composite catalyst renders PP alloys with a more random sequence distribution and equally well domain distribution of EPR.This research provides a new route to the controlled preparation of catalyzed PP alloys.关键词：Ziegler-Natta/metallocene composite catalyst;Catalyzed polypropylene alloy;Reversible deactivation;Triethylaluminum
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发布时间：2021-03-19
Research Article
- 摘要：To decrease the toxicity of polyethyleneimine (PEI) and broaden the application of PEI in biomedical materials,amphiphilic graft copolymers of polyethyleneimine-graft-poly(p-dioxanone) (PEI-g-PPDO) have been synthesized via a graft from strategy using PEI as macro-initiator and stannous octoate (Sn(Oct)2) as catalyst.The molecular structure of the copolymer was characterized by FTIR,1H-NMR and 1H-13C-HMQC.The results suggested that the molecular structure of the copolymer could be effectively adjusted by monomer content in reagent.DSC was performed for investigating the thermal and crystalline properties of the copolymer.The crystallization behaviors of the copolymer directly depend on the graft chain length and the PPDO content.The micellization behavior of the copolymer in water was also studied by using pyrene as probe,and showed that the copolymer could form stable micelle in water.关键词：Polyethyleneimine;Poly(p-dioxanone);Graft copolymer
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发布时间：2021-03-19
Research Bulletin
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