Journal of Sol-Gel Science and Technology最新文献_第3页

Modified bentonite loaded with nonmetal doped titanium dioxide for the removal of heavy metal ions and dyes from wastewater

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-11 DOI: 10.1007/s10971-025-06683-y

Smitha Venu Sreekala, Anu Sreeja Pramod, Athulya Parola, Jayasooryan Kazhuthuttil Kochu, Resmi Thoppil Ramakrishnan

A facile, low-cost, and eco-friendly method for treating wastewater containing heavy metals and dyes has been developed in the present work. The novel integrated photocatalyst adsorbent system was successfully synthesized from natural bentonite encompassing delamination of the clay layers and an in-situ sol-gel process to load non-metal-doped titanium dioxide on the clay layers. The nanocomposite system thus synthesized was subjected to calcination at 500 °C. Nitrogen doping of the titanium dioxide nanoparticles in the modified nanocomposite system was enabled via chitosan precursor addition. The structural, morphological, and functional features of the synthesized nanocomposites were further evaluated using different characterization techniques such as Fourier Transform Infrared (FTIR) analysis, UV-visible spectral analysis, X-ray Diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS) analysis, Brunauer-Emmett-Teller Surface Area (BET) analysis, Scanning Electron Microscopic (SEM) analysis, and Atomic Absorption Spectrophotometric (AAS) analysis. The nanocomposite was then tested for its efficiency in the degradation of an organic dye, methylene blue, and for the adsorption of heavy metal ions (Cu) from model-contaminated water. A high photocatalytic efficiency of 93% was achieved by the nanocomposite when tested against aqueous methylene blue dye (10^-5 M) under UV light for about 1 h. The adsorption capacity of the nanocomposite in removing Cu²⁺ ions from model-contaminated water was found to be 13.82 mg g^-1 at optimal conditions of pH 6.0, initial concentration of 10 ppm, and adsorbent dosage of 0.05 g. The photocatalytic efficiency and adsorption capacity of the nanocomposite towards the removal of dyes and heavy metal ions from water could be attributed to the small size of the nitrogen-doped titanium dioxide nanoparticles ( ~ 7 nm) in the nanocomposite which provides an enhanced surface area of 131.2 m²g^-1. Thus, the study validates the potential of a modified bentonite system loaded with nitrogen-doped titanium dioxide for wastewater treatment via photocatalysis or adsorption processes.

Graphical Abstract

本研究开发了一种处理含重金属和染料废水的简便、低成本和生态友好型方法。新型集成光催化剂吸附剂系统由天然膨润土成功合成，包括粘土层的分层和在粘土层上负载非金属掺杂的二氧化钛的原位溶胶-凝胶过程。由此合成的纳米复合材料系统在 500 °C 下进行煅烧。通过添加壳聚糖前驱体，在改性纳米复合材料体系中实现了二氧化钛纳米粒子的氮掺杂。利用不同的表征技术，如傅立叶变换红外光谱（FTIR）分析、紫外-可见光谱分析、X 射线衍射分析（XRD）、X 射线光电子能谱（XPS）分析、布鲁诺-艾美特-泰勒表面积（BET）分析、扫描电子显微镜（SEM）分析和原子吸收分光光度法（AAS）分析，进一步评估了合成纳米复合材料的结构、形态和功能特征。然后测试了纳米复合材料在降解有机染料亚甲基蓝和吸附模型污染水中的重金属离子（Cu）方面的效率。在紫外光照射下，纳米复合材料对亚甲蓝染料（10-5 M）的光催化效率高达 93%；在 pH 值为 6.0、初始浓度为 10 ppm、吸附剂用量为 0.05 g 的最佳条件下，纳米复合材料去除模型污染水中 Cu2+ 离子的吸附容量为 13.82 mg g-1。纳米复合材料去除水中染料和重金属离子的光催化效率和吸附能力可归因于纳米复合材料中掺氮二氧化钛纳米颗粒的尺寸较小（约 7 nm），从而提供了 131.2 m2g-1 的增强表面积。因此，该研究验证了负载掺氮二氧化钛的改性膨润土系统通过光催化或吸附过程处理废水的潜力。

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引用次数: 0

Structural and gas sensing properties of NiO thin films deposited by a novel spin coating technique

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-11 DOI: 10.1007/s10971-025-06678-9

Enes Nayman, Mehmet Fatih Gozukizil, Bayram Armutci, Sinan Temel, Fatma Ozge Gokmen

This study presents the development and application of a novel sol-gel spin coating technique for the deposition of nickel oxide (NiO) thin films on glass substrates. The newly designed spin coating device operates without the need for a vacuum, providing a cost-effective alternative to traditional methods. NiO thin films were prepared using a sol-gel process, with various thicknesses and rotation speeds tested to idealize film quality. Structural and morphological analyses were conducted using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM), revealing that the 6-layer sample coated at 3000 rpm exhibited the best crystallization and surface homogeneity. Gas sensor tests were performed to evaluate the sensitivity of the NiO thin films to ethanol, NO₂, and H₂ gases. The results showed that the sensor responded stably and reproducibly over multiple gas exposure cycles. It also demonstrated the potential for reliable gas detection applications.

Graphical Abstract

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引用次数: 0

Bi-doped ZnO nanoparticles: enhanced structural and dielectric properties for device applications

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-11 DOI: 10.1007/s10971-025-06693-w

E. Bouzaiene, F. I. H. Rhouma, Amel Haouas, K. Khirouni, J. Dhahri

This document presents significant findings on the impact of Bi³⁺ substitution on the structural, dielectric, and electrical properties of ({{Bi}}_{x}{{Zn}}_{left(1-frac{3x}{2}right)}{rm{O}}) nanoparticles with Bi ratios of x = 0.005 and 0.007, synthesized via the sol-gel technique. X-ray diffraction (XRD) analysis confirms a hexagonal wurtzite structure, demonstrating the successful incorporation of Bi atoms into the ZnO lattice. Refinement results indicate that both the lattice parameters and unit cell volume increase with higher Bi content. X-ray peak broadening analysis was performed using the Debye-Scherrer and Williamson-Hall (W-H) methods to evaluate the crystallite size and lattice strain. Impedance spectroscopy measurements were carried out over a frequency range of 40 Hz to 10⁷ Hz and a temperature range of 320 K to 410 K to assess the influence of frequency and temperature on the dielectric properties of the synthesized samples. Comparative Nyquist plots at a fixed temperature of 320 K revealed a decrease in impedance with increasing Bi doping concentration. This reduction in impedance is associated with an increase in electrical conductivity and a decrease in relaxation time, confirming that Bi doping enhances conductivity at 320 K. Furthermore, the improved electrical conductivity suggests that the material could facilitate electron transfer, making it a promising candidate for humidity and gas sensing applications. Additionally, dielectric characterization confirmed that the dielectric constant increases with higher Bi doping levels. The observed high permittivity values recommend the synthesized Bi₀.₀₀₇Zn₀.₉₈₉₅O compound for potential use in high-frequency devices. A more in-depth study of the structural, electrical, and dielectric properties demonstrates that Bi-doping effectively modulates the structural, electrical, and dielectric characteristics of ZnO nanostructures. This tuning of properties opens up new possibilities for future applications in energy storage systems, as well as in microwave and semiconductor technologies.

Graphical Abstract

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引用次数: 0

Magnesium titanium phosphate ceramic electrolytes: structural, electrical and electrochemical properties

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-10 DOI: 10.1007/s10971-025-06691-y

N. A. Wahab, S. A. Kamil, S. B. R. S. Adnan, N. A. Dzulkurnain, N. A. Mustaffa

There has been significant research interest in Magnesium-ion Batteries for the last few years due to their potential in energy storage devices mainly focusing on all solid-state batteries. Herein, Mg_0.5Ti₂(PO₄)₃ was synthesized using sol–gel method and the structural, electrical and electrochemical properties of the sample were studied. The structure of the samples was analyzed using X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy measurements. Rietveld Refinement analysis confirmed the formation of rhombohedral structured of R3c space group with minor traces of TiP₂O₇ impurity for the sample sintered at temperatures 700 °C, 750 °C, 800 °C, 850 °C, 900 °C and 950 °C for 24 h. FTIR spectroscopy measurement showed a range from existing of the bands belong to the inorganic compound in the sample. The compound sintered at temperature 850 °C has been selected as the best sintering temperature based on the result from Rietveld Refinement analysis, Scanning Electron Microscopy and EDX analysis. Hence, the selected sample was conducted for measuring electrical and electrochemical properties of the sample. Impedance spectroscopy indicated the rise of total conductivity at high temperature which is 2.63 × 10⁻⁷ S cm⁻¹ compared to the total conductivity at room temperature. The activation energy require for ion conduction is Ea = 0.70 eV. The highest conducting sample was taken for linear sweep voltammetry analysis and the sample was electrochemically stable up to 1.5 V. Lastly, the ionic transference number value of the sample was 0.97. These findings indicate that Mg_0.5Ti₂(PO₄)₃ could serve as an effective electrolyte in all-solid-state battery batteries.

Graphical Abstract

由于镁离子电池在储能设备中的潜力，过去几年来对镁离子电池的研究一直备受关注，主要集中在全固态电池方面。本文采用溶胶-凝胶法合成了 Mg0.5Ti2(PO4)3，并研究了样品的结构、电学和电化学特性。利用 X 射线衍射 (XRD) 和傅立叶变换红外 (FTIR) 光谱测量分析了样品的结构。傅立叶变换红外光谱分析证实，在 700 ℃、750 ℃、800 ℃、850 ℃、900 ℃ 和 950 ℃ 温度下烧结 24 小时的样品形成了 R3c 空间群斜方体结构，并含有少量 TiP2O7 杂质。根据 Rietveld Refinement 分析、扫描电子显微镜和 EDX 分析的结果，选定 850 °C 为最佳烧结温度。因此，对所选样品进行了电学和电化学特性测量。阻抗光谱显示，与室温下的总电导率相比，高温下的总电导率上升了 2.63 × 10-7 S cm-1。离子传导所需的活化能为 Ea = 0.70 eV。取导电率最高的样品进行线性扫描伏安分析，该样品的电化学稳定性高达 1.5 V。最后，样品的离子转移数为 0.97。这些研究结果表明，Mg0.5Ti2(PO4)3 可作为全固态电池的有效电解质。

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引用次数: 0

Beidellite/montmorillonite-phosphorus-based dendrimer organoclays: structural features and chromate interaction analysis

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-10 DOI: 10.1007/s10971-024-06662-9

Mohamed Hajjaji, Abdellah Beraa, Régis Laurent, Anne-Marie Caminade

Organoclays are promising materials for pollutant retention, medicinal applications, and catalysis, making them an intriguing research topic. In this study, beidellite/montmorillonite and phosphorus-based dendrimer organoclays were prepared, and their microstructure was examined using X-ray diffraction, thermal analysis, Fourier-transform infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy, and high-resolution transmission electron microscopy. The study also investigated the dynamic and equilibrium adsorption of chromate onto these organoclays within a temperature range of 298–318 °C. It was found that the formation of organoclays involved the substitution of Na+ ions with dendrimers, and the structural configuration depended on the dendrimer size. Additionally, chromate retention by the organoclays occurred rapidly, with the kinetics data fitting well to the pseudo-second-order chemisorption kinetic rate equation. The adsorption kinetics were controlled by intragranular diffusion (diffusion coefficient ranging from 0.007 to 0.018 mmol.g⁻¹) and external diffusion (diffusion coefficient ranging from 0.011 to 0.06 min⁻¹). Thermodynamic data and adsorption isotherms modeling showed that chromate adsorption was spontaneous and endothermic, and the isotherms fitted well to the Temkin model. Chromate binding to the organoclay involved protonated amino groups of the dendrimer (first-generation), with an adsorption capacity of 15 mg of chromate per gram, slightly exceeding that of some other organoclays.

Graphical Abstract

有机粘土是一种在污染物截留、医药应用和催化方面具有广阔前景的材料，因此是一个引人入胜的研究课题。本研究制备了海泡石/蒙脱石和磷基树枝状聚合物有机粘土，并使用 X 射线衍射、热分析、傅立叶变换红外光谱、固态核磁共振光谱和高分辨率透射电子显微镜对其微观结构进行了研究。研究还调查了铬酸盐在 298-318 ℃ 温度范围内对这些有机陶土的动态和平衡吸附。研究发现，有机黏土的形成涉及 Na+ 离子与树枝状聚合物的置换，其结构构型取决于树枝状聚合物的尺寸。此外，有机黏土对铬酸盐的吸附速度很快，动力学数据与假二阶化学吸附动力学速率方程十分吻合。吸附动力学受控于粒内扩散（扩散系数范围为 0.007 至 0.018 mmol.g-1）和外部扩散（扩散系数范围为 0.011 至 0.06 min-1）。热力学数据和吸附等温线模型表明，铬酸盐的吸附是自发的、内热的，等温线与 Temkin 模型非常吻合。铬酸盐与有机黏土的结合涉及树枝状聚合物（第一代）的质子化氨基，其吸附容量为每克 15 毫克铬酸盐，略高于其他一些有机黏土的吸附容量。

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引用次数: 0

Polyimide nanofiber aerogel with hierarchical porosity: a novel platform in high-temperature oil absorption

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-10 DOI: 10.1007/s10971-025-06694-9

Lidong Tian, Yi Zhang, Yibin Liu, Shan Zhang

The development of advanced oil sorbents with superior thermal stability, high adsorption capacity, and excellent reusability is crucial for addressing hot oil leakage challenges, particularly in the petrochemical and machinery industries. This study presents a novel polyimide (PI) nanofiber aerogel (PIF-a) designed for high-temperature oil absorption. Utilizing electrospinning and post-treatment, PIF-a exhibits a hierarchical pore structure, ultralow density, and remarkable flexibility. At room temperature, PIF-a demonstrates an oil adsorption capacity of 83.1 g/g, surpassing conventional materials. Notably, PIF-a retains structural integrity up to 250 °C, with a hot oil adsorption capacity of 78.6 g/g at 200 °C. Despite repeated adsorption-desorption cycles, PIF-a’s capacity remains stable, retaining over 90% of its initial performance. This breakthrough material, with its exceptional thermal stability, rapid adsorption kinetics, and durable reusability, represents a significant advancement in high-temperature oil absorption technology, broadening the application potential of nanofiber-based materials in addressing environmental oil spill emergencies.

Graphical Abstract

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引用次数: 0

Zinc-doped cobalt ferrite nanoparticles: modified sol-gel synthesis, multifunctional properties, and cytotoxicity evaluation

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-10 DOI: 10.1007/s10971-025-06689-6

V. S. Sharon, V. K. Haripriya, Swapna S. Nair, E. Veena Gopalan, Aneesh George, K. A. Malini

The present work explores physical characteristics of zinc doped cobalt ferrite nanostructures. Co_1-xZn_xFe₂O₄(x = 0.0, 0.3, 0.5, 0.7, 1) nanoparticles were synthesized by a modified sol-gel method. The Rietveld refinement of the X-ray diffraction data confirms the cubic spinel structure of the ferrite phase in the Fd-3m space group. The crystallite size of the sample varies between 52–16 nm, and an increase in lattice parameter is noticed with zinc doping. The X-ray densities are also calculated. It is discovered that when zinc concentration rises, size falls, dislocation density rises, and packing factor decreases. At varying Zn ion concentrations, the tolerance factor (T) for Co_1-xZn_xFe₂O₄ ferrites is around 1, indicating the cubic spinel structure of ferrites. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX) were used for morphological and elemental composition studies of the synthesized samples. Frequency-dependent dielectric constant, dielectric loss, and ac conductivity have been investigated. The dielectric constant values were found to be in the range of high dielectric constant, so these materials were the promising candidates for technological applications such as gate dielectrics, capacitor dielectrics, and epitaxial dielectrics, etc. The bandgap energy calculated from UV-Visible analysis increases with zinc ion concentration (2.95–4.33 eV). The zinc substituted cobalt ferrite nanoparticles with tunable bandgap as well as dielectric properties can be easily prepared by the modified sol-gel method. In the present study, significant cytotoxicity was exhibited by the cobalt ferrite nanoparticles. The magnetic hysteresis (M-H) loops study shows the ferromagnetic nature of all the samples. The maximum saturation value M_S was obtained for Co_0.5Zn_0.5Fe₂O₄ sample which is 73.72 emu/g. The value of the remanent magnetization and coercive field of Co_0.3Zn_0.7Fe₂O₄ and ZnFe₂O₄ nanoparticles indicate its superparamagnetic nature.

Graphical Abstract

本研究探讨了掺锌钴铁氧体纳米结构的物理特性。采用改良溶胶-凝胶法合成了 Co1-xZnxFe2O4（x = 0.0、0.3、0.5、0.7、1）纳米粒子。X 射线衍射数据的里特维尔德细化证实了铁氧体相的立方尖晶石结构，空间群为 Fd-3m。样品的晶粒大小在 52-16 nm 之间，随着锌的掺入，晶格参数有所增加。同时还计算了 X 射线密度。结果发现，当锌浓度升高时，晶粒尺寸减小，位错密度升高，堆积因子降低。在不同的锌离子浓度下，Co1-xZnxFe2O4 铁氧体的容限因子（T）约为 1，表明铁氧体具有立方尖晶石结构。扫描电子显微镜（SEM）和能量色散光谱（EDAX）被用于合成样品的形态和元素组成研究。研究了随频率变化的介电常数、介电损耗和交流电导率。发现介电常数值处于高介电常数范围内，因此这些材料有望用于栅极电介质、电容器电介质和外延电介质等技术应用。紫外-可见光分析计算出的带隙能随锌离子浓度的增加而增加（2.95-4.33 eV）。通过改进的溶胶-凝胶法，可以很容易地制备出具有可调带隙和介电性能的锌取代钴铁氧体纳米粒子。在本研究中，钴铁氧体纳米粒子表现出明显的细胞毒性。磁滞（M-H）环研究表明所有样品都具有铁磁性。Co0.5Zn0.5Fe2O4 样品的最大饱和值 MS 为 73.72 emu/g。Co0.3Zn0.7Fe2O4 和 ZnFe2O4 纳米粒子的剩磁值和矫顽力场表明其具有超顺磁性。

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引用次数: 0

Silver nanoparticles functionalized calcite fibers derived from eggshell waste: a sustainable nanocomposite for microbial applications

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-10 DOI: 10.1007/s10971-025-06692-x

Shumaila Islam, Adil Alshoaibi, Nisrin Alnaim, Haifa M. Al Naim

Eggshells (ES) waste is produced in large quantities globally due to their rising consumption. The poor management of these wastes poses serious environmental risks and public health. Owing to antibacterial activity against Gram-positive bacterium Staphylococcus aureus (SA) and Methicillin-resistant Staphylococcus aureus (MRSA), eggshell (ES) derived calcite (CaCO₃) fibers (CFs) and silver nanoparticles (AgNPs) encapsulated CFs (ACFs) are synthesized by sol-gel method at 80 °C. The CFs and ACFs nanocomposite revealed a fiber-based porous structural network. The CFs and ACFs possessed a uniform distribution of Ca, Mg, C, O, and Ag. The CFs and ACFs nanocomposite revealed heterogeneous chemical bonding. The ACFs revealed thermal stability at ≤636 °C and crystallite size around 85 nm. For antimicrobial assessment, the ACF nanocomposite is found to be highly effective against SA and MRSA. The experimental finding suggested that low-temperature-based ACFs have the potential to inhibit a wide range of microbial pathogens.

Graphical Abstract

由于蛋壳消费量不断增加，全球产生了大量蛋壳（ES）废物。对这些废物的管理不善会对环境和公众健康造成严重危害。由于对革兰氏阳性菌金黄色葡萄球菌（SA）和耐甲氧西林金黄色葡萄球菌（MRSA）具有抗菌活性，在 80 °C 下采用溶胶-凝胶法合成了蛋壳（ES）衍生方解石（CaCO3）纤维（CFs）和银纳米颗粒（AgNPs）包裹的 CFs（ACFs）。CFs和ACFs纳米复合材料呈现出以纤维为基础的多孔结构网络。CFs和ACFs具有均匀的Ca、Mg、C、O和Ag分布。CFs 和 ACFs 纳米复合材料显示出异质化学键。ACFs 的热稳定性≤636 °C，结晶尺寸约为 85 nm。在抗菌评估中，发现 ACF 纳米复合材料对 SA 和 MRSA 非常有效。实验结果表明，低温基 ACF 具有抑制多种微生物病原体的潜力。

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引用次数: 0

Spectroscopic studies of molecules in sol-gel silica monoliths and thin films

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-07 DOI: 10.1007/s10971-025-06681-0

Jeffrey I. Zink

This article about sol-gel research in North America is focused on transparent sol-gel silica monoliths and nano-structured thin films containing encapsulated molecules. The research was a collaborative effort carried out at the University of California Los Angeles (UCLA). Our research was focused on two goals: using optical spectroscopy to understand the chemical and physical changes occurring during the sol to the xerogel transformation; and using spectroscopy to understand what was happening to the molecules themselves after encapsulation. The first section is a brief discussion of molecular probes used to monitor in real time the hydrolysis, condensation, gelation and drying of tetraethoxysilane (TEOS) formed in optical cuvettes. In the second section, we introduce dip coating of one hundred nanometer thin films and methods for measuring thickness and chemical changes in real time during film pulling. We include surfactant templated mesostructured films and real time observation of the structure development. Third, we design molecules to add to the initial sol such that they are placed in specific regions of the ordered structure of the templated film. We describe spectroscopic methods that prove their placement and use pairs of molecules for physical studies including intermolecular energy transfer. Finally, we describe “gentle” synthesis methods for encapsulating enzymes and other proteins that retain their optical and enzymatic properties. Spectroscopy provided quantitative information about the sol-gel processes, enzymatic activity, and optical sensor applications.

Graphical Abstract

The Graphical Abstract depicts an octagonal array of sol-gel silica monoliths containing enzymes. The largest monoliths have dimensions of approximately 5 × 5 × 15 mm. The original sol was placed in an optical cuvette and hydrolysis, condensation and slow, controlled drying in the cuvette produced the parallelepiped cuboid-shaped monoliths without cracking. The colors are caused by encapsulated metalloenzymes and the absorption spectra are the same as those of the enzymes in solution. In the center of the array is an artist’s depiction of an enzyme surrounded by the amorphous silica glass.

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引用次数: 0

Polyimide organic-inorganic hybrid composites with formed in situ inorganic nanophase: influence of host polyimide chemical structure on molecular dynamic and permeability

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology

Pub Date : 2025-02-06 DOI: 10.1007/s10971-025-06674-z

N. V. Kozak, T. A. Shantalii

To observe how changes in the structure of the host polymer affect the dynamic properties and permeability of polyimide matrices and nanocomposites the three series of hybrid organic-inorganic nanocomposites based on linear, branched or cardo polyimides and tetraethoxysilane (TEOS) were analyzed by EPR method using the stable nitroxyl radical 2,2,6,6,-tetramethylpiperidine-1-oxy (TEMPO) as a paramagnetic probe. The EPR data obtained were compared with the results of measuring the volume fraction of pores φ and dielectric permittivity ε as well as with X-ray structural analysis and optical microscopy. The introduction of an inorganic component in all cases led to a decrease in the segmental mobility of the linear and cardo polyimide-based composites as compared with the pure polyimide, due to partial immobilization of organic macrochains during the formation of inorganic microregions. For composites based on linear polyimide correlations are observed between the permeability values and the volume fraction of pores and the dielectric constant. EPR results agree with small angle X-ray scattering data that demonstrate formation of more heterogeneous structure of nanocomposites based on branched polyimide matrix as compared with linear one. According to optical microscopy the TEOS content, that allows obtaining most uniform distribution of inorganic inhomogeneities in the nanocomposites, depends on chemical structure of polyimide and is 40%, 50%, and 5% for linear, cardo and branched polyimides, respectively.

Graphical Abstract

为了观察主聚合物结构的变化如何影响聚酰亚胺基质和纳米复合材料的动态特性和渗透性，我们使用稳定的硝基自由基 2,2,6,6,-tetramethylpiperidine-1-oxy (TEMPO) 作为顺磁探针，通过 EPR 方法分析了基于线性、支链或 Cardo 聚酰亚胺和四乙氧基硅烷 (TEOS) 的三个系列的有机-无机杂化纳米复合材料。获得的 EPR 数据与测量孔隙体积分数 φ 和介电常数 ε 以及 X 射线结构分析和光学显微镜的结果进行了比较。与纯聚酰亚胺相比，在所有情况下引入无机成分都会导致线性聚酰亚胺基复合材料和硬质聚酰亚胺基复合材料的段流动性降低，这是由于在无机微区形成过程中有机大链被部分固定。对于基于线性聚酰亚胺的复合材料，可以观察到渗透率值与孔隙体积分数和介电常数之间的相关性。EPR 结果与小角 X 射线散射数据一致，表明与线性聚酰亚胺基体相比，基于支化聚酰亚胺基体的纳米复合材料形成了更多的异质结构。根据光学显微镜观察，TEOS 的含量取决于聚酰亚胺的化学结构，线性聚酰亚胺、硬质聚酰亚胺和支化聚酰亚胺的 TEOS 含量分别为 40%、50% 和 5%，而 TEOS 含量可使纳米复合材料中的无机不均匀性分布最为均匀。

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引用次数: 0