Preparation and Characterization of Binder for Inorganic Composites Made from Amorphous Mineral Raw Material

The preparation and characterization of a composite binder made through a sol-gel route from an amorphous mineral raw material has been studied. The amorphous mineral raw material is alumino-silicate based but contains also alkaline earth and some transition metal oxides. A stable sol can be prepared by dissolving the raw materials in formic acid. The drying and heat treatment of the subsequent gel has been studied by thermogravimetry, nuclear magnetic resonance, infrared spectroscopy as well as X-ray diffraction studies. The different constituents of the raw material have shown to play a major role during the drying and heat treatment of the gels. The binding effect of the binder was evaluated to be good by studying paper-binder composites as well as wetting properties.     

Effects of the Sol-Gel Processing on the Fluorescence Properties of Laser Dyes in Tetraethoxysilane Derived Matrices

Two fluorescent dyes were incorporated into sol-gel derived SiO₂ matrices. The dye was added to SiO₂ precursors of different degrees of pre-condensation and the spectroscopic properties of the immobilized dye were measured at various aging and drying stages of the resulting gels. The significant influence of the processing parameters on the spectroscopic properties is manifested in the relative intensity of a second red shifted emission band (550–560 nm), which was observed besides the typical coumarin emission band (495 nm). The appearance of this long wavelength emission might be attributed to dye aggregation or to other reactions with the ambient matrix forced by micro porosity phenomena.     

理论研究丁羟粘合剂化学键解离及其对力学性能的影响

端羟基聚丁烯(HTPB)是推进剂中的常用的粘合剂,老化是其贮存和使用中的重要问题。通过量子化学计算HTPB 与甲基二异腈酸酯(TDI)形成的网络模型简化结构中化学键的均裂解离能(BDE),分析了键能与老化分解的关系。键能计算结果证明可靠且可用于比较分析。与CH₂ 基团相连的C-O 键的BDE值最小,推测该键最弱并且在热老化过程会发生断裂分解,降解产物主要是CO₂。HTPB 中的烯丙基伯羟基与TDI 形成的聚氨酯中α-C-H 属于最弱的X-H(X=C, N)键,推测其容易受到自由基的进攻发生氢转移反应。对容易断裂分解的C-O 键,提出了可能的老化机理。计算的C-O 键断裂活化能与其解离能近似相等,热老化过程中断键生成自由基并通过无势垒过程释放出CO₂。整个过程的热老化半衰期是温度的指数衰减函数,表明随着温度的提高HTPB-TDI 聚氨酯老化加速。热力学计算证明老化形成的氨基自由基和烷基自由基能够重新结合。采用分子动力学动态分析方法,分析了HTPB-TDI 聚氨酯网络老化前后的结构变化及其对弹性力性质的影响,发现释放CO₂ 的过程伴随着体系密度降低。对假定的CO₂ 扩散聚集以及CO₂ 从体系中扩散消失的模型进行了模拟,发现拉伸模量和剪切模量在这两种情形下会增加。     

有机-无机复合骨修复材料

本文对近5年来有机/无机复合骨修复材料研究领域的进展进行了综述,根据材料组分的特点分析其在生物相容性、生物降解性、生物活性以及力学性能等方面的优缺点,同时探讨了目前骨修复材料领域存在的问题,并对今后人工骨替代材料的发展趋势作出了展望。     

The Sol-Gel Process as a Basic Technology for Nanoparticle-Dispersed Inorganic-Organic Composites

Nanoparticles containing hybrid materials became of interest for many areas in the last decade. The reason for this is the fact that, in addition to the molecular inorganic-organic hybrid network, the physical, electronical, optical or catalytical properties of nanoparticles resulting from the inorganic crystalline, glassy or metallic properties also can be used for the material tailoring. For this reason, a survey is given over some interesting developments. Furthermore, in case studies, examples are given for the effect of nanoparticles on the two component Ormosil type of hybrids composed of ethyl ortho-silicate (TEOS) and methylethoxy(methoxy)triethoxy silane (MTEOS, MTMOS). It was shown that the 6 nm SiO₂-containing nanocomposite hybrid sols can be dried in form of thick films up to 14 m after a one step dip-coating process and densified crack-free. This is attributed to the increase of relaxation ability and flexibility. This nanocomposite based on TEOS, MTEOS and particulate SiO₂ has been used to develop an industrial process for a new type of environmentally friendly glass fiber mat with a temperature resistance up to 600°C.     

An EXAFS Study on Iron-Cobalt-Silica Nanocomposite Materials Prepared by the Sol-Gel Method

The structural evolution of FeCo-SiO₂ xerogel and aerogel nanocomposite samples during their sol-gel preparation have been studied by EXAFS (extended X-ray absorption fine structure) technique. Depending on the precursors of the alloy nanoparticles different intermediate are formed which have a strong influence on the formation of the FeCo alloy of the desired composition. The porous structure also plays an important role.     

Tailoring Spontaneous Pillar Structure Using Phase-Separating Organosiloxane Sol-Gel Systems in Micro-Fabricated Grooves

A sharp transition to pillar structure has been observed in simple sol-gel systems accompanying phase separation inside rectangular-sectioned open grooves which were fabricated on a silica glass chip. The structural variation was investigated using two contrastive systems; one with a rapid sol-gel reaction and the other with a sluggish reaction. In the slower system, transition from web-like bicontinuous structure to pillar structure, we call it as “web-to-pillar transition”, occurred when the bulk characteristic length Λ_m exceeded the width of the groove D. On the other hand, the transition did not occur in the same condition in the faster system; it occurred when Λ_m became much longer than D. A consistent formation mechanism model was also proposed using a relation between interfacial curvatures and pressure.     

Effect of Heat Treatment and Additives on the Photochromic and Mechanical Properties of Sol-Gel Derived Photochromic Coatings Containing Spirooxazine

The experimental results on the photochromic and mechanical properties of coatings containing 1,3-dihydro-1,3,3-trimethylspiro[2H-indole-2,3′-(3H)-naphth(2,1-b)(1,4) oxazine] (SO) derived from 3-glycidyl-oxypropyltrimethoxysilane (GPTMS), bisphenolA (BPA) and 1-methylimidazole (MI) by sol-gel processing are presented. It is shown that heat treatment temperature is a conflicting factor to the photochromic intensity (ΔA ₀), photostability and abrasion resistance of the photochromic coatings. With increasing densification temperature the matrix rigidity increases leading to a decrease of ΔA ₀ and at the same time an enhancement of both abrasion resistance and photostability, the optimum heat treatment temperature is 110°C under our experimental conditions. By the use of certain additives, e.g., fluorosilanes (FAS), not only ΔA ₀ but also the photostability and the abrasion resistance of the photochromic coatings have been further improved.     

An Organic-Inorganic Silica Precursor Suitable for the Sol-Gel Synthesis in Aqueous Media

Partially polycondensed γ-aminopropylsilanetriol, (APSTOL) was prepared by hydrolyzing γ-aminopropyltriethoxysilane at a hydrolysis ratio 8.0. APSTOL contains up to 52% SiO₂ and can be easily dissolved in water, forming clear solutions remaining stable practically at any pH value. The thermal evolution of APSTOL when heating up to 1000°C was examined using TGA and FTIR techniques; the probable mechanism of the oxidative decomposition of organic groups, with the formation of imino- and carboxyl-containing intermediates, has been discussed. Two magnesium silicates of the enstatite and forsterite, compositions and two calcium silicates of the wollastonite and rankinite, compositions have been prepared, using corresponding acetates and APSTOL as M^IIO and SiO₂ precursors. The crystallization, processes in these systems were studied by TGA and XRD techniques, after heat treatments up to 1000°C. In all the systems, except rankinite, the parent silicates were found as the main crystalline phases.     

中国高校化学化工专业无机化学教材建设历史回顾与展望

20世纪50年代以前,中国高校无机化学教科书主要采用译著或国外原版教材。在20世纪60年代,我国无机化学教材建设工作进入了一个短暂繁荣期。现在高校广泛使用的无机化学教材源于我国在1977-1990年间编写的4部教材。2000年之后,虽然无机化学教材品种数明显增多,但精品较少。未来的无机化学教材编写应当考虑基础无机化学与中级无机化学内容的分工与衔接,以及加强教材与信息技术的融合。     

Solid Acid-Base Control of Inorganic/Organic Hybrids by Inorganic Components for Molecule-Selectivity

Solid acid-base properties of methylsiloxane-based inorganic/organic hybrids were controlled by incorporation of inorganic components other than Si into methylsiloxane networks. The effect of different inorganic components on the solid acid-base properties was estimated by first-principles calculations based on density functional theory (DFT). The deprotonation tends to occur in the order Si < Al < Nb inorganic components, suggesting that the acidity increases in the same order. Methylsiloxane-based hybrids with solid acid-base properties were also synthesized by incorporating inorganic components derived from metal alkoxides. Hammett indicators revealed that the solid acidity increased in the order Si < Al < Nb inorganic components, which was consistent with the results of first-principles calculations. Preliminary experiments revealed that the methylsiloxane-based hybrids also provided a solid basic nature by containing Ca and Y inorganic components derived from metal alkoxides. The acidic hybrids were found to have Brønsted acid sites from the FT-IR experiments of adsorbed pyridine on the hybrids.     

Molecular Dynamics Simulations for Effects of Fluoropolymer Binder Content in CL-20/TNT Based Polymer-Bonded Explosives

In order to better understand the role of binder content, molecular dynamics (MD) simulations were performed to study the interfacial interactions, sensitivity and mechanical properties of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-trinitrotoluene (CL-20/TNT) based polymer-bonded explosives (PBXs) with fluorine rubber F₂₃₁₁. The binding energy between CL-20/TNT co-crystal (1 0 0) surface and F₂₃₁₁, pair correlation function, the maximum bond length of the N–NO₂ trigger bond, and the mechanical properties of the PBXs were reported. From the calculated binding energy, it was found that binding energy increases with increasing F₂₃₁₁ content. Additionally, according to the results of pair correlation function, it turns out that H–O hydrogen bonds and H–F hydrogen bonds exist between F₂₃₁₁ molecules and the molecules in CL-20/TNT. The length of trigger bond in CL-20/TNT were adopted as theoretical criterion of sensitivity. The maximum bond length of the N–NO₂ trigger bond decreased very significantly when the F₂₃₁₁ content increased from 0 to 9.2%. This indicated increasing F₂₃₁₁ content can reduce sensitivity and improve thermal stability. However, the maximum bond length of the N–NO₂ trigger bond remained essentially unchanged when the F₂₃₁₁ content was further increased. Additionally, the calculated mechanical data indicated that with the increase in F₂₃₁₁ content, the rigidity of CL-20/TNT based PBXs was decrease, the toughness was improved.     

以学生发展为中心的无机化学课程立体化考核评价模式构建与实践

针对当前地方本科院校无机化学课程考核中存在的问题,以学生为中心,关注学习过程,并注重学生发展,构建了以学生发展为中心的无机化学课程立体化考核评价模式,弥补了终结性评价的不足。教学实践表明,该考核模式实施后,不仅学生的无机化学I和无机化学Ⅱ课程考试成绩分别提高了12.17%和13.92%,而且有效地激发了学生的学习兴趣,促进了教师教学方式的改变和学生学风的转变,实现了考试评价改革和课堂教学改革有机结合,提升了人才培养质量。     

Sol–Gel Synthesis of Metal–Phenolic Coordination Spheres and Their Derived Carbon Composites

A formaldehyde‐assisted metal–ligand crosslinking strategy is used for the synthesis of metal–phenolic coordination spheres based on sol–gel chemistry. A range of mono‐metal (Co, Fe, Al, Ni, Cu, Zn, Ce), bi‐metal (Fe‐Co, Co‐Zn) and multi‐metal (Fe‐Co‐Ni‐Cu‐Zn) species can be incorporated into the frameworks of the colloidal spheres. The formation of coordination spheres involves the pre‐crosslinking of plant polyphenol (such as tannic acid) by formaldehyde in alkaline ethanol/water solvents, followed by the aggregation assembly of polyphenol oligomers via metal–ligand crosslinking. The coordination spheres can be used as sensors for the analysis of nucleic acid variants with single‐nucleotide discrimination, and a versatile precursor for electrode materials with high electrocatalytic performance.     

基于微课的高校无机化学翻转课堂教学效果研究——以无机化学精品资源共享课为例

以微课视频为载体，对大一材料专业无机化学课程教学进行翻转课堂实验研究，通过试卷考试成绩和Likert 5级量表问卷得分对实施效果进行评价。发现经过36学时的无机化学授课后，实验班学生成绩提高比对照班更高，具有显著性差异，且呈现不及格率更低的情况。实验班学生在知识与技能，过程与方法，态度、情感与价值观3个维度下的多数指标问卷得分均显著高于对照班学生。表明该实验尝试提高了学生学习效果，优化了学生学习过程，改善了学生学习态度，提升了学生的能力。对上述结果进行了详细分析并对翻转课堂进一步应用于高校无机化学教学提出了建议。     

Synthesis and Characterization of Fluoro- and Chloro- bimetallic Alkoxides as Precursors for Luminescent Metal Oxide Materials via Sol-Gel Technique

Heterobimetallic alkoxides are broadly recognized as versatile precursors for luminescence materials, and efforts are being made to develop novel routes by applying the concept of geometrical molecular design, for their synthesis and to design a single source precursor suited to photoluminescent materials. Novel and new series of bimetallic alkoxides has been prepared by metathesis route. They exhibit a lower sensitivity towards hydrolysis and so they are easier to handle as compared to other alkoxides. All the compounds were characterized by elemental analysis, FT-IR and multinuclear NMR spectroscopies. FT-IR revealed that the molecular structure of these metal alkoxides was retained to a large extent in 4 ： 1 halogenated alcohol-benzene solution. The heteronuclear NMR spectroscopy provided useful information about chemical shifts for better understanding the likely structure based on interactions with their coordinate metals. The mass spectra show similar types of fragmentation pattern. SEM-EDS analyses showed consistency with the formulation. XRD patterns show an enhanced homogeneity at high temperature. TGA measurements show that thermal decomposition occured in steps that depended entirely on the chemical compositions and the synthesis routes. SEM observation reveals that the morphology and particle size strongly depend on synthesis routes for their precursors.     

环境专业无机化学的碳捕集工程实例教学

以化学吸收在碳捕集工艺中的应用为例,将工程实例教学引入环境专业无机化学课程。该教学应用酸碱质子理论、化学计量学、化学热力学、化学动力学等相关知识,解决了碳捕集工艺中的部分关键问题,即选取适宜的吸收剂及解吸方法,采用合理的方法以提高吸收产量及速率。此外,该教学亦培养了学生的工程和科学研究思维,提高了学生分析和解决相关问题的能力。     

锂电池用无机固态电解质

液态锂离子电池存在易燃易爆、易短路等致命的安全问题,同时也存在续航里程焦虑等技术问题,开发安全性能好、能量密度高的锂离子电池是行业发展的迫切需求。与传统液态锂离子电池相比,全固态电池具有使用安全、理论比容量高等优点,所以得到了广泛的研究,被誉为下一代电池主流技术。其中,无机固态电解质在全固态电池中扮演着重要的角色,国内外的科研人员对此进行了大量的研究工作。本文介绍了不同类型无机固态电解质的最新进展,其中包括氧化物固态电解质、硫化物固态电解质和卤化物固态电解质;并对无机固态电解质的界面问题、晶体结构、制备方法以及掺杂改性等方面的研究进行了阐述。最后,对近几年来无机固态电解质还有待解决的问题进行了讨论,同时对其未来的研究方向作出了展望。     

大一新生无机化学课程思政的探索与实践

大学一年级是本科生学习环境和学习方法从高中向大学转折的重要时期,也是他们树立良好思想品质的关键期.无机化学是化学化工类本科生进入大学的第一门专业基础课,通过将爱国主义教育、绿色化学思想以及科学精神等课程思政内容恰当地融入到理论课和实验课中,可以帮助学生树立正确的世界观、人生观和价值观,并培养其对专业的认可及正确的专业伦...     

Mechanical Properties of Regenerated Cellulose Fibres for Composites

Summary: A broad variety of regenerated cellulose fibres was subjected to single fibre tensile tests in order to determine the modulus of elasticity, tensile strength, and failure strain. The results were compared to glass fibres and flax fibres, which are considered the most important technical and natural fibres, respectively. With regard to their modulus of elasticity and tensile strength, regenerated cellulose fibres showed clearly lower values than glass fibres, even when their low density was taken into account. The average modulus of elasticity and tensile strength of regenerated cellulose fibres was also lower than the values measured for flax fibres, but when variability was considered, both fibres performed similarly. In terms of interfacial shear strength with polypropylene, lyocell fibres performed significantly less well than sized glass fibre and ramie fibre. The most important difference between regenerated cellulose fibres and both glass and flax fibres is their high failure strain and thus high work to fracture. The high work to fracture of regenerated cellulose fibres makes them particularly useful for composite applications where high fracture toughness is required.