MICROPOROUS AND MESOPOROUS MATERIALS
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2021
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IF 5.455
Guanzheng Zhuang,Li Li,Mengyuan Li,Peng Yuan
Maya blue is an ancient hybrid pigment composed of indigo and microporous palygorskite , with a fantastic hue and outstanding stability. Its color-causing and stabilization mechanism are unsolved problems. In this work, different palygorskite materials were obtained by heating at 180, 300 and 570 °C, with raw palygorskite as a reference. Maya blue-like pigments were prepared from these palygorskite materials and solid indigo. The microporous structure of palygorskite and the status of inside water molecules were investigated by thermal analysis , X-ray diffraction, Fourier transform infrared and microporous analysis. The color properties, chemical resistance and photostability of pigments were characterized by reflectance spectra, CIE color parameters and color differences after the attack of concentrated nitric acid , dimethyl sulfoxide , and visible light exposure equaling to about 100 years. It was confirmed that the greenish-blue and stable hybrid pigment could only be prepared when indigo molecules were inserted into the micropores of palygorskite. Zeolitic water molecules inside the micropores should be removed because they hindered the insertion of indigo molecules. The key to immobilizing indigo molecules inside micropores was hydrogen bonds between indigo and coordinated water (C O … …H–OH). This study emphasized the important role of micropores and hydrogen bonds in the synthesis of organic-inorganic hybrid pigments.
研究领域:
材料科学
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化学
✓ 已验证
DOI
高影响因子
DYES AND PIGMENTS
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2022
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IF 5.122
Li Li,Guanzheng Zhuang,Mengyuan Li,Peng Yuan,Liangliang Deng,Haozhe Guo
Maya blue is a greenish-blue and stable pigment composed of indigo and palygorskite or sepiolite . Previous studies implied that the properties of Maya blue were influenced by different hydroxyl groups in the clay structure, e.g., zeolitic water, coordinated water, and structural hydroxyls. Therefore, an in-depth investigation was planned to analyze the structures and properties of indigo-sepiolite hybrid pigments in this work. Sepiolite materials were heated at 160, 360, 610, and 880 °C to remove zeolitic water, the first coordinated water, the second coordinated water, and structural hydroxyls. A series of Maya blue simulants were prepared by heating the mixture of indigo and sepiolite materials at 180 °C. Reflectance spectroscopy and CIE 1976 color space were employed to characterize color properties and color differences of hybrid pigments. Chemical resistance to concentrated HNO 3 and dimethyl sulfoxide (DMSO), and photostability under visible light were evaluated. Microporous analysis and Fourier transform infrared spectroscopy were applied to study the indigo-sepiolite interaction. Coordinated water was essential for the greenish-blue color and outstanding stability of Maya blue, while zeolitic water and structural hydroxyls did not affect pigments’ properties. Indigo molecules were confirmed to be inserted into sepiolite channels and formed hydrogen bonds with coordinated water at one side. Structural hydroxyls were insignificant for the formation of Maya blue. This work provides a guideline for preparing stable clay-dye hybrid pigments.
研究领域:
材料科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
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2025
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IF 4.7
Li Li,Qian Liu,Guanzheng Zhuang,Jixing Fan,Peng Yuan,Fei Xu
Thermal treatment is a key step in synthesizing Maya blue pigments. While palygorskite-based Maya blue has been extensively studied, the preparation of sepiolite-based pigments remains underexplored. This study synthesized sepiolite-based Maya blue by heating indigo-sepiolite mixtures at 100–500 °C for 1–72 h, systematically investigating the effects of temperature and duration on pigment color and stability. Mechanistic insights were provided using XRD, surface area and micropore analysis, HRTEM, and FTIR. The optimal preparation conditions were identified as 100–200 °C with heating durations under 8 h. Below 200 °C, increasing temperature and time enhanced the greenish-blue hue and improved chemical and photostability due to the conversion of indigo oligomers to monomers and their diffusion into sepiolite channels. No evidence of strong interactions, such as hydrogen bonding or coordination, was found between indigo and sepiolite. Indigo encapsulation within sepiolite's channels likely explains its stability, while the conversion of intermolecular to intramolecular hydrogen bonds accounts for its coloration. Above 300 °C, indigo degradation caused pigment darkening. HRTEM showed no significant structural changes in sepiolite after heating. Sepiolite's nanostructure, microporosity, and diverse surface groups make it ideal for clay-dye hybrid pigments. These findings advance the understanding and application of sepiolite-based organic-inorganic hybrid materials.
研究领域:
材料科学
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化学
✓ 已验证
产品关联
DOI
高影响因子
CLAYS AND CLAY MINERALS
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2025
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IF 2.1
Li Li,Guanzheng Zhuang,Yanfu Wei,Mohammad Fahimizadeh,Peng Yuan
Sepiolite is considered a suitable substrate for Maya blue pigment. However, the interaction between sepiolite and indigo dye has not been fully understood. Previous studies have demonstrated that pre-treatment of sepiolite by heating or acid was useful in identifying the sepiolite–indigo interaction. The purpose of the present study was to prepare a series of hybrid sepiolite–indigo pigments after modifying the sepiolite using various alkali treatments (NaOH), then to evaluate their properties with respect to color, chemical resistance, and photostability. Samples were characterized using reflectance spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy, and N2 adsorption-desorption. Under alkaline conditions, Si4+ and Mg2+ ions in sepiolite partially dissolved, disrupting the coordinated water associated with them. Mg2+ ions precipitated and blocked the structural channels of the sepiolite. The impact of the alkali treatment on the microporous structure and coordinated water of sepiolite significantly influenced the color properties and stability of the hybrid pigments. Proper alkaline treatment enhanced the greenish hue and chemical stability of the pigment, while severe treatments apparently compromised the structural integrity of the sepiolite, thus diminishing the quality of the hybrid pigment. Results from this study provide new insights into the color-causing and stabilizing mechanisms of sepiolite-based Maya blue pigment and also provide guidance for developing hybrid pigments based on clay minerals and organic dyes.
研究领域:
材料科学
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考古化学
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矿物学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
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2024
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IF 5.3
Jixing Fan,Qian Liu,Li,Li,Guanzheng Zhuang,Peng Yuan
Maya Blue, a hybrid pigment that can be synthesized by heating a mixture of palygorskite (or sepiolite) and indigo, has unclear relationships between the structural features of clay substrates, heating atmosphere, colors, and stability. This study investigates the color properties, stability, and clay-dye interactions of Maya Blue pigments based on palygorskite and sepiolite, heated under air and vacuum conditions (180 °C for 8 h). Reflectance spectra, CIE color parameters, surface properties, and Fourier-transform infrared spectroscopy were employed to evaluate these pigments. Results indicate that indigo monomers can penetrate the channels of both palygorskite and sepiolite, conferring a greenish-blue hue and high stability. However, the diffusion of indigo is determined by the size match between the channel and indigo monomers. In palygorskite, indigo monomers can diffuse only upon heating because the channel size is only a little bit larger than the indigo molecule, while in sepiolite, lager channels allow easy diffusion, even without heating. However, sepiolite's larger channels make indigo molecules more prone to chemical degradation or migration. Under vacuum conditions, indigo molecules more easily diffuse into the channels of both clay minerals, yielding pigments with higher saturation and enhanced stability. These findings highlight the size-matching between clay minerals' micropores and organic molecules and offer valuable guidance for optimizing the preparation process of clay-dye hybrid pigments.
研究领域:
材料科学
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化学
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考古学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）