最新刊期
卷 ， 期 7 ， 2015
- 摘要：In recent years, with the development of regenerative medicine technique, there has been a heated attention and research about reconstruction of human organs by means of tissue engineering.One important factor of this technique is the building of scaffold, which has significant impact on the structure and nature of regeneration tissue.This review focused on biodegradable materials and reported the influence of design and molding process on tissue engineering scaffold based on different textile technology.Three textile structures, knitting waving and braiding, can control the morphology of polymer aggregation and cannot be mutually alternated in some clinical practice.Because they can create distinct three dimensional structures and biomechanics, which play vital roles in regulate cell activity and tissue regeneration.Textile technology broadens the artificial biodegradable polymer materials used in the tissue engineering.A wide range scaffolds with different biomechanics and biodegradation ability can be designed to satisfy clinical requirements.This kind of work is indispensable in promoting the clinical application of tissue engineering.关键词：Degradable;Polymer;Textile;Reinforcement;Tissue engineering scaffold
- 43
- |
- 20
- |
- 0
发布时间：2021-03-19 - 摘要：Polysilanes are composed of SiSi in main chains.The delocalization of -orbitals along the silicon backbone, results in a HOMO-LUMO band gap as low as 3~4 eV, which leads to a strong absorption in UV region and unique conducting or semiconducting properties with doping.At the same time, linear polysilane also tends to show a good solubility in several solvents.These properties will meet some potential applications as photoconductors, semiconductors, nonlinear optical materials, LEDs and photoresists.However, polysilanes containing SiCl or SiH bonds are moisture and air sensitive, and their optical/conductive properties are unacceptable comparing to other functional polymers.For this reason, the functional modification of polysilane is necessary.In this review, firstly, the relationship between the structure and the electrical characteristics of polysilane is summarized.Conjugate effect, electronic effect and steric hindered effect of substitution provide significant changes in the electronic structure, and then affect the optical and electrical properties of the polysilane.Secondly, the recent progress in polysilane modification methods is classified and reviewed in detail.Post-functionalization is focused on the mild reaction conditions and plenty of selections in functional side groups.Finally, the feasibility in applying polysilanes as base material is prospected.关键词：Polysilane;Post-functionalization;Organic functional materials
- 29
- |
- 15
- |
- 1
发布时间：2021-03-19
Reviews
- 摘要：In order to investigate the explicit electro-optical properties and self-assembly variations of photoluminescent polymers under different micro-environments, three multiple and environmental responsive polyfluorene-based blue light-emitting copolymers (Pa, Pb and Pc) were successfully synthesized through Suzuki coupling reaction.The molecular structures of the copolymers were fully characterized by 1H-NMR, 13C-NMR, elemental analysis and gel-permeation chromatograph, respectively.The photophysical properties and self-assembly behaviors of polymers Pa, Pb and Pc were examined through UV-Vis absorption, photoluminescent smission spectra, dynamic laser light scattering and transmission electron microscopy.The experimental results indicated that the polymers took on wide band gap of 3.09 eV with blue emission in thin solid films.The photoluminescent changing of copolymers in different solvents or temperature were studied to correlate the aggregation-induced emission properties with the chemical structures of copolymers, and it was found that the aggregation induced emission properties of polymers Pa, Pb and Pc were determined by the volume proportion of water in the mixture solvent of water and tetrahydrofuran.The size and morphology of the vesicles formed from polymer Pa, Pb and Pc can be effectively tuned in a range of 900 nm to 10 nm.It can further make polymer P-N to be water-soluble and temperature-responsive by introducing poly(N-isopropyl acrylamide) into the main chain of polymer Pb through atom transfer radical polymerization.The photoluminescent emission profile of polymer P-N is adjusted by changing the temperature of polymer P-N in tetrahydrofuran, while the size of the formed vesicle in the mixture solvent of water and tetrahydrofuran is increased when the temperatures of polymer P-N in the mixture solvents are below or above lower critical solution temperature of poly(N-isopropyl acrylamide).This work can serve as an excellent exploratory example for the fine self-assembly control principle in the amphiphilic photoluminescent copolymers with branched and diversified side chains through the multiple weak interactions of polyfluorene-based -conjugated copolymers.关键词：Blue-light;Aggregation-induced emission;Multiple;Environmental responsive;Fluorene
- 33
- |
- 11
- |
- 1
发布时间：2021-03-19 - 摘要：The fulvic acid (FA) was prepared with Xinjiang local weathered coal by HNO3 oxidation technology, and then quaternary fulvic acid (QFA) was synthesized with FA.The QFA intercalated saponite (QFA-saponite) was prepared with saponite by ultrasonic intercalation.Poly(lactic acid) (PLA)/QFA-saponite nanocomposites were in situ polymerized with D, L-lactide and QFA-saponite and with stannous octoate as the catalyst.The effects of polymerization time, polymerization temperature, the addition amount of catalyst and QFA-saponite on the molecular weight of PLA were investigated by orthogonal experiment, respectively.The optimum conditions were as follows:polymerization time was 12 h, the addition amount of stannous octoate was 3 wt%, polymerization temperature was 150 ℃ and the addition amount of QFA-saponite was 2 wt%, respectively.Under the optimum conditions, the molecular weight of PLA/QFA-saponite nanocomposites was 95300.FTIR analysis showed that the quaternary ammonium ions were introduced into fulvic acid.The structure of QFA-saponite was characterized by X-ray diffraction (XRD).It was shown that QFA-saponite had co-existence structure with intercalation and partial exfoliation, and its basal spacing was 1.57 nm, which was increased by 0.17 nm compared with that of saponite.The structure of PLA/QFA-saponite nanocomposites was investigated by XRD, polarized optical microscopy (POM) and thermal gravimetric analysis (TGA), respectively.The results showed that exfoliated PLA based nanocomposites were obtained by in situ polymerization, and QFA-saponite significantly improved the crystallinity properties and thermal stability of PLA.Antibacterial experiments showed that QFA-saponite had antibacterial and sterilization properties against Escherichia coli, Bacillus subtilis, Aspergillus and Penicillium.Meanwhile, PLA/QFA-saponite nanocomposites also had good antibacterial properties.关键词：PLA;QFA-saponite;In situ polymerization;Nanocomposites
- 25
- |
- 10
- |
- 2
发布时间：2021-03-19 - 摘要：PA6 nanofibrous membrane was first fabricated by electrospinning technique and then PA6@LDH composite nanofibrous membrane was synthesized by hydrothermal method of a mix of LDH precursor and PA6 nanofibrous membrane.Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Energy dispersive detector (EDX), X-ray diffraction (XRD) were used to confirm the formation of LDH on the PA6 nanofibers.The result of SEM revealed that PA6@LDH nanofibrous membrane had a better morphology and a lot of nanoparticles successfully adhered to the surface of PA6 nanofibrous membrane.FTIR, EDX and XRD proved that the nanoparticles were LDH.Cr(Ⅵ)-removal experiments were carried out to study the influence of Mg/Al molar ratio and pH value.The results indicated that the best Mg/Al molar ratio was 3, the highest Cr(Ⅵ) adsorption occurred at pH value of 2 and the adsorption capacity could be as high as 242 mg per gram of membrane, which was much higher than the most reported research results.Moreover, the adsorption experiment also showed that the adsorption process belonged to Langmuir adsorption model and the kinetics of the adsorption followed the pseudo-second-order model.Meanwhile, the freestanding membrane could be easily separated from liquid solutions and showed excellent cyclic utilization performance.Therefore, the PA6@LDH nanofibrous membrane could be a good candidate for the development of new environmental remediation nanomaterials.关键词：Electrospinning;Nanofibrous membrane;Layered double hydroxide;Hexavalent chromium
- 30
- |
- 13
- |
- 7
发布时间：2021-03-19 - 摘要：The hydrogen-bonded films were prepared via layer-by-layer assembly of poly(vinylpyrrolidone) (PVPON, hydrogen bond acceptors) and poly(acrylic acid) (PAA, hydrogen bond donors).UV-Visible spectra, FTIR spectra and AFM were used to investigate the hydrogen bond detachment and the film disintegration in acidic solvents:formic acid, trifluoroacetic acid, phosphoric acid and poly(phosphoric acid).The dissolution rate of the PVPON/PAA thin film in different acids was queued as:trifluoroacetic acid phosphoric acid formic acid.The experimental results indicated that the mechanism of hydrogen bond detachment was not the same in different acids.Trifluoroacetic acid shows strong interaction with PAA, which induces the detachment of hydrogen bonds between PVPON and PAA, and thus the PVPON/PAA film dissolves.However, phosphoric acid or poly(phosphoric acid) has strong interaction with PVPON, which makes hydrogen bonds between PVPON and PAA break and the thin film decomposes.Poly(phosphoric acid) has more hydrogen bonding donor groups than phosphoric acid, and hence the interaction between poly(phosphoric acid) and PVPON exhibits an synergetic effect.Formic acid and PAA both belong to the family of carboxylic acids.It is very hard for formic acid to replace PAA to form hydrogen bond with PVPON, and hence the film dissolution rate in formic acid is very low.关键词：Hydrogen bond detachment;Layer-by-layer assembly;Polymer complex
- 31
- |
- 11
- |
- 2
发布时间：2021-03-19 - 摘要：A novel polyvinyl alcohol (PVA) grafted 4'-formoxylbenzo-15-crown-5-ether (FB15C5) (PVA-g-FB15C5) for lithium isotopes separation was prepared from PVA and FB15C5 as starting materials via acetalization reaction.The effects of the reaction conditions such as catalyst content (A), crown ether content (B) and PVA concentration (c) on immobilization amount of crown ether were investigated using the response surface method.The results showed that the immobilization amount of crown ether obtained under the optimum conditions of catalyst content of 0.79 g, crown ether content of 0.51 g and PVA concentration of 3.7104 mg/L was 2.11 mmol/g.Further, the single stage separation factor for lithium isotopes increased with an increase in the softness of counter anion in lithium salts during the solid-liquid extraction for lithium isotopes separation via PVA-g-FB15C5 with the immobilization amount of crown ether of 2.11 mmol/g.Moreover, the maximum value of single stage separation factor obtained by PVA-g-FB15C5 was 1.039 when LiBr aqueous solution was used as an extraction solution at 20 ℃.It was also found that the heavier isotope -7Li was enriched in the polymer phase during the process of solid-liquid extraction, whereas the lighter one -6Li was concentrated in the solution phase.关键词：4'-Formoxylbenzo-15-crown-5-ether;Polyvinyl alcohol;Solid-liquid extraction;Response surface method;Lithium isotopes separation
- 29
- |
- 12
- |
- 7
发布时间：2021-03-19 - 摘要：A kind of polyrotaxane (PR)-based block copolymers was synthesized via the atom transfer radical polymerization (ATRP) of hydroxylethylene acrylate (HEA) initiated by polypseudorotaxanes (PPRs) built from a distal 2-bromoisobutyryl end-capped polypropylene glycol-polyethylene glycol- polypropylene glycol (PPO-PEO-PPO) with a varying amount of -cyclodextrins (-CDs) in the presence of Cu(I)Cl and N, N, N', N', N-pentamethyldiethylenetriamine (PMDETA) as catalyst at 20 ℃ in aqueous solution.The supramolecular structure of the resulting copolymers was characterized by means of 1H-NMR, GPC, FTIR, WXRD, DSC and TGA measurements.It was shown that the PHEA segments were attached to two ends of PPRs to give rise to the PR-based block copolymers featured by a characteristic channel-type crystal structure.The entrapped -CD number was increased with the feeding molar ratio, but only about one third added -CDs were retained on the polymer chain after the ATRP process.However, the polymerization degree of PHEA (DP) segments was well controllable with changing the molar feed ratio.In addition, -CDs were observed to favourably aggregate around the PPO segments and nearly cannot accommodate with the PEG segments after incubation in water and freeze-drying.However, according to TGA analyses, there were around one-third of the threaded -CDs enabling to slide to the PEO segments after being treated with DMF and anhydrous ether.The results suggested that these PR-based block copolymers exhibit the solvent-responsibility with the potential to be used as solid smart materials.关键词：Atom transfer radical polymerization;Polyrotaxane;Hydroxyethylene acrylate;-Cyclo-dextrin;Self-assembly
- 23
- |
- 10
- |
- 0
发布时间：2021-03-19 - 摘要：Hydrophobic fluorinated polyurethanes (FPU) with no hydrophilic CH2OH groups were prepared, by using the method of introducing fluorine with perfluoroalkyl ethanol (TEOH-10) for modification of diphenylmethane diisocyanate (MDI) and controlling the MDI adding dosage and time. Water resistance experiments indicated that the FPU showed strong hydrophobic properties, owing to the low surface energy of fluorocarbon chains (CF2CF3) migrated to the surface of the material and formed the organic fluorine membrane which was equivalent to the lotus leaf hydrophobic effect. Especially when the molar ratio of TEOH-10 was 0.3~0.5 to the theoretical quantity of MDI, the water absorption of FPU was only between 0.0182% and 0.0146%, and the high bonding force of FPU was maintained at 10.31~10.79 MPa after soaking in water for 3200 h. The erosion wear experiments showed that the anti-erosion performance of FPU was continuously improved with the increase of fluoride content, however, the cohesive force of FPU was continuously reduced because of the increasing fluoride content. When the mole ratio of TEOH-10/MDI was 0.5, the cavitation erosion amount of FPU reduced from 2.375610-3 kg to 0.933410-3 kg, and the cohesive force of FPU stayed above 10 MPa. These hydrophobic fluorinated polyurethanes are promising to be used as a protective coating of under-water flow parts.关键词：Hydrophobic fluorinated polyurethane;Fluorinated organic membrane;Flow components;Hydrophobic;Anti-erosion performance
- 51
- |
- 18
- |
- 11
发布时间：2021-03-19 -
Preparation and Performance of SSPEEK/Na-MMT Composite Proton Exchange Membranes for VRB Application
摘要：A grafted PEEK with graft chains of poly(sodium styrene sulfonate) (SSPEEK) has been prepared through atom transfer radical polymerization (ATRP) for use as a proton conducting membrane in vanadium redox flow battery (VRB).The Na-montmorillonite (Na-MMT) was introduced into the SSPEEK membrane by solution blending process to obtain a composite membrane.The composite membranes possess good thermal stability according to the TG analysis.The scanning electron microscopy indicates that the Na-MMT was uniformly dispersed in the polymer matrix.When the addition of Na-MMT reaches 9 phr, the permeability for vanadium ion of the composite membrane is 4.8810-6 cm2 min-1, which is lower than that of virgin SPFEK membrane (1.2410-5 cm2 min-1) and Nafion 117 (6.0410-6 cm2 min-1).The discharge time of the VRB assembled with the composite membrane is up to 215 min at 30 mA cm-2, which is higher than the Nafion's 198 min under the same measurement condition.The VRB single cell employing the SPFEK/Na-MMT membrane exhibits high coulombic efficiency which is about the same as that 8 Nafion 117.关键词：Sulfonated PEEK proton exchange membrane;SSPEEK/Na-MMT composite membrane;All-vanadium redox flow battery;Vanadium ion permeability- 36
- |
- 8
- |
- 1
发布时间：2021-03-19 - 摘要：Influence of alkyl trimethylammonium bromide (CnTAB) on rheological behavior of sodium carboxymethylcellulose (NaCMC) in entangled semi-dilute solution was investigated with respect to tail length of CnTAB.Both critical aggregation concentration (cac) and viscosity were studied.cac was achieved by steady-state fluorescence using pyrene as a probe.Effect of CnTAB tail length on formation of micelles in water and NaCMC solution were quantified by calculating the Gibbs free energy.A strong thicken effect of CnTAB at high concentrations on the entangled semi-dilute solution of NaCMC was found.According to transmission electron microscopy images, both isolated micelles (ca. 5 nm) at low NaCMC concentrations and large aggregates (ca. 30 nm) at high NaCMC concentrations can be seen.Excluding the viscosity reduction by the neutralization of charges induced by NaCMC, the isolated micelles act as hard spheres, causing a viscosity change of the NaCMC solution following Einstein law.On the other hand, percolation appears at high CnTAB concentrations and the micellar aggregates spread to form a network penetrating the entanglement network of NaCMC macromolecules.It is found for the first time that the viscosity of entangled semi-dilute solution increases according to the percolation theory with mean-field calculation.This indicates that long range interaction dominates in the aggregation and percolation behavior of micellar aggregates.At the onset of micellar percolation, critical volume fraction of micelles increases while mean distance between micelle surfaces decreases with increasing tail length of CnTAB.关键词：Polyelectrolyte;Surfactant;Entangled semi-dilute solution;Critical aggregation concentration;Percolation
- 25
- |
- 11
- |
- 1
发布时间：2021-03-19 -
Transformation of the Counterion of Active Species and Anionic Block Copolymerization of PBMA-b-PMMA
摘要：7Li-NMR was used to characterize the mixed system of n-butyl lithium (n-BuLi) and potassium t-butoxide (t-BuOk) with different molar ratios in THF and cyclohexane.The anionic block-copolymerization of butyl methacrylate (BMA) and methyl methacrylate (MMA) was initiated by 1, 1-diphenyl hexyl lithium and using phenol lithium, sodium t-butoxide and t-BuOk as the side reaction inhibitors.GPC and1H-NMR were used to characterize the structure of the block copolymers.It was found that the exchange reaction of Li in n-BuLi and K in t-BuOK could be generated, in which the inactive lithium t-butoxide and active species with K as the counterion formed.The new species had admirable impact on inhibiting the side reaction in the anionic polymerization of the polar monomers, such as MMA.The surplus t-BuOK in the system could further promote the inhibition effect.When the mole ratio of nt-BuOK/nn-BuLi was not lower than 20, the total yield of the block copolymerization of BMA and MMA could reach up to 100% and the molecular weight distribution was only 1.40 with unimodal distribution even when the copolymerization temperature was up to 40 ℃.Mn determined by GPC well coincided with the calculated theoretically data.The value of nMMA/nBMA in copolymer determined by 1H-NMR was also well close to that of raw material.The results could lay an industrial foundation for the block copolymerization of polar monomers, such as MMA.关键词：Potassium t-Butoxide;Counterion exchange;Side reaction inhibition;Butyl methacrylade;Methyl methacrylate- 41
- |
- 11
- |
- 2
发布时间：2021-03-19 - 摘要：Polyvinylidene fluoride (PVDF) membranes as supports were in situ modified by surface-initiated electronic activation of regeneration atom transfer radical polymerization (SI-AGET ATRP) of 4-vinylpyridine (4VP) functional monomer.The pyridine pendant groups at the grafted P4VP side-chains were in turn entrapped with Keggin-type phosphotugnstic acid (H3PW12O40 nH2O, HPW) catalysts on modified membranes via electrostatic interaction to prepare a novel hybrid catalytic membrane.The results of the polymerizations demonstrated the features of living/controlled surface-initiated grafted polymerization and the grafted yields of poly(4-vinylpyridine) (P4VP) linearly increased with polymerization reaction times.The grafted yields reached to 2.25 mg/cm2 when the polymerization time was 16 h.And the same time, the lumpy structure aggregation appeared on the surface of modified membranes by reason of the collapse of tightly packed grafted P4VP with high grafted yields.Subsequently, the quaternization of the grafted P4VP with bromohexadecane was carried out to create the cationic composite membranes, containing dense and reactive quaternary ammonium pyridine groups.The pendant pyridine and pyridinium groups facilitated the electrostatic assembly of HPW onto the P4VP-grafted membranes.Supported-HPW catalysts were homogeneously loaded on the PVDF-g-QP4VP membrane surface and pores and maintained the primary Keggin structure.The water contact angles values of PVDF-g-QP4VP/HPW catalytic membranes decreased from 80.4 to 57.8, this result exhibited the significant effect on the wettability of membranes through loading the hydrophilic catalysts.关键词：PVDF membrane;SI-AGET ATRP;Poly(4-vinylpyridine);Phosphotungstic acid
- 23
- |
- 11
- |
- 0
发布时间：2021-03-19 - 摘要：In order to improve the ions transfer properties of gel polymer electrolytes (GPEs), three star-shaped hybrid polymers with different polymerization degrees of arms:POSS-(PMMA3)8, POSS-(PMMA6)8, POSS-(PMMA9)8, containing a polyhedral oligomeric silsesquioxane (POSS) as a core with octa-poly (methyl methacrylate) (PMMA) chains as arms, were used as modifier and blended with PMMA to prepare the composite GPEs in the paper, respectively.The influence of arms structure of star-shaped polymers on the electrochemical performance of GPEs was investigated.The results showed that all composites GPEs containing POSS star-shaped polymers gave access to higher ionic conductivity than that of pure PMMA-based GPE.Star-shaped polymer with the shortest PMMA arms, POSS-(PMMA3)8 modified GPE possessed the highest ionic conductivity, which was 3.5 times higher than that of pure PMMA-based GPE in the room temperature.In addition, the contents of POSS star-shaped polymers and lithium salt also had effect on the performance of composite GPEs.It was found that when the concentration of lithium salt in the gel system was 0.6 mol/L, and the content of star-shaped polymers in the polymer matrix was 15 wt%, the ionic conductivity would reach the highest value, 2.7310-4 S/cm.Moreover the effect of temperature on the ion transfer performance of composite GPEs was investigated, and the rule of ion transfer along with temperature was accorded with the Arrhenius equation.Based on the results mentioned above, the ion conductive microstructure model of the composite GPEs was constructed.关键词：Octa-chloropropyl polyhedral oligomeric silsesquioxane;Methyl methacrylate;Ion transmission performance;AC impedance
- 33
- |
- 9
- |
- 4
发布时间：2021-03-19 - 摘要：Using Brownian dynamics simulation and calculations of the most sophisticated version of the tube model, the GLaMM model, we explore the near equilibrium and fast startup shear rheological behavior of entangled polymer fluids.In the nearly linear flow regime a detailed comparison between the rheometric measurements and GLaMM theoretical calculations is performed.The overall agreement is found to be satisfactory but several minor disagreements, e.g., the measurements and calculations reveal totally different stress relaxation dynamics on the time scale in units of t/R.However, during startup shear, an explicit comparison between the simulation and the theoretical description from the GLaMM theory shows irreconcilable differences on the time scale in units of t/d, which confirms our previous results, but the difference can disappear in the nearly linear flow regime.In addition, the results of our simulations about the relationship between the strain max at the overshoot point and WiR or t/R are also compared and found to behave in a very similar manner with several literature data sets but disagree with those predicted by the GLaMM theory.These findings call into question the barrier-free chain retraction mechanism as envisioned in the tube model.关键词：Non-linear rheology;Brownian dynamics;Tube model;GLaMM theory;Startup shear
- 37
- |
- 19
- |
- 3
发布时间：2021-03-19
Research Article
- 摘要：In order to improve the performance of quaternized polysulfone, layered double hydroxide (LDH) was prepared via coprecipitation and incorporated into chloromethylated polysulfone (CMPSF) solution to fabricate organic-inorganic membranes.Then the obtained hybrid membranes were converted into anion-exchange membranes (AEM) by quaternization and alkalization.The X-ray diffraction was used to characterize LDH and AEM samples.The analysis of XRD suggested that LDH had an exfoliated morphology in the hybrid membrane with 3% LDH.When the content of LDH increased to 5%, LDH demonstrated an intercalated-exfoliated morphology in the hybrid membrane.While LDH showed an ordered structure in the hybrid membrane with 10% LDH, which displayed basal peaks characteristic of LDH.These results were consistent with the scanning electron microscopy (SEM) images.The water uptake, swelling ratio, mechanical property and ion conductivity of AEMs were also investigated.The results showed that the AEM containing 5% LDH had the best comprehensive performances, including the lowest water uptake and swelling ratio, the highest ultimate stress and ion conductivity.These ultimate values of the hybrid membrane with 5% LDH were 55% (water uptake) and 18% (swelling ratio) at 60 ℃, 25.8 MPa (mechanical property), 3.8110-2 S/cm (ion conductivity) at 95 ℃, respectively, which was promising for AEM fuel cells.关键词：Layered double hydroxide;Anion-exchange membrane;Ionic conductivity;Fuel cell
- 40
- |
- 11
- |
- 0
发布时间：2021-03-19
Research Bulletin
- Postal code：100190
- Tel：010-62588927 Email：gfzxb@iccas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备05002797号-8
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0