最新刊期
卷 ， 期 6 ， 2014
- 摘要：Graphene/rubber nanocomposites has attracted much attention.Many research results confirmed that graphene is one of the ideal fillers for rubber.In this paper,the preparation methods of graphene/rubber composites including emulsion blending,solution blending,and mechanical blending,as well as the mechanical properties and electrical conductivity,gas barrier properties and thermal behavior were reviewed.The future potentials and problems of graphene/rubber composites were discussed.关键词：Graphene;Rubber;Nanocomposites
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发布时间：2021-03-19 - 摘要：The extraordinary performances of polymer-matrix nanocomposites endow them with important fundamental and application research values.Graphene,as the first 2-dimensional material,has outstanding electrical,mechanical and thermal properties.Moreover,its preparation method is easy and inexpensive,and can be scaled up for mass production.Therefore,graphene is one of the most attractive filling materials in high-performance polymer nanocomposites.The dispersity of graphene in a polymer matrix,and the interfacial interaction between the two are key to the exploitation of the nanocomposite performances.In this review,different interfacial interactions between graphene and polymer matrices,including hydrogen bonding,- stacking,covalent bonding and coordination bonding were summarized.Besides,the advantages and disadvantages of these interfacial interactions,as well as their influences on high-performance polymer nanocomposites were discussed.关键词：Graphene;Polymer matrices;Nanocomposites;Interfacial interactions
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发布时间：2021-03-19 - 摘要：Graphene is a two dimensional honeycomb-like framework constructed by pure sp2-carbon atoms which exhibits extraordinary electronic and heat transport properties.Meanwhile,polymers are chain-like or network-like macromolecules formed by a series of monomers containing numerous heteroatoms (e.g.,H,O,N) and also functional groups.Due to the large specific surface area and excellent electrical properties of graphene,various high-performance graphene-based energy storage devices including lithium ion batteries and supercapacitors have been frequently demonstrated.Whilst,thanks to controllable structures and ultra-high surface areas,microporous polymers show potential in applications such as gas storage,catalysis and sensing.Recently,numerous transitional intermediates lying between graphene and polymers have attracted intense interest,being a new star in energy storage applications.Within this kind of nanomaterials,numerous graphene-like subunits are organically interconnected by small organic and/or polymeric fractions,forming diverse porous structures.With such structural characteristics,they are of well-designed combination of electron transport channels and ion transport channels,showing great potential in energy storage applications.Combined with recent progress made by our group and also others,we outline two representative approaches (bottom-up and top-down) for the synthesis of these novel materials (denoted as graphenal polymers),as well as exemplify their potential applications.关键词：Graphene;Polymer;Graphenal polymer;Bottom-up;Top-down
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发布时间：2021-03-19 - 摘要：Due to its special monolayer structure,graphene has interesting physical and chemical properties.Over the past ten years,graphene studies have has produced great effects on physics,chemistry,and material science and engineering,and have become one of the high-profile international frontiers and research focuses.The controllable preparation,assembly and functional applications of graphenes are essential for graphene studies.In recent years,researchers are constantly exploring the new ways for preparation and application of graphenes and their functional composites.Among them,the composite of graphene and conductive polymer polypyrrole (PPy) has attracted much attention in particular,and a series of valuable insight into the new graphene/polymer composites has been achieved.In this report,the recent important advances in controllable synthesis of graphene/PPy composites are summarized and some of the new developments in the field of electrochemical applications,including catalysis,actuator,supercapacitors,sensors,and so on,are discussed.关键词：Graphene;Polypyrrole;Controllable preparation;Electrochemical applications
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发布时间：2021-03-19 - 摘要：Starch,as a natural polymer,has unique microstructures and complex processing properties,which involves multiple physical and chemical reactions,i.e.water diffusion,granule expansion,gelatinization,melting,decomposition,recrystallization,etc.In this paper an attempt has been made to review the current state of knowledge and development on the microstructures and the phase transitions of starch under shear and shearless conditions.It reviews both fundamental science such as microstructures,phase transitions (especially for gelatinization,retrogradation and thermal stability) and rheological properties of different kinds of starches,and various processing techniques which have specific influneces on the phase changes.This paper also covers the general principles,capabilities,advantages and limitations of various techniques and methods available to study microstructures and phases transitions of starch.Based on the knowledge that have received widespread acceptance and those are still under debate,this comprehensive review aims at distinguishing the relationship between the microstructure and phase transitions.In particular,using corn starch with different ratios of amylose/amylopectin as model material,which provide a better understanding of the phase transitions and microstructure of starches,to develop the approach for product design and processing control of thermal procession of starch,and starch modification.The achievements in this area have increased our knowledge of polymer science,in particular that of natural polymers.
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发布时间：2021-03-19
Reviews
- 摘要：Supercritical solution impregnation (SSI) process was applied to prepare asymmetric chitosan films (ACFs) loaded with silver sulfadiazine (AgSD) suitable for wound dressing.ACFs with different dense layers (65 m and 125 m) and porous layers were first prepared using solvent casting and lyophilization method respectively,and then AgSD was loaded into ACFs using SSI process.The effects of impregnation pressure (from 8 MPa to 30 MPa) and temperature (40,50 and 60 ℃) on drug loading capacity (DLC) were investigated in detail,and the properties of AgSD-ACF were characterized such as morphology,water uptake (WU),water vapor transmission rate (WVTR),in vitro release,antibacterial and animal tests.The results showed that DLC of the AgSD-ACF increased with the elevation of the pressure and decreased when the pressure increased further; while the temperature affected the DLC in a complex manner,and the maximum DLC was achieved to be 5.0 mg/g at 20 MPa and 50 ℃.The in vitro release study indicated that the AgSD-ACF could prolong the release of AgSD to beyond 10 h under a sustained manner.The water uptake and water vapor transmission rate of AgSD-ACFs could be well adjusted by changing the thickness of the dense layer.AgSD-ACFs had a remarkable antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The result of animal test showed that AgSD-ACFs could promote the healing of the wounds in SD rats.The supercritical solution impregnation method makes it possible to fabricate drug loaded polymer matrix without using organic solvents and high temperature,which provide a promising way to prepare drug loaded films for potential applications in wound dressing.关键词：Supercritical solution impregnation;Wound dressing;Silver sulfadiazine;Asymmetric chitosan film
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发布时间：2021-03-19 - 摘要：The block polymer poly(carprolactone)-poly(quaternary ammounium salt) (PCL-b-PJDMA) was synthesized through ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP) reaction.The synthesis procedure was composed of following 4 steps:(1) LPCL was synthesized via ROP reaction of -caprolactone using laurinol as an initiator; (2) LPCL was functionalized to get a macrointiator PCL-Br for ATRP by the reaction with 2-bromine butyryl bromine (BIBB); (3) the quaternary ammounium salt named with JDMA was synthesized by quaternarization of methyl chloroacetate and dimethylaminoethyl methacrylate; (4) LPCL-b-PJDMA with different unit ratios were synthesized through ATRP reaction of JDMA using PMDETA/Cu(Ⅰ)Br as a catalyst and different unit number PCL-Br as the macrointiator.The molecular structure was mainly confirmed by 1H-NMR.Thermal behavior and hydrophilicity of polymers were measured by differential scanning calorimetry (DSC) and water contact angle experiments of the polymer membrane,respectively.The anti-bacterial property of the polymer films was measured by testing the survival rate of bacteria living on the films.The results showed that the Tc of obtained PCL-b-PJDMA first reduced and then increased with the increase of PCL units in PCL-b-PJDMA.All LPCL-b-PJDMA displayed better hydrophilicity than pure PCL and the hydrophilicity of LPCL-b-PJDMA was related to the ratio of PCL to PJDMA.The bacterial experiment result showed that all the polymer films had anti-bacterial ability to both gram-negative bacteria and gram-positive bacteria.关键词：Poly(carprolactone);Poly(quaternary ammounium salt);Block polymer;Anti-bacterial material
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发布时间：2021-03-19 - 摘要：Nonequlibrium molecular dynamics (NEMD) has been used to simulate the heat transport in single PE chains stretched along the main chain direction.The effects of chain length (L) and tensile strain () on thermal conductivity of single PE chains are investigated.Furthermore,the microscopic mechanism of heat transport in polymer chains is studied.The simulation results show that the thermal conductivity of PE increases with increasing L and ,and the trend gets gently.This trend about L is understood to be a result of competition between ballistic phonon transport and diffusive phonon transport in a single polymer chain and limitation from the finite-size effects.The trend about is determined by the growing phonon mean free path and decreasing number density of atoms during drawing.The spectrum of vibrational density of states (VDOS) presents some high frequency peaks which represent different vibrations (stretching,bending,etc.) in PE chains,and these high vibrations decrease with increasing .The low frequency peaks of spectrum of VDOS associated with low frequency modes of vibrations are strengthened at first and then weakened with increasing ,known to be significant for thermal conduction due to their thermal diffusivity.关键词：Polyethylene;Chain length;Tensile strain;Nonequlibrium molecular dynamics;Thermal conductivity;Vibrational density of states
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发布时间：2021-03-19 - 摘要：A series of polysiloxane/TiO2 composite films was prepared through in-situ hydrosilylation reaction of vinyl-terminated silicone oil and hydrogen silicone oil in the presence of anatase titanium sol particles or P25 type TiO2 powder particles,in order to achieve a homogeneous dispersion of TiO2 particles in the cross-linked substrate films.The chemical composition,cross-linking structure,morphology,tensile and optical properties of the composite films were characterized by attenuated total reflection Flourier transformed infrared spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,tensile tests,and UV/Vis spectroscopy.The stability of reaction system and the tensile property of the composite films were improved because of the chain extension of silicone oil and the reinforcement of SiO2.Hydrophilic TiO2 powder particles were easy to form macro-aggregates during the process of film formation.The agglomeration of TiO2 powder particles had negative influence on the mechanical and optical properties of the composite films.The surface of titanium sol particles prepared via a sol-gel process displayed lipophilicity as a result of the remaining of organic groups.The lipophilic surface of titanium sol particles improved the compatibility between titanium sol particles and polysiloxane.Titanium sol particles with a lipophilic surface could be uniformly dispersed in toluene and composite films without agglomeration.The resultant polysiloxane/titanium sol composite films showed good tensile properties,strong UV shielding and high transparency.关键词：Polysiloxane;Titanium sol;Composite film;Hydrosilylation reaction
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发布时间：2021-03-19 - 摘要：In this study hyperbranched polyacetals (HBPAs) were used as a new type of porogens to prepare porous biodegradable microspheres.HBPAs were synthesized through the transacetalization process,which was carried out with an AB2 type monomer of 4-(2-hydroxyethoxy)-benzaldehyde dimethyl acetal and a B2 type core of benzaldehyde dimethyl acetal catalyzed with pyridinium camphorsulfonate (PCS).The results demonstrated that HBPAs were highly pH sensitive.They degraded rapidly at pH 5.0,and barely degraded at pH 7.4.The porous biodegradable poly(lactic acid) (PLA) microspheres were prepared by blending HBPAs and PLA with the emulsion-solvent evaporation method and the blending microspheres were then placed in acidic conditions for 2 weeks.As HBPAs hydrolyzed faster than PLA,the HBPAs component was first degraded from the blending microspheres to form small pores in the PLA matrix.DSC results and degradation process of the blending microspheres showed that the phase separation appeared in the blending microspheres of HBPAs and PLA.This phase separation favored the hydrolysis of HBPAs in the blending microspheres.The pore size of the microspheres can be regulated by changing the weight ratio of HBPAs to PLA.With increasing the HBPAs amount,the pore size of the PLA microspheres increased in a linear manner.HBPAs,as a new type of porogens,offer a new method to prepare porous microspheres.关键词：Hyperbranchedpolyacetals;pH sensitive;Porogen;Porous microspheres
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发布时间：2021-03-19 - 摘要：Compared with 2D plate,3D tumor cell system is more like tumor tissue,for the 3D scaffold where cells grow can imitate the ECM in organisms,so that it could be used for evaluating anti-tumor efficacy of chemotherapeutic drugs with higher accuracy.There have been different ways to form a 3D scaffold,and electrospinning is the one with great potential.Although studies have shown that when exposed to drugs,greater amount of drugs are needed to kill the cells cultured on 3D scaffold,few studies have ever focused on the sensitive properties of 3D cell systems to drug delivery systems.As drug delivery system is going to be widely used in the future tumor treatment,in order to establish a drug delivery test model to predict the influence of drugs to tumor growth,a 3D cell culture scaffold composed of PCL and gelatin with high porosity,cell affinity and reasonable mechanical properties was fabricated through electrospinning method.One of the compositions PCL ensures the mechanical strength to avoid collapse and gelatin is a well known material with good biocompatibility.U87 was seeded on this scaffold,and the proliferation was monitored over 14 days with SEM and CLSM.It was found that U87 cells can not only adhere to the surface of the scaffold,but also migrate into the interior of the scaffold,forming a 3D cell system.When exposed to free DOX the electrospun scaffold was found to have lower drug sensitivity compared with the 2D cell culture plate.Further investigation of using Dox-loaded PEG-b-PCL micelles as the delivery system demonstrated the same result.关键词：Electrospinning;3D cell system;DOX;Micelle
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发布时间：2021-03-19 - 摘要：Cross-linked sterically stabilized latexes were synthesized by emulsion polymerization of 2-(diethylamino)ethyl methacrylate using a bifunctional ethylene glycol dimethacrylate cross-linker and a poly-(ethylene oxide)-based macromonomer as the stabilizer.These latexes exhibit reversible swelling properties in water by adjusting the solution pH.At low pH,they exist as swollen microgels as a result of protonation of the tertiary amine units.Deswelling occurs above pH=7 [the effective pKa of poly(2-(diethylamino)ethyl methacrylate)],leading to the formation of the original compact latex particles.PDEA-Pd nanocomposite particles were prepared via in situ reduction using NaBH4 as a reducing agent,based upon a polymer microgel template method.pH-responsive microgel-nano metal particle composite system can be prepared for catalyses which proceed under acidic conditions.The composite system of the microgel and the metal nanoparticles form homogeneous phase with the physics reaction,which can effectively improve the catalytic efficiency, and after completion of the reaction the system can be adjusted at alkaling conditions for recycling.TEM,UV-Vis,XRD and TGA were used to characterize Pd particle size,the PDEA-Na2PdCl4 composite microspheres interaction,Pd crystal form and Pd loadings.TEM images showed the Pd particle diameter was about 3.5 nm.The rate constant kapp for the reduction of 4-nitrophenol in presence of PDEA-Pd nanocomposite particles was studied by UV-Vis spectroscopy,which suggested the PDEA-Pd nanocomposite particles had good catalytic activity.The pH-responsive catalyst can be easily separated from the reaction mixture and readily recovered.关键词：Cationic microgel;pH-responsive;Pd nanoparticle;Catalytic activity
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发布时间：2021-03-19 - 摘要：Underwater superoleophobic composite films containing hydrophilic SiO2 nanoparticles and chitosan were prepared on glass substrates by a simple dip-coating method.By observing the surface morphologies with scanning electron microscope (SEM) and atomic force microscope (AFM) and measuring oil contact angles,factors affecting the morphology,roughness,contact angle and sliding angle of the film,such as the immersion time in the water and the volume ratio of hydrophilic SiO2-ethanol suspension to chitosan solution,were investigated in detail.With the increase of the volume ratio of hydrophilic SiO2-ethanol suspension to chitosan solution,more hydrophilic SiO2 powders accumulated on the surfaces of composite films,leading to a significant increase of underwater oleophobicity.With the increase of immersion time in the water,underwater oil contact angle (OCA) of the composite films first increased gradually and then slightly decreased after the films were immersed for 168 h.Meanwhile,the sliding angle (SA) of the films was also affected by the immersion time.When the volume ratio of hydrophilic SiO2-ethanol suspension to chitosan solution was 1:10 and 1:5,the chitosan-SiO2 composite films were oleophobic; and when the volume ratio of hydrophilic SiO2-ethanol suspension to chitosan solution was equal to or higher than 1:2,the chitosan-SiO2 composite films exhibited underwater superoleophobicity with underwater oil contact angles (OCA) higher than 150.When the chitosan-SiO2 composite film with the volume ratio of hydrophilic SiO2-ethanol suspension to chitosan solution 1:1 immersed in the water for 24 h,it showed an underwater oil contact angle (OCA) 157.8 and sliding angle (SA) 1.9,exhibiting outstanding underwater superoleophobicity.The chitosan-SiO2 composite films was applied to the manipulation of oil droplets underwater and realized the addition reaction of Br2 and styrene in oil droplet microreactors underwater.关键词：Underwater superoleophobicity;Chitosan;Hydrophilic silica powder;Underwater oil droplet microreactor;Contact angle
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发布时间：2021-03-19 - 摘要：A diamine with carboxyl-terminated polyethylene glycol (PEG) side chains (Lys-NH-PEG)was synthesized as chain extender for polyurethanes (PUs),using L-lysine,ethylenediamine and PEG bis-(carboxymethyl)ether as raw materials.Further to this,a comb-like polycarbonate urethane with PEG side chains (PCU-L-P) was synthesized using Lys-NH-PEG and 4,4'-diphenylmethane diisocyanate (MDI) as hard segment,and polycarbonate diol as soft segment.Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR) were used to confirm the chemical structure of PCU-L-P,whose number-average molecular weight was about 38000 determined by gel permeation chromatography (GPC).The solution of PCU-L-P (in dimethylformamide) can be transformed into hydrocolloid stabilized by the hydrophilic PEG side chains,with a mean particle size of about 213 nm and a zeta potential of -19 mV.Model protein albumin has been successfully grafted onto the colloidal particles,indicating the reactivity of the carboxyl groups at the PEG free ends.This reactive polyurethane can be used to graft various biomolecules for improving PUs' biofunctionality.关键词：Polyurethane;Polyethylene glycol;Hydrophilic modification;Albumin
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发布时间：2021-03-19 - 摘要：A new pyridazine-containing aromatic diamine monomer,3,6-bis(3-aminophenoxy)pyridazine,was successfully synthesized by a nucleophilic substitution reaction of 3,6-dichloropyridazine with meta-aminophenol in the presence of potassium hydroxide in dimethyl sulfoxide (DMSO).1H-NMR,FTIR and HPLC-MS were employed to confirm the diamine and intermediates structure.In order to maintain the thermal and mechanical properties,and improve the glass transition temperatures (Tg) and optical property,the novel aromatic heterocyclic diamine monomer was employed to synthesize a series of polyimides by polycondensation with various commercial aromatic dianhydrides in N,N-dimethylacetamide (DMAc) via the conventional two-step method,i.e.,ring-opening polycondensation forming the poly(amic acid)s (PAA) and further thermal imidization forming the pyridazine-containing polyimides.The resulting PAA possessed inherent viscosities in the range of 0.37~0.50 dL/g.High quality polyimide films could be prepared by casting the PAA solutions on glass plates.Experimental results indicated that the polyimide films had good thermal stability,with high initial decomposition temperature (Td 409 ℃) and Tg of 188~241 ℃,and the temperature at 5% and 10% weight loss of 421~448 and 458~473 ℃ at a nitrogen atmosphere,respectively.Moreover,the polyimide films showed outstanding mechanical properties with tensile strength of 46~102 MPa,tensile modulus of 2.7~3.5 GPa and elongation at break of 2.0%~6.5%.Most of the polyimide films had good chemical resistance,and were insoluble in common organic solvents,such as NMP,DMSO,DMF,m-cresol and CHCl3.The UV-Visible measurements indicated that the cut-off wavelength of polyimide films was in the range of 367~389 nm.The pyridazine-based polyimide films showed a good combination of properties.关键词：Nucleophilic substitution;Pyridazine diamine;Polyimide films
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发布时间：2021-03-19 - 摘要：The aim of this study is to balance the conductive properties with catalytic activity of the counter electrodes effectively and to resolve the complexity of production process.Using a kind of network conductive polyaniline as the catalyst and graphite filler as the conductive material,by means of screen printing the mixture of the two components on the FTO surface the polyaniline/graphite composite counter electrodes were fabricated successfully.The structure and catalytic and conductive characteristics of the electrodes were investigated with the scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).According to the SEM results,the network structure of conducting polyaniline still exists in the composite.The addition of graphite fills the space of the polyaniline matrix effectively.Based on the same original catalytic activity,the electrical conductivity of the counter electrode has been enhanced.With the aid of CV and EIS,the catalytic and conductive characteristics of the composite counter electrode were speculated.Tests on the photoelectric performance of the DSSCs with the composite counter electrodes show that when the graphite mass fraction reaches 10%,the dye-sensitized solar cell (DSSC) based on the polyaniline/graphite composite counter electrode may have the photoelectric conversion efficiency of 8.5%.It is 123% of the efficiency with traditional Pt electrode under the same conditions.关键词：Dye-sensitized solar cells;Counter electrode;Polyaniline;Mesh porous structure
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发布时间：2021-03-19 - 摘要：The ABC miktoarm star terpolymer MPEG-PTHF(-PDMA) was synthesized by the combination of click chemistry,atom transfer radical polymerization (ATRP) and cationic ring opening polymerization (CROP).A block copolymer of poly(ethylene glycol) (PEG) and poly(N,N-dimethylaminoethyl methacrylate) (PDMA) which bears an azido at diblock junction (MPEG-N3(-PDMA)) was first prepared by atom transfer radical polymerization.Then,an alkynyl-terminated narrow distributed polytetrahydrofuran (PTHF-Alk) was synthesized as another building block via cationic ring opening polymerization.The well-defined ABC miktoarm star shaped terpolymer was afforded by clicking MPEG-N3(-PDMA) onto the chain end of PTHF-Alk.The structure of the star terpolymer was characterized by the FTIR,NMR and SEC/MALLS.The self-assembly behavior of the polymer were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM).This star shaped terpolymer consists of a hydrophobic PTHF chain,a hydrophiphilic PEG chain and another stimuli-responsive PDMA chain.It can self-assemble into micelles with different sizes and morphologies at various pH values,such as 5.0,7.4 and 9.5.The micellar size also exhibits temperature-dependence at pH 7.4 and 9.5.The variation of size and morphology of the micelles with the solution pH and temperature is ascribed to the pH- and thermo-responsive properties of the PDMA block.关键词：Star polymer;Miktoarm copolymers;Controlled self-assembly;Stimuli-responsive
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发布时间：2021-03-19
Research Article
- 摘要：Monodisperse silica particles were prepared by the modified Stber method,and the SiO2 opal film was obtained by a vertical deposition self-assembly method.Polyaniline was infiltrated into the SiO2 opal template via electrochemical methods,so as to fabricate core-shell structured SiO2@PANI photonic crystal films.The electrochromic properties,contrast and response time of the SiO2@PANI film were characterized via cycle voltammograms and spectroelectrochemistry.It was found that the color of the SiO2@PANI film was bright and vibrant with a maximal contrast of 77%,which was superior to that of the pure PANI film (43%),and its response speed was faster.It is an effective method to improve the electrochromic performances of conducting polymers by introducing the photonic crystal structures.关键词：Photonic crystal;Silica microspheres;Polyaniline;Electrochromism
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发布时间：2021-03-19
Research Bulletin
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