Achieving a superior Na storage performance of Fe-based Prussian blue cathode by coating perylene tetracarboxylic dianhydride amine

Fe-based Prussian blue(Fe-PB)cathode material shows great application potential in sodium(Na)-ion batteries due to its high theoretical capacity,long cycle life,low cost,and simple preparation process.However,the crystalline water and vacancies of Fe-PB lattice,the low electrical conductivity,and the dissolution of metal ions lead to limited capacity and poor cycling stability.In this work,a perylene tetracarboxylic dianhydride amine(PTCDA)coating layer is successfully fabricated on the surface of Fe-PB by a liquid-phase method.The aminated PTCDA(PTCA)coating not only increases the specific surface area and electronic conductivity but also effectively reduces the crystalline water and vacancies,which avoids the erosion of Fe-PB by electrolyte.Consequently,the PTCA layer reduces the charge transfer resistance,enhances the Na-ion diffusion coefficient,and improves the structure stability.The PTCA-coated Fe-PB exhibits superior Na storage performance with a first discharge capacity of 145.2 mAh g^(−1) at 100 mA g^(−1).Long cycling tests exhibit minimal capacity decay of 0.027%per cycle over 1000 cycles at 1 A g^(−1).Therefore,this PTCA coating strategy has shown promising competence in enhancing the electrochemical performance of Fe-PB,which can potentially serve as a universal electrode coating strategy for Na-ion batteries.

高压拉曼光谱研究均苯四甲酸二酐

测量了常温常压下的均苯四甲酸二酐的拉曼光谱,并对所测量的各个拉曼谱线进行归属认证。获得了从常压到24GPa压强条件下的原位拉曼光谱,通过频率-压强关系曲线可以得出该材料在2Gpa存在晶体结构相变,定义了均苯四甲酸二酐在低于2GPa压强条件的晶体结构为相Ⅰ,高于2GPa压强条件的晶体结构相为相Ⅱ。在相变前后,绝大多数的拉曼谱线频率-压强曲线斜率变小,说明与相Ⅰ相比,各官能团对压强的敏感程度下降,相Ⅱ的分子晶体具有更紧密的堆积结构。拉曼光谱强度能够给出丰富的材料结构信息,通过对C—O伸缩振动的倍频(常压位于1837cm^(-1))和C=O伸缩振动基频(常压位于1865cm^(-1))的相对拉曼光谱强度随压强的变化规律进行分析,发现两拉曼谱线强度比在2GPa附近存在突变,为均苯四甲酸二酐在2GPa附近发生结构相变提供了实验依据。

高性能PET珠粒泡沫的制备及机理

聚对苯二甲酸乙二醇酯(PET)高温熔体强度低,难以通过超临界二氧化碳(scCO_(2))发泡技术制备高强度、高膨胀率的珠粒泡沫材料。本文建立了一种基于原位熔体增强的发泡新技术,利用聚对苯二甲酸丁二醇酯(PBT)有效负载扩链剂均苯四甲酸二酐(PMDA)得到扩链剂负载母粒(PMDA-MB)。通过PMDA-MB与PET的共混挤出制备了改性PET,有效地延长并支化PET分子链,大幅度地提升了熔体黏度,有效地改善了PET的发泡性能。进一步通过scCO_(2)珠粒发泡技术制备了具有优异的泡孔结构和高膨胀率的PET泡沫材料。结果表明,当PMDA-MB的质量分数为3%、发泡温度为244℃、发泡压力为25 MPa时,所得PET泡沫平均泡孔尺寸为100.8μm,泡孔密度1.91×10^(6)个/cm^(3),膨胀率达15.2,而且该PET珠粒泡沫材料的力学性能优良,拉伸强度达2.54 MPa,压缩强度达4.08 MPa。

Synthesis of a New Aromatic Dianhydride Containing Pyridine Ring and Related Polyimide

A new aromatic dianhydride monomer containing pyridine moiety, 2,6-bis[4＇-（3＂,4＂- dicarboxyphenoxy）benzoyl]-pyridine dianhydride （Md）, was synthesized in four steps, starting from 2,6-pyridinedicarboxyl chloride. A novel pyridine-containing polyimide was prepared via polycondensation of Md with ODA by two-step method. The resulting polyimide exhibits excellent solubility, film-forming capability and high thermal resistance.

含苝环有机半导体的光催化分解水研究进展

光催化分解水是太阳能向化学能转换的一种重要方式,其中高效稳定光催化剂的研制至关重要.具有平面共轭结构的苝类有机小分子是一类富含π电子的n-型半导体,具有结构易修饰、可见光吸收强以及光热稳定性高等优点,近年来在光催化领域研究广泛.我们总结了4类含有苝环结构的有机小分子苝四甲酸二酐、苝二酰亚胺、苝单酰亚胺以及苝四酸的特点.此外,从分子结构修饰、构筑聚合物、金属辅助、与其它材料复合及改变组装条件这几种方式对材料在光催化分解水方面的研究进展进行了综述,并对含有苝环结构的有机半导体材料在光催化分解水方面存在的问题和前景进行了分析和展望.

焙烧温度对均四甲苯气相氧化制均苯四甲酸二酐钒钛氧化物催化剂的影响

采用浸渍法经不同焙烧温度制备钒钛氧化物催化剂,以XRD、Raman和H_(2)-TPR等对催化剂物理化学性能进行表征,并在固定床装置上评价催化剂均四甲苯气相氧化反应性能。结果表明,钒钛氧化物催化剂中钒以TiO_(2)表面VO_(x)物种和晶体V_(2)O_(5)存在,焙烧温度可调变催化剂中表面VO_(x)物种和晶体V_(2)O_(5)的比例,焙烧温度越高,多聚的表面VO_(x)物种或晶体V_(2)O_(5)越多。500℃焙烧条件制备的催化剂具有合适的可还原性,弱酸位点相对较多,在均四甲苯气相氧化中性能最优,均酐质量收率可达85.8%。

超早强型聚羧酸减水剂的制备及性能研究

将环状二酸酐醇解制备端羟基接枝羧基的聚醚大单体CA-HPEG,再与氨基硅氧烷进行酰胺化反应制得改性聚醚LPEG,将LPEG与酰胺类单体引入共聚反应中,制备长侧链、短主链的超早强型聚羧酸减水剂SPE。对SPE进行工艺优化,并探讨SPE对水泥净浆流动度、砂浆早期强度及混凝土拌合物性能的影响,然后通过傅里叶红外光谱对LPEG及SPE的结构进行表征,X射线衍射仪对SPE的水泥水化产物进行分析。结果表明,改性聚醚CA-HPEG的最佳酯化条件为:n(1,2-环己二甲酸酐)∶n(HPEG5000)为2∶1,反应时间为2h,反应温度为60℃。SPE的最佳合成工艺参数为:n(LPEG)∶n(HPEG5000)=2∶3,n(AA)∶n(AM)=3∶1,n(AA+AM)∶n(LPEG+HPEG5000)=4.5,引发剂APS用量为聚醚单体质量的0.45%,链转移剂用量为聚醚单体质量的0.25%,反应温度为常温,滴加时间为3 h。最佳工艺合成的减水剂对混凝土的初凝及终凝时间均有较好的缩短效果,并且早期抗压强度增强效果明显。

脱卤法制备联苯四甲酸二酐反应关键影响因素研究

聚酰亚胺模塑料具有良好的热稳定性、化学稳定性和机械性能,广泛应用于食品、药品、化妆品等精细化工产品的生产过程,相关研究日益增加。作为联苯型聚酰亚胺的关键原料,联苯四甲酸二酐的制备过程日益受到关注。在各种制备方法中,脱卤偶联法过程反应条件温和,产品收率高,纯度好,相关研究较多。本研究以卤代邻苯二甲酸酐为原料,以钯碳作为催化剂,在盐酸羟胺还原剂参与的条件下,采用脱卤偶联法制备了联苯四甲酸二酐,系统考察了卤代烃类型、催化剂类型、催化剂用量、还原剂用量、反应气氛、反应温度、反应时长、成酐方式等关键影响因素对产物收率的影响,获得了适宜的脱卤偶联制备联苯四甲酸二酐的反应条件。

SYNTHESIS AND CHARACTERIZATION OF ORGANSOLUBLE POLYIMIDE AND COPOLYIMIDES FROM ALICYCLIC DIANHYDRIDE

A kind of highly organsoluble polyimide and copolyimides were successfully synthesized from bicyclo（2.2.2）-oct- 7-ene-2,3,5,6-tetracarboxylic dianhydride （BCDA）, the commercial diamine 4,4＇-methylenedianiline （MDA） and the designed diamine 4,4＇-methylenebis-（2-tert-butylaniline） （MBTBA）. The polyimide from BCDA and MBTBA is highly soluble in conventional low boiling point solvents （such as chloroform, tetrahydrofuran） at room temperature. But the solubility of the copolyimides in conventional solvents decreased with the molar ratio of MBTBA and MDA decreased. When the molar ratio of MBTBA and MDA was larger than 7/3, the copolyimides can be soluble in low boiling point solvents at room temperature to form a transparent, flexible, tough film by solution casting. When the molar ratio of MBTBA and MDA was between 7/3 and 1/9, they can only be soluble in hot dipolar aprotic solvents （such as DMF, NMP etc.） and form films too. The copolyimide was only soluble in m-cresol when the molar ratio of MBTBA and MDA was lower than 1/9. The number-average molecular weights of the soluble copolyimides were larger than 5.8 × 1064 g/mol by GPC and their polydispersity indices were higher than 1.4. Only one glass transition temperature of these copolyimides was detected around 400℃ by DMA. The copolyimides did not show appreciable decomposition up to 430℃ in N2.

A novel efficient synthetic method for 2,2′,3,3′-biphenyltetracarboxylic dianhydride

A novel approach to the synthesis of 2,2＇,3,3＇-biphenyltetracarboxylic dianhydride is described. The target compound was prepared by a nickel-catalyzed couplirtg reaction of dimethy 3-chlorophthalate （3-DMCP） for 4 h at 70-80 ℃, followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid, with overall yield of 68%. The structures of the products were characterized by IR, 1H NMR and ^13C NMR respectively.

Polyimide structure-Property Relationships I. Polyimide Properties υs Dianhydride Configuration

X-ray crystal structures of 2,2',3,3'-and 3, 3',4,4'-biphenyltetracarboxylic dianhydride (2,2',3,3'- and 3,3',4,4'-BPDA) were determined. The dianhydride isomers have different symmetry caused by difference in two anhydride group positions and the dihedral angles between the two phenyl rings are 62.9°for 2,2',3,3',-BPDA and 0°for 3,3',4,4'-BPDA respectively. The polyimides from 2,2',3,3'-BPDA exhibit enhanced solubility, higher thermal stability, and higher glasstransition temperature (Tg) compared with those from 3,3',4,4'-BPDA.

Modified disordered carbon prepared from 3,4,9,10-perylenetetracarboxylic dianhydride as an anode material for Li-ion batteries

To prepare an anode material for Li-ion batteries with high discharge capacity and good cycling stability, disordered carbon （DC） formed by calcinations of 3,4,9,10-perylenetetracarboxylic dianhydride was modified via an acid treatment using a mixture of HNO3 and H2SO4. The modified disordered carbon （MDC） was characterized by Fourier-transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） analysis, Brtmaner-Emmett-Teller （BET） analysis, and scanning electron microscopy （SEM）. FTIR spectra confirm the successful introduction of carbonyl groups onto the DC surface. Some pores appear in the columnar structure of MDC, as observed in SEM micro- graphs. Li＋ ions intercalation/deintercalation is facilitated by the modified morphology. Electrochemical tests show that the MDC exhibits a significant improvement in discharge capacity and cycling stability. These results indicate that the MDC has strong potential for use as an anode material in Li-ion batteries.

Facile Synthetic Method and Crystal Structure of 2,3,3',4'-Biphenyltetracarboxylic Dianhydride

A facile method for the synthesis of 2,3,3＇,4＇-biphenyltetracarboxylic dianhydride（a-BPDA） was reported,which comprises the steps of the dehalogenative coupling of dimethyl 4-chlorophthalate（4-DMCP） and dimethyl 3-chlorophthalate（3-DMCP） catalyzed by low-cost（Ph 3 P） 2 NiCl 2,the hydrolysis of tetra-ester and the dehydration of tetra-acid.In contrast to the conventional methods,this method has the advantage of low cost,convenient manipulation,available condition,high purity and good overall yield.Moreover,the single crystal structure of a-BPDA was analyzed by X-ray diffraction method.The X-ray data suggest that a-BPDA is a rigid,non-coplanar and non-linear structure.It contains three crystallographically independent molecules,in which the dihedral angles of the two linked phenyl rings are 44.75（4）°,46.37（3）° and 42.32（3）°,respectively.The title molecule is governed by a stronger intermolecular interaction in contrast to van der Waals interaction because of the special positions of anhydride groups.

Hydrogen Bonding-Mediated Assembly of Perelene Dianhydride and Pyridine Derivatives

Semi-empirical AMI method was used to study 1：1 and 1：2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the clectronic absorption spectra for the complexes, comparing that of the host, takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimcntal results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N H bond were obtained.

A Facile Synthetic Method for Biphenyltetracarboxylic Dianhydrides

We report a facile and high-yielding procedure for preparing biphenyltetracarboxylic dianhydrides (BPDAs). This method relies on a nickel-catalyzed electroreductive coupling reaction of dimethyl 3-chorophthalate (3-DMCP) and/or dimethyl 4-chorophthalate (4-DMCP) with subsequent hydrolysis of tetra-ester and dehydration of tetra-acid.

Microwave Accelerated Synthesis of 2,2',3,3'-Biphenyltetracarboxylic Dianhydride

Polyimides have been widely used in aerospace and mi- croelectronics due to their excellent mechanical properties and thermo oxidative stability^[1]. However, most of aromatic polyi- mides are severe difficult to process because of their bad solu- bility in common solvents and intractable in their fully imidized forms, which restrict their applications and developments^[2,3]. Therefore, many investigations were focused on improving the dissolvability of polyimides and it was found that the excellent solubilizing units could be obtained from substituted biphenyls^[4-7]. Biphenyltetracarboxylic dianhydrides（BPDAs） are the most important monomers for the synthesis of these compounds. Among them, the synthesis of 2,3,3＇,4＇-/3,3＇,4,4＇- biphenyltetracarboxylic dianhydride has been widely investi- gated, but only a few literatures reported the synthesis of 2,2＇,3,3＇-biphenyltetracarboxylic dianhydride（i-BPDA）^[8-10].

The Crystal Structure of Biphenyltetracarboxylic Dianhydride Isomers

Biphenyltetracarboxylic dianhydride (2,2',3,3' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/c, a=11.694(2), b=8.111(2), c=13 494(3) , β=103.47(3)°, V=1244.7(4) 3, Z=4, D c =1.570 g/cm 3 , F (000)=450, Mo Kα radiation( λ =0.71073), μ (Mo Kα )=0.092 mm -1 , R =0.0329 for 2180 observed reflections 〔 I>2σ(I) 〕. 3,3',4,4' Biphenyltetracarboxylic dianhydride (3,3',4,4' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/n, a=6.8720(14), b=5.1870(10), c=17.288(4), β=94.96(3)°, V= 613.9(2) 3, Z=2, D c =1 592 gcm -3 , F(000)=300 , μ (Mo Kα )=0.125mm -1 , R =0.0331 for 1079 observed reflections〔 I>2σ(I) 〕. The dianhydride isomers have different symmetry caused by alternating two anhydride group positions and the dihedral angle between the two phenyl rings are 62.9°for 2,2',3,3', BPDA and 0°for 3,3',4,4' BPDA respectively.

A Di-D-Fructose Dianhydride-Enriched Caramel Modulates Pig Fecal Microbiota Composition

A correlation has been previously described between bifidobacteria counts before and after the use of a dietary additive in human studies. However, to our knowledge no information on this topic has yet been reported in animals, and no information exists either on similar possible correlations of bacterial groups other than bifidobacteria. The potential prebiotic effects of di-D-fructose dianhydride (DFA)-enriched caramels have been previously reported in laboratory animals, poultry and pigs. In the present work, twelve growing male castrated pigs (41.8 ± 1.9 kg mean BW) were fed in succession on a control (no additive) or DFA-enriched caramel (20 g/kg) containing diets. Another group of 10 pigs (38.0 ± 3.7 kg mean BW) fed on a control diet without any additive was used as negative control. Bacterial log10 number of copies of the 16S rRNA gene was determined in fecal samples by using qPCR. Increased (P10 number of copies were determined in fecal samples of pigs fed on the caramel containing diet compared with non-caramel controls. In addition, for all bacterial groups studied microbiological values co-variated with initial counts and, except for enterobacteria, variations in the fecal bacterial numbers after caramel supplementation correlated (P< 0.05) with the fecal numbers before supplementation. In conclusion, the supplementation of pig diets with DFA-enriched caramels induced significant increases in the fecal number of copies of bacterial groups regarded as beneficial, and variations in the fecal number of copies correlated with the initial fecal number of copies.

Effects of difructose dianhydride (DFA)-Ⅳ on in vitro fertilization in pigs

Difructose dianhydride Ⅳ(DFA-Ⅳ) is produced from levan, which is a natural polysaccharide that belongs to the fructan family, through the activity of levan fructotransferase(LF) derived from microorganisms. Recently, DFA-Ⅳ has been expected to have diverse applications in the food and medical industry. Here, we examined the potential application of DFA-Ⅳ for in vitro fertilization(ⅣF) in pigs. In the assessment of acrosomal integrity during incubation, intact acrosomal or viable spermatozoa were highly sustained in 0.1% or 0.25% DFA-Ⅳ(69.8%-70.8%,P<0.05). Reactive oxygen species(ROS) levels during sperm incubation decreased following the addition of DFA-Ⅳ, and 0.1 %-0.5% DFA-Ⅳ in particular significantly decreased ROS production relative to that seen with no addition or 0.75% DFA-Ⅳ. Total fertilization(mono + polyspermic oocyte) rate was significantly higher in the addition of0.1% DFA-Ⅳ(94.2%) than with other concentrations(71.8%-86.7%, P<0.05). When using reduced ⅣF times and lower sperm numbers, we found that addition of 0.1%-0.5% DFA-Ⅳ significantly increased the fertilization rate(P<0.05). Fertilized oocytes treated with 0.1% DFA-Ⅳ exhibited higher embryonic development and blastocyst formation than those treated with other concentrations(P<0.05). Consequently, the addition of DFA-Ⅳ during ⅣF improved fertilization and embryonic development, suggesting the possible use of novel sugars for enhancement of assisted reproductive technology(ART) in mammals.

苝四羧酸二酐钠盐涂层改性石墨

锂离子电池石墨负极材料存在可逆容量和储锂电位低、离子扩散动力学和电解质相容性差等问题。在液相中用苝四羧酸二酐钠盐(PTCDA-Na)对石墨增加涂层进行改性,探讨有机涂层比例对石墨负极的影响。均匀稳定的PTCDA-Na有机涂层中的微孔结构有利于电解质的进入,可防止电解质与石墨负极的副反应,在抑制层状石墨的粉碎和结构坍塌的同时,提供更多的Li^(+)传输通道及可逆嵌脱的活性位点,提高结构稳定性。共轭羰基和苯环可参与电化学反应,提高负极的可逆容量。在0.01~3.00 V循环,质量分数为10%的PTCDA-Na有机涂层改性石墨的电化学性能较好:以1.0 C循环100次,容量保持率高达150.1%;以5.0 C循环500次,仍有80.0%的容量保持率。